Superstructure ZrV2O7 nanofibres: thermal expansion, electronic and lithium storage properties.

PubMed

Li, Qidong; Zhao, Yanming; Kuang, Quan; Fan, Qinghua; Dong, Youzhong; Liu, Xudong

2016-11-30

ZrV 2 O 7 has attracted much attention as a negative thermal expansion (NTE) material due to its isotropic negative structure. However, rarely has investigation of the lithium storage behaviors been carried out except our first report on it. Meanwhile, the electrochemical behaviors and energy storage characteristics have not been studied in depth and will be explored in this article. Herein, we report on the synthesis, characterization and lithium intercalation mechanism of superstructure ZrV 2 O 7 nanofibres that were prepared through a facile solution-based method with a subsequent annealing process. The thermal in situ XRD technique combined with the Rietveld refinement method is adopted to analyze the change in the temperature-dependent crystal structure. Benefiting from the nanostructured morphology and relatively high electronic conductivity, it presents acceptable cyclic stability and rate capability. According to the operando evolution of the XRD patterns obtained from electrochemical in situ measurements, the Li intercalation mechanism of the solid solution process with a subsequent conversion reaction can be concluded. Finally, the amorphous state of the electrodes after the initial fully discharged state can effectively enhance the electrochemical performances.

Light-directing omnidirectional circularly polarized reflection from liquid-crystal droplets.

PubMed

Fan, Jing; Li, Yannian; Bisoyi, Hari Krishna; Zola, Rafael S; Yang, Deng-Ke; Bunning, Timothy J; Weitz, David A; Li, Quan

2015-02-09

Constructing and tuning self-organized three-dimensional (3D) superstructures with tailored functionality is crucial in the nanofabrication of smart molecular devices. Herein we fabricate a self-organized, phototunable 3D photonic superstructure from monodisperse droplets of one-dimensional cholesteric liquid crystal (CLC) containing a photosensitive chiral molecular switch with high helical twisting power. The droplets are obtained by a glass capillary microfluidic technique by dispersing into PVA solution that facilitates planar anchoring of the liquid-crystal molecules at the droplet surface, as confirmed by the observation of normal incidence selective circular polarized reflection in all directions from the core of individual droplet. Photoirradiation of the droplets furnishes dynamic reflection colors without thermal relaxation, whose wavelength can be tuned reversibly by variation of the irradiation time. The results provided clear evidence on the phototunable reflection in all directions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Standard plans for timber bridge superstructures

Treesearch

James P. Wacker; Matthew S. Smith

2001-01-01

These standardized bridge plans are for superstructures consisting of treated timber. Seven superstructure types are includes: five longitudinal and two transverse deck systems. Both HS520 and HS25 loadings are included, along with L/360 and L/500 deflection criteria.

Integral ceramic superstructure evaluation using time domain optical coherence tomography

NASA Astrophysics Data System (ADS)

Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

2014-02-01

Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.

Joint Simultaneous Reconstruction of Regularized Building Superstructures from Low-Density LIDAR Data Using Icp

NASA Astrophysics Data System (ADS)

Wichmann, Andreas; Kada, Martin

2016-06-01

There are many applications for 3D city models, e.g., in visualizations, analysis, and simulations; each one requiring a certain level of detail to be effective. The overall trend goes towards including various kinds of anthropogenic and natural objects therein with ever increasing geometric and semantic details. A few years back, the featured 3D building models had only coarse roof geometry. But nowadays, they are expected to include detailed roof superstructures like dormers and chimneys. Several methods have been proposed for the automatic reconstruction of 3D building models from airborne based point clouds. However, they are usually unable to reliably recognize and reconstruct small roof superstructures as these objects are often represented by only few point measurements, especially in low-density point clouds. In this paper, we propose a recognition and reconstruction approach that overcomes this problem by identifying and simultaneously reconstructing regularized superstructures of similar shape. For this purpose, candidate areas for superstructures are detected by taking into account virtual sub-surface points that are assumed to lie on the main roof faces below the measured points. The areas with similar superstructures are detected, extracted, grouped together, and registered to one another with the Iterative Closest Point (ICP) algorithm. As an outcome, the joint point density of each detected group is increased, which helps to recognize the shape of the superstructure more reliably and in more detail. Finally, all instances of each group of superstructures are modeled at once and transformed back to their original position. Because superstructures are reconstructed in groups, symmetries, alignments, and regularities can be enforced in a straight-forward way. The validity of the approach is presented on a number of example buildings from the Vaihingen test data set.

11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH DOOR INTO WINCH ROOM IN THE SUPERSTRUCTURE (LABELED AT PASSAGE & HYDRAULIC MACHINERY ON PLAN). - U.S. Coast Guard Cutter WHITE HEATH, USGS Integrated Support Command Boston, 427 Commercial Street, Boston, Suffolk County, MA

Self-assembly of polyhedral metal-organic framework particles into three-dimensional ordered superstructures

NASA Astrophysics Data System (ADS)

Avci, Civan; Imaz, Inhar; Carné-Sánchez, Arnau; Pariente, Jose Angel; Tasios, Nikos; Pérez-Carvajal, Javier; Alonso, Maria Isabel; Blanco, Alvaro; Dijkstra, Marjolein; López, Cefe; Maspoch, Daniel

2018-01-01

Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals. Those superstructures feature a photonic bandgap that can be tuned by controlling the size of the ZIF-8 particles and is also responsive to the adsorption of guest substances in the micropores of the ZIF-8 particles. In addition, superstructures with different lattices can also be assembled by tuning the truncation of ZIF-8 particles, or by using octahedral UiO-66 MOF particles instead. These well-ordered, sub-micrometre-sized superstructures might ultimately facilitate the design of three-dimensional photonic materials for applications in sensing.

Control superstructure of rigid polyelectrolytes in oppositely charged hydrogels via programmed internal stress

NASA Astrophysics Data System (ADS)

Takahashi, Riku; Wu, Zi Liang; Arifuzzaman, Md; Nonoyama, Takayuki; Nakajima, Tasuku; Kurokawa, Takayuki; Gong, Jian Ping

2014-08-01

Biomacromolecules usually form complex superstructures in natural biotissues, such as different alignments of collagen fibres in articular cartilages, for multifunctionalities. Inspired by nature, there are efforts towards developing multiscale ordered structures in hydrogels (recognized as one of the best candidates of soft biotissues). However, creating complex superstructures in gels are hardly realized because of the absence of effective approaches to control the localized molecular orientation. Here we introduce a method to create various superstructures of rigid polyanions in polycationic hydrogels. The control of localized orientation of rigid molecules, which are sensitive to the internal stress field of the gel, is achieved by tuning the swelling mismatch between masked and unmasked regions of the photolithographic patterned gel. Furthermore, we develop a double network structure to toughen the hydrogels with programmed superstructures, which deform reversibly under large strain. This work presents a promising pathway to develop superstructures in hydrogels and should shed light on designing biomimetic materials with intricate molecular alignments.

46 CFR 108.133 - Hull superstructure, structural bulkheads, decks, and deckhouses.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Hull superstructure, structural bulkheads, decks, and deckhouses. 108.133 Section 108.133 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A... Protection § 108.133 Hull superstructure, structural bulkheads, decks, and deckhouses. Each hull...

77 FR 16172 - Application for Foreign Rebuilding Determination

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-20

... determinations and directs when vessels with coastwise trade endorsements whose hulls or superstructure are.... This company noted that the existing discretionary rebuild test of 7.5 to 10 percent of hull or... components of the hull or superstructure of a vessel. However, ``hull'' and ``superstructure'' remain defined...

46 CFR 108.133 - Hull superstructure, structural bulkheads, decks, and deckhouses.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Hull superstructure, structural bulkheads, decks, and deckhouses. 108.133 Section 108.133 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A... Protection § 108.133 Hull superstructure, structural bulkheads, decks, and deckhouses. Each hull...

46 CFR 108.133 - Hull superstructure, structural bulkheads, decks, and deckhouses.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Hull superstructure, structural bulkheads, decks, and deckhouses. 108.133 Section 108.133 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A... Protection § 108.133 Hull superstructure, structural bulkheads, decks, and deckhouses. Each hull...

46 CFR 45.109 - Strength of superstructures and deckhouses.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Strength of superstructures and deckhouses. 45.109... LOAD LINES Conditions of Assignment § 45.109 Strength of superstructures and deckhouses. Each... approved assigning authority with regard to general strength and weathertightness. The Commandant may use...

46 CFR 45.109 - Strength of superstructures and deckhouses.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Strength of superstructures and deckhouses. 45.109... LOAD LINES Conditions of Assignment § 45.109 Strength of superstructures and deckhouses. Each... approved assigning authority with regard to general strength and weathertightness. The Commandant may use...

Jointless bridges : final report.

DOT National Transportation Integrated Search

1981-01-01

The results of this study are reported in two parts. The first deals with the various methods states are employing to reduce the number of joints in bridge decks. The most common method is the use of integral abutments, where the superstructure is jo...

40 CFR 745.228 - Accreditation of training programs: public and commercial buildings, bridges and superstructures...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Accreditation of training programs: public and commercial buildings, bridges and superstructures. [Reserved] 745.228 Section 745.228... Accreditation of training programs: public and commercial buildings, bridges and superstructures. [Reserved] ...

46 CFR 67.177 - Application for foreign rebuilding determination.

Code of Federal Regulations, 2012 CFR

2012-10-01

... rebuilt when work performed on its hull or superstructure constitutes a quantum of work determined, to the... be considered rebuilt when work performed on its hull or superstructure constitutes a quantum of work... superstructure constitutes a quantum of work determined, to the maximum extent practicable, to be comparable to 7...

46 CFR 67.177 - Application for foreign rebuilding determination.

Code of Federal Regulations, 2011 CFR

2011-10-01

... rebuilt when work performed on its hull or superstructure constitutes a quantum of work determined, to the... be considered rebuilt when work performed on its hull or superstructure constitutes a quantum of work... superstructure constitutes a quantum of work determined, to the maximum extent practicable, to be comparable to 7...

46 CFR 67.177 - Application for foreign rebuilding determination.

Code of Federal Regulations, 2014 CFR

2014-10-01

... rebuilt when work performed on its hull or superstructure constitutes a quantum of work determined, to the... be considered rebuilt when work performed on its hull or superstructure constitutes a quantum of work... superstructure constitutes a quantum of work determined, to the maximum extent practicable, to be comparable to 7...

46 CFR 67.177 - Application for foreign rebuilding determination.

Code of Federal Regulations, 2013 CFR

2013-10-01

... rebuilt when work performed on its hull or superstructure constitutes a quantum of work determined, to the... be considered rebuilt when work performed on its hull or superstructure constitutes a quantum of work... superstructure constitutes a quantum of work determined, to the maximum extent practicable, to be comparable to 7...

46 CFR 45.58 - Correction: Short superstructure.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Correction: Short superstructure. 45.58 Section 45.58 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Freeboards § 45.58 Correction: Short superstructure. The minimum freeboard in summer for a type B vessel that...

46 CFR 45.58 - Correction: Short superstructure.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Correction: Short superstructure. 45.58 Section 45.58 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES GREAT LAKES LOAD LINES Freeboards § 45.58 Correction: Short superstructure. The minimum freeboard in summer for a type B vessel that...

46 CFR 67.177 - Application for foreign rebuilding determination.

Code of Federal Regulations, 2010 CFR

2010-10-01

... rebuilt when work performed on its hull or superstructure constitutes a quantum of work determined, to the... be considered rebuilt when work performed on its hull or superstructure constitutes a quantum of work... superstructure constitutes a quantum of work determined, to the maximum extent practicable, to be comparable to 7...

40 CFR 745.228 - Accreditation of training programs: public and commercial buildings, bridges and superstructures...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Accreditation of training programs: public and commercial buildings, bridges and superstructures. [Reserved] 745.228 Section 745.228... Accreditation of training programs: public and commercial buildings, bridges and superstructures. [Reserved] ...

Superstructure high efficiency photovoltaics

NASA Technical Reports Server (NTRS)

Wagner, M.; So, L. C.; Leburton, J. P.

1987-01-01

A novel class of photovoltaic cascade structures is introduced which features multijunction upper subcells. These superstructure high efficiency photovoltaics (SHEP's) exhibit enhanced upper subcell spectral response because of the additional junctions which serve to reduce bulk recombination losses by decreasing the mean collection distance for photogenerated minority carriers. Two possible electrical configurations were studied and compared: a three-terminal scheme that allows both subcells to be operated at their individual maximum power points and a two-terminal configuration with an intercell ohmic contact for series interconnection. The three-terminal devices were found to be superior both in terms of beginning-of-life expectancy and radiation tolerance. Realistic simulations of three-terminal AlGaAs/GaAs SHEP's show that one sun AMO efficiencies in excess of 26 percent are possible.

11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. BUOY DECK, NEAR PILOT HOUSE SUPERSTRUCTURE, LOOKING TOWARDS HATCH DOOR INTO WINCH ROOM IN THE SUPERSTRUCTURE (LABELED AS FASSAGE & HYDRAULIC MACHINERY ON PLAN), SHOWING UNDERSIDE OF GEARED WHEEL OF BOOM. - U.S. Coast Guard Cutter WHITE LUPINE, U.S. Coast Guard Station Rockland, east end of Tillson Avenue, Rockland, Knox County, ME

Glutaraldehyde-induced remineralization improves the mechanical properties and biostability of dentin collagen.

PubMed

Chen, Chaoqun; Mao, Caiyun; Sun, Jian; Chen, Yi; Wang, Wei; Pan, Haihua; Tang, Ruikang; Gu, Xinhua

2016-10-01

The purpose of this study was to induce a biomimetic remineralization process by using glutaraldehyde (GA) to reconstruct the mechanical properties and biostability of demineralized collagen. Demineralized dentin disks (35% phosphoric acid, 10s) were pretreated with a 5% GA solution for 3min and then cultivated in a calcium phosphate remineralization solution. The remineralization kinetics and superstructure of the remineralization layer were evaluated by Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and nanoindentation tests. The biostability was examined by enzymatic degradation experiments. A significant difference was found in dentin remineralization process between dentin with and without GA pretreating. GA showed a specific affinity to dentin collagen resulting in the formation of a cross-linking superstructure. GA pretreating could remarkably shorten remineralization time from 7days to 2days. The GA-induced remineralized collagen fibrils were well encapsulated by newly formed hydroxyapatite mineral nanocrystals. With the nano-hydroxyapatite coating, both the mechanical properties (elastic modulus and hardness) and the biostability against enzymatic degradation of the collagen were significantly enhanced, matching those of natural dentin. The results indicated that GA cross-linking of dentin collagen could promote dentin biomimetic remineralization, resulting in an improved mechanical properties and biostability. It may provide a promising tissue-engineering technology for dentin repair. Copyright © 2016 Elsevier B.V. All rights reserved.

Complex between triple helix of collagen and double helix of DNA in aqueous solution.

PubMed

Mrevlishvili, George M; Svintradze, David V

2005-06-01

We demonstrate in this paper that one example of a biologically important and molecular self-assembling complex system is a collagen-DNA ordered aggregate which spontaneously forms in aqueous solutions. Interaction between the collagen and the DNA leads to destruction of the hydration shell of the triple helix and stabilization of the double helix structure. From a molecular biology point of view this nano-scale self-assembling superstructure could increase the stability of DNA against the nucleases during collagen diseases and the growth of collagen fibrills in the presence of DNA.

Biomechanical factors associated with mandibular cantilevers: analysis with three-dimensional finite element models.

PubMed

Gonda, Tomoya; Yasuda, Daiisa; Ikebe, Kazunori; Maeda, Yoshinobu

2014-01-01

Although the risks of using a cantilever to treat missing teeth have been described, the mechanisms remain unclear. This study aimed to reveal these mechanisms from a biomechanical perspective. The effects of various implant sites, number of implants, and superstructural connections on stress distribution in the marginal bone were analyzed with three-dimensional finite element models based on mandibular computed tomography data. Forces from the masseter, temporalis, and internal pterygoid were applied as vectors. Two three-dimensional finite element models were created with the edentulous mandible showing severe and relatively modest residual ridge resorption. Cantilevers of the premolar and molar were simulated in the superstructures in the models. The following conditions were also included as factors in the models to investigate changes: poor bone quality, shortened dental arch, posterior occlusion, lateral occlusion, double force of the masseter, and short implant. Multiple linear regression analysis with a forced-entry method was performed with stress values as the objective variable and the factors as the explanatory variable. When bone mass was high, stress around the implant caused by differences in implantation sites was reduced. When bone mass was low, the presence of a cantilever was a possible risk factor. The stress around the implant increased significantly if bone quality was poor or if increased force (eg, bruxism) was applied. The addition of a cantilever to the superstructure increased stress around implants. When large muscle forces were applied to a superstructure with cantilevers or if bone quality was poor, stress around the implants increased.

Scalable One-pot Bacteria-templating Synthesis Route toward Hierarchical, Porous-Co3O4 Superstructures for Supercapacitor Electrodes

PubMed Central

Shim, Hyun-Woo; Lim, Ah-Hyeon; Kim, Jae-Chan; Jang, Eunjin; Seo, Seung-Deok; Lee, Gwang-Hee; Kim, T. Doohun; Kim, Dong-Wan

2013-01-01

Template-driven strategy has been widely used to synthesize inorganic nano/micro materials. Here, we used a bottom-up controlled synthesis route to develop a powerful solution-based method of fabricating three-dimensional (3D), hierarchical, porous-Co3O4 superstructures that exhibit the morphology of flower-like microspheres (hereafter, RT-Co3O4). The gram-scale RT-Co3O4 was facilely prepared using one-pot synthesis with bacterial templating at room temperature. Large-surface-area RT-Co3O4 also has a noticeable pseudocapacitive performance because of its high mass loading per area (~10 mg cm−2), indicating a high capacitance of 214 F g−1 (2.04 F cm−2) at 2 A g−1 (19.02 mA cm−2), a Coulombic efficiency averaging over 95%, and an excellent cycling stability that shows a capacitance retention of about 95% after 4,000 cycles. PMID:23900049

Recrystallization-induced self-assembly for the growth of Cu₂O superstructures.

PubMed

Shang, Yang; Shao, Yi-Ming; Zhang, Dong-Feng; Guo, Lin

2014-10-20

The assembly of inorganic nanoparticles (NPs) into 3D superstructures with defined morphologies is of particular interest. A novel strategy that is based on recrystallization-induced self-assembly (RISA) for the construction of 3D Cu2O superstructures and employs Cu2O mesoporous spheres with diameters of approximately 300 nm as the building blocks has now been developed. Balancing the hydrolysis and recrystallization rates of the CuCl precursors through precisely adjusting the experimental parameters was key to success. Furthermore, the geometry of the superstructures can be tuned to obtain either cubes or tetrahedra and was shown to be dependent on the growth behavior of bulk CuCl. The overall strategy extends the applicability of recrystallization-based processes for the guided construction of assemblies and offers unique insights for assembling larger particles into complicated 3D superstructures. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single crystalline silicene consist of various superstructures using a flexible ultrathin Ag(111) template on Si(111)

NASA Astrophysics Data System (ADS)

Hsu, Hung-Chang; Lu, Yi-Hung; Su, Tai-Lung; Lin, Wen-Chin; Fu, Tsu-Yi

2018-07-01

Using scanning tunneling microscopy, we studied the formation of silicene on an ultrathin Ag(111) film with a thickness of 6–12 monolayers, which was prepared on a Si(111) substrate. A low-energy electron diffraction pattern with an oval spot indicated that the ultrathin Ag(111) film is more disordered than the single-crystal Ag(111). After Si epitaxy growth, we still measured the classical 4 × 4, √13 × √13, and 2√3 × 2√3 silicene superstructures, which are the same as the silicene superstructure on single-crystal Ag(111). Growing silicene on a single-crystal Ag(111) bulk usually results in the formation of a defect boundary due to the inconsistent orientation of various superstructures. By comparing the angles and boundary conditions between various silicene superstructures on the ultrathin film and single-crystal Ag(111), we discovered that a consistent orientation of various superstructures without obvious boundary defects formed on the ultrathin Ag(111) film. The results indicated single crystalline silicene formation, which was attributed to the domain rotation and lateral shift of the disordered ultrathin Ag(111) film.

Superstructures at Te/Au(111) interface evolving upon increasing Te coverage

NASA Astrophysics Data System (ADS)

Guan, Jiaqi; Huang, Xiaochun; Xu, Xiaofeng; Zhang, Shuyuan; Jia, Xun; Zhu, Xuetao; Wang, Weihua; Guo, Jiandong

2018-03-01

By in-situ low temperature scanning tunneling microscopy, we systematically investigated the superstructure evolution at Te/Au(111) interface upon increasing Te coverage. Te atoms form one-dimensional √{ 3} R30∘ chains at ∼0.10 monolayer (ML) coverage. Two two-dimensional chiral superstructures, (√{ 111} ×√{ 111}) R 4 .7∘ and (3√{ 21} × 3√{ 21}) R 10 .9∘ , are selectively formed with the Te coverage below and above 1/3 ML, respectively. The two chiral superstructures can be converted to each other reversibly by adding Te atoms or moderately annealing. A honeycomb-like superstructure, decorated with adatoms that are distributed in quasi-one-dimensional chains, is observed by further increasing the Te coverage to 4/9 ML. At the Te/Au(111) interface, an interfacial state at -0.65 eV to -0.55 eV below the Fermi level is also resolved by scanning tunneling spectroscopy. The formation of these Te-induced high-order superstructures is accompanied by relaxation of gold atoms in the surface layer, indicating a strong Te-Au interaction. Our work demonstrates a reliable method to fabricate Te nanostructures on noble metals in a controlled way.

Characteristics of Latrines in Central Tanzania and Their Relation to Fly Catches

PubMed Central

Irish, Seth; Aiemjoy, Kristen; Torondel, Belen; Abdelahi, Faraji; Ensink, Jeroen H. J.

2013-01-01

The disposal of human excreta in latrines is an important step in reducing the transmission of diarrhoeal diseases. However, in latrines, flies can access the latrine contents and serve as a mechanical transmitter of diarrhoeal pathogens. Furthermore, the latrine contents can be used as a breeding site for flies, which may further contribute to disease transmission. Latrines do not all produce flies, and there are some which produce only a few, while others can produce thousands. In order to understand the role of the latrine in determining this productivity, a pilot study was conducted, in which fifty latrines were observed in and around Ifakara, Tanzania. The characteristics of the latrine superstructure, use of the latrine, and chemical characteristics of pit latrine contents were compared to the numbers of flies collected in an exit trap placed over the drop hole in the latrine. Absence of a roof was found to have a significant positive association (t=3.17, p=0.003) with the total number of flies collected, and temporary superstructures, particularly as opposed to brick superstructures (z=4.26, p<0.001), and increased total solids in pit latrines (z=2.57, p=0.01) were significantly associated with increased numbers of blowflies leaving the latrine. The number of larvae per gram was significantly associated with the village from which samples were taken, with the largest difference between two villages outside Ifakara (z=2.12, p=0.03). The effect of latrine superstructure (roof, walls) on fly production may indicate that improvements in latrine construction could result in decreases in fly populations in areas where they transmit diarrhoeal pathogens. PMID:23874475

Study on superstructure in ion co-doped BiFeO3 by using transmission electron microscopy

NASA Astrophysics Data System (ADS)

Pu, Shi-Zhou; Guo, Chao; Li, Mei-Ya; Chen, Zhen-Lian; Zou, Hua-Min

2015-04-01

La3+ and V5+ co-doped BiFeO3 ceramics are synthesized by rapid liquid sintering technique. The modulated structure in Bi0.85La0.15Fe0.97V0.03O3 is investigated by using transmission electron microscopy (TEM). Two kinds of superstructures are observed in the samples. One is the component modulated superstructure and twin-domain, which is generated by La3+ ordered substitution for Bi3+ and frequently appears. The chemical composition of the superstructure is explored by x-ray energy dispersive spectroscopy (EDS). The model of the ordered structure is proposed. Simulation based on the model is conducted. The second is the fluorite-type δ-Bi2O3 related superstructure. The relation between the ferroelectric property and the microstructure of the sample is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51372174, 11074193, and 51132001) and the Fundamental Research Funds for the Central Universities.

Reversible near-infrared light directed reflection in a self-organized helical superstructure loaded with upconversion nanoparticles.

PubMed

Wang, Ling; Dong, Hao; Li, Yannian; Xue, Chenming; Sun, Ling-Dong; Yan, Chun-Hua; Li, Quan

2014-03-26

Adding external, dynamic control to self-organized superstructures with desired functionalities is an important leap necessary in leveraging the fascinating molecular systems for applications. Here, the new light-driven chiral molecular switch and upconversion nanoparticles, doped in a liquid crystal media, were able to self-organize into an optically tunable helical superstructure. The resulting nanoparticle impregnated helical superstructure was found to exhibit unprecedented reversible near-infrared (NIR) light-guided tunable behavior only by modulating the excitation power density of a continuous-wave NIR laser (980 nm). Upon irradiation by the NIR laser at the high power density, the reflection wavelength of the photonic superstructure red-shifted, whereas its reverse process occurred upon irradiation by the same laser but with the lower power density. Furthermore, reversible dynamic NIR-light-driven red, green, and blue reflections in a single thin film, achieved only by varying the power density of the NIR light, were for the first time demonstrated.

Electronic and Structural Studies of Intercalated Graphite and Buckminsterfullerene.

NASA Astrophysics Data System (ADS)

Kelty, Stephen Paul

Under the direction of Prof. C. M. Lieber, the surface electronic and structural properties of binary MC_{rm x} and ternary rm MM^' C_{x } donor graphite intercalation compounds (GICs) were investigated using scanning tunneling microscopy (STM) and other surface sensitive techniques. The STM images revealed previously unobserved superstructures in the local density of states contours. These new superstructures include a commensurate 4.9 A periodicity (MC_8, where M = Li, K, Rb, Cs, KHg, rm K_2Hg_2 and rm K_2Tl _3). This superstructure has been interpreted as a modulation of the surface density of states due to the underlying commensurate intercalate lattice. Other GICs exhibit longer wavelength incommensurate superstructures, including: 19 A rm (KH_{0.8}C _8), 12 A rm (KH_{0.8 }C_4), 8.9 A rm (KHgC _4) and 7.5 A rm (KTl_ {1.5}C_8) periodicities. The direct -space wavelength of these incommensurate superstructures was found to scale inversely with the amount of charge transferred from the intercalate to the graphite layers. Such a correlation is consistent with the wavelength dependence on Fermi surface expansion of a charge density wave (CDW) state. STM investigations of adsorbed films of colloidal BiI_3, prepared by a solution-phase method, revealed the presence of mono-disperse 10-50 A single-layer particles with atomic resolution. This investigation demonstrated both the validity of the preparative method for the BiI_3 particles and the capability of the STM to atomically resolve small semiconducting particles. The structural and superconducting properties of alkali metal intercalated Buckminsterfullerene (C _{60}) were also investigated. A new preparatory method was developed using heavy metal alloys instead of pure alkali metal. Using these alloys, it was discovered that high superconducting fraction intercalation compounds could be prepared under milder conditions than by using the pure alkali metal. In addition, intercalation of Hg, Tl and Bi alloys of Cs was found to form a superconducting phase which has never been prepared by direct intercalation of Cs metal. Finally, other investigators have empirically derived a linear dependence of T_{ rm c} on lattice constant for intercalated C_{60}. This dependence has been used to model the electron pairing mechanism for the superconducting state. Investigations presented herein indicate that for lattice constants greater than 14.5 A, no further increases in T_{rm c} are observed. This finding places constraints on the above mentioned electron pairing models.

Isometric Scaling in Developing Long Bones Is Achieved by an Optimal Epiphyseal Growth Balance

PubMed Central

Stern, Tomer; Aviram, Rona; Rot, Chagai; Galili, Tal; Sharir, Amnon; Kalish Achrai, Noga; Keller, Yosi; Shahar, Ron; Zelzer, Elazar

2015-01-01

One of the major challenges that developing organs face is scaling, that is, the adjustment of physical proportions during the massive increase in size. Although organ scaling is fundamental for development and function, little is known about the mechanisms that regulate it. Bone superstructures are projections that typically serve for tendon and ligament insertion or articulation and, therefore, their position along the bone is crucial for musculoskeletal functionality. As bones are rigid structures that elongate only from their ends, it is unclear how superstructure positions are regulated during growth to end up in the right locations. Here, we document the process of longitudinal scaling in developing mouse long bones and uncover the mechanism that regulates it. To that end, we performed a computational analysis of hundreds of three-dimensional micro-CT images, using a newly developed method for recovering the morphogenetic sequence of developing bones. Strikingly, analysis revealed that the relative position of all superstructures along the bone is highly preserved during more than a 5-fold increase in length, indicating isometric scaling. It has been suggested that during development, bone superstructures are continuously reconstructed and relocated along the shaft, a process known as drift. Surprisingly, our results showed that most superstructures did not drift at all. Instead, we identified a novel mechanism for bone scaling, whereby each bone exhibits a specific and unique balance between proximal and distal growth rates, which accurately maintains the relative position of its superstructures. Moreover, we show mathematically that this mechanism minimizes the cumulative drift of all superstructures, thereby optimizing the scaling process. Our study reveals a general mechanism for the scaling of developing bones. More broadly, these findings suggest an evolutionary mechanism that facilitates variability in bone morphology by controlling the activity of individual epiphyseal plates. PMID:26241802

Hybrid framework with cobalt-chromium alloy and gold cylinder for implant superstructure: Bond strength and corrosion resistance.

PubMed

Yoshinari, Masao; Uzawa, Shinobu; Komiyama, Yataro

2016-10-01

The aim of this in vitro study was to evaluate tensile bond strengths and corrosion resistance of CoCr alloys joined with gold cylinder by a soldering system in comparison with the conventional cast-joining system. CoCr alloys joined with gold cylinder by a soldering system using a high-fusing gold solder (CoCr/Solder/Gold cylinder), gold alloy joined with gold cylinder by a cast joining system (Gold alloy/Gold cylinder) and CoCr castings were fabricated. The tensile bond strength and corrosion resistance in 0.9% NaCl solution (pH 7.4 and pH 2.3) were evaluated. Scanning electron microscopy (SEM) of the fractured surface and electron probe microanalysis (EPMA) of the joined interfaces were also performed. The tensile bond strengths of the CoCr/Solder/Gold cylinder specimens showed similar values as the Gold alloy/Gold cylinder specimens. SEM observation and EPMA analyses suggested firm bonding between the CoCr alloy and gold cylinder. The released elements from the CoCr/Solder/Gold cylinder specimens were similar to ones from CoCr castings. Results showed that superstructures made of CoCr alloys joined with the gold cylinder using a high-fusing gold solder had sufficient bond strength and high corrosion resistance. These hybrid frameworks with cobalt-chromium alloy and gold cylinder are promising prosthesis for implant superstructures with the low cost and favorable mechanical properties instead of conventional high-gold alloys. Copyright © 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Boron environments in Pyrex® glass--a high resolution, Double-Rotation NMR and thermodynamic modelling study.

PubMed

Howes, A P; Vedishcheva, N M; Samoson, A; Hanna, J V; Smith, M E; Holland, D; Dupree, R

2011-07-07

It is shown, using the important technological glass Pyrex® as an example, that 1D and 2D (11)B Double-Rotation (DOR) NMR experiments, in combination with thermodynamic modelling, are able to provide unique structural information about complex glasses. (11)B DOR NMR has been applied to Pyrex® glass in order to remove both dipolar and quadrupolar broadening of the NMR lines, leading to high resolution spectra that allow unambiguous, accurate peak fitting to be carried out, of particular importance in the case of the 3-coordinated [BO(3)] (B3) trigonal planar environments. The data obtained are of sufficient quality that they can be used to test the distributions of borate and borosilicate superstructural units predicted by the thermodynamics-based Model of Associated Solutions. The model predicts the dominant boron-containing chemical groupings in Pyrex® glass to be those associated with B(2)O(3) and sodium tetraborate (with smaller amounts of sodium triborate, sodium diborate, sodium pentaborate, danburite and reedmergnerite). Excellent agreement is found between model and experiment provided the (11)B peaks with isotropic chemical shifts of -1.4 ppm and 0.5 ppm are assigned to B4 species from borosilicate units ([B(OSi)(4)] and [B(OSi)(3)(OB)]) and borate superstructural units (mainly triborate rings with some pentaborate and diborate) respectively. The peaks with isotropic shifts of 14 ppm and 18.1 ppm are then assigned to B3 in borate superstructural units (mainly triborate and pentaborate along with connecting B3) and boroxol rings respectively. The assignments of the DOR NMR peaks, are supported by the presence of cross-peaks in (11)B spin-diffusion DOR NMR spectra which can be used to develop a structural model in which B(2)O(3)-like regions are linked, via borate and borosilicate superstructural units, to the majority silica network. Pyrex® is thus shown to have a heterogeneous structure, with distinct molecular groupings that are far removed from a random distribution of network polyhedra with only short-range order. This journal is © the Owner Societies 2011

Mythical systems: mathematic and logical theory

NASA Astrophysics Data System (ADS)

Nescolarde-Selva, J.; Usó-Doménech, J. L.; Lloret-Climent, M.

2015-01-01

The process of elaboration of the symbolic universe leads to exciting insights regarding the search for human emotional security. The symbols end up as explanatory axes of universal reality and on them are constructed myths that form a superstructure for belief systems. Human society is a multi-level system with a material structure (society), an ideological superstructure (belief systems, values, etc.) and a super superstructure with two parts: mythical (origin and justification) and utopic (final goal). All mythical belief systems have a numinous-religious nature.

22. Top 30/5. Plan of superstructure elevations. Wyoming Valley ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Top 30/5. Plan of superstructure elevations. - Wyoming Valley Flood Control System, Woodward Pumping Station, East of Toby Creek crossing by Erie-Lackawanna Railroad, Edwardsville, Luzerne County, PA

23. Top 30/6. Plan of superstructure sections. Wyoming Valley ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. Top 30/6. Plan of superstructure sections. - Wyoming Valley Flood Control System, Woodward Pumping Station, East of Toby Creek crossing by Erie-Lackawanna Railroad, Edwardsville, Luzerne County, PA

24. Top 30/7. Plan of superstructure details. Wyoming Valley ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. Top 30/7. Plan of superstructure details. - Wyoming Valley Flood Control System, Woodward Pumping Station, East of Toby Creek crossing by Erie-Lackawanna Railroad, Edwardsville, Luzerne County, PA

Interplay between intercalated oxygen superstructures and monolayer h -BN on Cu(100)

DOE PAGES

Ma, Chuanxu; Park, Jewook; Liu, Lei; ...

2016-08-18

The confinement effect of intercalated atoms in van der Waals heterostructures can lead to interesting interactions between the confined atoms or molecules and the overlaying two-dimensional (2D) materials. In this paper, we report the formation of ordered Cu(100) p(2×2) oxygen superstructures by oxygen intercalation under the monolayer hexagonal boron nitride (h-BN) on Cu after annealing. By using scanning tunneling microscopy and x-ray photoelectron spectroscopy, we identify the superstructure and reveal its roles in passivating the exposed Cu surfaces, decoupling h-BN and Cu, and disintegrating h-BN monolayers. The oxygen superstructure appears as a 2D pattern on the exposed Cu surface ormore » quasi-1D stripes of paired oxygen intercalated in the interface of h-BN and Cu predominantly oriented along the moiré modulations. The oxygen superstructure is shown to etch the overlaying h-BN monolayer in a thermal annealing process. After extended annealing, the h-BN monolayer disintegrates into nanoislands with zigzag edges. Finally, we discuss the implications of these findings on the stability and oxidation resistance of h-BN and relate them to challenges in process integration and 2D heterostructures.« less

A superstructure-based electrochemical assay for signal-amplified detection of DNA methyltransferase activity.

PubMed

Zhang, Hui; Yang, Yin; Dong, Huilei; Cai, Chenxin

2016-12-15

DNA methyltransferase (MTase) activity is highly correlated with the occurrence and development of cancer. This work reports a superstructure-based electrochemical assay for signal-amplified detection of DNA MTase activity using M.SssI as an example. First, low-density coverage of DNA duplexes on the surface of the gold electrode was achieved by immobilized mercaptohexanol, followed by immobilization of DNA duplexes. The duplex can be cleaved by BstUI endonuclease in the absence of DNA superstructures. However, the cleavage is blocked after the DNA is methylated by M.SssI. The DNA superstructures are formed with the addition of helper DNA. By using an electroactive complex, RuHex, which can bind to DNA double strands, the activity of M.SssI can be quantitatively detected by differential pulse voltammetry. Due to the high site-specific cleavage by BstUI and signal amplification by the DNA superstructure, the biosensor can achieve ultrasensitive detection of DNA MTase activity down to 0.025U/mL. The method can be used for evaluation and screening of the inhibitors of MTase, and thus has potential in the discovery of methylation-related anticancer drugs. Copyright © 2016 Elsevier B.V. All rights reserved.

5. EAST SIDE, TEST STAND AND ITS SUPERSTRUCTURE. Edwards ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. EAST SIDE, TEST STAND AND ITS SUPERSTRUCTURE. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

8. SOUTH REAR, SUPERSTRUCTURE. Looking north from deck. Edwards ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. SOUTH REAR, SUPERSTRUCTURE. Looking north from deck. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

LGSOWG CCT format CCB document: The standard CCT family of tape formats

NASA Technical Reports Server (NTRS)

1979-01-01

The tape format standardization approach recommended by the committee on CCT standardization is described and defined. All rules and conventions required to employ the superstructure approach to the CCT family of tape formats are presented for users of remote sensing data and producer of user tapes and the superstructure records are specified. The standard for future tape format design is presented as a guide to designing data records of a particular tape format. An example is provided showing how to incorporate the superstructure into an already established tape format.

Superstructure for high current applications in superconducting linear accelerators

DOEpatents

Sekutowicz, Jacek [Elbchaussee, DE; Kneisel, Peter [Williamsburg, VA

2008-03-18

A superstructure for accelerating charged particles at relativistic speeds. The superstructure consists of two weakly coupled multi-cell subunits equipped with HOM couplers. A beam pipe connects the subunits and an HOM damper is included at the entrance and the exit of each of the subunits. A coupling device feeds rf power into the subunits. The subunits are constructed of niobium and maintained at cryogenic temperatures. The length of the beam pipe between the subunits is selected to provide synchronism between particles and rf fields in both subunits.

Magneto-electronic coupling in modulated defect-structures of natural Fe{sub 1−x}S

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

Charilaou, M., E-mail: charilaou@mat.ethz.ch; Löffler, J. F.; Kind, J.

2015-08-28

We provide compelling experimental evidence that the low-temperature transition in natural non-stoichiometric Fe{sub 7}S{sub 8}, a major magnetic remanence carrier in the Earth's crust and in extraterrestrial materials, is a phenomenon caused by magnetic coupling between epitaxially intergrown superstructures. The two superstructures differ in their defect distribution, and consequently in their magnetic anisotropy. At T < 30 K, the magnetic moments of the superstructures become strongly coupled, resulting in a 12-fold anisotropy symmetry, which is reflected in the anisotropic magneto-resistance.

A Nonconventional Approach to Patterned Nanoarrays of DNA Strands for Template-Assisted Assembly of Polyfluorene Nanowires.

PubMed

Bae, Dong Geun; Jeong, Ji-Eun; Kang, Seok Hee; Byun, Myunghwan; Han, Dong-Wook; Lin, Zhiqun; Woo, Han Young; Hong, Suck Won

2016-08-01

DNA molecules have been widely recognized as promising building blocks for constructing functional nanostructures with two main features, that is, self-assembly and rich chemical functionality. The intrinsic feature size of DNA makes it attractive for creating versatile nanostructures. Moreover, the ease of access to tune the surface of DNA by chemical functionalization offers numerous opportunities for many applications. Herein, a simple yet robust strategy is developed to yield the self-assembly of DNA by exploiting controlled evaporative assembly of DNA solution in a unique confined geometry. Intriguingly, depending on the concentration of DNA solution, highly aligned nanostructured fibrillar-like arrays and well-positioned concentric ring-like superstructures composed of DNAs are formed. Subsequently, the ring-like negatively charged DNA superstructures are employed as template to produce conductive organic nanowires on a silicon substrate by complexing with a positively charged conjugated polyelectrolyte poly[9,9-bis(6'-N,N,N-trimethylammoniumhexyl)fluorene dibromide] (PF2) through the strong electrostatic interaction. Finally, a monolithic integration of aligned arrays of DNA-templated PF2 nanowires to yield two DNA/PF2-based devices is demonstrated. It is envisioned that this strategy can be readily extended to pattern other biomolecules and may render a broad range of potential applications from the nucleotide sequence and hybridization as recognition events to transducing elements in chemical sensors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Offshore platform structure intended to be installed in arctic waters, subjected to drifting icebergs

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

Kure, G.; Jenssen, D.N.; Naesje, K.

1984-09-11

An offshore platform structure, particularly intended to be installed in waters where drifting iceberg frequently appear, the platform structure being intended to be founded in a sea bed and comprises a substructure, a superstructure rigidly affixed to the substructure and extending vertically up above the sea level supporting a deck superstructure at its upper end. The horizontal cross-sectional area of the substructure is substantially greater than tath of the superstructure. The substructure rigidly supports a fender structure, the fender structure comprising an outer peripherally arranged wall and an inner cylindrical wall the inner and outer wall being rigidly interconnected bymore » means of a plurality of vertical and/or horizontal partition walls, dividing the fender structure into a plurality of cells or compartlents. The fender structure is arranged in spaced relation with respect to the superstructure.« less

Turbulent Superstructures in Rayleigh-Bénard convection at different Prandtl number

NASA Astrophysics Data System (ADS)

Schumacher, Jörg; Pandey, Ambrish; Ender, Martin; Westermann, Rüdiger; Scheel, Janet D.

2017-11-01

Large-scale patterns of the temperature and velocity field in horizontally extended cells can be considered as turbulent superstructures in Rayleigh-Bénard convection (RBC). These structures are obtained once the turbulent fluctuations are removed by a finite-time average. Their existence has been reported for example in Bailon-Cuba et al.. This large-scale order obeys a strong similarity with the well-studied patterns from the weakly nonlinear regime at lower Rayleigh number in RBC. In the present work we analyze the superstructures of RBC at different Prandtl number for Prandtl values between Pr = 0.005 for liquid sodium and 7 for water. The characteristic evolution time scales, the typical spatial extension of the rolls and the properties of the defects of the resulting superstructure patterns are analyzed. Data are obtained from well-resolved spectral element direct numerical simulations. The work is supported by the Priority Programme SPP 1881 of the Deutsche Forschungsgemeinschaft.

Effect of halo-vest components on stabilizing the injured cervical spine.

PubMed

Ivancic, Paul C; Beauchman, Naseem N; Tweardy, Lisa

2009-01-15

An in vitro biomechanical study. The objectives were to develop a new biofidelic skull-neck-thorax model capable of quantifying motion patterns of the cervical spine in the presence of a halo-vest; to investigate the effects of vest loosening, superstructure loosening, and removal of the posterior uprights; and to evaluate the ability of the halo-vest to stabilize the neck within physiological motion limits. Previous clinical and biomechanical studies have investigated neck motion with the halo-vest only in the sagittal plane or only at the injured spinal level. No previous studies have quantified three-dimensional intervertebral motion patterns throughout the injured cervical spine stabilized with the halo-vest or studied the effect of halo-vest components on these motions. The halo-vest was applied to the skull-neck-thorax model. Six osteoligamentous whole cervical spine specimens (occiput through T1 vertebra) were used that had sustained multiplanar ligamentous injuries at C3/4 through C7-T1 during a previous protocol. Flexibility tests were performed with normal halo-vest application, loose vest, loose superstructure, and following removal of the posterior uprights. Average total range of motion for each experimental condition was statistically compared (P < 0.05) with the physiologic rotation limit for each spinal level. Cervical spine snaking was observed in both the sagittal and frontal planes. The halo-vest, applied normally, generally limited average spinal motions to within average physiological limits. No significant increases in average spinal motions above physiologic were observed due to loose vest, loose superstructure, or removal of the posterior uprights. However, a trend toward increased motion at C6/7 in lateral bending was observed due to loose superstructure. The halo-vest, applied normally, effectively immobilized the cervical spine. Sagittal or frontal plane snaking of the cervical spine due to the halo-vest may reduce its immobilization capability at the upper cervical spine and cervicothoracic junction.

Construction of prestressed concrete single-tee bridge superstructures.

DOT National Transportation Integrated Search

1977-01-01

This report discusses in detail the construction of the first five precast, prestressed concrete, single-tee beam bridge superstructures to be let to contract in Virginia. The data suggest that this single-tee beam enables efficient construction of t...

Large-scale laboratory observations of wave forces on a highway bridge superstructure.

DOT National Transportation Integrated Search

2011-10-01

The experimental setup and data are presented for a laboratory experiment conducted to examine realistic wave forcing on a highway bridge : superstructure. The experiments measure wave conditions along with the resulting forces, pressures, and struct...

An industrialized construction approach to concrete superstructures for bridges.

DOT National Transportation Integrated Search

1974-01-01

The objective of this study was to develop drawings for a specific site or sites that incorporated the best concepts of industrialized bridge superstructure construction, that is, great emphasis was placed upon the use of modular design and assembly ...

Exploratory study of partial isolation of highway bridges.

DOT National Transportation Integrated Search

2011-01-01

A special class of seismically isolated bridges shares a common feature in that both ends of the superstructure are restrained and isolators over the columns of bridge uncouple the superstructure from the ground motions. They are defined as partial i...

Hierarchically Superstructured Prussian Blue Analogues: Spontaneous Assembly Synthesis and Applications as Pseudocapacitive Materials

DOE PAGES

Yue, Yanfeng; Zhang, Zhiyong; Binder, Andrew J.; ...

2014-11-10

Hierarchically superstructured Prussian blue analogues (hexa- conventional hybrid graphene/MnO 2 nanostructured textiles. cyanoferrate, M = Ni II, Co II and Cu II) are synthesized through Because sodium or potassium ions are involved in energy stor- a spontaneous assembly technique. In sharp contrast to mac- age processes, more environmentally neutral electrolytes can roporous-only Prussian blue analogues, the hierarchically su- be utilized, making the superstructured porous Prussian blue perstructured porous Prussian blue materials are demonstrated analogues a great contender for applications as high-per- to possess a high capacitance, which is similar to those of the formance pseudocapacitors.

Surface Superstructure of Carbon Nanotubes on Highly Oriented Pyrolytic Graphite Annealed at Elevated Temperatures

NASA Astrophysics Data System (ADS)

An, Bai; Fukuyama, Seiji; Yokogawa, Kiyoshi; Yoshimura, Masamichi

1998-06-01

Carbon nanotubes deposited on highly oriented pyrolytic graphite (HOPG) are annealed in ultra high vacuum. The effect of annealing temperature on the surface morphology of the carbon nanotubes on HOPG is examined by scanning tunneling microscopy. The ring-like surface superstructure of (\\sqrt {3}× \\sqrt {3})R30° of graphite is found on the carbon nanotubes annealed above 1593 K. The tips of the carbon nanotubes are destroyed and the stacking misarrangement between the upper and the lower walls of the tube join with HOPG resulting in the superstructure.

More Phases in the Affleck-Marston Mean Field Theory

NASA Astrophysics Data System (ADS)

Voo, Khee-Kyun; Mou, Chung-Yu

2003-03-01

The Affleck-Marston (AM) mean field theory is re-examined with emphasis on the possibility of inhomogeneous solutions. It is found that phases with superstructures upon the fundamental order Peierls and flux (such as topological stripes) may be developed at finite hole-dopings, and glassy phases dominate over the small hopping regime. These phases have an universal feature of always gapped Fermi level and may be related to the pseudogap observed in experiments, hence revealing a more intimate relationship between the theory and the high-Tc cuprates.

Construction of high-rise buildings in the Far East of Russia

NASA Astrophysics Data System (ADS)

Kudryavtsev, Sergey; Bugunov, Semen; Pogulyaeva, Evgeniya; Peters, Anastasiya; Kotenko, Zhanna; Grigor'yev, Danil

2018-03-01

The construction of high-rise buildings on plate foundation in geotechnical conditions of the Russian Far East is a complicated problem. In this respect foundation engineering becomes rather essential. In order to set a firm foundation it is necessary to take into account the pressure distribution at the structure base, in homogeneity of building deformation, which is due to collaborative geotechnical calculations complicated by a number of factors: actual over-placement of soils, the complex geometry of the building under construction, spatial work of the foundation ground with consideration for physical nonlinearity, the influence of the stiffness of the superstructure (reinforced concrete framing) upon the development of foundation deformations, foundation performance (the performance of the bed plate under the building and stairwells), the origination of internal forces in the superstructure with differential settlement. The solution of spatial problems regarding the mutual interaction between buildings and foundations with account of the factors mentioned above is fully achievable via the application of numerical modeling methodology. The work makes a review of the results of high-rise plate building numerical modeling in geotechnical conditions of the Russian Far East by way of the example of Khabarovsk city.

Hybrid FRP-concrete bridge deck system final report I : development and system performance validation.

DOT National Transportation Integrated Search

2009-10-01

In this study, the concept of the hybrid FRP-concrete structural systems was applied to both bridge : superstructure and deck systems. Results from the both experimental and computational analysis for : both the hybrid bridge superstructure and deck ...

18. CROWS NEST ATOP SUPERSTRUCTURE. Looking up from northeast corner ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. CROWS NEST ATOP SUPERSTRUCTURE. Looking up from northeast corner of run line deck. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

19. TRAVELING CRANE ATOP SUPERSTRUCTURE, FROM RUN LINE DECK. Looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. TRAVELING CRANE ATOP SUPERSTRUCTURE, FROM RUN LINE DECK. Looking up to north northeast. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

32. Another type of upper superstructure assembly found on the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

32. Another type of upper superstructure assembly found on the 1st and 4th spans. View is of north side of 4th span. - Cleves Bridge, Spanning Great Miami River on U.S. Highway 50, Cleves, Hamilton County, OH

Colloid-Interface-Assisted Laser Irradiation of Nanocrystals Superlattices to be Scalable Plasmonic Superstructures with Novel Activities.

PubMed

Huang, Liu; Wan, Xiaodong; Rong, Hongpan; Yao, Yuan; Xu, Meng; Liu, Jia; Ji, Muwei; Liu, Jiajia; Jiang, Lan; Zhang, Jiatao

2018-04-01

High-efficient charge and energy transfer between nanocrystals (NCs) in a bottom-up assembly are hard to achieve, resulting in an obstacle in application. Instead of the ligands exchange strategies, the advantage of a continuous laser is taken with optimal wavelength and power to irradiate the film-scale NCs superlattices at solid-liquid interfaces. Owing to the Au-based NCs' surface plasmon resonance (SPR) effect, the gentle laser irradiation leads the Au NCs or Au@CdS core/shell NCs to attach each other with controlled pattern at the interfaces between solid NCs phase and liquid ethanol/ethylene glycol. A continuous wave 532 nm laser (6.68-13.37 W cm -2 ), to control Au-based superlattices, is used to form the monolayer with uniformly reduced interparticle distance followed by welded superstructures. Considering the size effect to Au NCs' melting, when decreasing the Au NCs size to ≈5 nm, stronger welding nanostructures are obtained with diverse unprecedented shapes which cannot be achieved by normal colloidal synthesis. With the help of facile scale-up and formation at solid-liquid interfaces, and a good connection of crystalline between NCs, the obtained plasmonic superstructured films that could be facilely transferred onto different substrates exhibit broad SPR absorption in the visible and near-infrared regime, enhanced electric conductivities, and wide applications as surface enhanced Raman scattering (SERS)-active substrates. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Unknown Aspects of Self-Assembly of PbS Microscale Superstructures

PubMed Central

Querejeta-Fernández, Ana; Hernández-Garrido, Juan C.; Yang, Hengxi; Zhou, Yunlong; Varela, Aurea; Parras, Marina; Calvino-Gámez, José J.; González-Calbet, Jose M.; Green, Peter F.; Kotov, Nicholas A.

2012-01-01

A lot of interesting and sophisticated examples of nanoparticle (NP) self-assembly (SA) are known. From both fundamental and technological standpoints this field requires advancements in three principle directions: a) understanding the mechanism and driving forces of three-dimensional (3D) SA with both nano- and micro-levels of organization; b) understanding of disassembly/deconstruction processes; and c) finding synthetic methods of assembly into continuous superstructures without insulating barriers. From this perspective, we investigated the formation of well-known star-like PbS superstructures and found a number of previously unknown or overlooked aspects that can advance the knowledge of NP self-assembly in these three directions. The primary one is that the formation of large seemingly monocrystalline PbS superstructures with multiple levels of octahedral symmetry can be explained only by SA of small octahedral NPs. We found five distinct periods in the formation PbS hyperbranched stars: 1) nucleation of early PbS NPs with an average diameter of 31 nm; 2) assembly into 100–500 nm octahedral mesocrystals; 3) assembly into 1000–2500 nm hyperbranched stars; 4) assembly and ionic recrystallization into six-arm rods accompanied by disappearance of fine nanoscale structure; 5) deconstruction into rods and cubooctahedral NPs. The switches in assembly patterns between the periods occur due to variable dominance of pattern–determining forces that include vander Waals and electrostatic (charge-charge, dipole-dipole, and polarization) interactions. The superstructure deconstruction is triggered by chemical changes in the deep eutectic solvent (DES) used as the media. PbS superstructures can be excellent models for fundamental studies of nanoscale organization and SA manufacturing of (opto)electronics and energy harvesting devices which require organization of PbS components at multiple scales. PMID:22515512

Unknown aspects of self-assembly of PbS microscale superstructures.

PubMed

Querejeta-Fernández, Ana; Hernández-Garrido, Juan C; Yang, Hengxi; Zhou, Yunlong; Varela, Aurea; Parras, Marina; Calvino-Gámez, José J; González-Calbet, Jose M; Green, Peter F; Kotov, Nicholas A

2012-05-22

A lot of interesting and sophisticated examples of nanoparticle (NP) self-assembly (SA) are known. From both fundamental and technological standpoints, this field requires advancements in three principle directions: (a) understanding the mechanism and driving forces of three-dimensional (3D) SA with both nano- and microlevels of organization; (b) understanding disassembly/deconstruction processes; and (c) finding synthetic methods of assembly into continuous superstructures without insulating barriers. From this perspective, we investigated the formation of well-known star-like PbS superstructures and found a number of previously unknown or overlooked aspects that can advance the knowledge of NP self-assembly in these three directions. The primary one is that the formation of large seemingly monocrystalline PbS superstructures with multiple levels of octahedral symmetry can be explained only by SA of small octahedral NPs. We found five distinct periods in the formation PbS hyperbranched stars: (1) nucleation of early PbS NPs with an average diameter of 31 nm; (2) assembly into 100-500 nm octahedral mesocrystals; (3) assembly into 1000-2500 nm hyperbranched stars; (4) assembly and ionic recrystallization into six-arm rods accompanied by disappearance of fine nanoscale structure; (5) deconstruction into rods and cuboctahedral NPs. The switches in assembly patterns between the periods occur due to variable dominance of pattern-determining forces that include van der Waals and electrostatic (charge-charge, dipole-dipole, and polarization) interactions. The superstructure deconstruction is triggered by chemical changes in the deep eutectic solvent (DES) used as the media. PbS superstructures can be excellent models for fundamental studies of nanoscale organization and SA manufacturing of (opto)electronics and energy-harvesting devices which require organization of PbS components at multiple scales.

Impact of abutment rotation and angulation on marginal fit: theoretical considerations.

PubMed

Semper, Wiebke; Kraft, Silvan; Mehrhof, Jurgen; Nelson, Katja

2010-01-01

Rotational freedom of various implant positional index designs has been previously calculated. To investigate its clinical relevance, a three-dimensional simulation was performed to demonstrate the influence of rotational displacements of the abutment on the marginal fit of prosthetic superstructures. Idealized abutments with different angulations (0, 5, 10, 15, and 20 degrees) were virtually constructed (SolidWorks Office Premium 2007). Then, rotational displacement was simulated with various degrees of rotational freedom (0.7, 0.95, 1.5, 1.65, and 1.85 degrees). The resulting horizontal displacement of the abutment from the original position was quantified in microns, followed by a simulated pressure-less positioning of superstructures with defined internal gaps (5 µm, 60 µm, and 100 µm). The resulting marginal gap between the abutment and the superstructure was measured vertically with the SolidWorks measurement tool. Rotation resulted in a displacement of the abutment of up to 157 µm at maximum rotation and angulation. Interference of a superstructure with a defined internal gap of 5 µm placed on the abutment resulted in marginal gaps up to 2.33 mm at maximum rotation and angulation; with a 60-µm internal gap, the marginal gaps reached a maximum of 802 µm. Simulation using a superstructure with an internal gap of 100 µm revealed a marginal gap of 162 µm at abutment angulation of 20 degrees and rotation of 1.85 degrees. The marginal gaps increased with the degree of abutment angulation and the extent of rotational freedom. Rotational displacement of the abutment influenced prosthesis misfit. The marginal gaps between the abutment and the superstructure increased with the rotational freedom of the index and the angulation of the abutment.

40 CFR 745.230 - Work practice standards for conducting lead-based paint activities: public and commercial...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Work practice standards for conducting lead-based paint activities: public and commercial buildings, bridges and superstructures. [Reserved... and commercial buildings, bridges and superstructures. [Reserved] ...

9. WEST SIDE, TEST STAND AND SUPERSTRUCTURE. TEST STAND 1B ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. WEST SIDE, TEST STAND AND SUPERSTRUCTURE. TEST STAND 1-B IN DISTANCE. Looking east. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

40 CFR 745.230 - Work practice standards for conducting lead-based paint activities: public and commercial...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Work practice standards for conducting lead-based paint activities: public and commercial buildings, bridges and superstructures. [Reserved... and commercial buildings, bridges and superstructures. [Reserved] ...

Assembly of Nanorods into Designer Superstructures: The Role of Templating, Capillary Forces, Adhesion, and Polymer Hydration

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

Ciszek, Jacob W.; Huang, Ling; Tsonchev, Stefan

The assembly mechanism by which hundreds of thousands of two-segment gold-polypyrrole nanorods are assembled into kinetically controlled shape-directed superstructures is examined to predict the range of nanoparticle sizes and materials that can be utilized in their formation. Four processes are responsible for assembly: templating, capillary force assembly, adhesion, and polymer hydration. It is shown that templating, where rods are prepositioned for assembly, is scale invariant and that the energy-minimized state after this step is highly disordered. In addition, we predict that superstructures can be made independently from patterns of rods separated by a distance as small as six times themore » inter-rod spacing. Both modeling and experiment show that adhesion and polymer dehydration, which induces curvature in the superstructures, are applicable to other materials. However, the high surface energy and low elastic modulus of polypyrrole are advantageous toward generating three-dimensional structures, inducing curvature at gold/polypyrrole length ratios as large as 7:1.« less

The adsorption and dissociation of oxygen on Ag (111) supported χ3 borophene

NASA Astrophysics Data System (ADS)

Luo, W. W.; Liu, G.; Wang, X.; Lei, X. L.; Ouyang, C. Y.; Liu, S. Q.

2018-05-01

The superstructure of χ3 borophene on Ag (111) has recently been synthesized in experiment. In this work, we investigate its structural, electronic properties and the oxidation mechanism through first-principles calculations. We find the superstructure of χ3 borophene on Ag (111) maintain the planar characteristics, like its free-standing form, owing to the weakly interaction between adsorbate and substrate. Moreover, oxygen molecule can be spontaneously adsorbed on its superstructure in a manner of chemical adsorption. Importantly, the energy barrier of ∼0.35 eV for oxygen dissociation indicates its relative stability in ambient conditions compared with the active silicene. Furthermore, the mobility of O2-dissociation-induced O atom is poor at room temperature, implying the difficult migration of O atom on borophene surface. On the other hand, due to the strong Bsbnd O bonding, desorption of O2-dissociation-induced O atoms on superstructure of χ3 borophene becomes impossible, ultimately leading to form the boron oxides.

Laser ablation synthesis of Si-overdoped Ni1- x O with rocksalt-type derived superstructures and tailored optical properties

NASA Astrophysics Data System (ADS)

Chang, Yu-Ling; Lin, Shih-Siang; Zheng, Yuyuan; Shen, Pouyan; Chen, Shuei-Yuan

2017-04-01

Si-overdoped Ni1- x O nanocondensates/particulates with novel superstructures were fabricated by pulsed laser ablation (PLA) of Ni in tetraethyl orthosilicate and characterized using electron microscopy and optical spectroscopy. The Si-overdoped and C-H-mediated Ni1- x O turned out to have two kinds of rocksalt-type derived superstructures, i.e., (1) 2 × 2 × 2 type of high-pressure stabilized Ni2SiO4 spinel which occurred as platy domains in the particles with {135} facets and (2) 3 × 3 × 3 type intimately mixed with 1D 6 × (100) throughout the particles with {100}, {110}, and {111} facets. Such shaped and superstructured particles, more or less encapsulated with graphitic carbon and siliceous amorphous phase, showed phase and dopant-tailored optical properties, in particular violet and green photoluminescence and UV-visible absorbance for potential engineering applications and shed light on their occurrence in natural dynamic settings.

Automatic recognition of ship types from infrared images using superstructure moment invariants

NASA Astrophysics Data System (ADS)

Li, Heng; Wang, Xinyu

2007-11-01

Automatic object recognition is an active area of interest for military and commercial applications. In this paper, a system addressing autonomous recognition of ship types in infrared images is proposed. Firstly, an approach of segmentation based on detection of salient features of the target with subsequent shadow removing is proposed, as is the base of the subsequent object recognition. Considering the differences between the shapes of various ships mainly lie in their superstructures, we then use superstructure moment functions invariant to translation, rotation and scale differences in input patterns and develop a robust algorithm of obtaining ship superstructure. Subsequently a back-propagation neural network is used as a classifier in the recognition stage and projection images of simulated three-dimensional ship models are used as the training sets. Our recognition model was implemented and experimentally validated using both simulated three-dimensional ship model images and real images derived from video of an AN/AAS-44V Forward Looking Infrared(FLIR) sensor.

3D superstructures with an orthorhombic lattice assembled by colloidal PbS quantum dots.

PubMed

Ushakova, Elena V; Cherevkov, Sergei A; Litvin, Aleksandr P; Parfenov, Peter S; Kasatkin, Igor A; Fedorov, Anatoly V; Gun'ko, Yurii K; Baranov, Alexander V

2018-05-03

We report a new type of metamaterial comprising a highly ordered 3D network of 3-7 nm lead sulfide quantum dots self-assembled in an organic matrix formed by amphiphilic ligands (oleic acid molecules). The obtained 3D superstructures possess an orthorhombic lattice with the distance between the nanocrystals as large as 10-40 nm. Analysis of self-assembly and destruction of the superstructures in time performed by a SAXS technique shows that their morphology depends on the quantity of amphiphilic ligands and width of the quantum dot size and its distribution. Formation of the superstructures is discussed in terms of a model describing the lyotropic crystal formation by micelles from three-phase mixtures. The results show that the organic molecules possessing surfactant properties and capable of forming micelles with nanoparticles as a micelle core can be utilized as building blocks for the creation of novel metamaterials based on a highly ordered 3D network of semiconductors, metals or magnetic nanoparticles.

Hierarchical super-structure identified by polarized light microscopy, electron microscopy and nanoindentation: Implications for the limits of biological control over the growth mode of abalone sea shells

PubMed Central

2012-01-01

Background Mollusc shells are commonly investigated using high-resolution imaging techniques based on cryo-fixation. Less detailed information is available regarding the light-optical properties. Sea shells of Haliotis pulcherina were embedded for polishing in defined orientations in order to investigate the interface between prismatic calcite and nacreous aragonite by standard materialographic methods. A polished thin section of the interface was prepared with a defined thickness of 60 μm for quantitative birefringence analysis using polarized light and LC-PolScope microscopy. Scanning electron microscopy images were obtained for comparison. In order to study structural-mechanical relationships, nanoindentation experiments were performed. Results Incident light microscopy revealed a super-structure in semi-transparent regions of the polished cross-section under a defined angle. This super-structure is not visible in transmitted birefringence analysis due to the blurred polarization of small nacre platelets and numerous organic interfaces. The relative orientation and homogeneity of calcite prisms was directly identified, some of them with their optical axes exactly normal to the imaging plane. Co-oriented "prism colonies" were identified by polarized light analyses. The nacreous super-structure was also visualized by secondary electron imaging under defined angles. The domains of the super-structure were interpreted to consist of crystallographically aligned platelet stacks. Nanoindentation experiments showed that mechanical properties changed with the same periodicity as the domain size. Conclusions In this study, we have demonstrated that insights into the growth mechanisms of nacre can be obtained by conventional light-optical methods. For example, we observed super-structures formed by co-oriented nacre platelets as previously identified using X-ray Photo-electron Emission Microscopy (X-PEEM) [Gilbert et al., Journal of the American Chemical Society 2008, 130:17519–17527]. Polarized optical microscopy revealed unprecedented super-structures in the calcitic shell part. This bears, in principle, the potential for in vivo studies, which might be useful for investigating the growth modes of nacre and other shell types. PMID:22967319

The effect of different screw-tightening techniques on the stress generated on an internal-connection implant superstructure.

PubMed

Choi, Jung-Han; Lim, Young-Jun; Kim, Chang-Whe; Kim, Myung-Joo

2009-01-01

This study evaluated the effect of different screw-tightening sequences, forces, and methods on the stresses generated on a well-fitting internal-connection implant (Astra Tech) superstructure. A metal framework directly connected to four parallel implants was fabricated on a fully edentulous mandibular resin model. Six stone casts with four implant replicas were made from a pickup impression of the superstructure to represent a "well-fitting" situation. Stresses generated by four screw-tightening sequences (1-2-3-4, 4-3-2-1, 2-4-3-1, and 2-3-1-4), two forces (10 and 20 Ncm), and two methods (one-step and two-step) were evaluated. In the two-step method, screws were tightened to the initial torque (10 Ncm) in a predetermined screw-tightening sequence and then to the final torque (20 Ncm) in the same sequence. Stresses were recorded twice by three strain gauges attached to the framework (superior face midway between abutments). Deformation data were analyzed using multiple analysis of variance at a .05 level of statistical significance. In all stone casts, stresses were produced by the superstructure connection, regardless of screw-tightening sequence, force, and method. No statistically significant differences for superstructure preload stresses were found based on screw-tightening sequences (-180.0 to -181.6 microm/m) or forces (-163.4 and -169.2 microm/m) (P > .05). However, different screw-tightening methods induced different stresses on the superstructure. The two-step screw-tightening method (-180.1 microm/m) produced significantly higher stress than the one-step method (-169.2 microm/m) (P = .0457). Within the limitations of this in vitro study, screw-tightening sequence and force were not critical factors in the stress generated on a well-fitting internal-connection implant superstructure. The stress caused by the two-step method was greater than that produced using the one-step method. Further studies are needed to evaluate the effect of screw-tightening techniques on preload stress in various different clinical situations.

Electron-transfer dynamics in highly reduced states of simple and superstructured metalloporphyrins

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

Anxolabehere, E.; Lexa, D.; Saveant, J.M.

1992-02-06

The standard rate constants of the Fe(I){sup -}/Fe({open_quotes}0{close_quotes}){sup 2-} couple in a series of four simple and basket-handle superstructured porphyrins have been measured by means of fast cyclic voltammetry at mercury and gold ultramicroelectrodes. Analysis of the experimental data by the Marcus-Hush model revealed that the main rate-controlling factor of these very fast electron-transfer reactions is solvent reorganization. The presence of secondary amide groups borne by the basket-handle structure and located in the close vicinity of the metalloporphyrin center largely facilitates the reaction from a thermodynamic viewpoint. This facilitation of the reaction is not counterbalanced by any significant contribution ofmore » the fluctuational reorganization of the NHCO dipoles thanks to their attachment to the basket-handle chains. A few complementary experiments were carried out with zinc and copper porphyrins where the same general trends were observed. 16 refs., 3 figs., 2 tabs.« less

Pressure-dependence of the phase transitions and thermal expansion in zirconium and hafnium pyrovanadate

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

Gallington, Leighanne C.; Hester, Brett R.; Kaplan, Benjamin S.

Low or negative thermal expansion (NTE) has been previously observed in members of the ZrP 2O 7 family at temperatures higher than their order-disorder phase transitions. The thermoelastic properties and phase behavior of the low temperature superstructure and high temperature negative thermal expansion phases of ZrV 2O 7 and HfV 2O 7 were explored via in situ variable temperature/pressure powder x-ray diffraction measurements. The phase transition temperatures of ZrV 2O 7 and HfV 2O 7 exhibited a very strong dependence on pressure (~700 K GPa), with moderate compression suppressing the formation of their NTE phases below 513 K. Compression alsomore » reduced the magnitude of the coefficients of thermal expansion in both the positive and negative thermal expansion phases. Additionally, the high temperature NTE phase of ZrV 2O 7 was found to be twice as stiff as the low temperature positive thermal expansion superstructure (24 and 12 GPa respectively).« less

Conceptual design and exergy analysis of an integrated structure of natural gas liquefaction and production of liquid fuels from natural gas using Fischer-Tropsch synthesis

NASA Astrophysics Data System (ADS)

Niasar, Malek Shariati; Amidpour, Majid

2018-01-01

In this paper, utilizing absorption refrigeration system as an alternative to compression refrigeration system of MFC refrigeration cycle in an integrated superstructure with the main aim of reduction in required energy is investigated. High-energy consumption in such units is reduced because of the removal of a stage of the compression system, while the possibility of using waste energy through employing of absorption refrigeration system can be provided. A superstructure including cogeneration of heating, cooling and power for LNG production and liquid fuels using Fischer-Tropsch synthesis are investigated. Exergy analysis shows that the greatest amount of exergy destruction of equipment is related to the compressors by 28.99% and the lowest exergy destruction is related to the gas turbine by 0.17%. Integrated structure has overall thermal efficiency of 90% and specific power of 0.1988 kW h/(kg LNG)-1.

On the Stability of DNA Origami Nanostructures in Low-Magnesium Buffers.

PubMed

Kielar, Charlotte; Xin, Yang; Shen, Boxuan; Kostiainen, Mauri A; Grundmeier, Guido; Linko, Veikko; Keller, Adrian

2018-05-25

DNA origami have great potential as functional platforms in various biomedical applications. Many applications, however, are incompatible with the high Mg2+ concentrations commonly believed to be a prerequisite for maintaining DNA origami integrity. Here, we investigate DNA origami stability in low-Mg2+ buffers. DNA origami stability is found to crucially depend on the availability of residual Mg2+ ions for screening electrostatic repulsion. The presence of EDTA and phosphate ions may thus facilitate DNA origami denaturation by displacing Mg2+ ions from the DNA backbone and reducing the strength of the Mg2+-DNA interaction, respectively. Most remarkably, these buffer dependencies are affected by DNA origami superstructure. However, by rationally selecting buffer components and considering superstructure-dependent effects, the structural integrity of a given DNA origami nanostructure can be maintained in conventional buffers even at Mg2+ concentrations in the low-μM range. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

"Cleaning" the Surface of Hydroxyapatite Nanorods by a Reaction-Dissolution Approach.

PubMed

Cao, Binrui; Yang, Mingying; Wang, Lin; Xu, Hong; Zhu, Ye; Mao, Chuanbin

2015-10-21

Synthetic nanoparticles are always terminated with coating molecules, which are often cytotoxic and not desired in biomedicine. Here we propose a novel reaction-dissolution approach to remove the cytotoxic coating molecules. A two-component solution is added to the nanoparticle solution; one component reacts with the coating molecules to form a salt whereas another is a solvent for dissolving and thus removing the salt. As a proof of concept, this work uses a NaOH-ethanol solution to remove the cytotoxic linoleic acid molecules coated on the hydroxyapatite nanorods (HAP-NRs). The removal of the coating molecules not only significantly improves the biocompatibility of HAP-NRs but also enables their oriented attachment into tightly-bound superstructures, which mimic the organized HAP crystals in bone and enamel and can promote the osteogenic differentiation of mesenchymal stem cells. Our reaction-dissolution approach can be extended to the surface "cleaning" of other nanomaterials.

The effect of sulfated polysaccharides on the crystallization of calcite superstructures

NASA Astrophysics Data System (ADS)

Fried, Ruth; Mastai, Yitzhak

2012-01-01

Calcite with unique morphology and uniform size has been successfully synthesized in the presence of classes of polysaccharides based on carrageenans. In the crystallization of calcite, the choice of different carrageenans, (iota, lambda and kappa), as additives concedes systematic study of the influence of different chemical structures and particularly molecular charge on the formation of CaCO 3 crystals. The uniform calcite superstructures are formed by assemblies and aggregation of calcite crystals. The mechanism for the formation of calcite superstructures was studied by a variety of techniques, SEM, TEM, XRD, time-resolved conductivity and light scattering measurements, focusing on the early stages of crystals' nucleation and aggregation.

Structure Analyses of Highly Symmetric Superstructures Formed by Rodlike Mesogen

NASA Astrophysics Data System (ADS)

Saito, Kazuya; Kutsumizu, Shoichi

Process of structure determination of liquid-crystalline superstructures formed in a mesogenic series, bis(n-alkoxybenzoyl)hydrazine[BABH(n) ; n, the number of carbon atoms in the alkoxy group], is described. The chain-length (n) dependence of relative diffraction intensities from the Ia3d phase resolves the phase problem, leading to the structural description that the molecular centers are on the rods forming two interpenetrating jungle gyms. Theoretical consideration on the stability of superstructures and systematic MEM analysis reveal the coexistence of two aggregation modes (rods forming an extending jungle gym and closed sheets forming spherical shells) for the Im3m phase.

2. NORTH FRONT, FROM SUPERSTRUCTURE TO FLAME DEFLECTOR. Looking south ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. NORTH FRONT, FROM SUPERSTRUCTURE TO FLAME DEFLECTOR. Looking south southwest from Observation Post No. 1 (Building 8767). - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Dynamic Nanoparticles Assemblies

PubMed Central

WANG, LIBING; XU, LIGUANG; KUANG, HUA; XU, CHUANLAI; KOTOV, NICHOLAS A.

2012-01-01

CONSPECTUS Importance Although nanoparticle (NP) assemblies are at the beginning of their development, their unique geometrical shapes and media-responsive optical, electronic and magnetic properties have attracted significant interest. Nanoscale assembly bridges multiple sizes of materials: individual nanoparticles, discrete molecule-like or virus-like nanoscale agglomerates, microscale devices, and macroscale materials. The capacity to self-assemble can greatly facilitate the integration of nanotechnology with other technologies and, in particular, with microscale fabrication. In this Account, we describe developments in the emerging field of dynamic NP assemblies, which are spontaneously formed superstructures containing more than two inorganic nanoscale particles that display ability to change their geometrical, physical, chemical, and other attributes. In many ways, dynamic assemblies can represent a bottleneck in the ‘bottom-up’ fabrication of NP-based devices because they can produce a much greater variety of assemblies, but they also provide a convenient tool for variation of geometries and dimensions of nanoparticle assemblies. Classification Superstructures of NPs (and those held together by similar intrinsic forces) are classified into two groups: Class 1 where media and external fields can alter shape, conformation, and order of stable superstructures with a nearly constant number same. The future development of successful dynamic assemblies requires understanding the equilibrium in dynamic NP systems. The dynamic nature of Class 1 assemblies is associated with the equilibrium between different conformations of a superstructure and is comparable to the isomerization in classical chemistry. Class 2 assemblies involve the formation and/or breakage of linkages between the NPs, which is analogous to the classical chemical equilibrium for the formation of a molecule from atoms. Finer classification of NP assemblies in accord with established conventions in the field may include different size dimensionalities: discrete assemblies (artificial molecules), one-dimensional (spaced chains) and two-dimensional (sheets) and three-dimensional (superlattices, twisted structures) assemblies. Notably, these dimensional attributes must be regarded as primarily topological in nature because all of these superstructures can acquire complex three-dimensional shapes. Preparation We discuss three primary strategies used to prepare NP superstructures: (1) anisotropy-based assemblies utilizing either intrinsic force field anisotropy around NPs or external anisotropy associated with templates and/or applied fields; (2) assembly methods utilizing uniform NPs with isotropic interactions; and (3) methods based on mutual recognition of biomolecules, such as DNA and antigen-antibody interactions. Applications We consider optical, electronic, and magnetic properties of dynamic superstructures, focusing primarily on multiparticle effects in NP superstructures as represented by surface plasmon resonance, NP-NP charge transport, and multibody magnetization. Unique properties of NP superstructures are being applied to biosensing, drug delivery, and nanoelectronics. For both Class 1 and Class 2 dynamic assemblies, biosensing is the most dominant and well-developed area of dynamic nanostructures being successfully transitioned into practice. We can foresee the rapid development of dynamic NP assemblies toward applications in harvesting of dissipated energy, photonics, and electronics. The final part of the review is devoted to the fundamental questions facing dynamic assemblies of NPs in the future. PMID:22449243

40 CFR 745.229 - Certification of individuals and firms engaged in lead-based paint activities: public and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Certification of individuals and firms engaged in lead-based paint activities: public and commercial buildings, bridges and superstructures... paint activities: public and commercial buildings, bridges and superstructures. [Reserved] ...

3. DETAIL OF NORTH FRONT AND WEST SIDE, WITH SUPERSTRUCTURE, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. DETAIL OF NORTH FRONT AND WEST SIDE, WITH SUPERSTRUCTURE, FROM NEAR OBSERVATION POST NO. 3. Looking south southeast from below. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

15. SUPERSTRUCTURE PLANS, ELEVATION AND DETAILS, SHEET 4 OF 117, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. SUPERSTRUCTURE PLANS, ELEVATION AND DETAILS, SHEET 4 OF 117, 1920. - Sacramento River Water Treatment Plant Intake Pier & Access Bridge, Spanning Sacramento River approximately 175 feet west of eastern levee on river; roughly .5 mile downstream from confluence of Sacramento & American Rivers, Sacramento, Sacramento County, CA

Evaluation of effects of super-heavy loading on the US 41 bridge over the White River : appendices.

DOT National Transportation Integrated Search

2011-01-01

Built in 1958, the US-41 White River Bridge is a two-girder, riveted steel structure located in Hazelton, IN. The bridge is comprised of two, sixteen span superstructures sharing a common substructure. Each superstructure also contains four pin and h...

Evaluation of effects of super-heavy loading on the US 41 bridge over the White River.

DOT National Transportation Integrated Search

2011-01-01

Built in 1958, the US-41 White River Bridge is a two-girder, riveted steel structure located in Hazelton, IN. The bridge is comprised of two, sixteen span : superstructures sharing a common substructure. Each superstructure also contains four pin and...

Looking northeast from Test Stand 'A' superstructure towards Test Stand ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Looking northeast from Test Stand 'A' superstructure towards Test Stand 'D' tower (4223/E-24, left background), Test Stand 'C' tower (4217/E-18, center), and Test Stand 'B' (4215/E-16, right foreground). - Jet Propulsion Laboratory Edwards Facility, Edwards Air Force Base, Boron, Kern County, CA

Evaluation of the performance of a press-lam timber bridge : interim report no. 1, bridge installation and load test.

DOT National Transportation Integrated Search

1977-01-01

The report describes the installation and load test of the world's first press-lam timber bridge superstructure. A five-man crew replaced the substandard steel stringer-timber deck superstructure on Rte. 610 over Little Stoney Creek in Shenandoah Cou...

Globalisation in Africa: Reflecting on Peter Jarvis's Superstructure and Substructure Model

ERIC Educational Resources Information Center

Preece, Julia

2017-01-01

This paper reflects on Peter Jarvis' book "Globalisation, lifelong learning and the learning society," volume 2--in which he describes human learning within a global context and factors contributing to globalisation. He describes the relationship of power between countries manifested as the superstructure and sub structure. The paper…

Optically Reconfigurable Chiral Microspheres of Self-Organized Helical Superstructures with Handedness Inversion.

PubMed

Wang, Ling; Chen, Dong; Gutierrez-Cuevas, Karla G; Bisoyi, Hari Krishna; Fan, Jing; Zola, Rafael S; Li, Guoqiang; Urbas, Augustine M; Bunning, Timothy J; Weitz, David A; Li, Quan

2017-01-01

Optically reconfigurable monodisperse chiral microspheres of self-organized helical superstructures with dynamic chirality were fabricated via a capillary-based microfluidic technique. Light-driven handedness-invertible transformations between different configurations of microspheres were vividly observed and optically tunable RGB photonic cross-communications among the microspheres were demonstrated.

Marxian Approaches to Education.

ERIC Educational Resources Information Center

Carnoy, Martin

Traditional Marxist approaches to the state relegate superstructural institutions like the school to a minor role in the process of social change. More recent theories like those of Gramsci, Althusser, and Poulantzas raise the state and the class struggle in the state apparatuses to a much more prominent position: superstructure, including the…

Evaluation of effects of super-heavy loading on the US 41 bridge over the White River : technical summary.

DOT National Transportation Integrated Search

2011-01-01

Built in 1958, the US-41 White River Bridge is a two-girder, riveted steel structure located near Hazelton, IN. The bridge is comprised of two, sixteen span superstructures sharing a common substructure. Each superstructure also contains four pin and...

40 CFR 745.229 - Certification of individuals and firms engaged in lead-based paint activities: public and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Certification of individuals and firms engaged in lead-based paint activities: public and commercial buildings, bridges and superstructures... paint activities: public and commercial buildings, bridges and superstructures. [Reserved] ...

12. A CLOSE UP VIEW OF THE IRON SUPERSTRUCTURE OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. A CLOSE UP VIEW OF THE IRON SUPERSTRUCTURE OF THIS CAMELBACK TRUSS BRIDGE. THIS PHOTO SHOWS A DETAIL OF THE LATTICE WORK, AND AN INTERESTING CURVED BRACE MEMBER. - Freedom Bridge, Spanning West Fork of White River at County Road 590 South, Freedom, Owen County, IN

Fourier transform infrared spectroscopy of 2'-deoxycytidine aggregates in CDCl3 solutions

NASA Astrophysics Data System (ADS)

Biemann, Lars; Häber, Thomas; Maydt, Daniela; Schaper, Klaus; Kleinermanns, Karl

2011-03-01

We investigated the self-aggregation of 2'-deoxy-3',5'-bis(tert-butyldimethylsilyl)-cytidine dC(TBDMS)2 in CDCl3 solutions by Fourier transform infrared (FT-IR) spectroscopy and report the formation of larger aggregates than dimers in this solvent for the first time. The hydrogen bonding patterns in these complexes, which occur with increasing concentration may serve as a model for DNA super-structures such as triplexes. From the IR spectra, wavelength dependent absolute extinction coefficients of the monomer, dimer as well as a contribution from larger clusters which are supposedly trimers are deduced on the basis of a simple deconvolution method. Our results are supported by RI-B3LYP/TZVP calculations within the conductorlike screening model framework, to account for solvent effects in the ab initio calculations.

Constructing molecular structures on periodic superstructure of graphene/Ru(0001)

PubMed Central

Li, Geng; Huang, Li; Xu, Wenyan; Que, Yande; Zhang, Yi; Lu, Jianchen; Du, Shixuan; Liu, Yunqi; Gao, Hong-Jun

2014-01-01

We review the way to fabricate large-scale, high-quality and single crystalline graphene epitaxially grown on Ru(0001) substrate. A moiré pattern of the graphene/Ru(0001) is formed due to the lattice mismatch between graphene and Ru(0001). This superstructure gives rise to surface charge redistribution and could behave as an ordered quantum dot array, which results in a perfect template to guide the assembly of organic molecular structures. Molecules, for example iron phthalocyanine and C60, on this template show how the molecule–substrate interaction makes different superstructures. These results show the possibility of constructing ordered molecular structures on graphene/Ru(0001), which is helpful for practical applications in the future. PMID:24615151

Designing timber highway bridge superstructures using AASHTO?LRFD specifications

Treesearch

James P. Wacker; James S. Groenier

2007-01-01

The allowable-stress design methodology that has been used for decades to design timber bridge superstructures is being replaced in the near future. Beginning in October 2007, bridge designers will be required by the Federal Highway Administration (FHWA) to utilize the Load and Resistance Factor Design (LRFD) design specifications published by the American Association...

46 CFR 42.15-15 - Positions of hatchways, doorways and ventilators.

Code of Federal Regulations, 2010 CFR

2010-10-01

... exposed superstructure decks situated forward of a point located a quarter of the vessel's length from the forward perpendicular. (2) Position 2: Upon exposed superstructure decks situated abaft a quarter of the vessel's length from the forward perpendicular. [CGFR 68-60, 33 FR 10060, July 12, 1968, as amended by...

46 CFR 42.15-15 - Positions of hatchways, doorways and ventilators.

Code of Federal Regulations, 2011 CFR

2011-10-01

... exposed superstructure decks situated forward of a point located a quarter of the vessel's length from the forward perpendicular. (2) Position 2: Upon exposed superstructure decks situated abaft a quarter of the vessel's length from the forward perpendicular. [CGFR 68-60, 33 FR 10060, July 12, 1968, as amended by...

Incommensurate structure of a lillianite-type samarium chromium sulfide Sm{sub 2/3}Cr{sub 2}S{sub 4}

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

Lafond, A.; Cario, L.; Meerschaut, A.

1996-12-01

The structure of Sm{sub 2/3}Cr{sub 2}S{sub 4} has been solved from single-crystal X-ray diffraction data. This compound presents a 3 X a superstructure along a and an incommensurate superstructure along b close to 3 x b. The basic structure is described in the space group Pmnb with a = 3.5030(3) {Angstrom}, b = 10.9199(8) {Angstrom}, c = 12.7987(8) {Angstrom}, Z = 4, R = 0.046 for 916 observed reflections. The modulated structure refinement, taking into account the two superstructures, was carried out in a (3 + 2)D superspace group and leads to R = 0.063 for 1706 reflections. This structuremore » consists of staggered double columns of [CrS{sub 6}] octahedra connected by samarium atoms in a trigonal prismatic bicapped environment. This structure is reminiscent of that found in the lillianite mineral family. The statistical occupancy of samarium atoms (1/3), in agreement with the charge equilibrium (Sm{sup 3+}, Cr{sup 3+}, S{sup 2-}), is related to the superstructure.« less

Nanosized solvent superstructures in ultramolecular aqueous dilutions: twenty years' research using water proton NMR relaxation.

PubMed

Demangeat, Jean-Louis

2013-04-01

proton nuclear magnetic resonance (NMR) relaxation times T1, T2, T1/T2 are sensitive to motion and organization of water molecules. Especially, increase in T1/T2 reflects a higher degree of structuring. My purpose was to look at physical changes in water in ultrahigh aqueous dilutions. Samples were prepared by iterative centesimal (c) dilution with vigorous agitation, ranging between 3c and 24c (Avogadro limit 12c). Solutes were silica-lactose, histamine, manganese-lactose. Solvents were water, NaCl 0.15 M or LiCl 0.15 M. Solvents underwent strictly similar, simultaneous dilution/agitation, for each level of dilution, as controls. NMR relaxation was studied within 0.02-20 MHz. No changes were observed in controls. Increasing T1 and T1/T2 were found in dilutions, which persisted beyond 9c (manganese-lactose), 10c (histamine) and 12c (silica-lactose). For silica-lactose in LiCl, continuous decrease in T2 with increase in T1/T2 within the 12c-24c range indicated growing structuring of water despite absence of the initial solute. All changes vanished after heating/cooling. These findings were interpreted in terms of nanosized (>4-nm) supramolecular structures involving water, nanobubbles and ions, if any. Additional study of low dilutions of silica-lactose revealed increased T2 and decreased T1/T2 compared to solvent, within the 10(-3)-10(-6) range, reflecting transient solvent destructuring. This could explain findings at high dilution. Proton NMR relaxation demonstrated modifications of the solvent throughout the low to ultramolecular range of dilution. The findings suggested the existence of superstructures that originate stereospecifically around the solute after an initial destructuring of the solvent, developing more upon dilution and persisting beyond 12c. Copyright © 2013 The Faculty of Homeopathy. Published by Elsevier Ltd. All rights reserved.

46 CFR 174.080 - Flooding on self-elevating and surface type units.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Flooding on self-elevating and surface type units. 174... Drilling Units § 174.080 Flooding on self-elevating and surface type units. (a) On a surface type unit or... superstructure deck where superstructures are fitted must be assumed to be subject to simultaneous flooding. (b...

46 CFR 174.080 - Flooding on self-elevating and surface type units.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Flooding on self-elevating and surface type units. 174... Drilling Units § 174.080 Flooding on self-elevating and surface type units. (a) On a surface type unit or... superstructure deck where superstructures are fitted must be assumed to be subject to simultaneous flooding. (b...

46 CFR 174.080 - Flooding on self-elevating and surface type units.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Flooding on self-elevating and surface type units. 174... Drilling Units § 174.080 Flooding on self-elevating and surface type units. (a) On a surface type unit or... superstructure deck where superstructures are fitted must be assumed to be subject to simultaneous flooding. (b...

A Critical Reassessment of Marxian Base-Superstructure Explanations of the Role of Education in Social Change.

ERIC Educational Resources Information Center

Chun, Kyung-Kap

1986-01-01

Examines how four major versions of neo-Marxism (i.e., Hegelian, Phenomenological, Structuralist Marxism, and the Frankfurt School) attempt to overcome the base-superstructure thesis of the political economists of education. Considers the implicit social ontological and epistemological assumptions and the related theory of education of each.…

11. VIEW SHOWING THE SUPERSTRUCTURE OF THE SHED ROOF (REMOVED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. VIEW SHOWING THE SUPERSTRUCTURE OF THE SHED ROOF (REMOVED AUTUMN OF 1996) PROTECTING THE PRESENT INTAKE GATES- AND RAKE-LIFTING MECHANISMS AND THE TRASH RACKS (LOWER FOREGROUND), LOOKING NORTH. - Washington Water Power Company Post Falls Power Plant, Middle Channel Powerhouse & Dam, West of intersection of Spokane & Fourth Streets, Post Falls, Kootenai County, ID

A Field Assessment of Timber Highway Bridge Durability in the United States

Treesearch

J.P. Wacker; B.K. Brashaw; F. Jalinoos

2015-01-01

This paper summarizes a cooperative project to assess the current condition and life expectancy of 132 timber highway bridge superstructures at locations throughout the United States. Several superstructure types were included in this comprehensive effort, of which two-thirds were sawn timber stringer systems. In-depth inspections were conducted by the project team...

Creosote retention levels of timber highway bridge superstructures in Michigan’s Lower Peninsula.

Treesearch

James P. Wacker; Douglas M. Crawford; Merv O. Eriksson

2003-01-01

Environmental concerns about preservative bleeding (or migrating) from timber bridges have increased in recent years. This preliminary study examined the creosote retention levels at six timber highway bridges in Michigan's lower peninsula during the summer of 2000. Several test core samples were removed from the bridge superstructures (four bleeders and two...

Mapping of reciprocal space of La{sub 0.30}CoO{sub 2} in 3D: Analysis of superstructure diffractions and intergrowths with Co{sub 3}O{sub 4}

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

Brázda, Petr, E-mail: brazda@fzu.cz; Palatinus, Lukáš; Klementová, Mariana

2015-07-15

We have used electron diffraction tomography and powder X-ray diffraction to elucidate the structural properties of layered cobaltate γ-La{sub 0.30}CoO{sub 2}. The structure consists of hexagonal sheets of edge-sharing CoO{sub 6} octahedra interleaved by lanthanum monolayers. The La{sup 3+} cations occupy only one third of available P2 sites, forming a 2-dimensional a√3×a√3 superstructure in a–b plane. The results show that there exists no order in the mutual relative shift between the neighbouring La interlayers within the a–b plane. This is manifested in the observed monotonous decrease of the diffracted intensity of the superstructure diffractions along c{sup ⁎} in both X-raymore » and electron diffraction data. The observed lack of stacking order differentiates the La{sub x}CoO{sub 2} from its Ca and Sr analogues where at least a partial stacking order of the cationic interlayers is manifested in experimental data published in literature. - Highlights: • We use electron diffraction tomography for reciprocal space mapping of La{sub 0.30}CoO{sub 2}. • We observed a complete disorder of the stacking of Lanthanum interlayers. • Co{sub 3}O{sub 4} intergrown with La{sub 0.30}CoO{sub 2} crystals brings about fake superstructure diffractions. • Twinning of Co{sub 3}O{sub 4} enhances the problem of fake superstructure diffractions.« less

Impact of temperature on nitrification in biological activated carbon (BAC) filters used for drinking water treatment.

PubMed

Andersson, A; Laurent, P; Kihn, A; Prévost, M; Servais, P

2001-08-01

The impact of temperature on nitrification in biological granular activated carbon (GAC) filters was evaluated in order to improve the understanding of the nitrification process in drinking water treatment. The study was conducted in a northern climate where very cold water temperatures (below 2 degrees C) prevail for extended periods and rapid shifts of temperature are frequent in the spring and fall. Ammonia removals were monitored and the fixed nitrifying biomass was measured using a method of potential nitrifying activity. The impact of temperature was evaluated on two different filter media: an opened superstructure wood-based activated carbon and a closed superstructure activated carbon-based on bituminous coal. The study was conducted at two levels: pilot scale (first-stage filters) and full-scale (second-stage filters) and the results indicate a strong temperature impact on nitrification activity. Ammonia removal capacities ranged from 40 to 90% in pilot filters, at temperatures above 10 degrees C, while more than 90% ammonia was removed in the full-scale filters for the same temperature range. At moderate temperatures (4-10 degrees C), the first stage pilot filters removed 10-40% of incoming ammonia for both media (opened and closed superstructure). In the full-scale filters, a difference between the two media in nitrification performances was observed at moderate temperatures: the ammonia removal rate in the opened superstructure support (more than 90%) was higher than in the closed superstructure support (45%). At low temperatures (below 4 degrees C) both media performed poorly. Ammonia removal capacities were below 30% in both pilot- and full-scale filters.

Seismic soil structure interaction analysis for asymmetrical buildings supported on piled raft for the 2015 Nepal earthquake

NASA Astrophysics Data System (ADS)

Badry, Pallavi; Satyam, Neelima

2017-01-01

Seismic damage surveys and analyses conducted on modes of failure of structures during past earthquakes observed that the asymmetrical buildings show the most vulnerable effect throughout the course of failures (Wegner et al., 2009). Thus, all asymmetrical buildings significantly fails during the shaking events and it is really needed to focus on the accurate analysis of the building, including all possible accuracy in the analysis. Apart from superstructure geometry, the soil behavior during earthquake shaking plays a pivotal role in the building collapse (Chopra, 2012). Fixed base analysis where the soil is considered to be infinitely rigid cannot simulate the actual scenario of wave propagation during earthquakes and wave transfer mechanism in the superstructure (Wolf, 1985). This can be well explained in the soil structure interaction analysis, where the ground movement and structural movement can be considered with the equal rigor. In the present study the object oriented program has been developed in C++ to model the SSI system using the finite element methodology. In this attempt the seismic soil structure interaction analysis has been carried out for T, L and C types piled raft supported buildings in the recent 25th April 2015 Nepal earthquake (M = 7.8). The soil properties have been considered with the appropriate soil data from the Katmandu valley region. The effect of asymmetry of the building on the responses of the superstructure is compared with the author's research work. It has been studied/observed that the shape or geometry of the superstructure governs the response of the superstructure subjected to the same earthquake load.

46 CFR 45.127 - Position of structures, openings, and fittings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... quarter deck; (2) A superstructure deck or a trunk deck and forward of a point 1/4 L from the forward... deck aft of a point 1/4 L abaft the forward perpendicular; or (2) On a superstructure and trunk combination, that is H s or more n height, aft or a point 1/4 L abaft the forward perpendicular. ...

46 CFR 45.127 - Position of structures, openings, and fittings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... quarter deck; (2) A superstructure deck or a trunk deck and forward of a point 1/4 L from the forward... deck aft of a point 1/4 L abaft the forward perpendicular; or (2) On a superstructure and trunk combination, that is H s or more n height, aft or a point 1/4 L abaft the forward perpendicular. ...

Novel symmetrical coralloid Cu 3D superstructures: Solid-state synthesis from a Cu-carboxylate MOF and their in-situ thermal conversion

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

Chen Lingyun, E-mail: lychen@cqu.edu.c; Shen Yongming; Bai Junfeng, E-mail: bjunfeng@nju.edu.c

2009-08-15

We describe here a one-step solid-state process for the synthesis of metal three-dimensional (3D) superstructures from a metal-organic framework (MOF). Novel symmetrical coralloid Cu 3D superstructures with surface interspersed with clusters of Cu nanoparticles were successfully synthesized by thermolysis of the [Cu{sub 3}(btc){sub 2}] (btc=benzene-1,3,5-tricarboxylato) MOF in a one-end closed horizontal tube furnace (OCTF). The obtained products were characterized by TGA, FT-IR, XRD, EDX, SEM, TEM, HRTEM and SAED. Different reaction conditions were discussed. Furthermore, the synthesized Cu samples were converted into CuO microstructures by in-situ calcination in the air. In addition, the possible formation mechanism was also proposed. Thismore » method is a simple and facile route, which builds a direct linkage between metal-carboxylate MOF crystals and metal nano- or microstructures and also opens a new application field of MOFs. - Graphical abstract: Novel symmetrical coralloid Cu 3D superstructures were synthesized by thermolysis of the [Cu{sub 3}(btc){sub 2}] (btc=benzene-1,3,5-tricarboxylato) MOF microcrystals in a one-end closed horizontal tube furnace (OCTF).« less

Design of bridges against large tectonic deformation

NASA Astrophysics Data System (ADS)

Anastasopoulos, I.; Gazetas, G.; Drosos, V.; Georgarakos, T.; Kourkoulis, R.

2008-12-01

The engineering community has devoted much effort to understanding the response of soil-structure systems to seismic ground motions, but little attention to the effects of an outcropping fault offset. The 1999 earthquakes of Turkey and Taiwan, offering a variety of case histories of structural damage due to faulting, have (re)fueled the interest on the subject. This paper presents a methodology for design of bridges against tectonic deformation. The problem is decoupled in two analysis steps: the first (at the local level) deals with the response of a single pier and its foundation to fault rupture propagating through the soil, and the superstructure is modeled in a simplified manner; and the second (at the global level) investigates detailed models of the superstructure subjected to the support (differential) displacements of Step 1. A parametric study investigates typical models of viaduct and overpass bridges, founded on piles or caissons. Fixed-head piled foundations are shown to be rather vulnerable to faulting-induced deformation. End-bearing piles in particular are unable to survive bedrock offsets exceeding 10 cm. Floating piles perform better, and if combined with hinged pile-to-cap connections, they could survive much larger offsets. Soil resilience is beneficial in reducing pile distress. Caisson foundations are almost invariably successful. Statically-indeterminate superstructures are quite vulnerable, while statically-determinate are insensitive (allowing differential displacements and rotations without suffering any distress). For large-span cantilever-construction bridges, where a statically determinate system is hardly an option, inserting resilient seismic isolation bearings is advantageous as long as ample seating can prevent the deck from falling off the supports. An actual application of the developed method is presented for a major bridge, demonstrating the feasibility of design against tectonic deformation.

Competences of Dominican College Students in the Comprehension of Superstructure and Macrostructure of Expositive Texts

ERIC Educational Resources Information Center

Tavarez, Pedro J.; Gomez, Jorge; Mercedes, Arismendy

2016-01-01

The objective of this research is to determine the competences of students of Basic Spanish Language II (Let. 012) in the comprehension of the superstructure and macrostructure of expository texts, in two college Campuses; the UASD San Francisco de Macorís Campus, and the UASD Bonao Campus for the semester 2015-2. The theory is based on the…

Controlling superstructural ordering in the clathrate-I Ba 8 M 16 P 30 (M = Cu, Zn) through the formation of metal–metal bonds

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

Dolyniuk, J.; Whitfield, P. S.; Lee, K.

2017-01-01

Order–disorder–order phase transitions in the clathrate-I Ba8Cu16P30 were induced and controlled by aliovalent substitutions of Zn into the framework. Unaltered Ba8Cu16P30 crystallizes in an ordered orthorhombic (Pbcn) clathrate-I superstructure that maintains complete segregation of metal and phosphorus atoms over 23 different crystallographic positions in the clathrate framework. The driving force for the formation of this Pbcn superstructure is the avoidance of Cu–Cu bonds. This superstructure is preserved upon aliovalent substitution of Zn for Cu in Ba8Cu16-xZnxP30 with 0 < x < 1.6 (10% Zn/Mtotal), but vanishes at greater substitution concentrations. Higher Zn concentrations (up to 35% Zn/Mtotal) resulted in themore » additional substitution of Zn for P in Ba8M16+yP30-y (M = Cu, Zn) with 0 ≤ y ≤ 1. This causes the formation of Cu–Zn bonds in the framework, leading to a collapse of the orthorhombic superstructure into the more common cubic subcell of clathrate-I (Pm[3 with combining macron]n). In the resulting cubic phases, each clathrate framework position is jointly occupied by three different elements: Cu, Zn, and P. Detailed structural characterization of the Ba–Cu–Zn–P clathrates-I via single crystal X-ray diffraction, joint synchrotron X-ray and neutron powder diffractions, pair distribution function analysis, electron diffraction and high-resolution electron microscopy, along with elemental analysis, indicates that local ordering is present in the cubic clathrate framework, suggesting the evolution of Cu–Zn bonds. For the compounds with the highest Zn content, a disorder–order transformation is detected due to the formation of another superstructure with trigonal symmetry and Cu–Zn bonds in the clathrate-I framework. It is shown that small changes in the composition, synthesis, and crystal structure have significant impacts on the structural and transport properties of Zn-substituted Ba8Cu16P30.« less

Seismic performance assessment of base-isolated safety-related nuclear structures

USGS Publications Warehouse

Huang, Y.-N.; Whittaker, A.S.; Luco, N.

2010-01-01

Seismic or base isolation is a proven technology for reducing the effects of earthquake shaking on buildings, bridges and infrastructure. The benefit of base isolation has been presented in terms of reduced accelerations and drifts on superstructure components but never quantified in terms of either a percentage reduction in seismic loss (or percentage increase in safety) or the probability of an unacceptable performance. Herein, we quantify the benefits of base isolation in terms of increased safety (or smaller loss) by comparing the safety of a sample conventional and base-isolated nuclear power plant (NPP) located in the Eastern U.S. Scenario- and time-based assessments are performed using a new methodology. Three base isolation systems are considered, namely, (1) Friction Pendulum??? bearings, (2) lead-rubber bearings and (3) low-damping rubber bearings together with linear viscous dampers. Unacceptable performance is defined by the failure of key secondary systems because these systems represent much of the investment in a new build power plant and ensure the safe operation of the plant. For the scenario-based assessments, the probability of unacceptable performance is computed for an earthquake with a magnitude of 5.3 at a distance 7.5 km from the plant. For the time-based assessments, the annual frequency of unacceptable performance is computed considering all potential earthquakes that may occur. For both assessments, the implementation of base isolation reduces the probability of unacceptable performance by approximately four orders of magnitude for the same NPP superstructure and secondary systems. The increase in NPP construction cost associated with the installation of seismic isolators can be offset by substantially reducing the required seismic strength of secondary components and systems and potentially eliminating the need to seismically qualify many secondary components and systems. ?? 2010 John Wiley & Sons, Ltd.

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

Tao, J.; Sun, K.; Yin, W. -G.

The ground-state electronic order in doped manganites is frequently associated with a lattice modulation, contributing to their many interesting properties. However, measuring the thermal evolution of the lattice superstructure with reciprocal-space probes alone can lead to ambiguous results with competing interpretations. Here, we provide direct observations of the evolution of the superstructure in La 1/3Ca 2/3MnO 3 in real space, as well as reciprocal space, using transmission electron microscopic (TEM) techniques. We show that the transitions are the consequence of a proliferation of dislocations plus electronic phase separation. The resulting states are well described by the symmetries associated with electronic-liquid-crystalmore » (ELC) phases. Furthermore, our results resolve the long-standing controversy over the origin of the incommensurate superstructure and suggest a new structural model that is consistent with recent theoretical calculations.« less

Evolution of Moiré Profiles from van der Waals Superstructures of Boron Nitride Nanosheets

PubMed Central

Liao, Yunlong; Cao, Wei; Connell, John W.; Chen, Zhongfang; Lin, Yi

2016-01-01

Two-dimensional (2D) van der Waals (vdW) superstructures, or vdW solids, are formed by the precise restacking of 2D nanosheet lattices, which can lead to unique physical and electronic properties that are not available in the parent nanosheets. Moiré patterns formed by the crystalline mismatch between adjacent nanosheets are the most direct features for vdW superstructures under microscopic imaging. In this article, transmission electron microscopy (TEM) observation of hexagonal Moiré patterns with unusually large micrometer-sized lateral areas (up to ~1 μm2) and periodicities (up to ~50 nm) from restacking of liquid exfoliated hexagonal boron nitride nanosheets (BNNSs) is reported. This observation was attributed to the long range crystallinity and the contaminant-free surfaces of these chemically inert nanosheets. Parallel-line-like Moiré fringes with similarly large periodicities were also observed. The simulations and experiments unambiguously revealed that the hexagonal patterns and the parallel fringes originated from the same rotationally mismatched vdW stacking of BNNSs and can be inter-converted by simply tilting the TEM specimen following designated directions. This finding may pave the way for further structural decoding of other 2D vdW superstructure systems with more complex Moiré images. PMID:27188697

Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors: RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212).

PubMed

Yokosawa, Tadahiro; Awana, V P S Veer Pal Singh; Kimoto, Koji; Takayama-Muromachi, Eiji; Karppinen, Maarit; Yamauchi, Hisao; Matsui, Yoshio

2004-01-01

Microstructures of the RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212) magneto-superconductors have been investigated by using selected-area electron diffraction, convergent-beam electron diffraction, dark-field electron microscopy and high-resolution electron microscopy at room temperature. Both Ru-1212 and Ru-1222 consist of nm-size domains stacked along the [Formula: see text] direction, where the domains are formed by two types of superstructures due to ordering of rotated RuO(6) octahedra about the c-axis. In Ru-1212, both primitive-and body-centered tetragonal superstructures (the possible space groups: P4/mbm and I4/mcm) are derived to form the corresponding nm-domains. It is of great interest that Ru-1212 consists of domains of two crystallographically different superstructures, while the similar domains observed in Ru-1222 have crystallographically identical superstructure with an orthorhombic symmetry (possible space group: Aeam), related by 90 degrees rotation around the c-axis (Yokosawa et al., 2003, submitted for publication).

Mach Number effects on turbulent superstructures in wall bounded flows

NASA Astrophysics Data System (ADS)

Kaehler, Christian J.; Bross, Matthew; Scharnowski, Sven

2017-11-01

Planer and three-dimensional flow field measurements along a flat plat boundary layer in the Trisonic Wind Tunnel Munich (TWM) are examined with the aim to characterize the scaling, spatial organization, and topology of large scale turbulent superstructures in compressible flow. This facility is ideal for this investigation as the ratio of boundary layer thickness to test section spanwise extent ratio is around 1/25, ensuring minimal sidewall and corner effects on turbulent structures in the center of the test section. A major difficulty in the experimental investigation of large scale features is the mutual size of the superstructures which can extend over many boundary layer thicknesses. Using multiple PIV systems, it was possible to capture the full spatial extent of large-scale structures over a range of Mach numbers from Ma = 0.3 - 3. To calculate the average large-scale structure length and spacing, the acquired vector fields were analyzed by statistical multi-point methods that show large scale structures with a correlation length of around 10 boundary layer thicknesses over the range of Mach numbers investigated. Furthermore, the average spacing between high and low momentum structures is on the order of a boundary layer thicknesses. This work is supported by the Priority Programme SPP 1881 Turbulent Superstructures of the Deutsche Forschungsgemeinschaft.

Facile and one-pot solution synthesis of several kinds of 3D hierarchical flower-like α-Bi2O3 microspheres

NASA Astrophysics Data System (ADS)

Wang, Yajun; Li, Zexue; Yu, Haiyang; Feng, Changgen

2016-09-01

Several kinds of three-dimensional (3D) hierarchical constructed flower-like α-Bi2O3 microspheres were prepared successfully via a simple solution precipitation synthesis at 95∘C and ambient atmospheric pressure in 1h. The synthesis process was operated in ethanol-water system as solvent with the assistance of glycerin and oleic acid as capping agents. These flower-like α-Bi2O3 architectures with diameter of several micrometers were 3D self-assembled from nanorods or nanocubes step by step. By adjusting the concentration of the capping agents, various flower-like α-Bi2O3 microspheres were obtained. The formation of the flower-like superstructures was attributed to the modification of nucleation and growth kinetics, and the guidance of self-assembly approach by capping agents. The formation mechanism of these microstructures was discussed briefly.

Implant-supported fixed dental prostheses with CAD/CAM-fabricated porcelain crown and zirconia-based framework.

PubMed

Takaba, Masayuki; Tanaka, Shinpei; Ishiura, Yuichi; Baba, Kazuyoshi

2013-07-01

Recently, fixed dental prostheses (FDPs) with a hybrid structure of CAD/CAM porcelain crowns adhered to a CAD/CAM zirconia framework (PAZ) have been developed. The aim of this report was to describe the clinical application of a newly developed implant-supported FDP fabrication system, which uses PAZ, and to evaluate the outcome after a maximum application period of 36 months. Implants were placed in three patients with edentulous areas in either the maxilla or mandible. After the implant fixtures had successfully integrated with bone, gold-platinum alloy or zirconia custom abutments were first fabricated. Zirconia framework wax-up was performed on the custom abutments, and the CAD/CAM zirconia framework was prepared using the CAD/CAM system. Next, wax-up was performed on working models for porcelain crown fabrication, and CAD/CAM porcelain crowns were fabricated. The CAD/CAM zirconia frameworks and CAD/CAM porcelain crowns were bonded using adhesive resin cement, and the PAZ was cemented. Cementation of the implant superstructure improved the esthetics and masticatory efficiency in all patients. No undesirable outcomes, such as superstructure chipping, stomatognathic dysfunction, or periimplant bone resorption, were observed in any of the patients. PAZ may be a potential solution for ceramic-related clinical problems such as chipping and fracture and associated complicated repair procedures in implant-supported FDPs. © 2012 by the American College of Prosthodontists.

Convection Cells in the Atmospheric Boundary Layer

NASA Astrophysics Data System (ADS)

Fodor, Katherine; Mellado, Juan-Pedro

2017-04-01

In dry, shear-free convective boundary layers (CBLs), the turbulent flow of air is known to organise itself on large scales into coherent, cellular patterns, or superstructures, consisting of fast, narrow updraughts and slow, wide downdraughts which together form circulations. Superstructures act as transport mechanisms from the surface to the top of the boundary layer and vice-versa, as opposed to small-scale turbulence, which only modifies conditions locally. This suggests that a thorough investigation into superstructure properties may help us better understand transport across the atmospheric boundary layer as a whole. Whilst their existence has been noted, detailed studies into superstructures in the CBL have been scarce. By applying methods which are known to successfully isolate similar large-scale patterns in turbulent Rayleigh-Bénard convection, we can assess the efficacy of those detection techniques in the CBL. In addition, through non-dimensional analysis, we can systematically compare superstructures in various convective regimes. We use direct numerical simulation of four different cases for intercomparison: Rayleigh-Bénard convection (steady), Rayleigh-Bénard convection with an adiabatic top lid (quasi-steady), a stably-stratified CBL (quasi-steady) and a neutrally-stratified CBL (unsteady). The first two are non-penetrative and the latter two penetrative. We find that although superstructures clearly emerge from the time-mean flow in the non-penetrative cases, they become obscured by temporal averaging in the CBL. This is because a rigid lid acts to direct the flow into counter-rotating circulation cells whose axis of rotation remains stationary, whereas a boundary layer that grows in time and is able to entrain fluid from above causes the circulations to not only grow in vertical extent, but also to move horizontally and merge with neighbouring circulations. Spatial filtering is a useful comparative technique as it can be performed on boundary layers of the same depth, defined from the surface to the height at which the turbulent kinetic energy (TKE) is zero (in non-penetrative cases) or less than 10% of its maximum value (in penetrative cases). We find that with increasing filter width, the contribution of the filtered flow to the total TKE in the middle of the boundary layer decreases much more rapidly in the penetrative cases than in the non-penetrative cases. In particular, around 20-25% of the TKE at this height comes from small-scale turbulence with a length scale less than or equal to 15% of the boundary layer depth in the CBL, whereas in Rayleigh-Bénard convection, it is just 6-7%. This is consistent with visualisations, which show that entrainment creates additional small-scale mixing within the large-scale circulations in the CBL. Without entrainment, large-scale organisation predominates. Neither spatial nor temporal filtering are as successful at extracting superstructures in the penetrative cases as in the non-penetrative cases. Hence, these techniques depend not on the steadiness of the system, but rather on the presence of entrainment. We therefore intend to try other detection techniques, such as proper orthogonal decomposition, in order to make a rigorous assessment of which is most effective for isolating superstructures in all four cases.

The origin of the superstructure in Bi2Sr2CaCu2O(8+delta) as revealed by scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Kirk, M. D.; Nogami, J.; Baski, A. A.; Mitzi, D. B.; Kapitulnik, A.

1988-12-01

Real-space images with atomic resolution of the BiO plane of Bi2Sr2CaCu2O(8+delta) were obtained with a scanning tunneling microscope. Single-crystal samples were cleaved and imaged under ultrahigh vacuum conditions at room temperature. The images clearly show the one-dimensional incommensurate superstructure along the b-axis that is common to this phase. High-resolution images show the position of the Bi atoms, revelaing the structural nature of the superlattice. A missing row of Bi atoms occurs either every nine or ten atomic sites in both 110-line directions, accounting for the measured incommensurate periodicity of the superstructure. A model is proposed that includes missing rows of atoms, as well as displacements of the atomic positions along both the a- and c-axis directions.

The Origin of the Superstructure in Bi2Sr2CaCu2O8+dgr as Revealed by Scanning Tunneling Microscopy.

PubMed

Kirk, M D; Nogami, J; Baski, A A; Mitzi, D B; Kapitulnik, A; Geballe, T H; Quate, C F

1988-12-23

Real-space images with atomic resolution of the BiO plane of Bi(2)Sr(2)CaCu(2)O(8+delta) were obtained with a scanning tunneling microscope. Single-crystal samples were cleaved and imaged under ultrahigh vacuum conditions at room temperature. The images clearly show the one-dimensional incommensurate superstructure along the b-axis that is common to this phase. High-resolution images show the position of the Bi atoms, revealing the structural nature of the superlattice. A missing row of Bi atoms occurs either every nine or ten atomic sites in both (110) directions, accounting for the measured incommensurate periodicity of the superstructure. A model is proposed that includes missing rows of atoms, as well as displacements of the atomic positions along both the a- and c-axis directions.

Long-range two-dimensional superstructure in the superconducting electron-doped cuprate Pr 0.88 LaCe 0.12 CuO 4

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

Campbell, B. J.; Rosenkranz, S.; Kang, H. J.

2015-07-01

Utilizing single-crystal synchrotron x-ray scattering, we observe distorted CuO 2 planes in the electron- doped superconductor Pr 1-xLaCe xCuO 4+δ , x =0.12. Resolution-limited rods of scattering are indicative of a long-range two-dimensional 2√2 × 2√2 superstructure in the a-b plane, adhering to planar space-group symmetry p4gm, which is subject to stacking disorder perpendicular to the planes. This superstructure is present only in annealed, superconducting samples, but not in the as-grown, nonsuperconducting samples. These long-range distortions of the CuO 2 planes, which are generally considered to be detrimental to superconductivity, have avoided detection to date due to the challenges ofmore » observing and interpreting subtle diffuse-scattering features.« less

Direct observation of electronic-liquid-crystal phase transitions and their microscopic origin in La 1/3Ca 2/3MnO 3

DOE PAGES

Tao, J.; Sun, K.; Yin, W. -G.; ...

2016-11-22

The ground-state electronic order in doped manganites is frequently associated with a lattice modulation, contributing to their many interesting properties. However, measuring the thermal evolution of the lattice superstructure with reciprocal-space probes alone can lead to ambiguous results with competing interpretations. Here, we provide direct observations of the evolution of the superstructure in La 1/3Ca 2/3MnO 3 in real space, as well as reciprocal space, using transmission electron microscopic (TEM) techniques. We show that the transitions are the consequence of a proliferation of dislocations plus electronic phase separation. The resulting states are well described by the symmetries associated with electronic-liquid-crystalmore » (ELC) phases. Furthermore, our results resolve the long-standing controversy over the origin of the incommensurate superstructure and suggest a new structural model that is consistent with recent theoretical calculations.« less

Solar Synthesis of PbS-SnS2 Superstructure Nanoparticles.

PubMed

Brontvein, Olga; Albu-Yaron, Ana; Levy, Moshe; Feuerman, Daniel; Popovitz-Biro, Ronit; Tenne, Reshef; Enyashin, Andrey; Gordon, Jeffrey M

2015-08-25

We report the synthesis and supporting density-functional-theory computations for a closed-cage, misfit layered-compound superstructure from PbS-SnS2, generated by highly concentrated sunlight from a precursor mixture of Pb, SnS2, and graphite. The unique reactor conditions created in our solar furnace are found to be particularly conducive to the formation of these nanomaterials. Detailed structural and chemical characterization revealed a spontaneous inside-out formation mechanism, with a broad range of nonhollow fullerene-like structures starting at a diameter of ∼20 nm and a wall thickness of ∼5 layers. The computations also reveal a counterintuitive charge transfer pathway from the SnS2 layers to the PbS layers, which indicates that, in contrast to binary-layered compounds where it is principally van der Waals forces that hold the layers together, polar forces appear to be as important in stabilizing superstructures of misfit layered compounds.

Numerical Modeling of the Lake Mary Road Bridge for Foundation Reuse Assessment

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

Sitek, M. A.; Bojanowski, C.; Lottes, S. A.

This project uses numerical techniques to assess the structural integrity and capacity of the bridge foundations and, as a result, reduces the risk associated with reusing the same foundation for a new superstructure. Nondestructive test methods of different types were used in combination with the numerical modeling and analysis. The onsite tests included visual inspection, tomography, ground penetrating radar, drilling boreholes and coreholes, and the laboratory tests on recovered samples. The results were utilized to identify the current geometry of the structure with foundation, including the hidden geometry of the abutments and piers, and soil and foundation material properties. Thismore » data was used to build the numerical models and run computational analyses on a high performance computer cluster to assess the structural integrity of the bridge and foundations including the suitability of the foundation for reuse with a new superstructure and traffic that will increase the load on the foundations. Computational analysis is more cost-effective and gives an advantage of getting more detailed knowledge about the structural response. It also enables to go beyond non-destructive testing and find the failure conditions without destroying the structure under consideration.« less

Block-copolymer-controlled growth of CaCO3 microrings.

PubMed

Gao, Yun-Xiang; Yu, Shu-Hong; Cong, Huaiping; Jiang, Jun; Xu, An-Wu; Dong, W F; Cölfen, Helmut

2006-04-06

A novel way for directed solution growth of hollow superstructures of CaCO3 has been successfully developed on the basis of controlled self-assembly and polymer concentration gradients using a double-hydrophilic block copolymer with a hydrophobic modification as a directing agent. A formation mechanism of such rings is proposed on the basis of the formation of CaCO3 nanoparticles in unstructured block copolymer assemblies with subsequent aggregation of these primary nanoparticles. This leads to the formation of a polymer concentration gradient from the inside to the outside of the particle. As the polymer contains multiple chelating units, this leads to a selective dissolution of the center of the particle.

Intracellular modifications induced by poliovirus reduce the requirement for structural motifs in the 5' noncoding region of the genome involved in internal initiation of protein synthesis.

PubMed Central

Percy, N; Belsham, G J; Brangwyn, J K; Sullivan, M; Stone, D M; Almond, J W

1992-01-01

A series of genetic deletions based partly on two RNA secondary structure models (M. A. Skinner, V. R. Racaniello, G. Dunn, J. Cooper, P. D. Minor, and J. W. Almond, J. Mol. Biol. 207:379-392, 1989; E. V. Pilipenko, V. M. Blinov, L. I. Romanova, A. N. Sinyakov, S. V. Maslova, and V. I. Agol, Virology 168:201-209, 1989) was made in the cDNA encoding the 5' noncoding region (5' NCR) of the poliovirus genome in order to study the sequences that direct the internal entry of ribosomes. The modified cDNAs were placed between two open reading frames in a single transcriptional unit and used to transfect cells in culture. Internal entry of ribosomes was detected by measuring translation from the second open reading frame in the bicistronic mRNA. When assayed alone, a large proportion of the poliovirus 5' NCR superstructure including several well-defined stem-loops was required for ribosome entry and efficient translation. However, in cells cotransfected with a complete infectious poliovirus cDNA, the requirement for the stem-loops in this large superstructure was reduced. The results suggest that virus infection modifies the cellular translational machinery, so that shortened forms of the 5' NCR are sufficient for cap-independent translation, and that the internal entry of ribosomes occurs by two distinct modes during the virus replication cycle. Images PMID:1310772

Rotational superstructure in van der Waals heterostructure of self-assembled C 60 monolayer on the WSe 2 surface

DOE PAGES

Santos, Elton J. G.; Scullion, Declan; Chu, Ximo S.; ...

2017-08-23

Hybrid van der Waals (vdW) heterostructures composed of two-dimensional (2D) layered materials and self-assembled organic molecules are promising systems for electronic and optoelectronic applications with enhanced properties and performance. Control of molecular assembly is therefore paramount to fundamentally understand the nucleation, ordering, alignment, and electronic interaction of organic molecules with 2D materials. Here, we report the formation and detailed study of highly ordered, crystalline monolayers of C 60 molecules self-assembled on the surface of WSe 2 in well-ordered arrays with large grain sizes (~5 μm). Using high-resolution scanning tunneling microscopy (STM), we observe a periodic 2 × 2 superstructure inmore » the C 60 monolayer and identify four distinct molecular appearances. Using vdW-corrected ab initio density functional theory (DFT) simulations, we determine that the interplay between vdW and Coulomb interactions as well as adsorbate–adsorbate and adsorbate–substrate interactions results in specific rotational arrangements of the molecules forming the superstructure. The orbital ordering through the relative positions of bonds in adjacent molecules creates a charge redistribution that links the molecule units in a long-range network. Furthermore, this rotational superstructure extends throughout the self-assembled monolayer and opens a pathway towards engineering aligned hybrid organic/inorganic vdW heterostructures with 2D layered materials in a precise and controlled way.« less

Rotational superstructure in van der Waals heterostructure of self-assembled C 60 monolayer on the WSe 2 surface

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

Santos, Elton J. G.; Scullion, Declan; Chu, Ximo S.

Hybrid van der Waals (vdW) heterostructures composed of two-dimensional (2D) layered materials and self-assembled organic molecules are promising systems for electronic and optoelectronic applications with enhanced properties and performance. Control of molecular assembly is therefore paramount to fundamentally understand the nucleation, ordering, alignment, and electronic interaction of organic molecules with 2D materials. Here, we report the formation and detailed study of highly ordered, crystalline monolayers of C 60 molecules self-assembled on the surface of WSe 2 in well-ordered arrays with large grain sizes (~5 μm). Using high-resolution scanning tunneling microscopy (STM), we observe a periodic 2 × 2 superstructure inmore » the C 60 monolayer and identify four distinct molecular appearances. Using vdW-corrected ab initio density functional theory (DFT) simulations, we determine that the interplay between vdW and Coulomb interactions as well as adsorbate–adsorbate and adsorbate–substrate interactions results in specific rotational arrangements of the molecules forming the superstructure. The orbital ordering through the relative positions of bonds in adjacent molecules creates a charge redistribution that links the molecule units in a long-range network. Furthermore, this rotational superstructure extends throughout the self-assembled monolayer and opens a pathway towards engineering aligned hybrid organic/inorganic vdW heterostructures with 2D layered materials in a precise and controlled way.« less

The effect of different screw-tightening techniques on the strain generated on an internal-connection implant superstructure. Part 2: Models created with a splinted impression technique.

PubMed

Choi, Jung-Han

2011-01-01

This study aimed to evaluate the effect of different screw-tightening sequences, torques, and methods on the strains generated on an internal-connection implant (Astra Tech) superstructure with good fit. An edentulous mandibular master model and a metal framework directly connected to four parallel implants with a passive fit to each other were fabricated. Six stone casts were made from a dental stone master model by a splinted impression technique to represent a well-fitting situation with the metal framework. Strains generated by four screw-tightening sequences (1-2-3-4, 4-3-2-1, 2-4-3-1, and 2-3-1-4), two torques (10 and 20 Ncm), and two methods (one-step and two-step) were evaluated. In the two-step method, screws were tightened to the initial torque (10 Ncm) in a predetermined screw-tightening sequence and then to the final torque (20 Ncm) in the same sequence. Strains were recorded twice by three strain gauges attached to the framework (superior face midway between abutments). Deformation data were analyzed using multiple analysis of variance at a .05 level of statistical significance. In all stone casts, strains were produced by connection of the superstructure, regardless of screw-tightening sequence, torque, and method. No statistically significant differences in superstructure strains were found based on screw-tightening sequences (range, -409.8 to -413.8 μm/m), torques (-409.7 and -399.1 μm/m), or methods (-399.1 and -410.3 μm/m). Within the limitations of this in vitro study, screw-tightening sequence, torque, and method were not critical factors for the strain generated on a well-fitting internal-connection implant superstructure by the splinted impression technique. Further studies are needed to evaluate the effect of screw-tightening techniques on the preload stress in various different clinical situations.

7. VIEW NORTHWEST OF 'ISLAND' (TOWER OR SUPERSTRUCTURE) ON THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VIEW NORTHWEST OF 'ISLAND' (TOWER OR SUPERSTRUCTURE) ON THE DECK OF THE AIRCRAFT CARRIER JOHN F. KENNEDY. WHEN THE PHOTOGRAPH WAS TAKEN IN SEPTEMBER 1994, THE KENNEDY WAS IN DRY-DOCK FOR REFURBISHMENT UNDER THE 'SERVICE LIFE EXTENSION PROGRAM (SLEP). THE 'ISLAND' HOUSES THE SHIP'S BRIDGE AND A CONTROL CENTER FOR AIRCRAFT OPERATIONS. EXTENSIVE SCAFFOLDING WAS REQUIRED TO ALLOW FULL ACCESS TO THE PAINTERS AND TECHNICIANS WORKING HERE. - Naval Base Philadelphia-Philadelphia Naval Shipyard, Dry Dock No. 5, League Island, Philadelphia, Philadelphia County, PA

Finite Element and Analytical Analysis of Cracks in Thick Stiffened Plates Repaired with a Single Sided Composite Patch

DTIC Science & Technology

2014-06-01

DC,Tech. Rep. CG-D-05–00, 2000. [16] S. Kou, Welding Metallurgy , 2nd edition, Hoboken: Wiley Interscience, 2003. [17] C. Poe, “Stress intensity...continuous aluminum superstructure welded to the deck. The shape of the superstructure created numerous stress concentration areas. Of the greatest concern...study as it will help provide a conservative estimate. In marine applications almost all stiffening members are attached by welding . Unlike a

Turbulent thermal superstructures in Rayleigh-Bénard convection

NASA Astrophysics Data System (ADS)

Stevens, Richard J. A. M.; Blass, Alexander; Zhu, Xiaojue; Verzicco, Roberto; Lohse, Detlef

2018-04-01

We report the observation of superstructures, i.e., very large-scale and long living coherent structures in highly turbulent Rayleigh-Bénard convection up to Rayleigh Ra=109 . We perform direct numerical simulations in horizontally periodic domains with aspect ratios up to Γ =128 . In the considered Ra number regime the thermal superstructures have a horizontal extend of six to seven times the height of the domain and their size is independent of Ra. Many laboratory experiments and numerical simulations have focused on small aspect ratio cells in order to achieve the highest possible Ra. However, here we show that for very high Ra integral quantities such as the Nusselt number and volume averaged Reynolds number only converge to the large aspect ratio limit around Γ ≈4 , while horizontally averaged statistics such as standard deviation and kurtosis converge around Γ ≈8 , the integral scale converges around Γ ≈32 , and the peak position of the temperature variance and turbulent kinetic energy spectra only converge around Γ ≈64 .

Dynamic cholesteric liquid crystal superstructures photoaligned by one-step polarization holography

NASA Astrophysics Data System (ADS)

Li, Sen-Sen; Shen, Yuan; Chang, Zhen-Ni; Li, Wen-Song; Xu, Yan-Chao; Fan, Xing-Yu; Chen, Lu-Jian

2017-12-01

A convenient approach to modulate the fingerprint textures of methyl red (MR) doped cholesteric liquid crystals by asymmetric photoalignment in the green-light waveband is presented, resulting in the generation of voltage-controllable helical superstructures. The interaction between the MR molecules and the incident light polarization determines the initial twisted planar geometry, providing a multivariant control over the stripe directions of fingerprint textures by applying a proper electric field. The key factors for precise manipulation of fingerprint stripes in a predictable and rewritable manner are analyzed theoretically and investigated experimentally, which involves the alignment asymmetry, the ratio of cell gap to natural pitch length, and the chirality of chiral dopant. Dynamic periodic fingerprint textures in shapes of dashed curve and dashed line are further demonstrated by utilizing a facile one-step polarization holography process using two beams with orthogonal circular and orthogonal linear polarizations, respectively. It is believed that the practical approach described in this study would enrich the research contents of self-assembled hierarchical superstructures using soft liquid crystal building blocks.

Photochemically and Thermally Driven Full-Color Reflection in a Self-Organized Helical Superstructure Enabled by a Halogen-Bonded Chiral Molecular Switch.

PubMed

Wang, Hao; Bisoyi, Hari Krishna; Wang, Ling; Urbas, Augustine M; Bunning, Timothy J; Li, Quan

2018-02-05

Supramolecular approaches toward the fabrication of functional materials and systems have been an enabling endeavor. Recently, halogen bonding has been harnessed as a promising supramolecular tool. Herein we report the synthesis and characterization of a novel halogen-bonded light-driven axially chiral molecular switch. The photoactive halogen-bonded chiral switch is able to induce a self-organized, tunable helical superstructure, that is, cholesteric liquid crystal (CLC), when doped into an achiral liquid crystal (LC) host. The halogen-bonded switch as a chiral dopant has a high helical twisting power (HTP) and shows a large change of its HTP upon photoisomerization. This light-driven dynamic modulation enables reversible selective reflection color tuning across the entire visible spectrum. The chiral switch also displays a temperature-dependent HTP change that enables thermally driven red, green, and blue (RGB) reflection colors in the self-organized helical superstructure. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel symmetrical coralloid Cu 3D superstructures: Solid-state synthesis from a Cu-carboxylate MOF and their in-situ thermal conversion

NASA Astrophysics Data System (ADS)

Chen, Lingyun; Shen, Yongming; Bai, Junfeng; Wang, Chunzhao

2009-08-01

We describe here a one-step solid-state process for the synthesis of metal three-dimensional (3D) superstructures from a metal-organic framework (MOF). Novel symmetrical coralloid Cu 3D superstructures with surface interspersed with clusters of Cu nanoparticles were successfully synthesized by thermolysis of the [Cu 3( btc) 2] ( btc=benzene-1,3,5-tricarboxylato) MOF in a one-end closed horizontal tube furnace (OCTF). The obtained products were characterized by TGA, FT-IR, XRD, EDX, SEM, TEM, HRTEM and SAED. Different reaction conditions were discussed. Furthermore, the synthesized Cu samples were converted into CuO microstructures by in-situ calcination in the air. In addition, the possible formation mechanism was also proposed. This method is a simple and facile route, which builds a direct linkage between metal-carboxylate MOF crystals and metal nano- or microstructures and also opens a new application field of MOFs.

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

Zhao, Haishuang; Krysiak, Yaşar; Hoffmann, Kristin

The crystal structure and disorder phenomena of Al{sub 4}B{sub 2}O{sub 9}, an aluminum borate from the mullite-type family, were studied using automated diffraction tomography (ADT), a recently established method for collection and analysis of electron diffraction data. Al{sub 4}B{sub 2}O{sub 9}, prepared by sol-gel approach, crystallizes in the monoclinic space group C2/m. The ab initio structure determination based on three-dimensional electron diffraction data from single ordered crystals reveals that edge-connected AlO{sub 6} octahedra expanding along the b axis constitute the backbone. The ordered structure (A) was confirmed by TEM and HAADF-STEM images. Furthermore, disordered crystals with diffuse scattering along themore » b axis are observed. Analysis of the modulation pattern implies a mean superstructure (AAB) with a threefold b axis, where B corresponds to an A layer shifted by ½a and ½c. Diffraction patterns simulated for the AAB sequence including additional stacking disorder are in good agreement with experimental electron diffraction patterns. - Graphical abstract: Crystal structure and disorder phenomena of B-rich Al{sub 4}B{sub 2}O{sub 9} studied by automated electron diffraction tomography (ADT) and described by diffraction simulation using DISCUS. - Highlights: • Ab-initio structure solution by electron diffraction from single nanocrystals. • Detected modulation corresponding mainly to three-fold superstructure. • Diffuse diffraction streaks caused by stacking faults in disordered crystals. • Observed streaks explained by simulated electron diffraction patterns.« less

Nonstoichiometric control of tunnel-filling order, thermal expansion, and dielectric relaxation in tetragonal tungsten Bronzes Ba0.5-xTaO3-x.

PubMed

Pan, Fengjuan; Li, Xiaohui; Lu, Fengqi; Wang, Xiaoming; Cao, Jiang; Kuang, Xiaojun; Véron, Emmanuel; Porcher, Florence; Suchomel, Matthew R; Wang, Jing; Allix, Mathieu

2015-09-21

Ordering of interpolated Ba(2+) chains and alternate Ta-O rows (TaO)(3+) in the pentagonal tunnels of tetragonal tungsten bronzes (TTB) is controlled by the nonstoichiometry in the highly nonstoichiometric Ba0.5-xTaO3-x system. In Ba0.22TaO2.72, the filling of Ba(2+) and (TaO)(3+) groups is partially ordered along the ab-plane of the simple TTB structure, resulting in a √2-type TTB superstructure (Pbmm), while in Ba0.175TaO2.675, the pentagonal tunnel filling is completely ordered along the b-axis of the simple TTB structure, leading to a triple TTB superstructure (P21212). Both superstructures show completely empty square tunnels favoring Ba(2+) conduction and feature unusual accommodation of Ta(5+) cations in the small triangular tunnels. In contrast with stoichiometric Ba6GaTa9O30, which shows linear thermal expansion of the cell parameters and monotonic decrease of permittivity with temperature within 100-800 K, these TTB superstructures and slightly nonstoichiometric simple TTB Ba0.4TaO2.9 display abnormally broad and frequency-dependent extrinsic dielectric relaxations in 10(3)-10(5) Hz above room temperature, a linear deviation of the c-axis thermal expansion around 600 K, and high dielectric permittivity ∼60-95 at 1 MHz at room temperature.

Observation of polar order and thermochromic behaviour in a chiral bent-core system exhibiting exotic mesophases due to superstructural frustration.

PubMed

Punjani, Vidhika; Mohiuddin, Golam; Kaur, Supreet; Khan, Raj Kumar; Ghosh, Sharmistha; Pal, Santanu Kumar

2018-04-03

A new approach accompanied by superstructural frustration is reported. By attaching a cholesterol moiety directly to the central bent-core system it displayed exotic BPIII, BPII/I, Ncyb*, TGBA, SmAPA, SmA and SmX phases as shown by X-ray scattering results. While higher homologues of the series exhibited spontaneous formation of polar order (Ps ∼ 61 nC cm-2) upon applied voltage, the lower homologues showed thermochromic behaviour which can also be trapped via temperature quenching.

Experimental investigation of colorless ONU employing superstructured fiber Bragg gratings in WDM/OCDMA-PON

NASA Astrophysics Data System (ADS)

Wang, Dawei; Cheng, Liang; Chen, Biao

2009-11-01

Colorless optical network unit (ONU) is a very important concept for the wavelength division multiplexing (WDM) based passive optical networks (PON). We present a novel scheme to construct non-wavelength-selective ONUs in WDM/OCDMA-PON by making use of the broad spectrum band of superstructure fiber Bragg gratings (SSFBGs). The experiment results reveal that the spectrum-sliced encoded signals from different wavelength channels can be successfully decoded with the same SSFBGs, and thus the proposed colorless ONU scheme is proved to be feasible.

Simplified procedure for encapsulating cytochrome c in silica aerogel nanoarchitectures while retaining gas-phase bioactivity.

PubMed

Harper-Leatherman, Amanda S; Iftikhar, Mariam; Ndoi, Adela; Scappaticci, Steven J; Lisi, George P; Buzard, Kaitlyn L; Garvey, Elizabeth M

2012-10-16

Cytochrome c (cyt. c) has been encapsulated in silica sol-gels and processed to form bioaerogels with gas-phase activity for nitric oxide through a simplified synthetic procedure. Previous reports demonstrated a need to adsorb cyt. c to metal nanoparticles prior to silica sol-gel encapsulation and processing to form aerogels. We report that cyt. c can be encapsulated in aerogels without added nanoparticles and retain structural stability and gas-phase activity for nitric oxide. While the UV-visible Soret absorbance and nitric oxide response indicate that cyt. c encapsulated with nanoparticles in aerogels remains slightly more stable and functional than cyt. c encapsulated alone, these properties are not very different in the two types of aerogels. From UV-visible and Soret circular dichroism results, we infer that cyt. c encapsulated alone self-organizes to reduce contact with the silica gel in a way that may bear at least some resemblance to the way cyt. c self-organizes into superstructures of protein within aerogels when nanoparticles are present. Both the buffer concentration and the cyt. c concentration of solutions used to synthesize the bioaerogels affect the structural integrity of the protein encapsulated alone within the dried aerogels. Optimized bioaerogels are formed when cyt. c is encapsulated from 40 mM phosphate buffered solutions, and when the loaded cyt. c concentration in the aerogel is in the range of 5 to 15 μM. Increased viability of cyt. c in aerogels is also observed when supercritical fluid used to produce aerogels is vented over relatively long times.

Observation of Vacancies, Faults, and Superstructures in Ln5Mo2O12 (Ln = La, Y, and Lu) Compounds with Direct Mo-Mo Bonding.

PubMed

Colabello, Diane M; Sobalvarro, Elizabeth M; Sheckelton, John P; Neuefeind, Joerg C; McQueen, Tyrel M; Khalifah, Peter G

2017-11-06

Among oxide compounds with direct metal-metal bonding, the Y 5 Mo 2 O 12 (A 5 B 2 O 12 ) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B 2 O 10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal-metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal-metal bonding have integer oxidation states resulting from the lifting of orbital degeneracy typically induced by the metal-metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln 5 Mo 2 O 12 (Ln = La-Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo 2 O 10 and LaO 6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1-2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La 5 Mo 2 O 11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. This represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one-dimensional octahedral chains of this system.

Observation of Vacancies, Faults, and Superstructures in Ln 5Mo 2O 12 (Ln = La, Y, and Lu) Compounds with Direct Mo–Mo Bonding

DOE PAGES

Colabello, Diane M.; Sobalvarro, Elizabeth M.; Sheckelton, John P.; ...

2017-10-26

Among oxide compounds with direct metal–metal bonding, the Y 5Mo 2O 12 (A 5B 2O 12) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B 2O 10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal–metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal–metal bonding have integer oxidation states resulting from the lifting of orbital degeneracymore » typically induced by the metal–metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln 5Mo 2O 12 (Ln = La–Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown in this paper that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo 2O 10 and LaO 6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1–2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La 5Mo 2O 11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. Finally, this represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one-dimensional octahedral chains of this system.« less

Observation of Vacancies, Faults, and Superstructures in Ln 5Mo 2O 12 (Ln = La, Y, and Lu) Compounds with Direct Mo–Mo Bonding

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

Colabello, Diane M.; Sobalvarro, Elizabeth M.; Sheckelton, John P.

Among oxide compounds with direct metal–metal bonding, the Y 5Mo 2O 12 (A 5B 2O 12) structural family of compounds has a particularly intriguing low-dimensional structure due to the presence of bioctahedral B 2O 10 dimers arranged in one-dimensional edge-sharing chains along the direction of the metal–metal bonds. Furthermore, these compounds can have a local magnetic moment due to the noninteger oxidation state (+4.5) of the transition metal, in contrast to the conspicuous lack of a local moment that is commonly observed when oxide compounds with direct metal–metal bonding have integer oxidation states resulting from the lifting of orbital degeneracymore » typically induced by the metal–metal bonding. Although a monoclinic C2/m structure has been previously proposed for Ln 5Mo 2O 12 (Ln = La–Lu and Y) members of this family based on prior single crystal diffraction data, it is found that this structural model misses many important structural features. On the basis of synchrotron powder diffraction data, it is shown in this paper that the C2/m monoclinic unit cell represents a superstructure relative to a previously unrecognized orthorhombic Immm subcell and that the superstructure derives from the ordering of interchangeable Mo 2O 10 and LaO 6 building blocks. The superstructure for this reason is typically highly faulted, as evidenced by the increased breadth of superstructure diffraction peaks associated with a coherence length of 1–2 nm in the c* direction. Finally, it is shown that oxygen vacancies can occur when Ln = La, producing an oxygen deficient stoichiometry of La 5Mo 2O 11.55 and an approximately 10-fold reduction in the number of unpaired electrons due to the reduction of the average Mo valence from +4.5 to +4.05, a result confirmed by magnetic susceptibility measurements. Finally, this represents the first observation of oxygen vacancies in this family of compounds and provides an important means of continuously tuning the magnetic interactions within the one-dimensional octahedral chains of this system.« less

Seismic response evaluation of base-isolated reinforced concrete buildings under bidirectional excitation

NASA Astrophysics Data System (ADS)

Bhagat, Satish; Wijeyewickrema, Anil C.

2017-04-01

This paper reports on an investigation of the seismic response of base-isolated reinforced concrete buildings, which considers various isolation system parameters under bidirectional near-fault and far-fault motions. Three-dimensional models of 4-, 8-, and 12-story base-isolated buildings with nonlinear effects in the isolation system and the superstructure are investigated, and nonlinear response history analysis is carried out. The bounding values of isolation system properties that incorporate the aging effect of isolators are also taken into account, as is the current state of practice in the design and analysis of base-isolated buildings. The response indicators of the buildings are studied for near-fault and far-fault motions weight-scaled to represent the design earthquake (DE) level and the risk-targeted maximum considered earthquake (MCER) level. Results of the nonlinear response history analyses indicate no structural damage under DE-level motions for near-fault and far-fault motions and for MCER-level far-fault motions, whereas minor structural damage is observed under MCER-level near-fault motions. Results of the base-isolated buildings are compared with their fixed-base counterparts. Significant reduction of the superstructure response of the 12-story base-isolated building compared to the fixed-base condition indicates that base isolation can be effectively used in taller buildings to enhance performance. Additionally, the applicability of a rigid superstructure to predict the isolator displacement demand is also investigated. It is found that the isolator displacements can be estimated accurately using a rigid body model for the superstructure for the buildings considered.

Imprint of DES superstructures on the cosmic microwave background

DOE PAGES

Kovács, A.; Sánchez, C.; García-Bellido, J.; ...

2016-11-17

Here, small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshiftsmore » $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $$\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$$ and a hot imprint of superclusters $$\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$$ ; this is $$\\sim1.2\\sigma$$ higher than the expected $$|\\Delta T_{f}| \\approx 0.6~\\mu K$$ imprint of such super-structures in $$\\Lambda$$CDM. If we instead use an a posteriori selected filter size ($$R/R_{v}=0.6$$), we can find a temperature decrement as large as $$\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$$ for voids, which is $$\\sim2\\sigma$$ above $$\\Lambda$$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.« less

Imprint of DES superstructures on the cosmic microwave background

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

Kovács, A.; Sánchez, C.; García-Bellido, J.

Here, small temperature anisotropies in the Cosmic Microwave Background can be sourced by density perturbations via the late-time integrated Sachs-Wolfe effect. Large voids and superclusters are excellent environments to make a localized measurement of this tiny imprint. In some cases excess signals have been reported. We probed these claims with an independent data set, using the first year data of the Dark Energy Survey in a different footprint, and using a different super-structure finding strategy. We identified 52 large voids and 102 superclusters at redshiftsmore » $0.2 < z < 0.65$. We used the Jubilee simulation to a priori evaluate the optimal ISW measurement configuration for our compensated top-hat filtering technique, and then performed a stacking measurement of the CMB temperature field based on the DES data. For optimal configurations, we detected a cumulative cold imprint of voids with $$\\Delta T_{f} \\approx -5.0\\pm3.7~\\mu K$$ and a hot imprint of superclusters $$\\Delta T_{f} \\approx 5.1\\pm3.2~\\mu K$$ ; this is $$\\sim1.2\\sigma$$ higher than the expected $$|\\Delta T_{f}| \\approx 0.6~\\mu K$$ imprint of such super-structures in $$\\Lambda$$CDM. If we instead use an a posteriori selected filter size ($$R/R_{v}=0.6$$), we can find a temperature decrement as large as $$\\Delta T_{f} \\approx -9.8\\pm4.7~\\mu K$$ for voids, which is $$\\sim2\\sigma$$ above $$\\Lambda$$CDM expectations and is comparable to previous measurements made using SDSS super-structure data.« less

Collapse Mechanism Analysis in the Design of Superstructure Vehicle

NASA Astrophysics Data System (ADS)

Mohd Nor, M. K.

2016-11-01

The EU directive 2001/85/EC is an official European text which describes the specifications for “single deck class II and III vehicles” required to be approved by the regulation UN/ECE no.66 (R66). To prevent the catastrophic consequences by occupant during an accident, the Malaysian government has reinforced the same regulation upon superstructure construction. This paper discusses collapse mechanism analysis of a superstructure vehicle using a Crash D nonlinear analysis computer program based on this regulation. The analysis starts by hand calculation to define the required energy absorption by the chosen structure. Simple calculations were then performed to define the weakest collapse mechanism after undesirable collapse modes are eliminated. There are few factors highlighted in this work to pass the regulation. Using the selected cross section, Crash D simulation showed a good result. Generally, the deformation is linearly correlates to the energy absorption for the structure with low stiffness. Failure of critical members such as vertical lower side wall must be avoided to sustain safety of the passenger compartment and prevent from severe and fatal injuries to the trapped occupant.

Nonlinear analysis of collapse mechanism in superstructure vehicle

NASA Astrophysics Data System (ADS)

Nor, M. K. Mohd; Ho, C. S.; Ma'at, N.

2017-04-01

The EU directive 2001/85/EC is an official European text which describes the specifications for "single deck class II and III vehicles" required to be approved by the regulation UN/ECE no.66 (R66). To prevent the catastrophic consequences by occupant during an accident, the Malaysian government has reinforced the same regulation upon superstructure construction. This paper discusses collapse mechanism analysis of a superstructure vehicle using a Crash D nonlinear analysis computer program based on this regulation. The analysis starts by hand calculation to define the required energy absorption by the chosen structure. Simple calculations were then performed to define the weakest collapse mechanism after undesirable collapse modes are eliminated. There are few factors highlighted in this work to pass the regulation. Using the selected cross section, Crash D simulation showed a good result. Generally, the deformation is linearly correlates to the energy absorption for the structure with low stiffness. Failure of critical members such as vertical lower side wall must be avoided to sustain safety of the passenger compartment and prevent from severe and fatal injuries to the trapped occupant.

The influence of tightening sequence and method on screw preload in implant superstructures.

PubMed

Al-Sahan, Maha M; Al Maflehi, Nassr S; Akeel, Riyadh F

2014-01-01

This study evaluated the effect of six screw-tightening sequences and two tightening methods on the screw preload in implant-supported superstructures. The preload was measured using strain gauges following the screw tightening of a metal framework connected to four implants. The experiment included six sequences ([1] 1-2-3-4, [2] 4-2-3-1, [3] 4-3-1-2, [4] 1-4-2-3, [5] 2-3-4-1, and [6] 3-2-4-1), two methods (onestep, three-step), and five replications. Significant differences were found between tightening sequences and methods. In the three-step method, a higher total preload was found in sequences 2 (312 ± 85 N), 3 (246 ± 54 N), and 4 (310 ± 96 N). In the one-step method, a higher total preload was found in sequences 1 (286 ± 94 N), 5 (764 ± 142 N), and 6 (350 ± 69 N). It is concluded that the highest total screw preload was achieved when anterior implants of the superstructure were first tightened in one step, followed by posterior implants.

Bipartite electronic superstructures in the vortex core of Bi2Sr2CaCu2O8+δ

PubMed Central

Machida, T.; Kohsaka, Y.; Matsuoka, K.; Iwaya, K.; Hanaguri, T.; Tamegai, T.

2016-01-01

The central issue in the physics of cuprate superconductivity is the mutual relationship among superconductivity, pseudogap and broken-spatial-symmetry states. A magnetic field B suppresses superconductivity, providing an opportunity to investigate the competition among these states. Although various B-induced electronic superstructures have been reported, their energy, spatial and momentum-space structures are unclear. Here, we show using spectroscopic-imaging scanning tunnelling microscopy on Bi2Sr2CaCu2O8+δ that there are two distinct B-induced electronic superstructures, both being localized in the vortex core but appearing at different energies. In the low-energy range where the nodal Bogoliubov quasiparticles are well-defined, we observe the so-called vortex checkerboard that we identify as the B-enhanced quasiparticle interference pattern. By contrast, in the high-energy region where the pseudogap develops, the broken-spatial-symmetry patterns that pre-exist at B=0 T is locally enhanced in the vortex core. This evidences the competition between superconductivity and the broken-spatial-symmetry state that is associated with the pseudogap. PMID:27230420

Superstructures and multijunction cells for high efficiency energy conversion

NASA Technical Reports Server (NTRS)

Wagner, M.; Leburton, J. P.

1985-01-01

Potential applications of superlattices to photovoltaic structures are discussed. A single-bandgap, multijunction cell with selective electrodes for lateral transport of collected carriers is proposed. The concept is based on similar doping superlattice (NIPI) structures. Computer simulations show that by reducing bulk recombination losses, the spectral response of such cells is enhanced, particularly for poor quality materials with short diffusion lengths. Dark current contributions of additional junctions result in a trade-off between short-circuit current and open-circuit voltage as the number of layers is increased. One or two extra junctions appear to be optimal.

Intermixing behaviors of PCBM with CuPc on Au(1 1 1) surface

NASA Astrophysics Data System (ADS)

Masui, Akane; Sakaue, Hiroyuki; Takahagi, Takayuki; Suzuki, Hitoshi

2016-09-01

The behavior of phenyl-C61-butyric acid methyl ester (PCBM) and copper-phthalocyanine (CuPc) on a Au(1 1 1) surface was investigated using scanning tunneling microscopy (STM). When CuPc was deposited in addition to PCBM it entered and disturbed the regularly spaced double row superstructure of the PCBM molecules. PCBM intermixed with CuPc to form a new square shaped superstructure that consisted of six to eight PCBM molecules with a CuPc molecule in its center. The intermixing of these materials that was observed indicated that they possessed an attractive interaction.

First-principles study of giant thermoelectric power in incommensurate TlInSe2

NASA Astrophysics Data System (ADS)

Ishikawa, M.; Nakayama, T.; Wakita, K.; Shim, Y. G.; Mamedov, N.

2018-04-01

Ternary thallium compound TlInSe2 exhibits a giant Seebeck effect below around 410 K, where Tl atoms form one dimensional incommensurate (IC) arrays. To clarify the origin of large thermoelectric power in the IC phase, the electronic properties of Tl-atom super-structured TlInSe2 were studied using the first-principles calculations. It was shown that the super-structures induce strong binding states between Se-p orbitals in the nearest neighboring layers and produce large density of states near lower conduction bands, which might be one of the origins to produce large thermoelectric power.

Superstructures and Electronic Properties of Manganese-Phthalocyanine Molecules on Au(110) from Submonolayer Coverage to Ultrathin Molecular Films.

PubMed

Topyła, M; Néel, N; Kröger, J

2016-07-12

The adsorption of manganese-phthalocyanine molecules on Au(110) was investigated using a low-temperature scanning tunneling microscope. A rich variety of commensurate superstructures was observed upon increasing the molecule coverage from submonolayers to ultrathin films. All structures were associated with reconstructions of the Au(110) substrate. Molecules adsorbed in the second molecular layer exhibited negative differential conductance occurring symmetrically around zero bias voltage. A double-barrier tunneling model rationalized this observation in terms of a peaked molecular resonance at the Fermi energy together with a voltage drop across the molecular film.

In situ growth of CuInS2 nanocrystals on nanoporous TiO2 film for constructing inorganic/organic heterojunction solar cells

PubMed Central

2013-01-01

Inorganic/organic heterojunction solar cells (HSCs) have attracted increasing attention as a cost-effective alternative to conventional solar cells. This work presents an HSC by in situ growth of CuInS2(CIS) layer as the photoabsorption material on nanoporous TiO2 film with the use of poly(3-hexylthiophene) (P3HT) as hole-transport material. The in situ growth of CIS nanocrystals has been realized by solvothermally treating nanoporous TiO2 film in ethanol solution containing InCl3 · 4H2O, CuSO4 · 5H2O, and thioacetamide with a constant concentration ratio of 1:1:2. InCl3 concentration plays a significant role in controlling the surface morphology of CIS layer. When InCl3 concentration is 0.1 M, there is a layer of CIS flower-shaped superstructures on TiO2 film, and CIS superstructures are in fact composed of ultrathin nanoplates as ‘petals’ with plenty of nanopores. In addition, the nanopores of TiO2 film are filled by CIS nanocrystals, as confirmed using scanning electron microscopy image and by energy dispersive spectroscopy line scan analysis. Subsequently, HSC with a structure of FTO/TiO2/CIS/P3HT/PEDOT:PSS/Au has been fabricated, and it yields a power conversion efficiency of 1.4%. Further improvement of the efficiency can be expected by the optimization of the morphology and thickness of CIS layer and the device structure. PMID:23947562

pH-Sensitive polymer assisted self-aggregation of bis(pyrene) in living cells in situ with turn-on fluorescence

NASA Astrophysics Data System (ADS)

Duan, Zhongyu; Gao, Yu-Juan; Qiao, Zeng-Ying; Qiao, Shenglin; Wang, Yongmei; Hou, Chunyuan; Wang, Lei; Wang, Hao

2015-09-01

Supramolecular self-assemblies with various nanostructures in organic and aqueous solutions have been prepared with desired functions. However, in situ construction of self-assembled superstructures in physiological conditions to achieve expected biological functions remains a challenge. Here, we report a supramolecular system to realize the in situ formation of nanoaggregates in living cells. The bis(pyrene) monomers were dispersed inside of hydrophobic domains of pH-sensitive polymeric micelles and delivered to the lysosomes of cells. In the acidic lysosomes, the bis(pyrene) monomers were released and self-aggregated with turn-on fluorescence. We envision this strategy for in situ construction of supramolecular nanostructures in living cells will pave the way for molecular diagnostics in the future.

Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva

PubMed Central

Mellado-Valero, Ana; Igual Muñoz, Anna; Guiñón Pina, Virginia

2018-01-01

The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys. PMID:29361767

Electrochemical Behaviour and Galvanic Effects of Titanium Implants Coupled to Metallic Suprastructures in Artificial Saliva.

PubMed

Mellado-Valero, Ana; Muñoz, Anna Igual; Pina, Virginia Guiñón; Sola-Ruiz, Ma Fernanda

2018-01-22

The aim of the present study is to analyze the electrochemical behavior of five different dental alloys: two cobalt-chromium alloys (CoCr and CoCr-c), one nickel-chromium-titanium alloy (NiCrTi), one gold-palladium alloy (Au), and one titanium alloy (Ti6Al4V), and the galvanic effect when they are coupled to titanium implants (TiG2). It was carried out by electrochemical techniques (open circuit measurements, potentiodynamic curves and Zero-Resistance Ammetry) in artificial saliva (AS), with and without fluorides in different acidic conditions. The studied alloys are spontaneously passivated, but NiCrTi alloy has a very narrow passive domain and losses its passivity in presence of fluorides, so is not considered as a good option for implant superstructures. Variations of pH from 6.5 to 3 in artificial saliva do not change the electrochemical behavior of Ti, Ti6Al4V, and CoCr alloys, and couples, but when the pH of the artificial saliva is below 3.5 and the fluoride content is 1000 ppm Ti and Ti6Al4V starts actively dissolving, and CoCr-c superstructures coupled to Ti show acceleration of corrosion due to galvanic effects. Thus, NiCrTi is not recommended for implant superstructures because of risk of Ni ion release to the body, and fluorides should be avoided in acidic media because Ti, Ti6Al4V, and CoCr-c superstructures show galvanic corrosion. The best combinations are Ti/Ti6Al4V and Ti/CoCr as alternative of noble gold alloys.

Application of an ecological framework to examine barriers to the adoption of safer conception strategies by HIV-affected couples.

PubMed

Saleem, Haneefa T; Surkan, Pamela J; Kerrigan, Deanna; Kennedy, Caitlin E

2016-01-01

Safer conception interventions can significantly reduce the risk of horizontal HIV transmission between HIV-serodiscordant partners. However, prior to implementing safer conception interventions, it is essential to understand potential barriers to their adoption so that strategies can be developed to overcome these barriers. This paper examines potential barriers to the adoption of safer conception strategies by HIV-affected couples in Iringa, Tanzania using an ecological framework. We interviewed 30 HIV-positive women, 30 HIV-positive men and 30 health providers engaged in delivering HIV-related services. We also conducted direct observations at five health facilities. Findings suggest that there are multiple barriers to safer conception that operate at the individual, relational, environmental, structural, and super-structural levels. The barriers to safer conception identified are complex and interact across these levels. Barriers at the individual level included antiretroviral adherence, knowledge of HIV status, knowledge and acceptability of safer conception strategies, and poor nutrition. At the relational level, unplanned pregnancies, non-disclosure of status, gendered power dynamics within relationships, and patient-provider interactions posed a threat to safer conception. HIV stigma and distance to health facilities were environmental barriers to safer conception. At the structural level there were multiple barriers to safer conception, including limited safer conception policy guidelines for people living with HIV (PLHIV), lack of health provider training in safer conception strategies and preconception counseling for PLHIV, limited resources, and lack of integration of HIV and sexual and reproductive health services. Poverty and gender norms were super-structural factors that influenced and reinforced barriers to safer conception, which influenced and operated across different levels of the framework. Multi-level interventions are needed to ensure adoption of safer conception strategies and reduce the risk of HIV transmission between partners within HIV-serodiscordant couples.

Seismic isolation of small modular reactors using metamaterials

NASA Astrophysics Data System (ADS)

Witarto, Witarto; Wang, S. J.; Yang, C. Y.; Nie, Xin; Mo, Y. L.; Chang, K. C.; Tang, Yu; Kassawara, Robert

2018-04-01

Adaptation of metamaterials at micro- to nanometer scales to metastructures at much larger scales offers a new alternative for seismic isolation systems. These new isolation systems, known as periodic foundations, function both as a structural foundation to support gravitational weight of the superstructure and also as a seismic isolator to isolate the superstructure from incoming seismic waves. Here we describe the application of periodic foundations for the seismic protection of nuclear power plants, in particular small modular reactors (SMR). For this purpose, a large-scale shake table test on a one-dimensional (1D) periodic foundation supporting an SMR building model was conducted. The 1D periodic foundation was designed and fabricated using reinforced concrete and synthetic rubber (polyurethane) materials. The 1D periodic foundation structural system was tested under various input waves, which include white noise, stepped sine and seismic waves in the horizontal and vertical directions as well as in the torsional mode. The shake table test results show that the 1D periodic foundation can reduce the acceleration response (transmissibility) of the SMR building up to 90%. In addition, the periodic foundation-isolated structure also exhibited smaller displacement than the non-isolated SMR building. This study indicates that the challenge faced in developing metastructures can be overcome and the periodic foundations can be applied to isolating vibration response of engineering structures.

Modelling the growth of plants with a uniform growth logistics.

PubMed

Kilian, H G; Bartkowiak, D; Kazda, M; Kaufmann, D

2014-05-21

The increment model has previously been used to describe the growth of plants in general. Here, we examine how the same logistics enables the development of different superstructures. Data from the literature are analyzed with the increment model. Increments are growth-invariant molecular clusters, treated as heuristic particles. This approach formulates the law of mass action for multi-component systems, describing the general properties of superstructures which are optimized via relaxation processes. The daily growth patterns of hypocotyls can be reproduced implying predetermined growth invariant model parameters. In various species, the coordinated formation and death of fine roots are modeled successfully. Their biphasic annual growth follows distinct morphological programs but both use the same logistics. In tropical forests, distributions of the diameter in breast height of trees of different species adhere to the same pattern. Beyond structural fluctuations, competition and cooperation within and between the species may drive optimization. All superstructures of plants examined so far could be reproduced with our approach. With genetically encoded growth-invariant model parameters (interaction with the environment included) perfect morphological development runs embedded in the uniform logistics of the increment model. Copyright © 2014 Elsevier Ltd. All rights reserved.

N ,N'-dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

NASA Astrophysics Data System (ADS)

Fendrich, Markus; Lange, Manfred; Weiss, Christian; Kunstmann, Tobias; Möller, Rolf

2009-05-01

The growth of N ,N'-dimethylperylene-3,4,9,10-bis(dicarboximide) (DiMe-PTCDI) on KBr(001) and NaCl(001) surfaces has been studied. Experimental results have been achieved using frequency modulation atomic force microscopy at room temperature under ultrahigh vacuum conditions. On both substrates, DiMe-PTCDI forms molecular wires with a width of 10nm, typically, and a length of up to 600nm at low coverages. All wires grow along either the [110] direction (or [11¯0] direction, respectively) of the alkali halide (001) substrates. There is no wetting layer of molecules: atomic resolution of the substrates can be achieved between the wires. The wires are mobile on KBr but substantially more stable on NaCl. A p(2×2) superstructure in a brickwall arrangement on the ionic crystal surfaces is proposed based on electrostatic considerations. Calculations and Monte Carlo simulations using empirical potentials reveal possible growth mechanisms for molecules within the first layer for both substrates, also showing a significantly higher binding energy for NaCl(001). For KBr, the p(2×2) superstructure is confirmed by the simulations; for NaCl, a less dense, incommensurate superstructure is predicted.

Monitoring system of arch bridge for safety network management

NASA Astrophysics Data System (ADS)

Joo, Bong Chul; Yoo, Young Jun; Lee, Chin Hyung; Park, Ki Tae; Hwang, Yoon Koog

2010-03-01

Korea has constructed the safety management network monitoring test systems for the civil infrastructure since 2006 which includes airport structure, irrigation structure, railroad structure, road structure, and underground structure. Bridges among the road structure include the various superstructure types which are Steel box girder bridge, suspension bridge, PSC-box-girder bridge, and arch bridge. This paper shows the process of constructing the real-time monitoring system for the arch bridge and the measured result by the system. The arch type among various superstructure types has not only the structural efficiency but the visual beauty, because the arch type superstructure makes full use of the feature of curve. The main measuring points of arch bridges composited by curved members make a difference to compare with the system of girder bridges composited by straight members. This paper also shows the method to construct the monitoring system that considers the characteristic of the arch bridge. The system now includes strain gauges and thermometers, and it will include various sensor types such as CCTV, accelerometers and so on additionally. For the long term and accuracy monitoring, the latest optical sensors and equipments are applied to the system.

Stimuli-Driven Control of the Helical Axis of Self-Organized Soft Helical Superstructures.

PubMed

Bisoyi, Hari Krishna; Bunning, Timothy J; Li, Quan

2018-06-01

Supramolecular and macromolecular functional helical superstructures are ubiquitous in nature and display an impressive catalog of intriguing and elegant properties and performances. In materials science, self-organized soft helical superstructures, i.e., cholesteric liquid crystals (CLCs), serve as model systems toward the understanding of morphology- and orientation-dependent properties of supramolecular dynamic helical architectures and their potential for technological applications. Moreover, most of the fascinating device applications of CLCs are primarily determined by different orientations of the helical axis. Here, the control of the helical axis orientation of CLCs and its dynamic switching in two and three dimensions using different external stimuli are summarized. Electric-field-, magnetic-field-, and light-irradiation-driven orientation control and reorientation of the helical axis of CLCs are described and highlighted. Different techniques and strategies developed to achieve a uniform lying helix structure are explored. Helical axis control in recently developed heliconical cholesteric systems is examined. The control of the helical axis orientation in spherical geometries such as microdroplets and microshells fabricated from these enticing photonic fluids is also explored. Future challenges and opportunities in this exciting area involving anisotropic chiral liquids are then discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Failure behavior of concrete pile and super-structure dynamic response as a result of soil liquefaction during earthquake

NASA Astrophysics Data System (ADS)

Kaneda, Shogo; Hayashi, Kazuhiro; Hachimori, Wataru; Tamura, Shuji; Saito, Taiki

2017-10-01

In past earthquake disasters, numerous building structure piles were damaged by soil liquefaction occurring during the earthquake. Damage to these piles, because they are underground, is difficult to find. The authors aim to develop a monitoring method of pile damage based on superstructure dynamic response. This paper investigated the relationship between the damage of large cross section cementitious piles and the dynamic response of the super structure using a centrifuge test apparatus. A dynamic specimen used simple cross section pile models consisting of aluminum rod and mortar, a saturated soil (Toyoura sand) of a relative density of 40% and a super structure model of a natural period of 0.63sec. In the shaking table test under a 50G field (length scale of 1/50), excitation was a total of 3 motions scaled from the Rinkai wave at different amplitudes. The maximum acceleration of each of the excitations was 602gal, 336gal and 299gal. The centrifuge test demonstrated the liquefaction of saturated soil and the failure behavior of piles. In the test result, the damage of piles affected the predominant period of acceleration response spectrum on the footing of the superstructure.

Rapid Sintering of Li₂O-Nb₂O₅-TiO₂ Solid Solution by Air Pressure Control and Clarification of Its Mechanism.

PubMed

Nakano, Hiromi; Kamimoto, Konatsu; Yamamoto, Takahisa; Furuta, Yoshio

2018-06-11

We first successfully synthesized Li 1+ x − y Nb 1− x −3 y Ti x +4 y O₃ (LNT) solid solutions (0.13 ≤ x ≤ 0.18, 0 ≤ y ≤ 0.06) rapidly at 1373 K for one hour under 0.35 MPa by the controlling of air pressure using an air-pressure control atmosphere furnace. The composition is a formation area of a superstructure for LNT, in which the periodical intergrowth layer was formed in the matrix, and where it can be controlled by Ti content. Therefore, the sintering time depended on Ti content, and annealing was repeated for over 24 h until a homogeneous structure was formed using a conventional electric furnace. We clarified the mechanism of the rapid sintering using various microscale to nanoscale characterization techniques: X-ray diffraction, a scanning electron microscope, a transmission electron microscope (TEM), a Cs-corrected scanning TEM equipped with electron energy-loss spectroscopy, and X-ray absorption fine structure spectroscopy.

Evolving concepts of lunar architecture: The potential of subselene development

NASA Technical Reports Server (NTRS)

Daga, Andrew W.; Daga, Meryl A.; Wendel, Wendel R.

1992-01-01

In view of the superior environmental and operational conditions that are thought to exist in lava tubes, popular visions of permanent settlements built upon the lunar surface may prove to be entirely romantic. The factors that will ultimately come together to determine the design of a lunar base are complex and interrelated, and they call for a radical architectural solution. Whether lunar surface-deployed superstructures can answer these issues is called into question. One particularly troublesome concern in any lunar base design is the need for vast amounts of space, and the ability of man-made structures to provide such volumes in a reliable pressurized habitat is doubtful. An examination of several key environmental design issues suggests that the alternative mode of subselene development may offer the best opportunity for an enduring and humane settlement.

Colloidal alloys with preassembled clusters and spheres.

PubMed

Ducrot, Étienne; He, Mingxin; Yi, Gi-Ra; Pine, David J

2017-06-01

Self-assembly is a powerful approach for constructing colloidal crystals, where spheres, rods or faceted particles can build up a myriad of structures. Nevertheless, many complex or low-coordination architectures, such as diamond, pyrochlore and other sought-after lattices, have eluded self-assembly. Here we introduce a new design principle based on preassembled components of the desired superstructure and programmed nearest-neighbour DNA-mediated interactions, which allows the formation of otherwise unattainable structures. We demonstrate the approach using preassembled colloidal tetrahedra and spheres, obtaining a class of colloidal superstructures, including cubic and tetragonal colloidal crystals, with no known atomic analogues, as well as percolating low-coordination diamond and pyrochlore sublattices never assembled before.

System design optimization for stand-alone photovoltaic systems sizing by using superstructure model

NASA Astrophysics Data System (ADS)

Azau, M. A. M.; Jaafar, S.; Samsudin, K.

2013-06-01

Although the photovoltaic (PV) systems have been increasingly installed as an alternative and renewable green power generation, the initial set up cost, maintenance cost and equipment mismatch are some of the key issues that slows down the installation in small household. This paper presents the design optimization of stand-alone photovoltaic systems using superstructure model where all possible types of technology of the equipment are captured and life cycle cost analysis is formulated as a mixed integer programming (MIP). A model for investment planning of power generation and long-term decision model are developed in order to help the system engineer to build a cost effective system.

All tangled up: how cells direct, manage and exploit topoisomerase function

PubMed Central

Vos, Seychelle M.; Tretter, Elsa M.; Schmidt, Bryan H.; Berger, James M.

2015-01-01

Preface Topoisomerases are complex molecular machines that modulate DNA topology to maintain chromosome superstructure and integrity. Although capable of stand-alone activity in vitro, topoisomerases frequently are linked to larger pathways and systems that resolve specific DNA superstructures and intermediates arising from cellular processes such as DNA repair, transcription, replication, and chromosome compaction. Topoisomerase activity is indispensible to cells, but requires the transient breakage of DNA strands. This property has been exploited, often for significant clinical benefit, by various exogenous agents that interfere with cell proliferation. Despite decades of study, surprising findings involving topoisomerases continue to emerge with respect to their cellular function, regulation, and utility as therapeutic targets. PMID:22108601

Crystal Phase and Architecture Engineering of Lotus-Thalamus-Shaped Pt-Ni Anisotropic Superstructures for Highly Efficient Electrochemical Hydrogen Evolution.

PubMed

Zhang, Zhicheng; Liu, Guigao; Cui, Xiaoya; Chen, Bo; Zhu, Yihan; Gong, Yue; Saleem, Faisal; Xi, Shibo; Du, Yonghua; Borgna, Armando; Lai, Zhuangchai; Zhang, Qinghua; Li, Bing; Zong, Yun; Han, Yu; Gu, Lin; Zhang, Hua

2018-06-07

The rational design and synthesis of anisotropic 3D nanostructures with specific composition, morphology, surface structure, and crystal phase is of significant importance for their diverse applications. Here, the synthesis of well-crystalline lotus-thalamus-shaped Pt-Ni anisotropic superstructures (ASs) via a facile one-pot solvothermal method is reported. The Pt-Ni ASs with Pt-rich surface are composed of one Ni-rich "core" with face-centered cubic (fcc) phase, Ni-rich "arms" with hexagonal close-packed phase protruding from the core, and facet-selectively grown Pt-rich "lotus seeds" with fcc phase on the end surfaces of the "arms." Impressively, these unique Pt-Ni ASs exhibit superior electrocatalytic activity and stability toward the hydrogen evolution reaction under alkaline conditions compared to commercial Pt/C and previously reported electrocatalysts. The obtained overpotential is as low as 27.7 mV at current density of 10 mA cm -2 , and the turnover frequency reaches 18.63 H 2 s -1 at the overpotential of 50 mV. This work provides a new strategy for the synthesis of highly anisotropic superstructures with a spatial heterogeneity to boost their promising application in catalytic reactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bringing nanomagnetism to the mesoscale with artificial amorphous structures

NASA Astrophysics Data System (ADS)

Muscas, G.; Brucas, R.; Jönsson, P. E.

2018-05-01

In the quest for materials with emergent or improved properties, an effective route is to create artificial superstructures. Novel properties emerge from the coupling between the phases, but the strength of this coupling depends on the quality of the interfaces. Atomic control of crystalline interfaces is notoriously complicated and to elude that obstacle, we suggest here an all-amorphous design. Starting from a model amorphous iron alloy, we locally tune the magnetic behavior by creating boron-doped regions by means of ion implantation through a lithographic mask. This process preserves the amorphous environment, creating a non-topographic magnetic superstructure with smooth interfaces and no structural discontinuities. The absence of inhomogeneities acting as pinning centers for the magnetization reversal is demonstrated by the formation of magnetic vortexes for ferromagnetic disks as large as 20 µm in diameter embedded within a paramagnetic matrix. Rigid exchange coupling between two amorphous ferromagnetic phases in a microstructured sample is evidenced by an investigation involving first-order reversal curves. The sample consists of a soft matrix with embedded elements constituting a hard phase where the anisotropy originates from an elongated shape of the elements. We provide an intuitive explanation for the micrometer-range exchange coupling mechanism and discuss how to tailor the properties of all-amorphous superstructures.

Novel EGCG assisted ultrasound synthesis of self-assembled Ca2SiO4:Eu(3+) hierarchical superstructures: Photometric characteristics and LED applications.

PubMed

Venkataravanappa, M; Nagabhushana, H; Darshan, G P; Daruka Prasad, B; Vijayakumar, G R; Premkumar, H B; Udayabhanu

2016-11-01

This paper reports for the first time ultrasound, EGCG assisted synthesis of pure and Eu(3+) (1-5mol%) activated Ca2SiO4 nanophosphors having self-assembled superstructures with high purity. The shape, size and morphology of the product were tuned by controlling influential parameters. It was found that morphology was highly dependent on EGCG concentration, sonication time, pH and sonication power. The probable formation mechanism for various hierarchical superstructures was proposed. The PL studies of Ca2SiO4:Eu(3+) phosphors can be effectively excited by the near ultraviolet (UV) (396nm) light and exhibited strong red emission around 613nm, which was attributed to the Eu(3+) ((5)D0→(7)F2) transition. The concentration quenching phenomenon was explained based on energy transfer between defect and Eu(3+) ions, electron-phonon coupling and Eu(3+)-Eu(3+) interaction. The Judd-Ofelt intensity parameters and radiative properties were estimated by using PL emission spectra. The photometric studies indicate that the obtained phosphors could be a promising red component for possible applications in the field of white light emitting diodes. Copyright © 2016 Elsevier B.V. All rights reserved.

Phase transition hysteresis and anomalous Curie-Weiss behavior of ferroelectric tetragonal tungsten bronzes Ba2RETi2Nb3O15:RE=Nd,Sm

NASA Astrophysics Data System (ADS)

Prades, Marta; Beltrán, Héctor; Masó, Nahum; Cordoncillo, Eloisa; West, Anthony R.

2008-11-01

The ferroelectric tetragonal tungsten bronze (TTB) phases, Ba2RETi2Nb3O15:RE=Nd,Sm, were prepared by low temperature solvothermal synthesis. The permittivity versus temperature data of sintered ceramics show two unusual features: first, a hysteresis of 50-100 °C between values of the Curie temperature Tc on heat-cool cycles and second: a huge depression in the Curie-Weiss temperature T0. Both effects are attributed to the complex nature of their TTB-related crystal structures with different superstructures above and below Tc and the difficulty in nucleating ferroelectric domains on cooling through Tc. Several factors may contribute to the latter difficulty: first, the structures contain two sets of crystallographic sites for the "active" Ti, Nb ions; second, the distribution of Ti and Nb over these two sets of sites is not random but partially ordered; and third, below Tc a weak commensurate superstructure perpendicular to the polar c&barbelow; axis is present, but above Tc a weak incommensurate superstructure in a similar orientation is present. Hence the formation of the ferroelectric structure on cooling requires both nucleation of polar domains involving two sets of cation sites and structural change from an incommensurate to a commensurate supercell.

Superstructure Ta2O5 mesocrystals derived from (NH4)2Ta2O3F6 mesocrystals with efficient photocatalytic activity.

PubMed

Yu, Xin; Li, Wei; Huang, Jian; Li, Zhonghua; Liu, Jiawen; Hu, PingAn

2018-02-06

Superstructured mesocrystalline Ta 2 O 5 nanosheets were successfully prepared from mesocrystalline (NH 4 ) 2 Ta 2 O 3 F 6 nanorods by the annealing method for the first time. The as-prepared mesocrystalline Ta 2 O 5 nanosheets in this work showed remarkable visible light absorption, mainly due to the formation of oxygen vacancy defects in the mesocrystalline Ta 2 O 5 nanosheets, which was also confirmed by XPS spectra, Raman spectra and EPR spectra. Besides, the mesocrystalline Ta 2 O 5 nanosheets showed a highly enhanced photocatalytic activity of 11 268.24 μmol g -1 h -1 , about 3.95 times that of commercial Ta 2 O 5 . Moreover, the specific surface area of the mesocrystalline Ta 2 O 5 -800 nanosheets was 16.34 m 2 g -1 , about 5.32 times that of the commercial Ta 2 O 5 (3.072 m 2 g -1 ). The valence band XPS spectra indicated a strong oxidizing ability of the mesocrystalline Ta 2 O 5 nanosheets in comparison to that of commercial Ta 2 O 5 . The formation of superstructured Ta 2 O 5 mesocrystals generated long lifetime carriers and effective conduction pathways, which greatly enhanced the photocatalytic activity for hydrogen production.

What causes the Besnus transition in monoclinic pyrrhotite?

NASA Astrophysics Data System (ADS)

Gehring, A. U.; Koulialias, D.; Löffler, J. F.; Charilaou, M.

2016-12-01

Monoclinic 4C pyrrhotite (ideal formula Fe7S8) is a major magnetic remanence carrier in the Earth's crust and in extraterrestrial materials. Because of its low-temperature magnetic transition around 30 K also known as Besnus transition, this mineral phase is easily detectable in rock samples. An intrinsic origin of the Besnus transition due to a crystallographic change similar to that in the Verwey transition has generally been postulated (1). Although the physical properties of pyrrhotite have intensively been studied, the physics behind the pronounced change in magnetization at the low-temperature transition is still unresolved. To address this question we performed structural and magnetic analyses on a natural pyrrhotite single crystal (Fe6.6S8) from Auerbach, Germany (2,3). Chemical analysis, X-ray diffractometry and transmission electron microscopy show that this pyrrhotite consists of an intergrowth of 4C and an incommensurate 5C* superstructure that are polymorphs with different vacancy distributions. The occurrence of two superstructures is magnetically confirmed by symmetric inflection points in the hysteresis measurements above the transition at about 30 K. The disappearance of the inflection points and the associated change of the hysteresis parameters indicate that the two superstructures become embedded to form a unitary magnetic anisotropy system at the transition. This embedding of the 5C* into the 4C pyrrhotite at about 30 K is directly visible by the occurrence of additional 4-fold and 12-fold symmetry terms in magnetic anisotropy and anisotropic magnetic resistivity mesarurements, respectively. From this it follows that the Besnus transition in monoclinic pyrrhotite is an extrinsic magnetic phenomenon with respect to the 4C superstructure, i.e., a coupling effect, and therefore the physics behind it is in fact different from that of the well-known Verwey transition. (1) Rochette et al., The IRM Quarterly, 21, 1 (2011); (2) Charilaou et al., J. Appl. Phys., 118, 083903 (2015); (3) Koulialias et al., Geophys. J. Int., 204, 961-967 (2016).

Commensurate Superstructure of the {Cu(NO3)(H2O)}(HTae)(Bpy) Coordination Polymer: An Example of 2D Hydrogen-Bonding Networks as Magnetic Exchange Pathway.

PubMed

Fernández de Luis, Roberto; Larrea, Edurne S; Orive, Joseba; Lezama, Luis; Arriortua, María I

2016-11-21

The average and commensurate superstructures of the one-dimensional coordination polymer {Cu(NO 3 )(H 2 O)}(HTae)(Bpy) (H 2 Tae = 1,1,2,2-tetraacetylethane, Bpy = 4,4'-bipyridine) were determined by single-crystal X-ray diffraction, and the possible symmetry relations between the space group of the average structure and the superstructure were checked. The crystal structure consists in parallel and oblique {Cu(HTae)(Bpy)} zigzag metal-organic chains stacked along the [100] crystallographic direction. The origin of the fivefold c axis in the commensurate superstructure is ascribed to a commensurate modulation of the coordination environment of the copper atoms. The commensurately ordered nitrate groups and coordinated water molecules establish a two-dimensional hydrogen-bonding network. Moreover, the crystal structure shows a commensurate to incommensurate transition at room temperature. The release of the coordination water molecules destabilizes the crystal framework, and the compound shows an irreversible structure transformation above 100 °C. Despite the loss of crystallinity, the spectroscopic studies indicate that the main building blocks of the crystal framework are retained after the transformation. The hydrogen-bonding network not only plays a crucial role stabilizing the crystal structure but also is an important pathway for magnetic exchange transmission. In fact, the magnetic susceptibility curves indicate that after the loss of coordinated water molecules, and hence the collapse of the hydrogen-bonding network, the weak anti-ferromagnetic coupling observed in the initial compound is broken. The electron paramagnetic resonance spectra are the consequence of the average signals from Cu(II) with different orientations, indicating that the magnetic coupling is effective between them. In fact, X- and Q-band data are reflecting different situations; the X-band spectra show the characteristics of an exchange g-tensor, while the Q-band signals are coming from both the exchange and the molecular g-tensors.

Dental implants with fixed prosthodontics in oligodontia: A retrospective cohort study with a follow-up of up to 25 years.

PubMed

Filius, Marieke A P; Cune, Marco S; Koopmans, Petra C; Vissink, Arjan; Raghoebar, Gerry M; Visser, Anita

2018-04-24

Long-term assessments of implant survival and treatment outcome in patients with oligodontia are lacking. The purpose of this retrospective clinical study was to assess which factors determine a long-term implant survival and treatment outcome of up to 25 years in a cohort of patients with oligodontia. The medical records of all patients with oligodontia treated with fixed implant prosthodontics between January 1991 and December 2015 in the Department of Oral and Maxillofacial Surgery at the University Medical Center Groningen, the Netherlands, were assessed. Specifically, this involved the retrieval of records on the need for and mode of bone augmentation, implant survival, and survival of and adverse events associated with the prosthodontics. The Kaplan-Meier estimator was used to analyze implant and superstructure survival. Log-rank tests were used to compare the survival of subgroups. A total of 126 patients with oligodontia were treated with dental implants. Of the 777 implants in total, 56 were lost, resulting in a 5-year cumulative survival of 95.7% (95% confidence interval [CI], 94.2% to 97.2%) and a 10-year cumulative survival of 89.2% (95% CI, 86.2% to 92.2%). The survival of implants placed in regions where bone augmentation surgery had been performed was significantly lower. The 5-year cumulative superstructure survival was 90.5% (95% CI, 87.6% to 93.5%), and the 10-year cumulative superstructure survival was 80.3% (95% CI, 75.3% to 85.3%). The performance of the screw-retained and cemented superstructures was comparable, but the survival of single crowns was significantly higher than the survival of fixed partial dentures (P<.001). Implant treatment is a predictable treatment option for patients with oligodontia with a favorable long-term outcome. Survival of implants in augmented areas is lower. Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Shear Bond Strength of Composite and Ceromer Superstructures to Direct Laser Sintered and Ni-Cr-Based Infrastructures Treated with KTP, Nd:YAG, and Er:YAG Lasers: An Experimental Study.

PubMed

Gorler, Oguzhan; Hubbezoglu, Ihsan; Ulgey, Melih; Zan, Recai; Guner, Kubra

2018-04-01

The aim of this study was to examine the shear bond strength (SBS) of ceromer and nanohybrid composite to direct laser sintered (DLS) Cr-Co and Ni-Cr-based metal infrastructures treated with erbium-doped yttrium aluminum garnet (Er:YAG), neodymium-doped yttrium aluminum garnet (Nd:YAG), and potassium titanyl phosphate (KTP) laser modalities in in vitro settings. Experimental specimens had four sets (n = 32) including two DLS infrastructures with ceromer and nanohybrid composite superstructures and two Ni-Cr-based infrastructures with ceromer and nanohybrid composite superstructures. Of each infrastructure set, the specimens randomized into four treatment modalities (n = 8): no treatment (controls) and Er:YAG, Nd:YAG, and KTP lasers. The infrastructures were prepared in the final dimensions of 7 × 3 mm. Ceromer and nanohybrid composite was applied to the infrastructures after their surface treatments according to randomization. The SBS of specimens was measured to test the efficacy of surface treatments. Representative scanning electron microscopy (SEM) images after laser treatments were obtained. Overall, in current experimental settings, Nd:YAG, KTP, and Er:YAG lasers, in order of efficacy, are effective to improve the bonding of ceromer and nanohybrid composite to the DLS and Ni-Cr-based infrastructures (p < 0.05). Nd:YAG laser is more effective in the DLS/ceromer infrastructures (p < 0.05). KTP laser, as second more effective preparation, is more effective in the DLS/ceromer infrastructures (p < 0.05). SEM findings presented moderate accordance with these findings. The results of this study supported the bonding of ceromer and nanohybrid composite superstructures to the DLS and Ni-Cr-based infrastructures suggesting that laser modalities, in order of success, Nd:YAG, KTP, and Er:YAG, are effective to increase bonding of these structures.

Comparative analysis of different joining techniques to improve the passive fit of cobalt-chromium superstructures.

PubMed

Barbi, Francisco C L; Camarini, Edevaldo T; Silva, Rafael S; Endo, Eliana H; Pereira, Jefferson R

2012-12-01

The influence of different joining techniques on passive fit at the interface structure/abutment of cobalt-chromium (Co-Cr) superstructures has not yet been clearly established. The purpose of this study was to compare 3 different techniques of joining Co-Cr superstructures by measuring the resulting marginal misfit in a simulated prosthetic assembly. A specially designed metal model was used for casting, sectioning, joining, and measuring marginal misfit. Forty-five cast bar-type superstructures were fabricated in a Co-Cr alloy and randomly assigned by drawing lots to 3 groups (n=15) according to the joining method used: conventional gas-torch brazing (G-TB), laser welding (LW), and tungsten inert gas welding (TIG). Joined specimens were assembled onto abutment analogs in the metal model with the 1-screw method. The resulting marginal misfit was measured with scanning electron microscopy (SEM) at 3 different points: distal (D), central (C), and mesial (M) along the buccal aspect of both abutments: A (tightened) and B (without screw). The Levene test was used to evaluate variance homogeneity and then the Welsch ANOVA for heteroscedastic data (α=.05). Significant differences were found on abutment A between groups G-TB and LW (P=.013) measured mesially and between groups G-TB and TIG (P=.037) measured centrally. On abutment B, significant differences were found between groups G-TB and LW (P<.001) and groups LW and TIG (P<.001) measured mesially; groups G-TB and TIG (P=.007) measured distally; and groups G-TB and TIG (P=.001) and LW and TIG (P=.007) measured centrally. The method used for joining Co-Cr prosthetic structures had an influence on the level of resulting passive fit. Structures joined by the tungsten inert gas method produced better mean results than did the brazing or laser method. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Mechanical properties and biocompatibility of melt processed, self-reinforced ultrahigh molecular weight polyethylene.

PubMed

Huang, Yan-Fei; Xu, Jia-Zhuang; Li, Jian-Shu; He, Ben-Xiang; Xu, Ling; Li, Zhong-Ming

2014-08-01

The low efficiency of fabrication of ultrahigh molecular weight polyethylene (UHMWPE)-based artificial knee joint implants is a bottleneck problem because of its extremely high melt viscosity. We prepared melt processable UHMWPE (MP-UHMWPE) by addition of 9.8 wt% ultralow molecular weight polyethylene (ULMWPE) as a flow accelerator. More importantly, an intense shear flow was applied during injection molding of MP-UHMWPE, which on one hand, promoted the self-diffusion of UHMWPE chains, thus effectively reducing the structural defects; on the other hand, increased the overall crystallinity and induced the formation of self-reinforcing superstructure, i.e., interlocked shish-kebabs and oriented lamellae. Aside from the good biocompatibility, and the superior fatigue and wear resistance to the compression-molded UHMWPE, the injection-molded MP-UHMWPE exhibits a noteworthy enhancement in tensile properties and impact strength, where the yield strength increases to 46.3 ± 4.4 MPa with an increment of 128.0%, the ultimate tensile strength and Young's modulus rise remarkably up to 65.5 ± 5.0 MPa and 1248.7 ± 45.3 MPa, respectively, and the impact strength reaches 90.6 kJ/m(2). These results suggested such melt processed and self-reinforced UHMWPE parts hold a great application promise for use of knee joint implants, particularly for younger and more active patients. Our work sets up a new method to fabricate high-performance UHMWPE implants by tailoring the superstructure during thermoplastic processing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Phase- and shape-controlled hydrothermal synthesis of CdS nanoparticles, and oriented attachment growth of its hierarchical architectures

NASA Astrophysics Data System (ADS)

Cao, Yali; Hu, Pengfei; Jia, Dianzeng

2013-01-01

Hydrothermal strategies were successfully used to control the phases and morphologies of CdS nanocrystals. In the absence of an external direction-controlling process, the hexagonal and cubic phase well-defined leaf- and flower-like CdS nanocrystals were controlled obtained via adjusting the reaction duration or the concentration of surfactant. Oriented attachment growth modes were suggested for the formation of CdS superstructures, which was clarified through the tracing of temporal evolution of CdS nanoparticles. The CdS superstructures were structured by primary building nanoparticles, and held excellent visible emission with a peak in the green regions. This strategy is very helpful for studying the phase and morphology controlled fabrication of sulfides nanocrystals.

Spontaneous PT symmetry breaking in Dirac-Kronig-Penney crystals

NASA Astrophysics Data System (ADS)

Longhi, Stefano; Cannata, Francesco; Ventura, Alberto

2011-12-01

We introduce a non-Hermitian PT invariant extension of the Dirac-Kronig-Penney model, describing the motion of a Dirac quasiparticle in a locally periodic sequence of imaginary δ-Dirac barriers and wells, and propose its optical realization using superstructure fiber Bragg gratings with alternating regions of optical gain and absorption. For the infinite crystal, we determine the band structure and show that the PT phase is always broken. For a finite crystal, we derive analytical expressions for reflection and transmission probabilities, and show that the PT phase is unbroken below a finite threshold of the δ-barrier area. In the proposed optical realization, the onset of PT symmetry breaking in the finite crystal corresponds to the lasing condition for the grating superstructures.

Experimental and theoretical study of the operation of longitudinal sidewalls in reinforced concrete superstructures

NASA Astrophysics Data System (ADS)

Bokarev, Sergey; Efimov, Stefan

2017-11-01

In the present article, we report results of a laboratory experimental study of reinforced-concrete superstructure fragments with extended longitudinal boxing sidewalls. The study included laboratory tests and numerical experiments performed using a finite element model of fragments generated in specialized simulation software. The distribution of horizontal pressures over the height of longitudinal boxing sidewalls, the dependence of the bending moment in the root section of the sidewalls on the ballast-bed thickness under sleepers, and some other characteristics were examined. The results of the experimental and theoretical study have shown a good convergence of obtained data to each other and to the data obtained by an improved engineering calculation procedure proposed by the present authors.

Do Sealing Materials Influence Superstructure Attachment in Implants?

PubMed

Biscoping, Stephanie; Ruttmann, Esther; Rehmann, Peter; Wöstmann, Bernd

This study aimed to evaluate the possible effect of sealing materials on superstructure attachment (ie, tightening/loosening torque and implant-abutment gap) in two different implant systems. A silicone, a chlorhexidine gel, and an industrial lubricant were tested. A 3D microscope was used for assessment of the implant-abutment gap, and the abutment screw was tightened and loosened with a digital torque screwdriver. A total of 20 implants per test group (10 BEGO Semados RI and 10 Nobel Biocare Replace Select Straight) were evaluated. The tested sealing materials did not influence the gap between implant and abutment, but the force necessary for loosening the abutment screws decreased significantly. Sealing materials may be useful against bacteria, but probably influence torque negatively.

Protein-directed self-assembly of a fullerene crystal.

PubMed

Kim, Kook-Han; Ko, Dong-Kyun; Kim, Yong-Tae; Kim, Nam Hyeong; Paul, Jaydeep; Zhang, Shao-Qing; Murray, Christopher B; Acharya, Rudresh; DeGrado, William F; Kim, Yong Ho; Grigoryan, Gevorg

2016-04-26

Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design.

Small angle neutron and X-ray studies of carbon structures with metal atoms

NASA Astrophysics Data System (ADS)

Lebedev, V. T.; Szhogina, A. A.; Bairamukov, V. Yu

2017-05-01

Encapsulation of metal atoms inside carbon single-wall cages or within multi-layer cells has been realized using molecular precursors and high temperature processes transforming them into desirable structures. Endohedral fullerenols Fe@C60(OH)X with 3d-metal (iron) have been studied by SANS in aqueous solutions where they form stable globular clusters with radii R C ∼ 10-12 nm and aggregation numbers N C ∼ 104. This self-assembly is a crucial feature of paramagnetic fullerenols as perspective contrast agents for Magneto-Resonance Imaging in medicine. Cellular carbon-metal structures have been created by the pyrolysis of diphthalocyanines of lanthanides and actinides. It was established that these ultra porous matrices consist of globular cells of molecular precursor size (∼ 1 nm) which are aggregated into superstructures. This provides retain of metal atoms inside matrices which may serve for safety storage of spent fuel of nuclear power plants.

Thermally Induced Structural Evolution and Performance of Mesoporous Block Copolymer-Directed Alumina Perovskite Solar Cells

PubMed Central

2015-01-01

Structure control in solution-processed hybrid perovskites is crucial to design and fabricate highly efficient solar cells. Here, we utilize in situ grazing incidence wide-angle X-ray scattering and scanning electron microscopy to investigate the structural evolution and film morphologies of methylammonium lead tri-iodide/chloride (CH3NH3PbI3–xClx) in mesoporous block copolymer derived alumina superstructures during thermal annealing. We show the CH3NH3PbI3–xClx material evolution to be characterized by three distinct structures: a crystalline precursor structure not described previously, a 3D perovskite structure, and a mixture of compounds resulting from degradation. Finally, we demonstrate how understanding the processing parameters provides the foundation needed for optimal perovskite film morphology and coverage, leading to enhanced block copolymer-directed perovskite solar cell performance. PMID:24684494

CCl 4 chemistry on the reduced selvedge of a α-Fe 2O 3(0 0 0 1) surface: a scanning tunneling microscopy study

NASA Astrophysics Data System (ADS)

Rim, Kwang Taeg; Fitts, Jeffrey P.; Müller, Thomas; Adib, Kaveh; Camillone, Nicholas; Osgood, Richard M.; Joyce, S. A.; Flynn, George W.

2003-09-01

Scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) were used to study the degradation of CCl 4 on the reduced selvedge of a natural single crystal α-Fe 2O 3(0 0 0 1) surface in ultrahigh vacuum. Before exposure to CCl 4, STM images indicate that approximately 85% of the reduced surface exhibits a Fe 3O 4(1 1 1) 2 × 2 termination, while the remaining 15% is terminated by 1 × 1 and superstructure phases. Images obtained after room temperature dosing with CCl 4 and subsequent flashing to 600 K reveal that chlorine atoms are adsorbed only on surface regions with the Fe 3O 4(1 1 1) 2 × 2 termination, not on 1 × 1 and superstructure regions. Chlorine atoms from dissociative adsorption of CCl 4 are observed to occupy two distinct positions located atop lattice protrusions and in threefold oxygen vacancy sites. However, in companion chemical labeling experiments, chlorine atoms provided by room temperature, dissociative Cl 2 adsorption on this surface are found to occupy sites atop lattice protrusions exclusively. The clear dissimilarity in STM feature shape and brightness at the two distinct chlorine adsorption sites arising from CCl 4 dissociation as well as the results of the Cl 2 chemical labeling experiments are best explained via reactions on a Fe 3O 4(1 1 1) 2 × 2 selvedge terminated by a 1/4 monolayer of tetrahedrally coordinated iron atoms. On this surface, adsorption atop an iron atom occurs for both the CCl 4 and Cl 2 dissociative reactions. A second adsorption site, assigned as binding to second layer iron atoms left exposed following surface oxygen atom abstraction resulting in the formation of phosgene (COCl 2), only appears in the case of reaction with CCl 4. The reaction mechanism and active site requirements for CCl 4 degradation on iron oxide surfaces are discussed in light of this evidence and in the context of our previously reported results from Auger electron spectroscopy (AES), LEED, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy studies.

OCDMA Over WDM PON—Solution Path to Gigabit-Symmetric FTTH

NASA Astrophysics Data System (ADS)

Kitayama, Ken-Ichi; Wang, Xu; Wada, Naoya

2006-04-01

It will be revealed that a myth of deploying low bit-rate uplink fiber-to-the-home (FTTH) services while providing a high bit-rate downlink is wrong. Therefore, for the future broadband FTTH services, the focus should be on the capability to provide gigabit-or even multigigabits-per-second both in up-and downlinks, namely gigabit symmetric systems. Optical code-division multiple access (OCDMA) now deserves a revisit as a powerful alternative to time-division multiple access and wavelength-division multiple (WDM) access in FTTH systems. In this paper, the authors will first highlight the OCDMA systems. The system architecture and its operation principle, code design, optical en/decoding, using a long superstructured fiber Bragg grating (SSFBG) en/decoder, and its system performance will be described. Next, an OCDMA over WDM passive optical network (PON) as a solution for the gigabit-symmetric FTTH systems will be proposed. The system architecture and the WDM interchannel crosstalk will be studied. It will be shown that by taking advantage of reflection spectrum notches of the SSFBG en/decoder, the WDM interchannel crosstalk can be suppressed and can enable OCDMA over WDM PON to simultaneously provide multigigabit-per-second up-and downlinks to a large number of users.

Acetanilide mediated reversible assembly and disassembly of Au nanoparticles.

PubMed

Murugadoss, A; Kar, Manoranjan; Chattopadhyay, Arun

2008-08-01

Herein we report the generation of Au nanoparticles (NPs) by sparingly soluble acetanilide in water. We also report the formation of linear chain-like superstructures of self-assembled Au NPs, in the presence of excess acetanilide. This was achieved in two different ways. In the first method, acetanilide was added, with increasing concentration, into aqueous HAuCl(4) to produce Au NPs as well as for the formation of assembly, which varied according to the concentration of acetanilide. The other route involved formation of spherical Au NPs at the lowest concentration of acetanilide, which was followed by the formation of assembly of various lengths upon further addition of variable amount of acetanilide. The assemblies were stable in aqueous solution for days with characteristic UV-vis absorption spectra consisting of two peaks. While the wavelength of the first peak remained the same, the position of the second peak changed to longer wavelength with increasing acetanilide concentration. Interestingly, the linear chain-like arrays could be broken into individual particles by first dilution of the solution concentration followed by treatment with ultrasonic waves. The individual Au NPs again formed linear chain-like arrays upon addition of excess acetanilide.

Influence of different materials and techniques to transfer molding in multiple implants.

PubMed

Faria, Júlio C B; Cruz, Fernando L G; Silva-Concílio, Laís R; Neves, Ana C C

2012-01-01

The aim of this study was to compare different materials and techniques used in transfer molding of multiple implants, by evaluating the space between implants and superstructure. Four external hexagon implants were fixed in a master template and the same on a superstructure. Transfer molding of implants were done using the direct and indirect techniques, with transfers united or not, using the union chemically activated acrylic resin (QA) and other groups polymerized acrylic resin (FT), and sectioned and not split. The casts were made with polyether and models divided into 8 groups (n = 5). The space between the superstructure and the master implants was measured with a microscope and the data was analyzed statistically by Student's t test (p < 0.05). For the material of union there was no significant difference, except when the groups were compared with the resin Duralay QA (G4) and the resin Duolay FT (G8) and groups using resins Duolay QA (G5) and Duolay FT (G7) for the union of the transfers. When comparing the groups who had the union between the transfers and sectioned again united with those in which the union was not severed there was no statistically significant difference. QA resin was superior to the FT with respect to the union of transfers. Techniques with united transfers or not were similar.

New Oxide Materials for an Ultra High Temperature Environment

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

Perepezko, John H.

In this project, a new oxide material, Hf 6Ta 2O 17 has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf 6Ta 2O 17 with amore » complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf 6Ta 2O 17 superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO 2 and Ta 2O 5 and verified the low thermal conductivity of Hf 6Ta 2O 17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf 6Ta 2O 17, which shows an initial parabolic oxidation kinetics.« less

Molecular Engineering of Platinum(II) Terpyridine Complexes with Tetraphenylethylene-Modified Alkynyl Ligands: Supramolecular Assembly via Pt···Pt and/or π-π Stacking Interactions and the Formation of Various Superstructures.

PubMed

Cheng, Heung-Kiu; Yeung, Margaret Ching-Lam; Yam, Vivian Wing-Wah

2017-10-18

A series of platinum(II) terpyridine complexes with tetraphenylethylene-modified alkynyl ligands has been designed and synthesized. The introduction of the tetraphenylethylene motif has led to aggregation-induced emission (AIE) properties, which upon self-assembly led to the formation of metal-metal-to-ligand charge transfer (MMLCT) behavior stabilized by Pt···Pt and/or π-π interactions. Tuning the steric bulk or hydrophilicity through molecular engineering of the platinum(II) complexes has been found to alter their spectroscopic properties and result in interesting superstructures (including nanorods, nanospheres, nanowires, and nanoleaves) in the self-assembly process. The eye-catching color and emission changes upon varying the solvent compositions may have potential applications in chemosensing materials for the detection of microenvironment changes. Furthermore, the importance of the directional Pt···Pt and/or π-π interactions on the construction of distinctive superstructures has also been examined by UV-vis absorption and emission spectroscopy and transmission electron microscopy. This work represents the interplay of both inter- and intramolecular interactions as well as the energies of the two different chromophoric/luminophoric systems that may open up a new route for the development of platinum(II)-AIE hybrids as functional materials.

Light-Driven Reversible Transformation between Self-Organized Simple Cubic Lattice and Helical Superstructure Enabled by a Molecular Switch Functionalized Nanocage.

PubMed

Zhou, Kang; Bisoyi, Hari Krishna; Jin, Jian-Qiu; Yuan, Cong-Long; Liu, Zhen; Shen, Dong; Lu, Yan-Qing; Zheng, Zhi-Gang; Zhang, Weian; Li, Quan

2018-04-23

Self-organized stimuli-responsive smart materials with adjustable attributes are highly desirable for a plethora of device applications. Simple cubic lattice is quite uncommon in soft condensed matter due to its lower packing factor. Achieving a stable simple cubic soft lattice and endowing such a lattice with dynamic reconstruction capability solely by a facile light irradiation are of paramount significance for both fundamental studies and engineering explorations. Herein, an elegant stable self-organized simple cubic soft lattice, i.e., blue phase II, in a chiral liquid crystal (LC) system is disclosed, which is stable down to room temperature and exhibits both reversible lattice deformation and transformation to a helical superstructure, i.e., cholesteric LC, by light stimulation. Such an amazing trait is attained by doping a judiciously designed achiral photoresponsive molecular switch functionalized polyhedral oligomeric silsesquioxane nanocage into a chiral LC host. An unprecedented reversible collapse and reconstruction of such a high symmetric simple cubic blue phase II driven by light has been achieved. Furthermore, a well-defined conglomerate micropattern composed of simple cubic soft lattice and helical superstructure, which is challenging to fabricate in organic and inorganic crystalline materials, is produced using photomasking technology. Moreover, the promising photonic application based on such a micropattern is demonstrated. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tuning the superstructure of ultrahigh-molecular-weight polyethylene/low-molecular-weight polyethylene blend for artificial joint application.

PubMed

Xu, Ling; Chen, Chen; Zhong, Gan-Ji; Lei, Jun; Xu, Jia-Zhuang; Hsiao, Benjamin S; Li, Zhong-Ming

2012-03-01

An easy approach was reported to achieve high mechanical properties of ultrahigh-molecular-weight polyethylene (UHMWPE)-based polyethylene (PE) blend for artificial joint application without the sacrifice of the original excellent wear and fatigue behavior of UHMWPE. The PE blend with desirable fluidity was obtained by melt mixing UHMWPE and low molecular weight polyethylene (LMWPE), and then was processed by a modified injection molding technology-oscillatory shear injection molding (OSIM). Morphological observation of the OSIM PE blend showed LMWPE contained well-defined interlocking shish-kebab self-reinforced superstructure. Addition of a small amount of long chain polyethylene (2 wt %) to LMWPE greatly induced formation of rich shish-kebabs. The ultimate tensile strength considerably increased from 27.6 MPa for conventional compression molded UHMWPE up to 78.4 MPa for OSIM PE blend along the flow direction and up to 33.5 MPa in its transverse direction. The impact strength of OSIM PE blend was increased by 46% and 7% for OSIM PE blend in the direction parallel and vertical to the shear flow, respectively. Wear and fatigue resistance were comparable to conventional compression molded UHMWPE. The superb performance of the OSIM PE blend was originated from formation of rich interlocking shish-kebab superstructure while maintaining unique properties of UHMWPE. The present results suggested the OSIM PE blend has high potential for artificial joint application. © 2012 American Chemical Society

Pressure-dependence of the phase transitions and thermal expansion in zirconium and hafnium pyrovanadate

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

Gallington, Leighanne C.; Hester, Brett R.; Kaplan, Benjamin S.

Low or negative thermal expansion (NTE) has been previously observed in members of the ZrP{sub 2}O{sub 7} family at temperatures higher than their order-disorder phase transitions. The thermoelastic properties and phase behavior of the low temperature superstructure and high temperature negative thermal expansion phases of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} were explored via in situ variable temperature/pressure powder x-ray diffraction measurements. The phase transition temperatures of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} exhibited a very strong dependence on pressure (∼700 K GPa), with moderate compression suppressing the formation of their NTE phases below 513 K. Compression alsomore » reduced the magnitude of the coefficients of thermal expansion in both the positive and negative thermal expansion phases. Additionally, the high temperature NTE phase of ZrV{sub 2}O{sub 7} was found to be twice as stiff as the low temperature positive thermal expansion superstructure (24 and 12 GPa respectively). - Graphical abstract: The temperature at which ZrV{sub 2}O{sub 7} transforms to a phase displaying negative thermal expansion is strongly pressure dependent. The high temperature form of ZrV{sub 2}O{sub 7} is elastically stiffer than the low temperature form. - Highlights: • The order-disorder phase transition temperatures in ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} are strongly pressure dependent (∼700 K.GPa). • The high temperature (disordered) phase of ZrV{sub 2}O{sub 7} is much stiffer than the ambient temperature (ordered) phase. • Compression reduces the magnitude of the negative thermal expansion in the high temperature phase of ZrV{sub 2}O{sub 7}.« less

A bio-inspired N-doped porous carbon electrocatalyst with hierarchical superstructure for efficient oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Miao, Yue-E.; Yan, Jiajie; Ouyang, Yue; Lu, Hengyi; Lai, Feili; Wu, Yue; Liu, Tianxi

2018-06-01

The bio-inspired hierarchical "grape cluster" superstructure provides an effective integration of one-dimensional carbon nanofibers (CNF) with isolated carbonaceous nanoparticles into three-dimensional (3D) conductive frameworks for efficient electron and mass transfer. Herein, a 3D N-doped porous carbon electrocatalyst consisting of carbon nanofibers with grape-like N-doped hollow carbon particles (CNF@NC) has been prepared through a simple electrospinning strategy combined with in-situ growth and carbonization processes. Such a bio-inspired hierarchically organized conductive network largely facilitates both the mass diffusion and electron transfer during the oxygen reduction reactions (ORR). Therefore, the metal-free CNF@NC catalyst demonstrates superior catalytic activity with an absolute four-electron transfer mechanism, strong methanol tolerance and good long-term stability towards ORR in alkaline media.

Freud's metapsychological speculations.

PubMed

Fulgencio, Leopoldo

2005-02-01

In this paper, the author seeks to analyse the nature and function of metapsychological theory in Freudian psychoanalysis. He shows that Freudian psychoanalytic theory is composed of an empirical part--the psychology of clinical facts--and a speculative part--metapsychology. Freud considers this latter part as being a speculative superstructure of value that is only heuristic, capable of being supplanted by other superstructures of the same type. The author sustains the idea that this metapsychology is the fruit of speculative method, whose foundations were elaborated by philosophers and epistemologists before Freud, including Immanuel Kant and Ernst Mach. He concludes with considerations regarding the future of metapsychological theorisation, presenting criticisms of Freudian metapsychology offered by both philosophers and psychoanalysts, and pointing to the perspective opened by Donald W. Winnicott of a psychoanalysis without metapsychology.

Smectic Layer Origami via Preprogrammed Photoalignment.

PubMed

Ma, Ling-Ling; Tang, Ming-Jie; Hu, Wei; Cui, Ze-Qun; Ge, Shi-Jun; Chen, Peng; Chen, Lu-Jian; Qian, Hao; Chi, Li-Feng; Lu, Yan-Qing

2017-04-01

Hierarchical architecture is of vital importance in soft materials. Focal conic domains (FCDs) of smectic liquid crystals, characterized by an ordered lamellar structure, attract intensive attention. Simultaneously tailoring the geometry and clustering characteristics of FCDs remains a challenge. Here, the 3D smectic layer origami via a 2D preprogrammed photoalignment film is accomplished. Full control of hierarchical superstructures is demonstrated, including the domain size, shape, and orientation, and the lattice symmetry of fragmented toric FCDs. The unique symmetry breaking of resultant superstructures combined with the optical anisotropy of the liquid crystals induces an intriguing polarization-dependent diffraction. This work broadens the scientific understanding of self-assembled soft materials and may inspire new opportunities for advanced functional materials and devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchically Superstructured Metal Sulfides: Facile Perturbation-Assisted Nanofusion Synthesis and Visible Light Photocatalytic Characterizations

DOE PAGES

Yue, Yanfeng; Li, Yunchao; Bridges, Craig A.; ...

2016-11-29

A novel and simple perturbation-assisted nanofusion (PNF) synthetic strategy was developed for the fabrication of stable hierarchically superstructured metal sulfides. This promising approach, based on a kinetically controlled precipitation to simultaneously condense and re-dissolve polymorphic nanocrystallites, provides the resultant samples with a unique mesoporous framework. This PNF approach is environmentally friendly, produces gram-scale products in a matter of hours, and is complimentary to traditional hard or soft templating methods for the construction of mesoporous metal sulfides. PNF derived hierarchical porous CdS exhibited a vastly improved photocatalytic performance over its commercial bulk counterpart under visible light irradiation, demonstrating the advantage ofmore » the porous morphology for photocatalysis resulting from the enlarged surface area and the easy accessibility of the mesopores.« less

46 CFR 42.15-10 - Doors.

Code of Federal Regulations, 2010 CFR

2010-10-01

... superstructures shall be fitted with doors of steel or other equivalent material, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent...

46 CFR 42.15-10 - Doors.

Code of Federal Regulations, 2011 CFR

2011-10-01

... superstructures shall be fitted with doors of steel or other equivalent material, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent...

46 CFR 42.15-10 - Doors.

Code of Federal Regulations, 2013 CFR

2013-10-01

... superstructures shall be fitted with doors of steel or other equivalent material, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent...

46 CFR 42.15-10 - Doors.

Code of Federal Regulations, 2014 CFR

2014-10-01

... superstructures shall be fitted with doors of steel or other equivalent material, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent...

46 CFR 42.15-10 - Doors.

Code of Federal Regulations, 2012 CFR

2012-10-01

... superstructures shall be fitted with doors of steel or other equivalent material, permanently and strongly attached to the bulkhead, and framed, stiffened and fitted so that the whole structure is of equivalent...

A new interpretation of the Besnus transition in monoclinic pyrrhotite

NASA Astrophysics Data System (ADS)

Gehring, Andreas

2016-04-01

Non-stoichiometric monoclinic 4C pyrrhotite (ideal formula: Fe7S8) is a major magnetic remanence carrier in the Earth's crust and in extraterrestrial materials. Because of its low-temperature magnetic transition around 30 K also known as Besnus transition, this mineral phase is easily detectable in natural samples. Considering the rock magnetic literature, an intrinsic origin of the Besnus transition similar to that of the Verwey transition has generally been assumed. Although the physical properties of pyrrhotite have intensively been studied, the mechanism behind the pronounced change in magnetization at the low-temperature transition is still debated. To address this question we performed magnetization experiments on a natural pyrrhotite crystal (Fe6.6S8) that consists of an epitaxial intergrowth of a commensurate 4C and an incommensurate 5C* superstructure that are different in their defect structure (1,2). The occurrence of two monoclinic superstructures detected by X-ray diffractometry is magnetically confirmed by symmetric inflection points in hysteresis measurements above the transition at about 30 K. The disappearance of the inflection points and the associated change of the hysteresis parameters indicate that the two superstructures become strongly coupled to form a unitary magnetic anisotropy system at the transition. From this it follows that the Besnus transition in monoclinic pyrrhotite is an extrinsic magnetic phenomenon with respect to the 4C superstructure and therefore the physics behind it is in fact different from that of the well-known Verwey transition. Finally, this novel interpretation explains the rock magnetic data for the low-temperature transition that has been reported for monoclinic pyrrhotite. It will also provide deeper understanding of magnetism in monoclinic pyrrhotite, which in turn will enable a more profound insight to the magnetization properties of the Earth's crust. 1.) Charilaou, M., Kind, J., Koulialias, D., Weidler, P.G., Mensing, C., Löffler, J.F. & Gehring, A.U., 2015. J. Appl. Phys., 118, 083903. 2.) Koulialias, D., Kind, J., Charilaou, M., Weidler, P.G., Löffler, J.F. & Gehring, A.U. 2016. Geophys. J. Int., 204, 961-967.

Structural stiffness identification of bridge superstructures : final report.

DOT National Transportation Integrated Search

1996-01-01

Accurate measures of bridge stiffness are important when determining structural integrity. This information should be an integral part of any comprehensive bridge maintenance program, especially considering the nation's aging infrastructure. Informed...

A Layered Solution Crystal Growth Technique and the Crystal Structure of (C 6H 5C 2H 4NH 3) 2PbCl 4

NASA Astrophysics Data System (ADS)

Mitzi, D. B.

1999-07-01

Single crystals of the organic-inorganic perovskite (C6H5C2H4NH3)2PbCl4 have been grown at room temperature using a layered solution approach. The bottom solution layer, contained within a long straight tube, consists of PbCl2 dissolved in concentrated aqueous HCl. A less dense layer of methanol is carefully placed on top of the HCl/PbCl2 solution using a syringe. Finally, a stoichiometric quantity of C6H5C2H4NH2 (relative to the PbCl2) is added to the top of the column. As the layers slowly diffuse together, well-formed crystals of (C6H5C2H4NH3)2PbCl4 appear near the interface between the HCl/PbCl2 and C6H5C2H4NH2 solutions. The thick, plate-like crystals are well suited for X-ray crystallography studies. Room temperature intensity data were refined using a triclinic (Poverline1) cell (a=11.1463(3) Å, b=11.2181(3) Å, c=17.6966(5) Å, α= 99.173(1)°, β=104.634(1)°, γ=89.999(1)°, V=2111.8(1) Å3, Z=4, Rf/Rw=0.031/0.044). The organic-inorganic layered perovskite structure features well-ordered sheets of corner-sharing distorted PbCl6 octahedra separated by bilayers of phenethylammonium cations. Tilting and rotation of the PbCl6 octahedra within the perovskite sheets, coupled with organic cation ordering, leads to the unusual in-sheet 2ap×2ap superstructure, where ap is the lattice constant for the ideal cubic perovskite.

Hillsboro Canal bridge monitoring.

DOT National Transportation Integrated Search

2011-12-01

This report describes the implementation of a testing and monitoring program for bridge 930338 in Belle Glade. Glass-fiber : reinforced polymer (GFRP) deck panels and plates were installed over an existing steel superstructure using grouted steel : s...

1. SHAFT HOUSE, NORTH ELEVATION; (HEADFRAME INCORPORATED INTO THE STRUCTURE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. SHAFT HOUSE, NORTH ELEVATION; (HEADFRAME INCORPORATED INTO THE STRUCTURE IS VISIBLE AS THE PROJECTING SUPERSTRUCTURE). - Joker Mine, Shafthouse, Medicine Bow National Forest, Northwest of Keystone, Keystone, Albany County, WY

Submerged flow bridge scour under clear water conditions

DOT National Transportation Integrated Search

2012-09-01

Prediction of pressure flow (vertical contraction) scour underneath a partially or fully submerged bridge superstructure : in an extreme flood event is crucial for bridge safety. An experimentally and numerically calibrated formulation is : developed...

Seismic response of precast segmental bridge superstructures.

DOT National Transportation Integrated Search

2006-12-01

Precast segmental construction of bridges can accelerate construction and minimize the cost of bridges in highly congested urban environments and environmentally sensitive regions. Despite their proven benefits, the use of precast segmental bridges i...

Lifting and protecting residential structures from subsidence damage using airbags

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

Triplett, T.L.; Bennett, R.M.

1998-12-31

Conventional practice in protecting residential structures from subsidence damage concentrates on saving the superstructure. The foundation is sacrificed, even though it represents the structural component with the greatest replacement cost. In this study, airbags were used to lift a 20 ft x 30 ft structure to test their ability to protect both the foundation and superstructure from ground settlement. Two contiguous sides of the test foundation were unreinforced, and the other two contiguous sides incorporated footing and wall reinforcement. The airbags successfully lifted the structure without causing damage, even on the unreinforced sides. This paper gives a procedure for determiningmore » airbag spacing, and describes installation and operation techniques of the airbags. The paper then focuses on the performance of the airbags in lifting the structure, and shows that airbags can preserve existing foundations during subsidence movements.« less

Interplay between spherical confinement and particle shape on the self-assembly of rounded cubes.

PubMed

Wang, Da; Hermes, Michiel; Kotni, Ramakrishna; Wu, Yaoting; Tasios, Nikos; Liu, Yang; de Nijs, Bart; van der Wee, Ernest B; Murray, Christopher B; Dijkstra, Marjolein; van Blaaderen, Alfons

2018-06-08

Self-assembly of nanoparticles (NPs) inside drying emulsion droplets provides a general strategy for hierarchical structuring of matter at different length scales. The local orientation of neighboring crystalline NPs can be crucial to optimize for instance the optical and electronic properties of the self-assembled superstructures. By integrating experiments and computer simulations, we demonstrate that the orientational correlations of cubic NPs inside drying emulsion droplets are significantly determined by their flat faces. We analyze the rich interplay of positional and orientational order as the particle shape changes from a sharp cube to a rounded cube. Sharp cubes strongly align to form simple-cubic superstructures whereas rounded cubes assemble into icosahedral clusters with additionally strong local orientational correlations. This demonstrates that the interplay between packing, confinement and shape can be utilized to develop new materials with novel properties.

Investigation of Thermal Hardening of the FCC Material Containing Strengthening Particles with an L12 Superstructure

NASA Astrophysics Data System (ADS)

Daneyko, O. I.; Kulaeva, N. A.; Kovalevskaya, C. A.; Kolupaeva, S. N.

2015-07-01

A mathematical model of plastic deformation of dispersion-hardened materials with an fcc matrix containing strengthening particles with an L12 superstructure having a coherent relationship with the matrix is presented. The model is based on the balance equations of deformation defects of different types with taking into account their transformation during plastic deformation. The influence of scale characteristics of the hardening phase, temperature, and deformation rate on the evolution of the dislocation subsystem and strain hardening of an alloy with an fcc matrix hardened by particles with an L12 super structure is studied. A temperature anomaly of mechanical properties is found for the materials with different fcc matrices (Al,Cu, Ni). It is shown that the temperature anomaly is more pronounced for the material with larger volume fraction of the hardening phase.

Ultrasensitive SERS detection of VEGF based on a self-assembled Ag ornamented-AU pyramid superstructure.

PubMed

Zhao, Sen; Ma, Wei; Xu, Liguang; Wu, Xiaoling; Kuang, Hua; Wang, Libing; Xu, Chuanlai

2015-06-15

For the first time, we demonstrated the fabrication of silver nanoparticle ornamented-gold nanoparticle pyramids (Ag-Au Pys) using an aptamer-based self-assembly process and investigated their surface-enhanced Raman scattering (SERS) properties in the detection of vascular endothelial growth factor (VEGF). Under optimized conditions, the SERS signal was negatively related to VEGF concentration over the range 0.01-1.0 fM and the limit of detection (LOD) was as low as 22.6 aM. The matrix effect and the specificity of this developed method were further examined, and the results showed that the superstructure sensor was ultrasensitive and highly selective. This developed aptamer-based SERS detection method suggests that it may be a promising strategy for a variety of sensing applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Extended and quasi-continuous tuning of quantum cascade lasers using superstructure gratings and integrated heaters

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

Bidaux, Yves, E-mail: yves.bidaux@alpeslasers.ch; Institute for Quantum Electronics, ETH-Zurich, CH-8093 Zurich; Bismuto, Alfredo, E-mail: alfredo.bismuto@alpeslasers.ch

2015-11-30

In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 μm, and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel to the other, while predictable and mode-hop free tuning can be obtained in each channel modulating the laser current with a side mode suppression ratio as high as 30 dB. The resulting device behaves effectively as a switchable multicolour tunable source. Tuning up to 6.5% of the central wavelength is observed. To prove the importance of the developed devices for high resolutionmore » molecular spectroscopy, a N{sub 2}O absorption spectrum has been measured.« less

Direct observation of hierarchical nucleation of martensite and size-dependent superelasticity in shape memory alloys.

PubMed

Liu, Lifeng; Ding, Xiangdong; Li, Ju; Lookman, Turab; Sun, Jun

2014-02-21

Martensitic transformation usually creates hierarchical internal structures beyond mere change of the atomic crystal structure. Multi-stage nucleation is thus required, where nucleation (level-1) of the underlying atomic crystal lattice does not have to be immediately followed by the nucleation of higher-order superstructures (level-2 and above), such as polysynthetic laths. Using in situ transmission electron microscopy (TEM), we directly observe the nucleation of the level-2 superstructure in a Cu-Al-Ni single crystal under compression, with critical super-nuclei size L2c around 500 nm. When the sample size D decreases below L2c, the superelasticity behavior changes from a flat stress plateau to a continuously rising stress-strain curve. Such size dependence definitely would impact the application of shape memory alloys in miniaturized MEMS/NEMS devices.

Magnetic Superstructure and Metal-Insulator Transition in Mn-Substituted Sr3Ru2O7

NASA Astrophysics Data System (ADS)

Hossain, M. A.; Bohnenbuck, B.; Chuang, Y.-D.; Geck, J.; Tokura, Y.; Yoshida, Y.; Hussain, Z.; Keimer, B.; Sawatzky, G. A.; Damascelli, A.

2010-03-01

We present a temperature-dependent resonant elastic soft x-ray scattering (REXS) study of the metal-insulator transition in Sr3(Ru1-xMnx)2O7, performed at both Ru and Mn L-edges. Resonant magnetic superstructure reflections, which indicate an incipient instability of the parent compound, are detected below the transition. Based on modelling of the REXS intensity from randomly distributed Mn impurities, we establish the inhomogeneous nature of the metal-insulator transition, with an effective percolation threshold corresponding to an anomalously low x˜0.05 Mn substitution. In collaboration with A.G. Cruz Gonzalez, J.D. Denlinger (Berkeley Lab), I. Zegkinoglou, M.W. Haverkort (MPI, Stuttgart), I.S. Elfimov, D.G. Hawthorn (UBC), R. Mathieu, S. Satow, H. Takagi (Tokyo), H.-H. Wu and C. Sch"ußler-Langeheine (Cologne).

Effect of a Stepped Si(100) Surface on the Nucleation Process of Ge Islands

NASA Astrophysics Data System (ADS)

Yesin, M. Yu.; Nikiforov, A. I.; Timofeev, V. A.; Mashanov, V. I.; Tuktamyshev, A. R.; Loshkarev, I. D.; Pchelyakov, O. P.

2018-03-01

Nucleation of Ge islands on a stepped Si(100) surface is studied. It is shown by diffraction of fast electrons that at a temperature of 600°C, constant flux of Si, and deposition rate of 0.652 Å/s, a series of the 1×2 superstructure reflections completely disappears, if the Si (100) substrate deviated by an angle of 0.35° to the (111) face is preliminarily heated to 1000°C. The disappearance of the 1×2 superstructure reflexes is due to the transition from the surface with monoatomic steps to that with diatomic ones. Investigations of the Ge islands' growth were carried out on the Si(100) surface preliminarily annealed at temperatures of 800 and 1000°C. It is shown that the islands tend to nucleate at the step edges.

Paramagnetic decoration of DNA origami nanostructures by Eu³⁺ coordination.

PubMed

Opherden, Lars; Oertel, Jana; Barkleit, Astrid; Fahmy, Karim; Keller, Adrian

2014-07-15

The folding of DNA into arbitrary two- and three-dimensional shapes, called DNA origami, represents a powerful tool for the synthesis of functional nanostructures. Here, we present the first approach toward the paramagnetic functionalization of DNA origami nanostructures by utilizing postassembly coordination with Eu(3+) ions. In contrast to the usual formation of toroidal dsDNA condensates in the presence of trivalent cations, planar as well as rod-like DNA origami maintain their shape and monomeric state even under high loading with the trivalent lanthanide. Europium coordination was demonstrated by the change in Eu(3+) luminescence upon binding to the two DNA origami. Their natural circular dichroism in the Mg(2+)- and Eu(3+)-bound state was found to be very similar to that of genomic DNA, evidencing little influence of the DNA origami superstructure on the local chirality of the stacked base pairs. In contrast, the magnetic circular dichroism of the Mg(2+)-bound DNA origami deviates from that of genomic DNA. Furthermore, the lanthanide affects the magnetic properties of DNA in a superstructure-dependent fashion, indicative of the existence of superstructure-specific geometry of Eu(3+) binding sites in the DNA origami that are not formed in genomic DNA. This simple approach lays the foundation for the generation of magneto-responsive DNA origami nanostructures. Such systems do not require covalent modifications and can be used for the magnetic manipulation of DNA nanostructures or for the paramagnetic alignment of molecules in NMR spectroscopy.

Garden-like perovskite superstructures with enhanced photocatalytic activity

NASA Astrophysics Data System (ADS)

Ye, Meidan; Wang, Mengye; Zheng, Dajiang; Zhang, Nan; Lin, Changjian; Lin, Zhiqun

2014-03-01

By subjecting amorphous flower-like TiO2 to a facile hydrothermal synthesis in the presence of Sr2+, garden-like perovskite SrTiO3 superstructures were achieved. The amorphous TiO2 was preformed using ZnO flowers as templates. Different three-dimensional SrTiO3 architectures were coexisted in the garden, including SrTiO3 flowers composed of several hollow sword-shaped petals, many sheet-shaped petals or numerous flake-shaped petals, and SrTiO3 grass consisting of a number of long blades. These SrTiO3 superstructures were simultaneously grown on fluorine-doped tin oxide (FTO) substrates. On the basis of a comprehensive study on the effects of growth time, temperature, initial concentrations of precursor, and pH, the formation of these various hierarchical architectures was attributed primarily to the dissolution of amorphous TiO2 and precipitation of perovskite crystals, followed by the Ostwald ripening process of perovskite nanocrystals and self-organization of perovskite building blocks. Interestingly, this approach can be readily extended to create other perovskite structures, including dendritic BaTiO3 and nest-like CaTiO3, as well as PbTiO3 transformed from plate-like pyrochlore Pb2Ti2O6 after post-thermal treatment. Garden-like SrTiO3 superstructures showed a superior photocatalytic performance when compared to other as-prepared semiconductors and perovskite materials (i.e., ZnO, TiO2, BaTiO3, CaTiO3 and PbTiO3), probably due to their intrinsic photocatalytic activity and special garden-like features with a coexistence of various structures that significantly facilitated the adsorption and diffusion of methyl blue (MB) molecules and oxygen species in the photochemical reaction of MB degradation.By subjecting amorphous flower-like TiO2 to a facile hydrothermal synthesis in the presence of Sr2+, garden-like perovskite SrTiO3 superstructures were achieved. The amorphous TiO2 was preformed using ZnO flowers as templates. Different three-dimensional SrTiO3 architectures were coexisted in the garden, including SrTiO3 flowers composed of several hollow sword-shaped petals, many sheet-shaped petals or numerous flake-shaped petals, and SrTiO3 grass consisting of a number of long blades. These SrTiO3 superstructures were simultaneously grown on fluorine-doped tin oxide (FTO) substrates. On the basis of a comprehensive study on the effects of growth time, temperature, initial concentrations of precursor, and pH, the formation of these various hierarchical architectures was attributed primarily to the dissolution of amorphous TiO2 and precipitation of perovskite crystals, followed by the Ostwald ripening process of perovskite nanocrystals and self-organization of perovskite building blocks. Interestingly, this approach can be readily extended to create other perovskite structures, including dendritic BaTiO3 and nest-like CaTiO3, as well as PbTiO3 transformed from plate-like pyrochlore Pb2Ti2O6 after post-thermal treatment. Garden-like SrTiO3 superstructures showed a superior photocatalytic performance when compared to other as-prepared semiconductors and perovskite materials (i.e., ZnO, TiO2, BaTiO3, CaTiO3 and PbTiO3), probably due to their intrinsic photocatalytic activity and special garden-like features with a coexistence of various structures that significantly facilitated the adsorption and diffusion of methyl blue (MB) molecules and oxygen species in the photochemical reaction of MB degradation. Electronic supplementary information (ESI) available: FESEM images and the XRD pattern of SrTiO3 films (effects of growth temperature, initial precursor concentration, and pH value), EDS analysis of ZnO, TiO2 and SrTiO3, the XRD pattern and PL spectra of PbTiO3, UV-vis spectra of different films, and UV photo-degradation of MB. See DOI: 10.1039/c3nr05564g

Crystallization and Microphase Separation in Chiral Block Copolymers

NASA Astrophysics Data System (ADS)

Ho, Rong-Ming

2012-02-01

Block copolymers composed of chiral entities, denoted as chiral block copolymers (BCP*s), were designed to fabricate helical architectures from self-assembly. A helical phase (denoted H*) was discovered in the self-assembly of poly(styrene)-b-poly(L-lactide) (PS-PLLA) BCPs*. To examine the phase behavior of the PS-PLLA, self-assembled superstructures resulting from the competition between crystallization and microphase separation of the PS-PLLA in solution were examined. A kinetically controlled process by changing non-solvent addition rate was utilized to control the BCP* self-assembly. Single-crystal lozenge lamellae were obtained by the slow self-assembly (i.e., slow non-solvent addition rate) of PS-PLLA whereas amorphous helical ribbon superstructures were obtained from the fast self-assembly (i.e., fast non-solvent addition rate). As a result, the formation of helical architectures from the self-assembly of the PS-PLLA reflects the impact of chirality on microphase separation, but the chiral effect might be overwhelmed by crystallization. Consequently, various crystalline PS-PLLA nanostructures in bulk were obtained by controlling the crystallization temperature of PLLA (Tc,PLLA) at which crystalline helices and crystalline cylinders occur while Tc,PLLA=x Tg,PS, respectively. Anisotropic arrangement of the PLLA crystallites grown within the microdomains was identified. The formation of this exclusive crystalline growth is attributed to the spatial confinement effect for crystallization. While Tc,PLLA=x Tg,PS, the preferential growth may modulate the curvature of microdomains by shifting the molecular chains to access the fast path for crystalline growth due to the increase in chain mobility. As a result, a spring-like behavior of the helical nanostructure can be driven by crystallization so as to dictate the transformation of helices and to result in crystalline cylinders.

Development of bridge girder movement criteria for accelerated bridge construction.

DOT National Transportation Integrated Search

2014-06-01

End diaphragms connect multiple girders to form a bridge superstructure system for effective resistance to earthquake loads. Concrete : girder bridges that include end diaphragms consistently proved to perform well during previous earthquake events. ...

Concrete bridge deck condition assessment and improvement strategies.

DOT National Transportation Integrated Search

2004-11-01

The aging and deterioration of bridges in Utah mandates increasingly cost-effective strategies for bridge maintenance, rehabilitation, and repair (MR&R). Although the substructures and superstructures of bridges in Utah are in relatively good structu...

Glulam timber deck bridges : final report.

DOT National Transportation Integrated Search

1979-01-01

This report discusses the construction and initial condition of the Virginia Department of Highways and Transportation's first three bridges built with glulam panels on steel stringers. The data show that superstructures with glulam deck panels are m...

47 CFR 80.141 - General provisions for ship stations.

Code of Federal Regulations, 2013 CFR

2013-10-01

... storm, subfreezing air temperatures associated with gale force winds causing severe icing on superstructures, or winds of force 10 or above on the Beaufort scale for which no storm warning has been received...

47 CFR 80.141 - General provisions for ship stations.

Code of Federal Regulations, 2012 CFR

2012-10-01

... storm, subfreezing air temperatures associated with gale force winds causing severe icing on superstructures, or winds of force 10 or above on the Beaufort scale for which no storm warning has been received...

47 CFR 80.141 - General provisions for ship stations.

Code of Federal Regulations, 2011 CFR

2011-10-01

... storm, subfreezing air temperatures associated with gale force winds causing severe icing on superstructures, or winds of force 10 or above on the Beaufort scale for which no storm warning has been received...

47 CFR 80.141 - General provisions for ship stations.

Code of Federal Regulations, 2014 CFR

2014-10-01

... storm, subfreezing air temperatures associated with gale force winds causing severe icing on superstructures, or winds of force 10 or above on the Beaufort scale for which no storm warning has been received...

47 CFR 80.141 - General provisions for ship stations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... storm, subfreezing air temperatures associated with gale force winds causing severe icing on superstructures, or winds of force 10 or above on the Beaufort scale for which no storm warning has been received...

40 CFR 745.228 - Accreditation of training programs: public and commercial buildings, bridges and superstructures...

Code of Federal Regulations, 2012 CFR

2012-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.228...

40 CFR 745.228 - Accreditation of training programs: public and commercial buildings, bridges and superstructures...

Code of Federal Regulations, 2014 CFR

2014-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.228...

40 CFR 745.228 - Accreditation of training programs: public and commercial buildings, bridges and superstructures...

Code of Federal Regulations, 2013 CFR

2013-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.228...

Considerations for administering underwater contracts.

DOT National Transportation Integrated Search

1984-01-01

State highway and transportation agencies are required to inspect all bridges on the public road system using guidelines established by AASHTO. Procedures for inspecting the superstructures are well known and the expertise to perform them is availabl...

Superstructure based on β-CD self-assembly induced by a small guest molecule†

PubMed Central

De Sousa, Frederico B.; Lima, Ana C.; Denadai, Ângelo M. L.; Anconi, Cleber P. A.; De Almeida, Wagner B.; Novato, Willian T. G.; Dos Santos, Hélio F.; Drum, Chester L.; Langer, Robert

2014-01-01

The size, shape and surface chemistry of nanoparticles play an important role in cellular interaction. Thus, the main objective of the present study was the determination of the β-cyclodextrin (β-CD) self-assembly thermodynamic parameters and its structure, aiming to use these assemblies as a possible controlled drug release system. Light scattering measurements led us to obtain the β-CD’s critical aggregation concentration (cac) values, and consequently the thermodynamic parameters of the β-CD spontaneous self-assembly in aqueous solution: ΔaggGo = − 16.31 kJ mol−1, ΔaggHo = − 26.48 kJ mol−1 and TΔaggSo = − 10.53 kJ mol−1 at 298.15 K. Size distribution of the self-assembled nanoparticles below and above cac was 1.5 nm and 60–120 nm, respectively. The number of β-CD molecules per cluster and the second virial coefficient were identified through Debye’s plot and molecular dynamic simulations proposed the three-fold assembly for this system below cac. Ampicillin (AMP) was used as a drug model in order to investigate the key role of the guest molecule in the self-assembly process and the β-CD:AMP supramolecular system was studied in solution, aiming to determine the structure of the supramolecular aggregate. Results obtained in solution indicated that the β-CD’s cac was not affected by adding AMP. Moreover, different complex stoichiometries were identified by nuclear magnetic resonance and isothermal titration calorimetry experiments. PMID:22234498

13. Telephoto view looking east showing center pier and deck ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. Telephoto view looking east showing center pier and deck superstructure. Jet Lowe, photographer, 1983 - Neshanic Station Lenticular Truss Bridge, State Route 567, spanning South Branch of Raritan River, Neshanic Station, Somerset County, NJ

Properties of fouled railroad ballast (phase 1).

DOT National Transportation Integrated Search

2012-10-01

Ballasted tracks are the most common tracks used in the railroad industry and are designed to provide a stable, safe, and efficient rail : foundation. A ballasted track consists of superstructure (ties, fasteners, and rails) and substructure (ballast...

19. DETAIL, WEST ABUTMENT, FROM NORTH, SHOWING SQUARED STONE MASONRY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. DETAIL, WEST ABUTMENT, FROM NORTH, SHOWING SQUARED STONE MASONRY ABUTMENT, WITH PORTION OF SUPERSTRUCTURE - Virginia Department of Transportation Bridge No. 6051, Spanning Catoctin Creek at State Route 673 (Featherbottom Road), Waterford, Loudoun County, VA

50 CFR 300.14 - Vessel identification.

Code of Federal Regulations, 2010 CFR

2010-10-01

... § 300.212, that documentation number must be preceded by the characters “USA” and a hyphen (that is, “USA-”). (ii) The markings must be displayed at all times on the vessel's side or superstructure, port...

50 CFR 300.14 - Vessel identification.

Code of Federal Regulations, 2012 CFR

2012-10-01

... § 300.212, that documentation number must be preceded by the characters “USA” and a hyphen (that is, “USA-”). (ii) The markings must be displayed at all times on the vessel's side or superstructure, port...

50 CFR 300.14 - Vessel identification.

Code of Federal Regulations, 2014 CFR

2014-10-01

... § 300.212, that documentation number must be preceded by the characters “USA” and a hyphen (that is, “USA-”). (ii) The markings must be displayed at all times on the vessel's side or superstructure, port...

50 CFR 300.14 - Vessel identification.

Code of Federal Regulations, 2011 CFR

2011-10-01

... § 300.212, that documentation number must be preceded by the characters “USA” and a hyphen (that is, “USA-”). (ii) The markings must be displayed at all times on the vessel's side or superstructure, port...

50 CFR 300.14 - Vessel identification.

Code of Federal Regulations, 2013 CFR

2013-10-01

... § 300.212, that documentation number must be preceded by the characters “USA” and a hyphen (that is, “USA-”). (ii) The markings must be displayed at all times on the vessel's side or superstructure, port...

Differential settlement of a geosynthetic reinforced soil abutment : full-scale investigation.

DOT National Transportation Integrated Search

2015-05-01

The Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) uses alternating layers of closely spaced : geosynthetic reinforcement and well-compacted granular fill to support the bridge superstructure and form an integrated roadway : approach...

46 CFR 28.385 - Structural fire protection for vessels that operate with more than 49 individuals on board.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SECURITY UNINSPECTED VESSELS REQUIREMENTS FOR COMMERCIAL FISHING INDUSTRY VESSELS Requirements for Vessels...) Construction. The hull, structural bulkheads, columns and stanchions must be composed of steel. Superstructures...

Neutron diffraction study of the formation of ordered antiphase domains in cubic titanium carbide TiC{sub 0.60}

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

Khidirov, I., E-mail: khidirov@inp.uz; Parpiev, A. S.

2013-05-15

A series of superstructural reflections (described within the sp. gr. Fd3m) are found to be split into three symmetric parts in the neutron powder diffraction pattern of titanium carbide TiC{sub 0.60} annealed at a temperature of 600 Degree-Sign C. No splitting of superstructural reflections is observed in the neutron diffraction pattern of TiC{sub 0.60} annealed at relatively high temperatures (780 Degree-Sign C). This phenomenon can be explained by that fact that the ordering of carbon atoms at relatively high temperatures (780 Degree-Sign C) is accompanied by the formation of randomly oriented rather large antiphase domains (APDs) (450 A). At relativelymore » low temperatures (600 Degree-Sign C), stacking faults arise in the arrangement of partially ordered carbon atoms. In this case, relatively small ordered APDs (290 A) are formed, along with disordered ones.« less

Self-Assembled Ag-MXA Superclusters with Structure-Dependent Mechanical Properties.

PubMed

Qin, Xiaoyun; Luo, Dan; Xue, Zhenjie; Song, Qian; Wang, Tie

2018-03-01

The low elastic modulus and time-consuming formation process represent the major challenges that impede the penetration of nanoparticle superstructures into daily life applications. As observed in the molecular or atomic crystals, more effective interactions between adjacent nanoparticles would introduce beneficial features to assemblies enabling optimized mechanical properties. Here, a straightforward synthetic strategy is showed that allows fast and scalable fabrication of 2D Ag-mercaptoalkyl acid superclusters of either hexagonal or lamellar topology. Remarkably, these ordered superstructures exhibit a structure-dependent elastic modulus which is subject to the tether length of straight-chain mercaptoalkyl acids or the ratio between silver and tether molecules. These superclusters are plastic and moldable against arbitrarily shaped masters of macroscopic dimensions, thereby opening a wealth of possibilities to develop more nanocrystals with practically useful nanoscopic properties. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stability and dynamic of strain mediated adatom superlattices on Cu<111 >

NASA Astrophysics Data System (ADS)

Kappus, Wolfgang

2013-03-01

Substrate strain mediated adatom equilibrium density distributions have been calculated for Cu<111 > surfaces using two complementing methods. A hexagonal adatom superlattice in a coverage range up to 0.045 ML is derived for repulsive short range interactions. For zero short range interactions a hexagonal superstructure of adatom clusters is derived in a coverage range about 0.08 ML. Conditions for the stability of the superlattice against formation of dimers or clusters and degradation are analyzed using simple neighborhood models. Such models are also used to investigate the dynamic of adatoms within their superlattice neighborhood. Collective modes of adatom diffusion are proposed from the analogy with bulk lattice dynamics and methods for measurement are suggested. The recently put forward explanation of surface state mediated interactions for superstructures found in scanning tunneling microscopy experiments is put in question and strain mediated interactions are proposed as an alternative.

Hierarchical Co-Assembly Enhanced Direct Ink Writing.

PubMed

Li, Longyu; Zhang, Pengfei; Zhang, Zhiyun; Lin, Qianming; Wu, Yuyang; Cheng, Alexander; Lin, Yunxiao; Thompson, Christina M; Smaldone, Ronald A; Ke, Chenfeng

2018-04-23

Integrating intelligent molecular systems into 3D printing materials and transforming their molecular functions to the macroscale with controlled superstructures will unleash great potential for the development of smart materials. Compared to macromolecular 3D printing materials, self-assembled small-molecule-based 3D printing materials are very rare owing to the difficulties of facilitating 3D printability as well as preserving their molecular functions macroscopically. Herein, we report a general approach for the integration of functional small molecules into 3D printing materials for direct ink writing through the introduction of a supramolecular template. A variety of inorganic and organic small-molecule-based inks were 3D-printed, and their superstructures were refined by post-printing hierarchical co-assembly. Through spatial and temporal control of individual molecular events from the nano- to the macroscale, fine-tuned macroscale features were successfully installed in the monoliths. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

RAPID COMMUNICATION: Study of superstructure II in multiferroic BiMnO3

NASA Astrophysics Data System (ADS)

Ge, Bing-Hui; Li, Fang-Hua; Li, Xue-Ming; Wang, Yu-Mei; Chi, Zhen-Hua; Jin, Chang-Qing

2008-09-01

The crystal structure of the minor phase, named superstructure II, existing in multiferroic compound BiMnO3 has been studied by electron diffraction and high-resolution transmission electron microscopy. Domains of major and minor phases coexisting in BiMnO3 were observed in high-resolution electron microscope images. The unit cell of minor phase was determined to be triclinic with the size 4×4×4 times as large as the distorted perovskite subcell. The [111] and [10bar 1] projected structure maps of the minor phase have been derived from the corresponding images by means of the image processing. A possible rough three-dimensional (3D) structure model was proposed based on the 3D structural information extracted from the two projected structure maps. Since there is no inversion centre in the proposed model, the minor phase may contribute to the ferroelectric property of BiMnO3.

STM/STS study on electronic superstructures in the superconducting state of high-Tc cuprate Bi2Sr2CaCu2O8+δ

NASA Astrophysics Data System (ADS)

Mizuta, S.; Kurosawa, T.; Takeyama, K.; Momono, N.; Ishii, Y.; Yoshida, H.; Oda, M.; Ido, M.

2018-03-01

We report STM/STS measurements at 8 K in underdoped Bi2Sr2CaCu2O8+δ crystals (T c = 76 K and hole-doping level p ∼ 0.12) whose energy spectra around the Fermi level are characterized by a two-gap structure consisting of spatially inhomogeneous pseudogap (PG) and comparatively homogeneous superconducting gap (SCG). Two electronic superstructures, checkerboard modulation (CBM) and Cu-O-Cu bond-centered modulation (BCM), are observed with mapping spectral weights at low energies within the SCG and the ratio of spectral weights at ±ΔPG (PG energy), respectively. On the basis of the present findings, we suggest that the lower-energy scale CBM is an intrinsic property of Cu-O planes and can coexist with the BCM whose characteristic energy is ∼ΔPG in identical regions in real space.

LT-STM/STS studies of clean armchair edge

NASA Astrophysics Data System (ADS)

Ju, Zheng; Zhang, Wenhan; Wu, Weida; Weida Wu Team

It was predicted and observed that the passivated zigzag edges of graphene host highly localized edge state. This edge state is predicted to be spin-polarized, which is appealing for spintronic applications. In contrast, no edge state was expected at passivated armchair graphene edge. Here we report low temperature scanning tunneling microscopy and spectroscopy (STM/STS) studies of electronic properties of clean monoatomic step edges on cleaved surface of HOPG. Most of step edges are armchair edges, in agreement with previous STM results. We observed only (√{ 3} ×√{ 3}) R30° superstructure near armchair edges, which has been reported in previous STM studies. On the other hand, no honeycomb superstructure was observed in our STM data. In addition, our STM results reveal an intriguing localized electronic state at clean armchair edges. Spectroscopic and spatial evolution of this edge state will be presented. This work is supported by NSF DMR-1506618.

Traffic on complex networks: Towards understanding global statistical properties from microscopic density fluctuations

NASA Astrophysics Data System (ADS)

Tadić, Bosiljka; Thurner, Stefan; Rodgers, G. J.

2004-03-01

We study the microscopic time fluctuations of traffic load and the global statistical properties of a dense traffic of particles on scale-free cyclic graphs. For a wide range of driving rates R the traffic is stationary and the load time series exhibits antipersistence due to the regulatory role of the superstructure associated with two hub nodes in the network. We discuss how the superstructure affects the functioning of the network at high traffic density and at the jamming threshold. The degree of correlations systematically decreases with increasing traffic density and eventually disappears when approaching a jamming density Rc. Already before jamming we observe qualitative changes in the global network-load distributions and the particle queuing times. These changes are related to the occurrence of temporary crises in which the network-load increases dramatically, and then slowly falls back to a value characterizing free flow.

A simultaneous pressure and temperature sensor based on a superstructure fiber grating

NASA Astrophysics Data System (ADS)

Lin, Chia-Min; Liu, Wen-Fung; Fu, Ming-Yue; Sheng, Hao-Jan; Bor, Sheau-Shung; Tien, Chuen-Lin

2004-12-01

We demonstrated that a high-sensitivity fiber sensor based on a superstructure fiber grating (SFG) can simultaneously measure the pressure and temperature by encapsulating the grating in a polymer-half-filled metal cylinder, in which there are two openings on opposite sides of the wall filled with the polymer to sense the pressure. The mechanism of sensing pressure is to transfer the pressure into the axial extended-strain. According to the optical characteristics of an SFG composed of a fiber Bragg grating (FBG) and long period grating (LPG), the various pressure and temperature will cause the variation of the center-wavelength and reflection simultaneously. Thus, the sensor can be used for the measurement both of the pressure and temperature. The pressure sensitivity of 2.28×10-2MPa-1 and the temperature sensitivity both of 0.015nm/°C and -0.143dB/°C are obtained.

Delocalized Surface State in Epitaxial Si(111) Film with Spontaneous √3 × √3 Superstructure

PubMed Central

Chen, Jian; Du, Yi; Li, Zhi; Li, Wenbin; Feng, Baojie; Qiu, Jinlan; Cheng, Peng; Xue Dou, Shi; Chen, Lan; Wu, Kehui

2015-01-01

The “multilayer silicene” films were grown on Ag(111), with increasing thickness above 30 monolayers (ML). Scanning tunneling microscopy (STM) observations suggest that the “multilayer silicene” is indeed a bulk-like Si(111) film with a (√3 × √3)R30° honeycomb superstructure on surface. The possibility for formation of Si(111)(√3 × √3)R30°-Ag reconstruction on the surface can be distinctively ruled out by peeling off the surface layer with the STM tip. On this surface, delocalized surface state as well as linear energy-momentum dispersion was observed from quasiparticle interference patterns. Our results indicate that a bulklike silicon film with diamondlike structure can also host delocalized surface state, which is even more attractive for potential applications, such as new generation of nanodevices based on Si. PMID:26316281

Design considerations for quasi-phase-matching in doubly resonant lithium niobate hexagonal micro-resonators

NASA Astrophysics Data System (ADS)

Sono, Tleyane J.; Riziotis, Christos; Mailis, Sakellaris; Eason, Robert W.

2017-09-01

Fabrication capabilities of high optical quality hexagonal superstructures by chemical etching of inverted ferroelectric domains in lithium niobate platform suggests a route for efficient implementation of compact hexagonal microcavities. Such nonlinear optical hexagonal micro-resonators are proposed as a platform for second harmonic generation (SHG) by the combined mechanisms of total internal reflection (TIR) and quasi-phase-matching (QPM). The proposed scheme for SHG via TIR-QPM in a hexagonal microcavity can improve the efficiency and also the compactness of SHG devices compared to traditional linear-type based devices. A simple theoretical model based on six-bounce trajectory and phase matching conditions was capable for obtaining the optimal cavity size. Furthermore numerical simulation results based on finite difference time domain beam propagation method analysis confirmed the solutions obtained by demonstrating resonant operation of the microcavity for the second harmonic wave produced by TIR-QPM. Design aspects, optimization issues and characteristics of the proposed nonlinear device are presented.

From Solute, Fluidic and Particulate Precursors to Complex Organizations of Matter.

PubMed

Rao, Ashit; Cölfen, Helmut

2018-03-24

The organization of matter from its constitutive units recruits intermediate states with distinctive degrees of self-association and molecular order. Existing as clusters, droplets, gels as well as amorphous and crystalline nanoparticles, these precursor forms have fundamental contributions towards the composition and structure of inorganic and organic architectures. In this personal account, we show that the transitions from atoms, molecules or ionic species to superstructures of higher order are intertwined with the interfaces and interactions of precursor and intermediate states. Structural organizations distributed across different length scales are explained by the multistep nature of nucleation and crystallization, which can be guided towards functional hybrid materials by the strategic application of additives, templates and reaction environments. Thus, the non-classical pathways for material formation and growth offer conceptual frameworks for elucidating, inducing and directing fascinating material organizations of biogenic and synthetic origins. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flower-like superstructures of AIE-active tetraphenylethylene through solvophobic controlled self-assembly

NASA Astrophysics Data System (ADS)

Salimimarand, Mina; La, Duong Duc; Kobaisi, Mohammad Al; Bhosale, Sheshanath V.

2017-02-01

The development of well-organized structures with high luminescent properties in the solid and aggregated states is of both scientific and technological interest due to their applications in nanotechnology. In this paper we described the synthesis of amphiphilic and dumbbell shaped AIE-active tetraphenylethylene (TPE) derivatives and studied their self-assembly with solvophobic control. Interestingly, both TPE derivatives form a 3D flower-shape supramolecular structure from THF/water solutions at varying water fractions. SEM microscopy was used to visualise step-wise growth of flower-shape assembly. TPE derivatives also show good mechanochromic properties which can be observed in the process of grinding, fuming and heating. These TPE derivative self-assemblies are formed due to two main important properties: (i) the TPE-core along with alkyl chains, optimizing the dispersive interactions within a construct, and (ii) amide-linkage through molecular recognition. We believe such arrangements prevent crystallization and favour the directional growth of flower-shape nanostructures in a 3D fashion.

Complementary ab initio and X-ray nanodiffraction studies of Ta2O5

PubMed Central

Hollerweger, R.; Holec, D.; Paulitsch, J.; Bartosik, M.; Daniel, R.; Rachbauer, R.; Polcik, P.; Keckes, J.; Krywka, C.; Euchner, H.; Mayrhofer, P.H.

2015-01-01

The complex structure of Ta2O5 led to the development of various structural models. Among them, superstructures represent the most stable configurations. However, their formation requires kinetic activity and long-range ordering processes, which are hardly present during physical vapor deposition. Based on nano-beam X-ray diffraction and concomitant ab initio studies, a new metastable orthorhombic basic structure is introduced for Ta2O5 with lattice parameters a = 6.425 Å, b = 3.769 Å and c = 7.706 Å. The unit cell containing only 14 atoms, i.e. two formula unit blocks in the c direction, is characterized by periodically alternating the occupied oxygen site between two possible positions in succeeding 002-planes. This structure can be described by the space group 53 (Pncm) with four Wyckoff positions, and exhibits an energy of formation of −3.209 eV atom−1. Among all the reported basic structures, its energy of formation is closest to those of superstructures. Furthermore, this model exhibits a 2.5 eV band gap, which is closer to experimental data than the band gap of any other basic-structure model. The sputtered Ta2O5 films develop only a superstructure if annealed at temperatures >800 °C in air or vacuum. Based on these results and the conveniently small unit cell size, it is proposed that the basic-structure model described here is an ideal candidate for both structure and electronic state descriptions of orthorhombic Ta2O5 materials. PMID:25642136

Diamondlike carbon coating as a galvanic corrosion barrier between dental implant abutments and nickel-chromium superstructures.

PubMed

Ozkomur, Ahmet; Erbil, Mehmet; Akova, Tolga

2013-01-01

The objectives of this study were to evaluate the galvanic corrosion behavior between titanium and nickel-chromium (Ni-Cr) alloy, to investigate the effect of diamondlike carbon (DLC) coating over titanium on galvanic corrosion behavior between titanium and Ni-Cr alloy, and to evaluate the effect of DLC coating over titanium abutments on the fit and integrity of prosthetic assemblies by scanning electron microcopy (SEM). Five Ni-Cr and 10 titanium disks with a diameter of 5 mm and thickness of 3 mm were prepared. DLC coating was applied to five titanium disks. Electrode samples were prepared, and open circuit potential measurements, galvanic current measurements over platinum electrodes, and potentiodynamic polarization tests were carried out. For the SEM evaluation, 20 Ni-Cr alloy and 10 gold alloy superstructures were cast and prepared over 30 abutments. DLC coating was applied to 10 of the abutments. Following the fixation of prosthetic assemblies, the samples were embedded in acrylic resin and cross sectioned longitudinally. Internal fit evaluations were carried out through examination of the SEM images. Titanium showed more noble and electrochemically stable properties than Ni-Cr alloy. DLC coating over the cathode electrode served as an insulating film layer over the surface and prevented galvanic coupling. Results of the SEM evaluations indicated that the DLC-coated and titanium abutments showed no statistically significant difference in fit. Hence, no adverse effects on the adaptation of prosthetic components were found with the application of DLC coating over abutment surfaces. DLC coating might serve as a galvanic corrosion barrier between titanium abutments and Ni-Cr superstructures.

C60 superstructure and carbide formation on the Al-terminated Al9Co2(001 ) surface

NASA Astrophysics Data System (ADS)

Ledieu, J.; Gaudry, É.; de Weerd, M.-C.; Gille, P.; Diehl, R. D.; Fournée, V.

2015-04-01

We report the formation of an ordered C60 monolayer on the Al9Co2 (001) surface using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and ab initio calculations. Dosing fullerenes at 300 K results in a disordered overlayer. However, the adsorption of C60 with the sample held between 573-673 K leads to a [4, -2 ∣1 ,3 ] phase. The growth of C60 proceeds with the formation of two domains which are mirror symmetric with respect to the [100] direction. Within each domain, the superstructure unit cell contains six molecules and this implies an area per fullerene equal to 91 Å2. The molecules exhibit two types of contrast (bright and dim) which are bias dependent. The adsorption energies and preferred molecular configuration at several possible adsorption sites have been determined theoretically. These calculations lead to a possible scheme describing the configuration of each C60 in the observed superstructure. Several defects (vacancies, protrusions,…) and domain boundaries observed in the film are also discussed. If the sample temperature is higher than 693 K when dosing, impinging C60 molecules dissociate at the surface, hence leading to the formation of a carbide film as observed by STM and LEED measurements. The formation of Al4C3 domains and the molecular dissociation are confirmed by XPS/UPS measurements acquired at different stages of the experiment. The cluster substructure present at the Al9Co2 (001) surface dictates the carbide domain orientations.

Stress levels for well-fitting implant superstructures as a function of tightening force levels, tightening sequence, and different operators.

PubMed

Nissan, J; Gross, M; Shifman, A; Assif, D

2001-07-01

Unfavorable stress distribution and occlusal overload have been reported to result in failures ranging from screw loosening to loss of osseointegration. The purpose of this study was to assess the effect of different tightening forces and sequences, with different operators, on stresses generated on an accurately fitting implant superstructure on multiple working casts made with a splinted impression technique. The effects of different tightening forces (10 and 20 Ncm) were assessed with the use of 30 stone casts made from a metal master model with a splinted impression technique. Stresses generated were recorded by 4 strain gauges attached to the superior surface of the master framework. A multiple analysis of variance with repeated measures was performed to test for significant differences among the groups. Tightening force values at 10 Ncm ranged from 150.43 to 256 Ncm. At 20 Ncm, microstrain values ranged from 149.43 to 284.37 Ncm. Microstrain values related to the sequence of tightening ranged from 150.8 to 308.43 Ncm (left to right) and 154.63 to 274.80 Ncm (right to left). For the different operators, microstrain values ranged from 100.13 to 206.07 Ncm. No statistically significant differences among the variables of tightening force, tightening sequence, and operators were found ( P >.05). The interaction between groups and strain gauges was also found to be nonsignificant (P >.05). The potential of variable tightening force and tightening sequence to generate unfavorable preload stresses can be minimized through use of the splinted impression technique, which ensures an accurately fitting superstructure.

Adsorbate-induced reconstruction in the phase 1 × 2-3H/Rh(110)

NASA Astrophysics Data System (ADS)

Michl, M.; Nichtl-Pecher, W.; Oed, W.; Landskron, H.; Heinz, K.; Müller, K.

1989-10-01

The 1 × 2-3H superstructure of hydrogen on Rh(110) at coverage θ = {3}/{2} is analysed by low energy electron diffraction at 90 K. The spectra of eight beams are recorded with a computer-controlled TV measurement technique which yields low noise data even for weak superstructure spots by multiple averaging. Comparison to full dynamical calculations shows that a kinematic treatment of the hydrogen layer diffraction coupled to the full dynamical diffraction of the substrate is a very good approximation. Spectra computed in this way are compared with experimental data by R-factor evaluation. The three non-equivalent hydrogen atoms are found to adsorb in quasi-three-fold coordinated adsorption sites with slightly different local configurations and with H-Rh bond lengths between 1.87 and 1.93 Å to the first-layer rhodium atoms. Interaction between the adatoms seems to weaken the bonding to the adjacent atom in the second layer, so that H-Rh bond lengths larger than 2.17 Å result. A slight reconstruction of the substrate is necessary to bring superstructure spot intensities near the experimentally observed level. Rhodium atoms bonded to two hydrogen atoms are moved out of the surface by 0.03 ± 0.02 Å relative to Rh atoms bonded to only a single H atom. The relaxation of the first Rh layer spacing is determined to be {d 12}/{d 0} = -3.8 ± 1% and {d 22}/{d 0} = 0 ± 1% . The best fit Pendry R-factor is 0.33.

46 CFR 45.159 - Special conditions of assignment for type A vessels.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... Therefore the following additional requirements must be met to qualify for type A freeboards: (a) Machinery... providing they lead to a space or passageway as strong as an enclosed superstructure from which a second...

46 CFR 45.159 - Special conditions of assignment for type A vessels.

Code of Federal Regulations, 2011 CFR

2011-10-01

.... Therefore the following additional requirements must be met to qualify for type A freeboards: (a) Machinery... providing they lead to a space or passageway as strong as an enclosed superstructure from which a second...

46 CFR 69.113 - Superstructure tonnage.

Code of Federal Regulations, 2011 CFR

2011-10-01

... is one-half the nearest breadth. If an end is in the form of an arc or curve having a decided flat...-third of the interval between the points at which the breadths are taken. The product is the square foot...

46 CFR 69.113 - Superstructure tonnage.

Code of Federal Regulations, 2010 CFR

2010-10-01

... is one-half the nearest breadth. If an end is in the form of an arc or curve having a decided flat...-third of the interval between the points at which the breadths are taken. The product is the square foot...

Field study of a pedestrian bridge of reinforced plastic.

DOT National Transportation Integrated Search

1985-01-01

A discussion of the behavior of the superstructure of a pedestrian bridge fabricated with glass-reinforced plastic under a field load test is presented. Experimental measurements of elastic vertical deflections were 1.8 times greater than those predi...

Permeability, resistivity and strength of fouled railroad ballast.

DOT National Transportation Integrated Search

2014-04-01

Ballaste : d tracks are the most common tracks used in the railroad industry and are designed to provide a stable, safe, and efficient r : ail foundation. A : ballasted track consists of superstructure (ties, fasteners, and rails), and substructure (...

Differential settlement of a geosynthetic reinforced soil abutment : full-scale investigation : summary report.

DOT National Transportation Integrated Search

2015-05-01

The Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) uses alternating layers of closely spaced : geosynthetic reinforcement and well-compacted granular fill to support the bridge superstructure and form an integrated roadway : approach...

Long-term behavior of integral abutment bridges : [technical summary].

DOT National Transportation Integrated Search

2011-01-01

Integral abutment bridges, a type of jointless bridge, are the construction option of choice when designing highway bridges in many parts of the country. Rather than providing an expansion joint to separate the substructure from the superstructure to...

A fitness-for-purpose evaluation of fracture critical electro-slag welds.

DOT National Transportation Integrated Search

2009-03-01

A fitness-for-purpose evaluation was performed on the electro-slag flange welds of the West Fremont bridge approach : superstructures, per the request of FHWA. This evaluation required gathering knowledge of the material properties, fabrication : def...

Calibration of load and resistance factors in LRFD foundation design specifications

DOT National Transportation Integrated Search

2011-02-01

This report summarizes the findings and recommendations on the impact of foundation settlements on the reliability of bridge superstructures. As a collaborative effort of an overall initiative for the development of LRFD foundation design specificati...

Instrumentation of the Red River Bridge at Boyce, Louisiana : final report.

DOT National Transportation Integrated Search

1991-01-01

The report describes the instrumentation program of Red River Bridge at Boyce, Louisiana. The objectives of the program were to measure and evaluate time-dependent deformations, deflections, and temperatures of the Red River Bridge superstructure. To...

Instrumentation of the Red River Bridge at Boyce, Louisiana : final report.

DOT National Transportation Integrated Search

1988-08-01

The report describes the instrumentation program of Red River Bridge at Boyce, Louisiana. The objectives of the program were to measure and evaluate time-dependent deformations, deflections, and temperatures of the Red River Bridge superstructure. To...

Nanoscale superstructures assembled by polymerase chain reaction (PCR): programmable construction, structural diversity, and emerging applications.

PubMed

Kuang, Hua; Ma, Wei; Xu, Liguang; Wang, Libing; Xu, Chuanlai

2013-11-19

Polymerase chain reaction (PCR) is an essential tool in biotechnology laboratories and is becoming increasingly important in other areas of research. Extensive data obtained over the last 12 years has shown that the combination of PCR with nanoscale dispersions can resolve issues in the preparation DNA-based materials that include both inorganic and organic nanoscale components. Unlike conventional DNA hybridization and antibody-antigen complexes, PCR provides a new, effective assembly platform that both increases the yield of DNA-based nanomaterials and allows researchers to program and control assembly with predesigned parameters including those assisted and automated by computers. As a result, this method allows researchers to optimize to the combinatorial selection of the DNA strands for their nanoparticle conjugates. We have developed a PCR approach for producing various nanoscale assemblies including organic motifs such as small molecules, macromolecules, and inorganic building blocks, such as nanorods (NRs), metal, semiconductor, and magnetic nanoparticles (NPs). We start with a nanoscale primer and then modify that building block using the automated steps of PCR-based assembly including initialization, denaturation, annealing, extension, final elongation, and final hold. The intermediate steps of denaturation, annealing, and extension are cyclic, and we use computer control so that the assembled superstructures reach their predetermined complexity. The structures assembled using a small number of PCR cycles show a lower polydispersity than similar discrete structures obtained by direct hybridization between the nanoscale building blocks. Using different building blocks, we assembled the following structural motifs by PCR: (1) discrete nanostructures (NP dimers, NP multimers including trimers, pyramids, tetramers or hexamers, etc.), (2) branched NP superstructures and heterochains, (3) NP satellite-like superstructures, (4) Y-shaped nanostructures and DNA networks, (5) protein-DNA co-assembly structures, and (6) DNA block copolymers including trimers and pentamers. These results affirm that this method can produce a variety of chemical structures and in yields that are tunable. Using PCR-based preparation of DNA-bridged nanostructures, we can program the assembly of the nanoscale blocks through the adjustment of the primer intensity on the assembled units, the number of PCR cycles, or both. The resulting structures are highly complex and diverse and have interesting dynamics and collective properties. Potential applications of these materials include chirooptical materials, probe fabrication, and environmental and biomedical sensors.

Ion Fast Ignition-Establishing a Scientific Basis for Inertial Fusion Energy --- Final Report

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

Stephens, Richard Burnite; Foord, Mark N.; Wei, Mingsheng

The Fast Ignition (FI) Concept for Inertial Confinement Fusion (ICF) has the potential to provide a significant advance in the technical attractiveness of Inertial Fusion Energy reactors. FI differs from conventional ?central hot spot? (CHS) target ignition by decoupling compression from heating: using a laser (or heavy ion beam or Z pinch) drive pulse (10?s of nanoseconds) to create a dense fuel and a second, much shorter (~10 picoseconds) high intensity pulse to ignite a small volume within the dense fuel. The compressed fuel is opaque to laser light. The ignition laser energy must be converted to a jet ofmore » energetic charged particles to deposit energy in the dense fuel. The original concept called for a spray of laser-generated hot electrons to deliver the energy; lack of ability to focus the electrons put great weight on minimizing the electron path. An alternative concept, proton-ignited FI, used those electrons as intermediaries to create a jet of protons that could be focused to the ignition spot from a more convenient distance. Our program focused on the generation and directing of the proton jet, and its transport toward the fuel, none of which were well understood at the onset of our program. We have developed new experimental platforms, diagnostic packages, computer modeling analyses, and taken advantage of the increasing energy available at laser facilities to create a self-consistent understanding of the fundamental physics underlying these issues. Our strategy was to examine the new physics emerging as we added the complexity necessary to use proton beams in an inertial fusion energy (IFE) application. From the starting point of a proton beam accelerated from a flat, isolated foil, we 1) curved it to focus the beam, 2) attached the foil to a superstructure, 3) added a side sheath to protect it from the surrounding plasma, and finally 4) studied the proton beam behavior as it passed through a protective end cap into plasma. We built up, as we proceeded, a self-consistent picture of the quasi-neutral plasma jet that is the proton beam that, for the first time, included the role of the hot electrons in shaping the jet. Controlling them?through design of the accelerating surface and its connection to the surrounding superstructure?is critical; their uniform spread across the proton accelerating area is vital, but their presence in the jet opposes focus; their electron flow away from the acceleration area reduces conversion efficiency but can also increase focusing ability. The understanding emerging from our work and the improved simulation tools we have developed allow designing structures that optimize proton beams for focused heating. Our findings include: ? The achievable focus of proton beams is limited by the thermal pressure gradient in the laser-generated hot electrons that drive the process. This bending can be suppressed using a controlled flow of hot electrons along the surrounding cone wall, which induces a local transverse focusing sheath electric field. The resultant (vacuum-focused) spot can meet IFE requirements. ? Confinement of laser-generated electrons to the proton accelerating area can be achieved by supporting targets on thin struts. That increases laser-to-proton conversion energy by ~50%. As noted above, confinement should not be total; necessary hot-electron leakage into the surrounding superstructure for proton focusing can be controlled by with the strut width/number. ? Proton jets are further modified as they enter the fuel through the superstructure?s end cap. They can generate currents during that transit that further focus the proton beams. We developed a new ion stopping module for LSP code that properly accounted for changes in stopping power with ionization (e.g. temperature), and will be using it in future studies. The improved understanding, new experimental platforms, and the self-consistent modeling capability allow researchers a new ability to investigate the interaction of large ion currents with warm dense matter. That is of direct importance to the creation and investigation of all aspects of warm dense matter as well as to proton-ignited FI.« less

Use of Solid Waste (Foundry Slag) Mortar and Bamboo Reinforcement in Seismic Analysis for Single Storey Masonry Building

NASA Astrophysics Data System (ADS)

Ahmad, S.; Husain, A.; Ghani, F.; Alam, M. N.

2013-11-01

The conversion of large amount of solid waste (foundry slag) into alternate source of building material will contribute not only as a solution to growing waste problem, but also it will conserve the natural resources of other building material and thereby reduce the cost of construction. The present work makes an effort to safe and economic use of recycle mortar (1:6) as a supplementary material. Conventional and recycled twelve prisms were casted with varying percentage of solid waste (foundry slag) added (0, 10, 20, 30 %) replacing cement by weight and tested under compression testing machine. As the replacement is increasing, the strength is decreasing. 10 % replacement curve is very closed to 0 % whereas 20 % is farther and 30 % is farthest. 20 % replacement was chosen for dynamic testing as its strength is within permissible limit as per IS code. A 1:4 scale single storey brick model with half size brick was fabricated on shake table in the lab for dynamic testing using pure friction isolation system (coarse sand as friction material µ = 0.34). Pure friction isolation technique can be adopted economically in developing countries where low-rise building prevails due to their low cost. The superstructure was separated from the foundation at plinth level, so as to permit sliding of superstructure during severe earthquake. The observed values of acceleration and displacement responses compare fairly with the analytical values of the analytical model. It also concluded that 20 % replacement of cement by solid waste (foundry slag) could be safely adopted without endangering the safety of the masonry structures under seismic load.To have an idea that how much energy is dissipated through this isolation, the same model with fixed base was tested and results were compared with the isolated free sliding model and it has been observed that more than 60 % energy is dissipated through this pure friction isolation technique. In case of base isolation, no visible cracks were observed up to the table force of 4.25 kN (1,300 rpm), whereas for fixed base failure started at 800 rpm.To strengthen the fixed base model, bamboo reinforcement were used for economical point of view. Another model of same dimension with same mortar ratio was fabricated on the shake table with bamboo reinforcement as plinth band and lintel band. In addition another four round bamboo bars of 3 mm diameter were placed at each of the four corners of the model. The building model was tested and found very encouraging and surprising results. The model failure started at 1,600 rpm, which means that this model is surviving the double force in comparison with the non-bamboo reinforcement.

Methods for removing concrete decks from bridge girders : [tech transfer summary].

DOT National Transportation Integrated Search

2014-08-01

Although bridges are typically designed to last for 75 years (AWS 2012), : bridge decks deteriorate at a faster rate (Flowers et al. 2010). Full-depth : replacement of bridge decks that can be performed without replacing the : bridge superstructures ...

View of West end of central lift span truss web ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of West end of central lift span truss web of Tensaw River Bridge, showing web brace of lift girder superstructure, looking west - Tensaw River Lift Bridge, Spanning Tensaw River at U.S. Highway 90, Mobile, Mobile County, AL

Seismic testing of precast segmental bridges, Phase III : bridge system test.

DOT National Transportation Integrated Search

2005-06-01

This report discusses the main findings of a test examining the seismic behavior of a precast, post-tensioned, segmental bridge : superstructure with a cast-in-place, hollow, rectangular column. The half-scale specimen modeled a prototype bridge from...

Soil-structure interaction studies for understanding the behavior of integral abutment bridges.

DOT National Transportation Integrated Search

2012-03-01

Integral Abutment Bridges (IAB) are bridges without any joints within the bridge deck or between the : superstructure and the abutments. An IAB provides many advantages during construction and maintenance of : a bridge. Soil-structure interactions at...

Wave loading on bridge decks : final report, December 2009.

DOT National Transportation Integrated Search

2009-12-01

This report covers the results of experimental and theoretical analyses of wave loading on bridge superstructures. A number of wave tank tests were performed on both slab and girder type spans with different water depths, span positions relative to t...

Development of a guideline for estimating tsunami forces On bridge superstructures.

DOT National Transportation Integrated Search

2011-10-01

"The Pacific Northwest is vulnerable to seismic events in the Cascadia Subduction Zone (CSZ) that could generate a : large tsunami that could devastate coastal infrastructure such as bridges. In this context, this paper describes the : development of...

11. DETAIL SHOWING ROLLING ENGINE DECK AND NORTHEAST TRUSS OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. DETAIL SHOWING ROLLING ENGINE DECK AND NORTHEAST TRUSS OF SUPERSTRUCTURE. Looking northeast. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Accurate and Rapid Determination of Fatigue Damage in Bridge Superstructures

DOT National Transportation Integrated Search

1992-12-01

Fifteen representative steel bridges throughout the State of Illinois were : instrumented with foil strain gages to determine their frequencies of loading : and the magnitudes of stresses induced by traffic over a 3 to 8-hour period, : depending on t...

Project 2d: Calibration of Load and Resistance Factors in LRFD Foundation Design Specifications

DOT National Transportation Integrated Search

2011-02-01

This report summarizes the findings and recommendations on the impact of foundation settlements on the reliability of bridge superstructures. As a : collaborative effort of an overall initiative for the development of LRFD foundation design specifica...

Shear in high strength concrete bridge girders : technical report.

DOT National Transportation Integrated Search

2013-04-01

Prestressed Concrete (PC) I-girders are used extensively as the primary superstructure components in Texas highway bridges. : A simple semi-empirical equation was developed at the University of Houston (UH) to predict the shear strength of PC I-girde...

Assessment of weathering steel bridge performance in Iowa and development of inspection and maintenance techniques.

DOT National Transportation Integrated Search

2013-02-01

Weathering steel is commonly used as a cost-effective alternative for bridge superstructures, as the costs and environmental : impacts associated with the maintenance/replacement of paint coatings are theoretically eliminated. The performance of : we...

Modifying Ship Air-Wake Vortices for Aircraft Operations

NASA Technical Reports Server (NTRS)

Lamar, John E.

2004-01-01

Columnar-vortex generators (CVG) have been proposed as means to increase the safety of takeoffs and landings of aircraft on aircraft or helicopter carriers and other ships at sea. According to the proposal, CVGs would be installed at critical edge locations on ships to modify the vortices in the air wakes of the ships. The desired effects of modifications are to smooth airflows over takeoff and landing deck areas and divert vortices from takeoff and landing flight paths. With respect to aircraft operations, the wake flows of primary interest are those associated with the bow and side edges of aircraft-carrier decks and with superstructures of ships in general (see Figure 1). The bow and deck-edge vortices can adversely affect airplane and helicopter operations on carriers, while the superstructure wakes can primarily affect operations of helicopters. The concept of the CVG is not new; what is new is the proposed addition of CVGs to ship structures to effect favorable modifications of air wakes. Figure 2 depicts a basic CVG, vertical and horizontal CVGs installed on a simple superstructure, and horizontal CVGs installed on the bow and deck edges. The vertical CVGs would be closed at the deck but open at the top. Each horizontal CVG would be open at both ends. The dimensions of the CVGs installed on the aft edges of the superstructure would be chosen so that the portion of the flow modified by the vertical CVGs would interact synergistically with the portion of the flow modified by the horizontal CVG to move the air wake away from the takeoff-and-landing zone behind the superstructure. The deck-edge CVGs would be mounted flush with, and would extend slightly ahead of the bow of, the flight deck. The overall length of each tube would exceed that of the flight deck. Each deck-edge CVG would capture that portion of the airflow that generates a deck-edge vortex and would generate a columnar vortex of opposite sense to that of the unmodified vortex. The vortex generated by the CVG could be dispersed at its base, thereby removing unwanted turbulence in the path of an approaching airplane. The deck-edge CVGs would promote smooth flow over the entire flight deck. In the case of a Nimitz-class aircraft carrier like that of Figure 1, there would be a CVG on each of the outer edges of the two left portions of the flight deck and a single CVG on the right side of the flight deck. The forward-most CVG on the left side would take the generated vortex underneath the angled flight deck. A CVG could also be installed on the bow of the flight deck to smooth the flow of air onto the flight deck. In the case of wind incident on the deck from an azimuth other than straight ahead, the vortex generated by the bow CVG could, perhaps, be used to feed the CVG(s) of the leeward side edge of the flight deck.

Development Length for Headed Bars in Slab-Column Joints of RC Slab Bridges

DOT National Transportation Integrated Search

2015-12-04

In accordance with the Caltrans Seismic Design Criteria, the superstructure in a slab bridge should remain essentially elastic and only the pile extensions/columns are permitted to develop inelastic deformations during a seismic event. Hence, the lon...

Evaluation of long-term prestress losses in post-tensioned box-girder bridges.

DOT National Transportation Integrated Search

2011-03-01

Most of the recent highway bridges built in California have post-tensioned, cast-in-place, concrete box-girder superstructures rigidly connected to bridge columns. However, methods provided in the current (2007 and 2010) AASHTO LRFD Bridge Design Spe...

46 CFR 42.25-5 - Definitions of terms used in this subpart.

Code of Federal Regulations, 2010 CFR

2010-10-01

... timber carried on an uncovered part of a freeboard or superstructure deck. The term does not include wood... comply with certain conditions relating to its construction which are set out in § 42.25-10. [CGFR 68-60...

40 CFR 63.1381 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... fiberglass to which a phenol-formaldehyde binder has been applied. Building insulation means bonded wool fiberglass insulation, having a loss on ignition of less than 8 percent and a density of less than 32... includes foundations, superstructure and retaining walls, raw material charger systems, heat exchangers...

40 CFR 63.1381 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... fiberglass to which a phenol-formaldehyde binder has been applied. Building insulation means bonded wool fiberglass insulation, having a loss on ignition of less than 8 percent and a density of less than 32... includes foundations, superstructure and retaining walls, raw material charger systems, heat exchangers...

40 CFR 63.1381 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... fiberglass to which a phenol-formaldehyde binder has been applied. Building insulation means bonded wool fiberglass insulation, having a loss on ignition of less than 8 percent and a density of less than 32... includes foundations, superstructure and retaining walls, raw material charger systems, heat exchangers...

Long-term monitoring of the HPC Charenton Canal Bridge : tech summary.

DOT National Transportation Integrated Search

2011-08-01

In 1997, the Louisiana Department of Transportation and Development (LADOTD) began to design the : Charenton Canal Bridge using HPC for both the superstructure and the substructure. As a part of the project, : a research contract was awarded to assis...

Forces in wingwalls from thermal expansion of skewed semi-integral bridges : executive summary report.

DOT National Transportation Integrated Search

2010-11-01

Bridges that utilize expansion joints have an overall higher maintenance cost due to leakage at the expansion joint leading to deterioration of the joint, as well as structural components beneath the joint including the superstructure and substructur...

Use of railroad flat cars for low-volume road bridges.

DOT National Transportation Integrated Search

1999-08-01

In an attempt to solve the bridge problem faced by many county engineers, this : investigation focused on a low cost bridge alternative that consists of using railroad flatcars : (RRFC) as the bridge superstructure. The intent of this study was to de...

Implementation and non-destructive evaluation of composite structural shapes in the Tom's Creek Bridge.

DOT National Transportation Integrated Search

2000-01-01

A bridge rehabilitation utilizing a hybrid fiber reinforced polymeric composite has been completed in Blacksburg, Virginia. This project involved replacing the superstructure in the Tom's Creek Bridge, a rural short-span traffic bridge with a timber ...

Academic Culture.

ERIC Educational Resources Information Center

Clark, Burton R.

With fragmentation the dominant trend in academic settings around the world, the larger wholes of profession, enterprise, and system are less held together by integrative ideology. Strong ideological bonding is characteristic of the parts, primarily the disciplines. The larger aggregations are made whole mainly by formal superstructure, many…

All-in-one bioprobe devised with hierarchical-ordered magnetic NiCo2O4 superstructure for ultrasensitive dual-readout immunosensor for logic diagnosis of tumor marker.

PubMed

Dai, Hong; Gong, Lingshan; Zhang, Shupei; Xu, Guifang; Li, Yilin; Hong, Zhensheng; Lin, Yanyu

2016-03-15

A new enzyme-free all-in-one bioprobe, consisted of hematin decorated magnetic NiCo2O4 superstructure (ATS-MNS-Hb), was designed for ultrasensitive photoelectrochemical and electrochemical dual-readout immunosensing of carcinoembryonic antigen (CEA) on carbon nanohorns (CNH) support. Herein, the MNS, possessed hierarchical-ordered structure, good porosity and magnetism, acted as nanocarrier to absorb abundant Hb molecular after functionalization, providing a convenient collection means by magnetic control as well as enhanced dual-readout sensing performances. CNH superstructures were employed as support to immobilize abounding captured antibodies, and then as-designed dual mode bioprobe, covalent binding with secondary antibody of CEA, was introduced for ultrasensitive detection of CEA by sandwich immunosensing. Photoelectrochemical response originated from plentiful hematin molecular, a excellent photosensitizer with good visible light harvesting efficiency, absorbed by functionalized porous MNS. The resultant concentration dependant linear calibration range was from 10 fg/mL to 1 ng/mL with ultralow detection limit of 10 fg/mL. For electrochemical process, catalase-like property of MNS was validated, moreover, MNS-Hb hybrid exhibited much higher mimic enzyme catalytic activity and evidently amplified electrocatalytic signal, performing a wide dynamic linear range from 1 ng/mL to 40 ng/mL with low detection limit of 1 ng/mL. Additionally, due to the improved accuracy of dual signals detection, the exact diagnoses of serum samples were gotten by operating resulting dual signals with AND logic system. This work demonstrated the promising application of MNS in developing ultrasensitive, cost-effective and environment friendly dual-readout immunosensor and accurate diagnoses strategy for tumor markers. Copyright © 2015 Elsevier B.V. All rights reserved.

Zr 2Ir 6B with an eightfold superstructure of the cubic perovskite-like boride ZrIr 3B 0.5: Synthesis, crystal structure and bonding analysis

NASA Astrophysics Data System (ADS)

Hermus, Martin; Fokwa, Boniface P. T.

2010-04-01

Single phase powder samples and single crystals of Zr 2Ir 6B were successfully synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. Superstructure reflections were observed both on powder and on single crystal diffraction data, leading to an eightfold superstructure of ZrIr 3B x phase. The new phase, which has a metallic luster, crystallizes in space group Fm3¯m (no. 225) with the lattice parameters a=7.9903(4) Å, V=510.14(4) Å 3. Its crystal structure was refined on the basis of powder as well as single crystal data. The single crystal refinement converged to R1=0.0239 and w R2=0.0624 for all 88 unique reflections and 6 parameters. Zr 2Ir 6B is isotypic to Ti 2Rh 6B and its structure can be described as a defect double perovskite, A2BB' O6, where the A site is occupied by zirconium, the B site by boron, the O site by iridium but the B' site is vacant, leading to the formation of empty and boron-filled octahedral Ir 6 clusters. According to the result of tight-binding electronic structure calculations, Ir-B and Ir-Zr interactions are mainly responsible for the structural stability of the phase. According to COHP bonding analysis, the strongest bonding occurs for the Ir-B contacts, and the Ir-Ir bonding within the empty clusters is two times stronger than that in the BIr 6 octahedra.

Broadening and shifting of Bragg reflections of nanoscale-microtwinned LT-Ni3Sn2

NASA Astrophysics Data System (ADS)

Leineweber, Andreas; Krumeich, Frank

2013-12-01

The effect of nanoscale microtwinning of long-range ordered domains in LT-Ni3Sn2 on its diffraction behaviour was studied by X-ray powder diffraction and electron microscopy. LT-Ni3Sn2 exhibits a Ni2In/NiAs-type structure with a superstructure breaking the symmetry relative to the hexagonal high-temperature (HT) to the orthorhombic low-temperature (LT) phase, implying three different twin-domain orientations. The microstructure was generated by annealing HT-Ni3Sn2 considerably below the order-disorder transition temperature, establishing the LT phase avoiding too much domain coarsening. High-resolution electron microscopy reveals domain sizes of 100-200 Å compatible with the Scherrer broadening of the superstructure reflections recorded by X-ray diffraction. Whereas the orthorhombic symmetry of the LT phase leads in powder-diffraction patterns from coarse-domain size material to splitting of the fundamental reflections, this splitting does not occur for the LT-Ni3Sn2 with nanoscale domains. Instead, a (pseudo)hexagonal indexing is possible giving hexagonal lattice parameters, which are, however, incompatible with the positions of the superstructure reflections. This can be attributed to interference between X-rays scattered by the differently oriented, truly orthorhombic domains leading to merging of the fundamental reflections. These show pronounced anisotropic microstrain-like broadening, where the integral breadths ? on the reciprocal d-spacing scale of a series of higher order reflection increase in a non-linear fashion with upward curvature with the reciprocal d-spacings ? of these reflections. Such a type of unusual microstrain broadening appears to be typical for microstructures which are inhomogeneous on the nanoscale, and in which the structural inhomogeneities lead to small phase shifts of the scattered radiation from different locations (e.g. domains).

L'Ordine Nuovo: The Legacy of Antonio Gramsci and the Education of Adults.

ERIC Educational Resources Information Center

Armstrong, Paul F.

1988-01-01

The author presents a biography of Antonio Gramsci and discusses the influence of Karl Marx on Gramsci's key ideas concerning mode of production, superstructure, hegemony, consciousness, praxis, and intellectuals. Gramsci's emphasis on adult education for socialism is discussed. (CH)

An applied hydropedological perspective on the rendering of ecosystem services from urban soils

EPA Science Inventory

Ecosystem services are benefits to human populations derived from natural capitals like soil. When a soil is urbanized during infrastructure and superstructure development, the related processes modulate the state and quality of natural resources, along with the form and function...

46 CFR 92.07-10 - Construction.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Construction. 92.07-10 Section 92.07-10 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CARGO AND MISCELLANEOUS VESSELS CONSTRUCTION AND ARRANGEMENT Structural Fire Protection § 92.07-10 Construction. (a) The hull, superstructure, structural...

Shear repair of P/C box beams using carbon fiber reinforced polymer (CFRP) fabric.

DOT National Transportation Integrated Search

2006-01-01

The report documents the retrofit work carried out on the KY3297 Bridge over Little Sandy River in Carter County, Kentucky. Field investigation and evaluation revealed that the bridge superstructure was deficient in shear. The repair work was carried...

Appliques for the maintenance of lead-based painted bridges : a laboratory assessment of field-performance characteristics.

DOT National Transportation Integrated Search

2004-01-01

Approximately 3,500 bridges in Virginia having steel superstructures are coated with lead-based paints. Many of these bridges are in need of paint maintenance. This research evaluated applique technology, an alternative to the conventional paradigm...

75 FR 2132 - Maine Maritime Academy; Notice of Declaration of Intention and Petition for Relief Filing and...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-14

... be mounted to floats attached to a concrete superstructure, concrete or stone blocks, and other... listed above, and use the power from the test devices to heat water or charge 3 or 4 batteries which...

40 CFR 61.161 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... conditioned to produce molten glass. The unit includes foundations, superstructure and retaining walls, raw... aerosols. Malfunction means any sudden failure of air pollution control equipment or process equipment or... melted by indirect heating. The openings of the vessels are in the outside wall of the furnace and are...

Surface structure of Bi2Sr2CaCu2O(8+delta) high-temperature superconductors studied using low-energy electron diffraction

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Wells, B. O.; Mitzi, D. B.; Lindau, I.

1988-12-01

The surface structure of Bi2Sr2CaCu2O(8+delta) has been studied using low-energy electron diffraction (LEED). Sharp diffraction spots indicative of a well-ordered surface are observed. The LEED patterns unequivocally show that this type of material preferentially cleaves along the a-b planes of the nearly tetragonal unit cell. A superstructure extending along one of the axes in the a-b plane (b) is found to have a periodicity of 27 + or - 0.5 A, in good agreement with earlier studies of the three-dimensional crystal structure. The superstructure at the surface is nonlocal in character and reflects the long-range superlattice of the bulk along the b axis. Intensity modulations of the diffraction spots oriented along the b axis are also reported and discussed in terms of the cell dimension of the unit cell along the b axis.

Scanning tunneling microscopy investigation of copper phthalocyanine and truxenone derivative binary superstructures on graphite.

PubMed

Liu, Jia; Wang, Dong; Wang, Jie-Yu; Pei, Jian; Wan, Li-Jun

2011-02-01

The binary self-assembly of copper phthalocyanine (CuPc) and 2,3,7,8,12,13-hexahexyloxy-truxenone (TrO23) at the solid/liquid interface of highly oriented pyrolytic graphite (HOPG) was investigated by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Pseduohexagonal and linear patterned superstructures of CuPc are obtained by co-adsorbing with TrO23. High-resolution STM images reveal the structural details of the arrangement of TrO23 and CuPc in the binary assembly structures. The molecular ratio between CuPc and TrO23 in the adlayer can be modulated by the CuPc concentration in liquid phase. The electronic properties of CuPc and TrO23 in the co-adsorbed self-assembly are investigated by STS. The results presented here are helpful to the design and fabrication of multi-component functional molecular nanostructures. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electron Diffraction Evidence for the Ordering of Excess Nickel Atoms by Relation to Stoichiometry in Nickel-Rich Beta'-Nial Formation of a Nickel-Aluminum (Ni2al) Superlattices

NASA Technical Reports Server (NTRS)

Reynaud, F.

1988-01-01

In electron diffraction patterns of nickel-rich beta-NiAl alloys, many anomalies are observed. One of these is the appearance of diffuse intensity maxima between the reflexions of the B2 structure. This is explained by the short-range ordering of the excess nickel atoms on the simple cubic sublattice occupied only by aluminum atoms in the stoichiometric, perfectly ordered NiAl alloy. After annealing Ni 37.5 atomic percent Al and Ni 37.75 atomic percent Al for 1 week at 300 and 400 C, the diffuse intensity maxima transformed into sharp superstructure reflexions. These reflexions are explained by the formation of the four possible variants of an ordered hexagonal superstructure corresponding to the Ni2Al composition. This structure is closely related to the Ni2Al3 structure (same space group) formed by the ordering of vacancies on the nickel sublattice in aluminum-rich beta-NiAl alloys.

The effect of heat treatments applied to superstructure porcelain on the mechanical properties and microstructure of lithium disilicate glass ceramics.

PubMed

Özdemir, Hatice; Özdoğan, Alper

2018-01-30

The aim of this study was to investigate that heat treatments with different numbers applied to superstructure porcelain whether effects microstructure and mechanical properties of lithium disilicate ceramic (LDC). Eighty disc-shaped specimens were fabricated from IPS e.max Press. Specimens were fired at heating values of porcelain in different numbers and divided four groups (n=5). Initial Vickers hardness were measured and X-ray diffraction (XRD) analysis was performed. Different surface treatment were applied and then Vickers hardness, surface roughness and environmental scanning electron microscopy (ESEM) analysis were performed. Data were analyzed with Varyans analysis and Tukey HSD test (α=0.05). Initial hardness among groups was no significant different (p>0.05), but hardness and surface roughness after surface treatments were significant different (p<0.05). Lithium disilicate (LD) peaks decrease depended on firing numbers. ESEM observations showed that firing number and surface treatments effect microstructure of LDC. Increasing firing numbers and surface treatments effect the microstructure of LDC.

FAST TRACK COMMUNICATION: Reinterpreting the Cu Pd phase diagram based on new ground-state predictions

NASA Astrophysics Data System (ADS)

Bärthlein, S.; Hart, G. L. W.; Zunger, A.; Müller, S.

2007-01-01

Our notions of the phase stability of compounds rest to a large extent on the experimentally assessed phase diagrams. Long ago, it was assumed that in the Cu-Pd system for xPd<=25% there are at least two phases at high temperature (L12 and a L12-based superstructure), which evolve into a single L12-ordered phase at low temperature. By constructing a first-principles Hamiltonian, we predict a yet undiscovered Cu7Pd ground state at xPd = 12.5% (referred to as S1 below) and an L12-like Cu9Pd3 superstructure at 25% (referred to as S2). We find that in the low-temperature regime, a single L12 phase cannot be stable, even with the addition of anti-sites. Instead we find that an S2-phase with S1-like ordering tendency will form. Previous short-range order diffraction data are quantitatively consistent with these new predictions.

Atomistic origin of an ordered superstructure induced superconductivity in layered chalcogenides.

PubMed

Ang, R; Wang, Z C; Chen, C L; Tang, J; Liu, N; Liu, Y; Lu, W J; Sun, Y P; Mori, T; Ikuhara, Y

2015-01-27

Interplay among various collective electronic states such as charge density wave and superconductivity is of tremendous significance in low-dimensional electron systems. However, the atomistic and physical nature of the electronic structures underlying the interplay of exotic states, which is critical to clarifying its effect on remarkable properties of the electron systems, remains elusive, limiting our understanding of the superconducting mechanism. Here, we show evidence that an ordering of selenium and sulphur atoms surrounding tantalum within star-of-David clusters can boost superconductivity in a layered chalcogenide 1T-TaS2-xSex, which undergoes a superconducting transition in the nearly commensurate charge density wave phase. Advanced electron microscopy investigations reveal that such an ordered superstructure forms only in the x area, where the superconductivity manifests, and is destructible to the occurrence of the Mott metal-insulator transition. The present findings provide a novel dimension in understanding the relationship between lattice and electronic degrees of freedom.

Helically structured metal–organic frameworks fabricated by using supramolecular assemblies as templates† †Electronic supplementary information (ESI) available: Detailed TEM images and other extensive figures. See DOI: 10.1039/c4sc03278k Click here for additional data file.

PubMed Central

Wang, Hui; Zhu, Wei; Li, Jian; Tian, Tian; Lan, Yue; Gao, Ning; Wang, Chen; Zhang, Meng; Faul, Charl F. J.

2015-01-01

The controlled formation of MOF-based superstructures with well-defined nanoscale sizes and exquisite morphologies represents a big challenge, but can trigger a new set of properties distinct from their bulk counterparts. Here we report on the use of a self-assembled organic object to template the first example of a nanoscale metal–organic framework (MOF) with a helical morphology. Two prototypical MOFs (HKUST-1 and MIL-100) were used to exemplify the growth of such materials on supramolecular assemblies. Interestingly, it was found that, dependent on the nature of the precursors, not only could well-defined helical MOF nanotubes be facilely fabricated, but novel helical bundle nanostructures could also be formed. These resultant MOF superstructures show additional optical properties and could be used as precursors for the preparation of chiral nanocarbons. PMID:28757993

Observation of surface superstructure induced by systematic vacancies in the topological Dirac semimetal Cd3As2

NASA Astrophysics Data System (ADS)

Butler, Christopher J.; Tseng, Yi; Hsing, Cheng-Rong; Wu, Yu-Mi; Sankar, Raman; Wang, Mei-Fang; Wei, Ching-Ming; Chou, Fang-Cheng; Lin, Minn-Tsong

2017-02-01

The Dirac semimetal phase found in Cd3As2 is protected by a C4 rotational symmetry derived from a corkscrew arrangement of systematic Cd vacancies in its complicated crystal structure. It is therefore surprising that no microscopic observation, direct or indirect, of these systematic vacancies has so far been described. To this end, we revisit the cleaved (112) surface of Cd3As2 using a combined approach of scanning tunneling microscopy and ab initio calculations. We determine the exact position of the (112) plane at which Cd3As2 naturally cleaves, and describe in detail a structural periodicity found at the reconstructed surface, consistent with that expected to arise from the systematic Cd vacancies. This reconciles the current state of microscopic surface observations with those of crystallographic and theoretical models, and demonstrates that this vacancy superstructure, central to the preservation of the Dirac semimetal phase, survives the cleavage process and retains order at the surface.

Experimental and Analytical Seismic Studies of a Four-Span Bridge System with Innovative Materials

NASA Astrophysics Data System (ADS)

Cruz Noguez, Carlos Alonso

As part of a multi-university project utilizing the NSF Network for Earthquake Engineering Simulation (NEES), a quarter-scale model of a four-span bridge incorporating plastic hinges with different advanced materials was tested to failure on the three shake table system at the University of Nevada, Reno (UNR). The bridge was the second test model in a series of three 4-span bridges, with the first model being a conventional reinforced-concrete (RC) structure. The purpose of incorporating advanced materials was to improve the seismic performance of the bridge with respect to two damage indicators: (1) column damage and (2) permanent deformations. The goals of the study presented in this document were to (1) evaluate the seismic performance of a 4-span bridge system incorporating SMA/ECC and built-in rubber pad plastic hinges as well as post-tensioned piers, (2) quantify the relative merit of these advanced materials and details compared to each other and to conventional reinforced concrete plastic hinges, (3) determine the influence of abutment-superstructure interaction on the response, (4) examine the ability of available elaborate analytical modeling techniques to model the performance of advanced materials and details, and (5) conduct an extensive parametric study of different variations of the bridge model to study several important issues in bridge earthquake engineering. The bridge model included six columns, each pair of which utilized a different advanced detail at bottom plastic hinges: shape memory alloys (SMA), special engineered cementitious composites (ECC), elastomeric pads embedded into columns, and post-tensioning tendons. The design of the columns, location of the bents, and selection of the loading protocol were based on pre-test analyses conducted using computer program OpenSees. The bridge model was subjected to two-horizontal components of simulated earthquake records of the 1994 Northridge earthquake. Over 340 channels of data were collected. The test results showed the effectiveness of the advanced materials in reducing damage and permanent displacements. The damage was minimal in plastic hinges with SMA/ECC and those with built-in elastomeric pads. Conventional RC plastic hinges were severely damaged due to spalling of concrete and rupture of the longitudinal and transverse reinforcement. Extensive post-test analytical studies were conducted and it was determined that a computational model of the bridge that included bridge-abutment interaction using OpenSees was able to provide satisfactory estimations of key structural parameters such as superstructure displacements and base shears. The analytical model was also used to conduct parametric studies on single-column and bridge-system response under near-fault ground motions. The effects of vertical excitations and transverse shear-keys at the bridge abutments on the superstructure displacement and column drifts were also explored.

Semiconducting large bandgap oxides as potential thermoelectric materials for high-temperature power generation?

NASA Astrophysics Data System (ADS)

Backhaus-Ricoult, M.; Rustad, J.; Moore, L.; Smith, C.; Brown, J.

2014-08-01

Semiconducting large bandgap oxides are considered as interesting candidates for high-temperature thermoelectric power generation (700-1,200 °C) due to their stability, lack of toxicity and low cost, but so far they have not reached sufficient performance for extended application. In this review, we summarize recent progress on thermoelectric oxides, analyze concepts for tuning semiconductor thermoelectric properties with view of their applicability to oxides and determine key drivers and limitations for electrical and thermal transport properties in oxides based on our own experimental work and literature results. For our experimental assessment, we have selected representative multicomponent oxides that range from materials with highly symmetric crystal structure (SrTiO3 perovskite) over oxides with large densities of planar crystallographic defects (Ti n O2 n-1 Magnéli phases with a single type of shear plane, NbO x block structures with intersecting shear planes and WO3- x with more defective block and channel structures) to layered superstructures (Ca3Co4O9 and double perovskites) and also include a wide range of their composites with a variety of second phases. Crystallographic or microstructural features of these oxides are in 0.3-2 nm size range, so that oxide phonons can efficiently interact with them. We explore in our experiments the effects of doping, grain size, crystallographic defects, superstructures, second phases, texturing and (to a limited extend) processing on electric conductivity, Seebeck coefficient, thermal conductivity and figure of merit. Jonker and lattice-versus-electrical conductivity plots are used to compare specific materials and material families and extract levers for future improvement of oxide thermoelectrics. We show in our work that oxygen vacancy doping (reduction) is a more powerful driver for improving the power factor for SrTiO3, TiO2 and NbO x than heterovalent doping. Based on our Seebeck-conductivity plots, we derived a set of highest achievable power factors. We met these best values in our own experiments for our titanium oxide- and niobium oxide-based materials. For strontium titanate-based materials, the estimated highest power factor was not reached; further material improvement is possible and can be reached for materials with higher carrier densities. Our results show that periodic crystallographic defects and superstructures are most efficient in reducing the lattice thermal conductivity in oxides, followed by hetero- and homovalent doping. Due to the small phonon mean free path in oxides, grain boundary scattering in nanoceramics or materials with nanodispersions is much less efficient. We investigated the impact of texturing in Ca3Co4O9 ceramics on thermoelectric performance; we did not find any improvement in the overall in-plane performance of a textured ceramic compared to the corresponding random ceramic.

Field test of a new procedure for removing lead-based paint from bridges.

DOT National Transportation Integrated Search

2000-01-01

According to the National Bridge Inventory, of the more than 200,000 steel bridges listed, between 80 and 90 percent were painted with lead-based paint. Of the approximately 7,000 bridges in Virginia with steel superstructures, well over half were pa...

Acoustic emission testing of in-service conventionally reinforced concrete deck girder superstructures on highway bridges : final report.

DOT National Transportation Integrated Search

2008-09-01

Three reports were produced from research sponsored by the Oregon Department of Transportation on acoustic emission (AE). The first describes the evaluation of AE techniques applied to two reinforced concrete (RC) bridge girders, which were loaded to...

13. DETAIL SHOWING OXYGEN (LEFT) AND HYDROGEN (RIGHT) PREVALVES ON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. DETAIL SHOWING OXYGEN (LEFT) AND HYDROGEN (RIGHT) PREVALVES ON SECOND DECK OF SUPERSTRUCTURE, ABOVE THE ENGINE. Looking northwest. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

46 CFR 45.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... with no openings. (r) Steel means steel and materials with which structures can be made equivalent to steel with respect to such parameters as yield strength, total deflection, flexural life, or resistance.... (i) Superstructure means a deck structure on the freeboard deck, extending from side to side of the...

Precast concrete elements for accelerated bridge construction : laboratory testing of precast substructure components, Boone County bridge.

DOT National Transportation Integrated Search

2009-01-01

Vol. 1-1: In July 2006, construction began on an accelerated bridge project in Boone County, Iowa that was composed of precast substructure : elements and an innovative, precast deck panel system. The superstructure system consisted of full-depth dec...

5. VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CENTRAL CUT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CENTRAL CUT AND MORTARED STONE PIER AND ASSOCIATED STEEL SUPERSTRUCTURE (CENTER), AND CANTILEVERED NORTHERN TRUSS SECTION (RIGHT). FACING NORTHWEST. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

The CoQH2/CoQ Ratio Serves as a Sensor of Respiratory Chain Efficiency.

PubMed

Guarás, Adela; Perales-Clemente, Ester; Calvo, Enrique; Acín-Pérez, Rebeca; Loureiro-Lopez, Marta; Pujol, Claire; Martínez-Carrascoso, Isabel; Nuñez, Estefanía; García-Marqués, Fernando; Rodríguez-Hernández, María Angeles; Cortés, Ana; Diaz, Francisca; Pérez-Martos, Acisclo; Moraes, Carlos T; Fernández-Silva, Patricio; Trifunovic, Aleksandra; Navas, Plácido; Vazquez, Jesús; Enríquez, Jose A

2016-04-05

Electrons feed into the mitochondrial electron transport chain (mETC) from NAD- or FAD-dependent enzymes. A shift from glucose to fatty acids increases electron flux through FAD, which can saturate the oxidation capacity of the dedicated coenzyme Q (CoQ) pool and result in the generation of reactive oxygen species. To prevent this, the mETC superstructure can be reconfigured through the degradation of respiratory complex I, liberating associated complex III to increase electron flux via FAD at the expense of NAD. Here, we demonstrate that this adaptation is driven by the ratio of reduced to oxidized CoQ. Saturation of CoQ oxidation capacity induces reverse electron transport from reduced CoQ to complex I, and the resulting local generation of superoxide oxidizes specific complex I proteins, triggering their degradation and the disintegration of the complex. Thus, CoQ redox status acts as a metabolic sensor that fine-tunes mETC configuration in order to match the prevailing substrate profile. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Computational Fluid Dynamic Analysis of Hydrodynamic forces on inundated bridge decks

NASA Astrophysics Data System (ADS)

Afzal, Bushra; Guo, Junke; Kerenyi, Kornel

2010-11-01

The hydraulic forces experienced by an inundated bridge deck have great importance in the design of bridges. Flood flows or hurricane add significant hydrodynamic loading on bridges, possibly resulting in failure of the bridge superstructures. The objective of the study is to establish validated computational practice to address research needs of the transportation community via computational fluid dynamic simulations. The reduced scale experiments conducted at Turner-Fairbank Highway Research Center establish the foundations of validated computational practices to address the research needs of the transportation community. Three bridge deck prototypes were used: a typical six-girder highway bridge deck, a three-girder deck, and a streamlined deck designed to better withstand the hydraulic forces. Results of the study showed that the streamlined deck significantly reduces drag, lift, and moment coefficient in comparison to the other bridge deck types. The CFD results matched the experimental data in terms of the relationship between inundation ratio and force measured at the bridge. The results of the present research will provide a tool for designing new bridges and retrofitting old ones.

Toward Design Principles for Diffusionless Transformations: The Frustrated Formation of Co–Co Bonds in a Low-Temperature Polymorph of GdCoSi 2

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

Vinokur, Anastasiya I.; Fredrickson, Daniel C.

Diffusionless (or displacive) phase transitions allow inorganic materials to show exquisite responsiveness to external stimuli, as is illustrated vividly by the superelasticity, shape memory, and magnetocaloric effects exhibited by martensitic materials. In this Article, we present a new diffusionless transition in the compound GdCoSi 2, whose origin in frustrated bonding points toward generalizable design principles for these transformations. We first describe the synthesis of GdCoSi 2 and the determination of its structure using single crystal X-ray diffraction. While previous studies based on powder X-ray diffraction assigned this compound to the simple CeNi 1–xSi 2 structure type (space group Cmcm), ourmore » structure solution reveals a superstructure variant (space group Pbcm) in which the Co sublattice is distorted to create zigzag chains of Co atoms. DFT-calibrated Hückel calculations, coupled with a reversed approximation Molecular Orbital (raMO) analysis, trace this superstructure to the use of Co–Co isolobal bonds to complete filled 18 electron configurations on the Co atoms, in accordance with the 18–n rule. The formation of these Co–Co bonds is partially impeded, however, by a small degree of electron transfer from Si-based electronic states to those with Co–Co σ* character. The incomplete success of Co–Co bond creation suggests that these interactions are relatively weak, opening the possibility of them being overcome by thermal energy at elevated temperatures. In fact, high-temperature powder and single crystal X-ray diffraction data, as well as differential scanning calorimetry, indicate that a reversible Pbcm to Cmcm transition occurs at about 380 K. This transition is diffusionless, and the available data point toward it being first-order. We expect that similar cases of frustrated interactions could be staged in other rare earth–transition metal–main group phases, providing a potentially rich source of compounds exhibiting diffusionless transformations and the unique properties these transitions mediate.« less

Hybrid WDM/OCDMA for next generation access network

NASA Astrophysics Data System (ADS)

Wang, Xu; Wada, Naoya; Miyazaki, T.; Cincotti, G.; Kitayama, Ken-ichi

2007-11-01

Hybrid wavelength division multiplexing/optical code division multiple access (WDM/OCDMA) passive optical network (PON), where asynchronous OCDMA traffic transmits over WDM network, can be one potential candidate for gigabit-symmetric fiber-to-the-home (FTTH) services. In a cost-effective WDM/OCDMA network, a large scale multi-port encoder/decoder can be employed in the central office, and a low cost encoder/decoder will be used in optical network unit (ONU). The WDM/OCDMA system could be one promising solution to the symmetric high capacity access network with high spectral efficiency, cost effective, good flexibility and enhanced security. Asynchronous WDM/OCDMA systems have been experimentally demonstrated using superstructured fiber Bragg gratings (SSFBG) and muti-port OCDMA en/decoders. The total throughput has reached above Tera-bit/s with spectral efficiency of about 0.41. The key enabling techniques include ultra-long SSFBG, multi-port E/D with high power contrast ratio, optical thresholding, differential phase shift keying modulation with balanced detection, forward error correction, and etc. Using multi-level modulation formats to carry multi-bit information with single pulse, the total capacity and spectral efficiency could be further enhanced.

Innovative concepts for marginal fields (advanced monotower developments)

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

Smith, M.T.; Marks, V.E.

1995-12-01

The braced monotower provides a safe, functional and cost effective solution for topsides up to 500 tonnes, with up to 8 wells and standing in water depths of up to 70 meters. It is both simple in concept and structurally efficient. The superstructure is supported by a single column which is stayed by three symmetrically orientated legs. A broad mudline base is also provided to limit pile loads. The final concept offers complete protection to the risers and conductors from ship impact, as all appurtenances are housed within the central column. The basic design philosophy of the low intervention platformmore » is to minimize the onboard equipment to that vitally needed to produce hydrocarbon. The concept eliminates the life support functions that on a normal North Sea platform can contribute up to 50% of the topside dry weight. A system of Zero Based Engineering is used that ensures each item of equipment contributes more to the NPV of the platform than the fully built-up through life cost. This effectively eliminates the operator preference factor and the ``culture`` cost.« less

Substructure hybrid testing of reinforced concrete shear wall structure using a domain overlapping technique

NASA Astrophysics Data System (ADS)

Zhang, Yu; Pan, Peng; Gong, Runhua; Wang, Tao; Xue, Weichen

2017-10-01

An online hybrid test was carried out on a 40-story 120-m high concrete shear wall structure. The structure was divided into two substructures whereby a physical model of the bottom three stories was tested in the laboratory and the upper 37 stories were simulated numerically using ABAQUS. An overlapping domain method was employed for the bottom three stories to ensure the validity of the boundary conditions of the superstructure. Mixed control was adopted in the test. Displacement control was used to apply the horizontal displacement, while two controlled force actuators were applied to simulate the overturning moment, which is very large and cannot be ignored in the substructure hybrid test of high-rise buildings. A series of tests with earthquake sources of sequentially increasing intensities were carried out. The test results indicate that the proposed hybrid test method is a solution to reproduce the seismic response of high-rise concrete shear wall buildings. The seismic performance of the tested precast high-rise building satisfies the requirements of the Chinese seismic design code.

Sustainability Trends Reflected in the Architecture of the European Examples

NASA Astrophysics Data System (ADS)

Gumińska, Anna

2017-10-01

In modern architecture, one of the leading trends are striving to obtain the most economical energy-efficient building. Eco-development focuses on contemporary use, inter alia, the technological and material solutions that meet the conditions in most of the existing laws by using renewable energy sources. These findings apply primarily to new objects. Old, historical already existing superstructure is treated in a manner less demanding adaptation to environmental conditions, mainly on the behaviour of the aesthetic. This can be disadvantageous for these properties due to increased operating costs, and thus the loss of attractiveness. At work, an attempt was made on the basis of the analysis of the literature and documentation shoot made “in situ” possible use of latest technological developments to both the renewal of the historical buildings of the central areas of European cities through the renovation of an existing building or the emergence of subsidiary buildings while preserving the cultural values, aesthetic or symbolic objects, the environment. Analyzed examples show possibilities of adapting new and upgraded properties both to your power requirements, green and to the context of the existing built environment and cultural heritage.

Design, construction and load testing of the bridge on Arnault Branch, Washington County, Missouri using innovative technologies.

DOT National Transportation Integrated Search

2010-02-01

The superstructure and instrumentation designs of a three-span bridge are presented in this report. The three spans include a : precast box-girder bridge, a precast deck on steel girder and a precast deck on concrete girder. They were designed to com...

23. Photographic copy of blueprints and plans (from the originals ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. Photographic copy of blueprints and plans (from the originals in possession of Detroit District, U.S. Army Corps of Engineers, Duluth, Minnesota). North pier of Duluth Canal, 1899, concrete superstructure - Duluth Ship Canal, North Pier, North end of Minnesota Point at Canal Park, Duluth, St. Louis County, MN

Wind monitoring of the Saylorville and Red Rock Reservoir Bridges with remote, cellular-based notifications : tech transfer summary.

DOT National Transportation Integrated Search

2012-05-01

Following high winds on January 24, 2006, at least five people claimed to have seen or felt the superstructure of the Saylorville Reservoir Bridge in central Iowa moving both vertically and laterally. Since that time, the Iowa Department of Transport...

Synthesis of New Solid Electrolytes.

DTIC Science & Technology

1982-03-01

Subsequently, some of these new peaks were identified as the peaks belonging to the 3 x 3 cubic superstructure first described by Kierkegaard 2 . In...34 ’ I i " I II i REFERENCES 1. C. Bush, B . S.- Thesis, Polytechnic institute of New York, 1977. 2. L. Hagman and P. Kierkegaard , Acta Chem

Foundations of Library and Information Science.

ERIC Educational Resources Information Center

Rubin, Richard E.

This book provides information science students and librarians the background and techniques they need to meet the challenges of the library profession today. The book begins with a discussion of the practice of librarianship and the place of libraries within the broader perspective of the information superstructure. Topics covered include the…

Wind monitoring of the Saylorville and Red Rock Reservoir Bridges with remote, cellular-based notifications.

DOT National Transportation Integrated Search

2012-05-01

Following a high wind event on January 24, 2006, at least five people claimed to have seen or felt the superstructure of the Saylorville Reservoir Bridge in central Iowa moving both vertically and laterally. Since that time, the Iowa Department of Tr...

Detail, squared cut stone masonry center pier, from northwest, showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail, squared cut stone masonry center pier, from northwest, showing original cut stone masonry, concrete-encased nose on upstream end, portion of squared cut stone masonry south abutment, and portion of truss superstructure - Castle Garden Bridge, Township Route 343 over Bennetts Branch of Sinnemahoning Creek, Driftwood, Cameron County, PA

46 CFR 42.25-15 - Stowage.

Code of Federal Regulations, 2014 CFR

2014-10-01

..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND FOREIGN VOYAGES BY SEA Special... length which is the total length of the well or wells between superstructures. Where there is no limiting... cargoes where there is no bulkhead. (2) Lashings shall be not less than 3/4-inch close link chain or...

Evaluation of the in-service performance of the Tom's Creek Bridge fiber-reinforced polymer superstructure.

DOT National Transportation Integrated Search

2003-01-01

The Tom's Creek Bridge is a small-scale demonstration project involving the use of fiber-reinforced polymer (FRP) composite girders as the main load carrying members. It is a simply supported, short-span bridge located along Tom's Creek Road in Black...

Evaluation of Erection Procedures of the Horizontally Curved Steel I-Girder Ford City Veterans Bridge

DOT National Transportation Integrated Search

2002-03-06

In the case of horizontally steel curved I-girder bridges, it is important to carefully analyze the erection sequence of the superstructure so as to ensure that difficulties do not arise in the field during construction of the bridge. Generally, prob...

46 CFR 42.25-15 - Stowage.

Code of Federal Regulations, 2013 CFR

2013-10-01

..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND FOREIGN VOYAGES BY SEA Special... length which is the total length of the well or wells between superstructures. Where there is no limiting... cargoes where there is no bulkhead. (2) Lashings shall be not less than 3/4-inch close link chain or...

46 CFR 42.25-15 - Stowage.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND FOREIGN VOYAGES BY SEA Special... length which is the total length of the well or wells between superstructures. Where there is no limiting... cargoes where there is no bulkhead. (2) Lashings shall be not less than 3/4-inch close link chain or...

46 CFR 42.25-15 - Stowage.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND FOREIGN VOYAGES BY SEA Special... length which is the total length of the well or wells between superstructures. Where there is no limiting... cargoes where there is no bulkhead. (2) Lashings shall be not less than 3/4-inch close link chain or...

46 CFR 42.25-15 - Stowage.

Code of Federal Regulations, 2012 CFR

2012-10-01

..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) LOAD LINES DOMESTIC AND FOREIGN VOYAGES BY SEA Special... length which is the total length of the well or wells between superstructures. Where there is no limiting... cargoes where there is no bulkhead. (2) Lashings shall be not less than 3/4-inch close link chain or...

77 FR 5767 - Application(s) for Duty-Free Entry of Scientific Instruments

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-06

... x-ray analysis. The data collected will be applied to energy storage and conversion, environmental...: The instrument will be used to study superstructures formed by semiconductor and metal nanoparticles... semiconductors, metals, ceramics, polymers, etc. Justification for Duty-Free Entry: There are no instruments of...

Pennsylvania hardwood timber bridges : field performance after 10 years

Treesearch

James P. Wacker; Carlito Calil

2004-01-01

Several hardwood demonstration timber bridges were built by the Pennsylvania Department of Transportation in the early nineteen nineties. These bridge superstructures are of the recently developed stress-laminated deck design-type using Red Oak lumber laminations that were pressure-treated with creosote preservatives. This paper will describe the data acquisition...

Structural transformation of biochar black carbon by C60 superstructure: Environmental implications

USDA-ARS?s Scientific Manuscript database

Aqueous fullerene C60 nanoparticles (nC60) are frequently considered within the environmental engineering community as the aggregate of 60-carbon molecules. This study employed transmission electron microscopy (TEM) and x-ray diffraction (XRD) to demonstrate that nC60 formed via prolonged stirring ...

46 CFR 72.05-5 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-10-01

... one deck, into which the hull, superstructure, and deckhouses are required to be divided by fire... open will be considered as being increased by an amount equal to the gross area of the balcony divided... should be treated as such for fire control purposes. In this regard, particular attention should be given...

46 CFR 174.207 - Damaged stability criteria.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Permeability of spaces. The permeability of a floodable space must be as specified by Table 174.207(b) of this...) Equipped with arrangements, such as stop check-valves, to prevent progressive flooding of the spaces with... permit progressive flooding of the spaces with which they connect. (d) Buoyancy of superstructure. For...

46 CFR 174.207 - Damaged stability criteria.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Permeability of spaces. The permeability of a floodable space must be as specified by Table 174.207(b) of this...) Equipped with arrangements, such as stop check-valves, to prevent progressive flooding of the spaces with... permit progressive flooding of the spaces with which they connect. (d) Buoyancy of superstructure. For...

46 CFR 174.207 - Damaged stability criteria.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Permeability of spaces. The permeability of a floodable space must be as specified by Table 174.207(b) of this...) Equipped with arrangements, such as stop check-valves, to prevent progressive flooding of the spaces with... permit progressive flooding of the spaces with which they connect. (d) Buoyancy of superstructure. For...

46 CFR 174.207 - Damaged stability criteria.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Permeability of spaces. The permeability of a floodable space must be as specified by Table 174.207(b) of this...) Equipped with arrangements, such as stop check-valves, to prevent progressive flooding of the spaces with... permit progressive flooding of the spaces with which they connect. (d) Buoyancy of superstructure. For...

29 CFR 776.29 - Instrumentalities and channels of interstate commerce.

Code of Federal Regulations, 2010 CFR

2010-07-01

... OF 1938 Construction Industry Individual Employee Coverage in the Construction Industry § 776.29... construction employees from being engaged in commerce. 32 Mitchell v. Vollmer, ante; Bennett. v. V. P. Loftis... to employees who are engaged on such work as repairing or replacing abutments and superstructures on...

40 CFR 745.229 - Certification of individuals and firms engaged in lead-based paint activities: public and...

Code of Federal Regulations, 2012 CFR

2012-07-01

...) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.229 Certification of individuals and firms engaged in lead-based... engaged in lead-based paint activities: public and commercial buildings, bridges and superstructures...

40 CFR 745.230 - Work practice standards for conducting lead-based paint activities: public and commercial...

Code of Federal Regulations, 2012 CFR

2012-07-01

... SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.230 Work practice standards for conducting lead-based paint activities: public... lead-based paint activities: public and commercial buildings, bridges and superstructures. [Reserved...

40 CFR 745.230 - Work practice standards for conducting lead-based paint activities: public and commercial...

Code of Federal Regulations, 2013 CFR

2013-07-01

... SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.230 Work practice standards for conducting lead-based paint activities: public... lead-based paint activities: public and commercial buildings, bridges and superstructures. [Reserved...

40 CFR 745.229 - Certification of individuals and firms engaged in lead-based paint activities: public and...

Code of Federal Regulations, 2013 CFR

2013-07-01

...) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.229 Certification of individuals and firms engaged in lead-based... engaged in lead-based paint activities: public and commercial buildings, bridges and superstructures...

40 CFR 745.229 - Certification of individuals and firms engaged in lead-based paint activities: public and...

Code of Federal Regulations, 2014 CFR

2014-07-01

...) TOXIC SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.229 Certification of individuals and firms engaged in lead-based... engaged in lead-based paint activities: public and commercial buildings, bridges and superstructures...

40 CFR 745.230 - Work practice standards for conducting lead-based paint activities: public and commercial...

Code of Federal Regulations, 2014 CFR

2014-07-01

... SUBSTANCES CONTROL ACT LEAD-BASED PAINT POISONING PREVENTION IN CERTAIN RESIDENTIAL STRUCTURES Lead-Based Paint Activities § 745.230 Work practice standards for conducting lead-based paint activities: public... lead-based paint activities: public and commercial buildings, bridges and superstructures. [Reserved...

18. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox copy of original plans, dated 1932, by Wisconsin Highway Commission. Xerox copy in possession of Westbrook Associated Engineers, Spring Green, Wisconsin. SUPERSTRUCTURE DETAILS. - Chippewa River Bridge, Spanning Chippewa River at State Highway 35, Nelson, Buffalo County, WI

16. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox copy of original plans, dated 1932, by Wisconsin Highway Commission. Xerox copy in possession of Westbrook Associated Engineers, Spring Green, Wisconsin. SUPERSTRUCTURE DETAILS. - Chippewa River Bridge, Spanning Chippewa River at State Highway 35, Nelson, Buffalo County, WI

17. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. Wayne Chandler, Photographer, August 1993 Photographic copy of Xerox copy of original plans, dated 1932, by Wisconsin Highway Commission. Xerox copy in possession of Westbrook Associated Engineers, Spring Green, Wisconsin. SUPERSTRUCTURE DETAILS. - Chippewa River Bridge, Spanning Chippewa River at State Highway 35, Nelson, Buffalo County, WI

385. Delineator Unknown December 1932 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

385. Delineator Unknown December 1932 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; ROCKER POSTS AND BEARING; CONTRACT NO. 6; DRAWINGS NO. 42 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Apparent Km of mitochondria for oxygen computed from Vmax measured in permeabilized muscle fibers is lower in water enriched in oxygen by electrolysis than injection

PubMed Central

Zoll, Joffrey; Bouitbir, Jamal; Sirvent, Pascal; Klein, Alexis; Charton, Antoine; Jimenez, Liliana; Péronnet, François R; Geny, Bernard; Richard, Ruddy

2015-01-01

Background It has been suggested that oxygen (O2) diffusion could be favored in water enriched in O2 by a new electrolytic process because of O2 trapping in water superstructures (clathrates), which could reduce the local pressure/content relationships for O2 and facilitate O2 diffusion along PO2 gradients. Materials and methods Mitochondrial respiration was compared in situ in saponin-skinned fibers isolated from the soleus muscles of Wistar rats, in solution enriched in O2 by injection or the electrolytic process 1) at an O2 concentration decreasing from 240 µmol/L to 10 µmol/L (132 mmHg to 5 mmHg), with glutamate–malate or N, N, N′, N′-tetramethyl-p-phenylenediamine dihydrochloride (TMPD)–ascorbate (with antimycin A) as substrates; and 2) at increasing adenosine diphosphate (ADP) concentration with glutamate–malate as substrate. Results As expected, maximal respiration decreased with O2 concentration and, when compared to glutamate–malate, the apparent Km O2 of mitochondria for O2 was significantly lower with TMPD–ascorbate with both waters. However, when compared to the water enriched in O2 by injection, the Km O2 was significantly lower with both electron donors in water enriched in O2 by electrolysis. This was not associated with any increase in the sensitivity of mitochondria to ADP; no significant difference was observed for the Km ADP between the two waters. Conclusion In this experiment, a higher affinity of the mitochondria for O2 was observed in water enriched in O2 by electrolysis than by injection. This observation is consistent with the hypothesis that O2 diffusion can be facilitated in water enriched in O2 by the electrolytic process. PMID:26203225

Apparent Km of mitochondria for oxygen computed from Vmax measured in permeabilized muscle fibers is lower in water enriched in oxygen by electrolysis than injection.

PubMed

Zoll, Joffrey; Bouitbir, Jamal; Sirvent, Pascal; Klein, Alexis; Charton, Antoine; Jimenez, Liliana; Péronnet, François R; Geny, Bernard; Richard, Ruddy

2015-01-01

It has been suggested that oxygen (O2) diffusion could be favored in water enriched in O2 by a new electrolytic process because of O2 trapping in water superstructures (clathrates), which could reduce the local pressure/content relationships for O2 and facilitate O2 diffusion along PO2 gradients. Mitochondrial respiration was compared in situ in saponin-skinned fibers isolated from the soleus muscles of Wistar rats, in solution enriched in O2 by injection or the electrolytic process 1) at an O2 concentration decreasing from 240 µmol/L to 10 µmol/L (132 mmHg to 5 mmHg), with glutamate-malate or N, N, N', N'-tetramethyl-p-phenylenediamine dihydrochloride (TMPD)-ascorbate (with antimycin A) as substrates; and 2) at increasing adenosine diphosphate (ADP) concentration with glutamate-malate as substrate. As expected, maximal respiration decreased with O2 concentration and, when compared to glutamate-malate, the apparent Km O2 of mitochondria for O2 was significantly lower with TMPD-ascorbate with both waters. However, when compared to the water enriched in O2 by injection, the Km O2 was significantly lower with both electron donors in water enriched in O2 by electrolysis. This was not associated with any increase in the sensitivity of mitochondria to ADP; no significant difference was observed for the Km ADP between the two waters. In this experiment, a higher affinity of the mitochondria for O2 was observed in water enriched in O2 by electrolysis than by injection. This observation is consistent with the hypothesis that O2 diffusion can be facilitated in water enriched in O2 by the electrolytic process.

DEMOLISHING A COLD WARE ERA FULE STORAGE BASIN SUPERSTRUCTURE LADEN WITH ASBESTOS

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

LLOYD ER; STEVENS JM; DAGAN EB

The K East (KE) Basin facilities are located near the north end of the Hanford Site's 100 K area. The facilities were built in 1950 as part of the KE Reactor complex and constructed within 400 meters of the Columbia River, which is the largest river in the Pacific Northwest and by volume the fourth largest river in the United States. The basin, located adjacent to the reactor, was used for the underwater storage of irradiated nuclear fuel discharged from the reactor. The basin was covered by a superstructure comprising steel columns and beams, concrete, and cement asbestos board (CAB)more » siding. The project's mission was to complete demolition of the structure over the KE Basin within six months of turnover from facility deactivation activities. The demolition project team applied open-air demolition techniques to bring the facility to slab-on-grade. Several innovative techniques were used to control contamination and maintain contamination control within the confines of the demolition exclusion zone. The techniques, which focused on a defense-in-depth approach, included spraying fixatives on interior and exterior surfaces before demolition began; applying fixatives during the demolition; misting using a fine spray of water during demolition; and demolishing the facility systematically. Another innovative approach that made demolition easier was to demolish the building with the non-friable CAB remaining in place. The CAB siding covered the exterior of the building and portions of the interior walls, and was an integral part of the multiple-layered roof. The project evaluated the risks involved in removing the CAB material in a radiologically contaminated environment and determined that radiological dose rates and exposure to radiological contamination and industrial hazards would be significantly reduced by using heavy equipment to remove the CAB during demolition. The ability to perform this demolition safely and without spreading contamination (radiological or asbestos) demonstrates that contaminated structures can be torn down successfully using similar open-air demolition techniques.« less

DEMOLISHING A COLD-WAR-ERA FUEL STORAGE BASIN SUPERSTRUCTURE LADEN WITH ASBESTOS

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

LLOYD ER; ORGILL TK; DAGAN EB

The K East (KE) Basin facilities are located near the north end of the Hanford Site's 100 K area. The facilities were built in 1950 as part of the KE Reactor complex and constructed within 400 meters of the Columbia River, which is the largest river in the Pacific Northwest and by volume the fourth largest river in the United States. The basin, located adjacent to the reactor, was used for the underwater storage of irradiated nuclear fuel discharged from the reactor. The basin was covered by a superstructure comprising steel columns and beams, concrete, and cement asbestos board (CAB)more » siding. The project's mission was to complete demolition of the structure over the K East basin within six months of tumover from facility deactivation activities. The demolition project team implemented open-air demolition techniques to demolish the facility to slab-on-grade. Several innovative techniques were used to control contamination and maintain contamination control within the confines of the demolition exclusion zone. The techniques, which focused on a defense-in-depth approach, included spraying fixatives on interior and exterior surfaces before demolition began; applying fixatives; misting using a fine spray of water during demolition; and demolishing the facility systematically. Another innovation that aided demolition was to demolish the building with the non-friable CAB remaining in place. The CAB siding covered the exterior of the building, portions of the interior walls, and was an integral part of the multiple layered roof. The project evaluated the risks involved in removing the CAB material in a radiologically contaminated environment and determined that radiological dose rates and exposure to radiological contamination and industrial hazards would be significantly reduced by removing the CAB during demolition using heavy equipment. The ability to perform this demolition safely and without spreading contamination (radiological or asbestos) demonstrates that similar open-air demolition ofcontaminated structures can be performed successfully.« less

Creep and shrinkage effects on integral abutment bridges

NASA Astrophysics Data System (ADS)

Munuswamy, Sivakumar

Integral abutment bridges provide bridge engineers an economical design alternative to traditional bridges with expansion joints owing to the benefits, arising from elimination of expensive joints installation and reduced maintenance cost. The superstructure for integral abutment bridges is cast integrally with abutments. Time-dependent effects of creep, shrinkage of concrete, relaxation of prestressing steel, temperature gradient, restraints provided by abutment foundation and backfill and statical indeterminacy of the structure introduce time-dependent variations in the redundant forces. An analytical model and numerical procedure to predict instantaneous linear behavior and non-linear time dependent long-term behavior of continuous composite superstructure are developed in which the redundant forces in the integral abutment bridges are derived considering the time-dependent effects. The redistributions of moments due to time-dependent effects have been considered in the analysis. The analysis includes nonlinearity due to cracking of the concrete, as well as the time-dependent deformations. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) models for creep and shrinkage are considered in modeling the time dependent material behavior. The variations in the material property of the cross-section corresponding to the constituent materials are incorporated and age-adjusted effective modulus method with relaxation procedure is followed to include the creep behavior of concrete. The partial restraint provided by the abutment-pile-soil system is modeled using discrete spring stiffness as translational and rotational degrees of freedom. Numerical simulation of the behavior is carried out on continuous composite integral abutment bridges and the deformations and stresses due to time-dependent effects due to typical sustained loads are computed. The results from the analytical model are compared with the published laboratory experimental and field data. The behavior of the laterally loaded piles supporting the integral abutments is evaluated and presented in terms of the lateral deflection, bending moment, shear force and stress along the pile depth.

Effects of molecular chirality on self-assembly and switching in liquid crystals at the cross-over between rod-like and bent shapes.

PubMed

Ocak, Hale; Poppe, Marco; Bilgin-Eran, Belkız; Karanlık, Gürkan; Prehm, Marko; Tschierske, Carsten

2016-09-21

A bent-core compound derived from a 4-cyanoresorcinol core unit with two terephthalate based rod-like wings and carrying chiral 3,7-dimethyloctyloxy side chains has been synthesized in racemic and enantiomerically pure form and characterized by polarizing microscopy, differential scanning calorimetry, X-ray diffraction and electro-optical investigations to study the influence of molecular chirality on the superstructural chirality and polar order in lamellar liquid crystalline phases. Herein we demonstrate that the coupling of molecular chirality with superstructural layer chirality in SmCsPF domain phases (forming energetically distinct diastereomeric pairs) can fix the tilt direction and thus stabilize synpolar order, leading to bistable ferroelectric switching in the SmC* phases of the (S)-enantiomer, whereas tristable modes determine the switching of the racemate. Moreover, the mechanism of electric field induced molecular reorganization changes from a rotation around the molecular long axis in the racemate to a rotation on the tilt-cone for the (S)-enantiomer. At high temperature the enantiomer behaves like a rod-like molecule with a chirality induced ferroelectric SmC* phase and an electroclinic effect in the SmA'* phase. At reduced temperature sterically induced polarization, due to the bent molecular shape, becomes dominating, leading to much higher polarization values, thus providing access to high polarization ferroelectric materials with weakly bent compounds having only "weakly chiral" stereogenic units. Moreover, the field induced alignment of the SmCsPF(()*()) domains gives rise to a special kind of electroclinic effect appearing even in the absence of molecular chirality. Comparison with related compounds indicates that the strongest effects of chirality appear for weakly bent molecules with a relatively short coherence length of polar order, whereas for smectic phases with long range polar order the effects of the interlayer interfaces can override the chirality effects.

Improving the fit of implant prosthetics: an in vitro study.

PubMed

Yannikakis, Stavros; Prombonas, Anthony

2013-01-01

Accurate and passive fit between a prosthesis and its supporting implants has been considered a prerequisite for successful long-term osseointegration. The objective of this in vitro study was to evaluate the strain development during tightening of a five-unit screw-retained superstructure constructed using five different methods. Five-unit screw-retained fixed partial prostheses (n = 25) were fabricated on three implants embedded in an epoxy resin block using five different methods: (1) cobalt-chromium (Co-Cr), plastic cylinders, one-piece cast; (2) Co-Cr, plastic cylinders, framework sectioned, preceramic laser-welding soldering; (3) gold-platinum (Au-Pt), gold cylinders, one-piece cast; (4) Au-Pt, gold cylinders, framework sectioned, preceramic laser-welding soldering; (5) Co-Cr, one-piece cast, and cementation to "passive abutments" (Southern Implants) after final finishing and polishing. Strain gauges (SG) were attached to the fixed partial prosthesis (FPP) and to the resin block to measure the stress created during screw tightening. The combination of Co-Cr alloy and plastic cylinders in a one-piece cast showed such an inadequate fit among the fabricated methods that this group was excluded from the remainder of the experiment. Specimens of Au-Pt cast on gold cylinders in one piece showed higher strain development than the other groups used in this study, with strains ranging from 223.1 to 2,198.1 Μm/m. Sectioning and soldering significantly improved the overall fit. FPPs of Co-Cr in a one-piece cast cemented to "passive abutments" produced the best level of fit, with the least strain development in the prosthesis and the resin block (59 to 204.6 Μm/m). Absolute fit of superstructures on implants is not possible using conventional laboratory procedures. Cementing FPPs onto prefabricated cylinders directly onto the implants significantly reduces strain development compared to the other fabrication methods.

Complexation of polyoxometalates with cyclodextrins.

PubMed

Wu, Yilei; Shi, Rufei; Wu, Yi-Lin; Holcroft, James M; Liu, Zhichang; Frasconi, Marco; Wasielewski, Michael R; Li, Hui; Stoddart, J Fraser

2015-04-01

Although complexation of hydrophilic guests inside the cavities of hydrophobic hosts is considered to be unlikely, we demonstrate herein the complexation between γ- and β-cyclodextrins (γ- and β-CDs) with an archetypal polyoxometalate (POM)--namely, the [PMo12O40](3-) trianion--which has led to the formation of two organic-inorganic hybrid 2:1 complexes, namely [La(H2O)9]{[PMo12O40]⊂[γ-CD]2} (CD-POM-1) and [La(H2O)9] {[PMo12O40]⊂[β-CD]2} (CD-POM-2), in the solid state. The extent to which these complexes assemble in solution has been investigated by (i) (1)H, (13)C, and (31)P NMR spectroscopies and (ii) small- and wide-angle X-ray scattering, as well as (iii) mass spectrometry. Single-crystal X-ray diffraction reveals that both complexes have a sandwich-like structure, wherein one [PMo12O40](3-) trianion is encapsulated by the primary faces of two CD tori through intermolecular [C-H···O═Mo] interactions. X-ray crystal superstructures of CD-POM-1 and CD-POM-2 show also that both of these 2:1 complexes are lined up longitudinally in a one-dimensional columnar fashion by means of [O-H···O] interactions. A beneficial nanoconfinement-induced stabilizing effect is supported by the observation of slow color changes for these supermolecules in aqueous solution phase. Electrochemical studies show that the redox properties of [PMo12O40](3-) trianions encapsulated by CDs in the complexes are largely preserved in solution. The supramolecular complementarity between the CDs and the [PMo12O40](3-) trianion provides yet another opportunity for the functionalization of POMs under mild conditions by using host-guest chemistry.

46 CFR 154.330 - Openings to accommodation, service, or control spaces.

Code of Federal Regulations, 2010 CFR

2010-10-01

... DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... and in the first tier of the superstructure must be a fixed type. (e) Air intakes and openings into... at not less than 207 kPa gauge (30 psig). (f) On liquefied toxic gas vessels, the closures required...

46 CFR 154.330 - Openings to accommodation, service, or control spaces.

Code of Federal Regulations, 2012 CFR

2012-10-01

... DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... and in the first tier of the superstructure must be a fixed type. (e) Air intakes and openings into... at not less than 207 kPa gauge (30 psig). (f) On liquefied toxic gas vessels, the closures required...

46 CFR 154.330 - Openings to accommodation, service, or control spaces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... and in the first tier of the superstructure must be a fixed type. (e) Air intakes and openings into... at not less than 207 kPa gauge (30 psig). (f) On liquefied toxic gas vessels, the closures required...

46 CFR 154.330 - Openings to accommodation, service, or control spaces.

Code of Federal Regulations, 2013 CFR

2013-10-01

... DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... and in the first tier of the superstructure must be a fixed type. (e) Air intakes and openings into... at not less than 207 kPa gauge (30 psig). (f) On liquefied toxic gas vessels, the closures required...

46 CFR 154.330 - Openings to accommodation, service, or control spaces.

Code of Federal Regulations, 2014 CFR

2014-10-01

... DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design... and in the first tier of the superstructure must be a fixed type. (e) Air intakes and openings into... at not less than 207 kPa gauge (30 psig). (f) On liquefied toxic gas vessels, the closures required...

22. Photographic copy of blueprints and plans (from the originals ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. Photographic copy of blueprints and plans (from the originals in possession of Detroit District, U.S. Army Corps of Engineers, Duluth, Minnesota). North pier of Duluth Canal, 1899, timber molds for concrete superstructure - Duluth Ship Canal, North Pier, North end of Minnesota Point at Canal Park, Duluth, St. Louis County, MN

46 CFR 45.133 - Air pipes.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Air pipes. 45.133 Section 45.133 Shipping COAST GUARD....133 Air pipes. (a) Where an air pipe to any tank extends above the freeboard or superstructure deck— (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid...

46 CFR 45.133 - Air pipes.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Air pipes. 45.133 Section 45.133 Shipping COAST GUARD....133 Air pipes. (a) Where an air pipe to any tank extends above the freeboard or superstructure deck— (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid...

46 CFR 45.133 - Air pipes.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Air pipes. 45.133 Section 45.133 Shipping COAST GUARD....133 Air pipes. (a) Where an air pipe to any tank extends above the freeboard or superstructure deck— (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid...

46 CFR 45.121 - Freeing port area: Changes for trunks and side coamings.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Freeing port area: Changes for trunks and side coamings... GREAT LAKES LOAD LINES Conditions of Assignment § 45.121 Freeing port area: Changes for trunks and side... substantially continuous hatchway side coamings between detached superstructures, the minimum area of the...

46 CFR 45.121 - Freeing port area: Changes for trunks and side coamings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Freeing port area: Changes for trunks and side coamings... GREAT LAKES LOAD LINES Conditions of Assignment § 45.121 Freeing port area: Changes for trunks and side... substantially continuous hatchway side coamings between detached superstructures, the minimum area of the...

46 CFR 45.121 - Freeing port area: Changes for trunks and side coamings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Freeing port area: Changes for trunks and side coamings... GREAT LAKES LOAD LINES Conditions of Assignment § 45.121 Freeing port area: Changes for trunks and side... substantially continuous hatchway side coamings between detached superstructures, the minimum area of the...

46 CFR 45.121 - Freeing port area: Changes for trunks and side coamings.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Freeing port area: Changes for trunks and side coamings... GREAT LAKES LOAD LINES Conditions of Assignment § 45.121 Freeing port area: Changes for trunks and side... substantially continuous hatchway side coamings between detached superstructures, the minimum area of the...

46 CFR 45.121 - Freeing port area: Changes for trunks and side coamings.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Freeing port area: Changes for trunks and side coamings... GREAT LAKES LOAD LINES Conditions of Assignment § 45.121 Freeing port area: Changes for trunks and side... substantially continuous hatchway side coamings between detached superstructures, the minimum area of the...

Development and Testing of a Completely Passive, Air Suspended, Air Propelled Personal Rapid Transit Vehicle

DOT National Transportation Integrated Search

1973-04-01

A prototype Uniflo vehicle base with mock-up superstructure was tested on 55 ft. of full-scale track. Sound treatment to meet NCA 60 at 25 ft. from the guideway enclosure and within the vehicle was proposed and the costs determined. A heating and coo...

Construction of a Virginia short-span bridge with the Strongwell 36-inch double-web I-beam.

DOT National Transportation Integrated Search

2005-01-01

The Route 601 Bridge in Sugar Grove, VA, spans 39 ft over Dickey Creek. The bridge is the first to use the Strongwell 36-in-deep fiber-reinforced polymer (FRP) double-web beam (DWB) in a vehicular bridge superstructure. Construction of the new bridge...

46 CFR 45.133 - Air pipes.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Air pipes. 45.133 Section 45.133 Shipping COAST GUARD....133 Air pipes. (a) Where an air pipe to any tank extends above the freeboard or superstructure deck— (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid...

46 CFR 45.133 - Air pipes.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Air pipes. 45.133 Section 45.133 Shipping COAST GUARD....133 Air pipes. (a) Where an air pipe to any tank extends above the freeboard or superstructure deck— (1) The exposed part of the air pipe must be made of steel and of sufficient thickness to avoid...

46 CFR 42.13-15 - Definitions of terms.

Code of Federal Regulations, 2011 CFR

2011-10-01

... of the midship section is of a hollow character, or where thick garboards are fitted, the distance is... provided by the actual midship section. (g) Block coefficient. The block coefficient (C b) is given by C b... the superstructures by alternative means, which are available at all times when bulkhead openings are...

46 CFR 42.13-15 - Definitions of terms.

Code of Federal Regulations, 2010 CFR

2010-10-01

... of the midship section is of a hollow character, or where thick garboards are fitted, the distance is... provided by the actual midship section. (g) Block coefficient. The block coefficient (C b) is given by C b... the superstructures by alternative means, which are available at all times when bulkhead openings are...

46 CFR 42.15-35 - Machinery space openings.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 2 2013-10-01 2013-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure deck...

46 CFR 42.15-35 - Machinery space openings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 2 2011-10-01 2011-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure deck...

46 CFR 42.15-35 - Machinery space openings.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 2 2014-10-01 2014-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure deck...

46 CFR 42.15-35 - Machinery space openings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure deck...

46 CFR 42.15-35 - Machinery space openings.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure deck...

Understanding the Mechanisms of Neoliberal Control: Lifelong Learning, Flexibility and Knowledge Capitalism

ERIC Educational Resources Information Center

Olssen, Mark

2006-01-01

This paper argues that Foucault's conception of "governmentality" provides a powerful tool for understanding learning and education and links the organisation of learning to both politics and economics in developed Western societies. What is offered by Foucault's conception, I will argue, is a new version of superstructural sociology, which…

Standard practice for washing and cleaning concrete bridge decks and substructure bridge seats including bridge bearings and expansion joints to prevent structural deterioration.

DOT National Transportation Integrated Search

2013-12-01

This study is a supplement to a previous study of bridge washing practices that focused on steel : superstructures. This study examined the perceived costs and benefits of routine washing of both : steel and concrete bridges, with emphasis on substru...

392. J.R.L., Delineator August 1933 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

392. J.R.L., Delineator August 1933 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - EAST BAY CROSSING; PIER El; ANCHORAGE STEEL WORK; CONTRACT NO. 7; SUP. DRAWING NO. 72A - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

388. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

388. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; SUSPENDED STRUCTURE; SIDE SPAN TRUSSES AT ANCHORAGES; CONTRACT NO. 6; DRAWING NO. 40 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

390. Delineator Unknown October 1933 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

390. Delineator Unknown October 1933 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - EAST BAY CROSSING; SPANS YBI TO El - E9 TO El ; TYPICAL CROSSSECTION; CONTRACT NO. 7; SUP. DRAWING NO. 82 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Preparation and high-performance microwave absorption of hierarchical dendrite-like Co superstructures self-assembly of nanoflakes

NASA Astrophysics Data System (ADS)

Yu, Miao; Wang, Lirui; Yang, Pingan; Fu, Jie

2017-12-01

Dendritic-like Co superstructures based on the self-assembly of nanoflakes that could efficiently suppress the eddy current were successfully synthesized via a facile, rapid, and energy-saving chemical reduction method. Since crystal structure, size, and special geometrical morphology, magnetism have a vital influence on microwave absorption properties, the as-obtained products were characterized by x-ray diffraction, scanning electron microscopy, vibrating sample magnetometry, and vector network analysis. The prepared dendritic Co possesses abundant secondary branches that extend to the 3D space. Their dimensions, spacing, sheet-like blocks, and high-ordering microstructures all contribute to the penetration, scattering, and attenuation of EM waves. The composites present attractive microwave absorption performances in the X band, as well as in the whole S band (2-4 GHz). This work investigates the mechanism of absorption for the as-obtained Co, offers a promising strategy for the fabrication of hierarchical Co microstructure assemblies by multi-leaf flakes and introduces the application of dendritic-like Co as a highly efficient absorber in the S band and X band.

Tunable emergent heterostructures in a prototypical correlated metal

NASA Astrophysics Data System (ADS)

Fobes, D. M.; Zhang, S.; Lin, S.-Z.; Das, Pinaki; Ghimire, N. J.; Bauer, E. D.; Thompson, J. D.; Harriger, L. W.; Ehlers, G.; Podlesnyak, A.; Bewley, R. I.; Sazonov, A.; Hutanu, V.; Ronning, F.; Batista, C. D.; Janoschek, M.

2018-05-01

At the interface between two distinct materials, desirable properties, such as superconductivity, can be greatly enhanced1, or entirely new functionalities may emerge2. Similar to in artificially engineered heterostructures, clean functional interfaces alternatively exist in electronically textured bulk materials. Electronic textures emerge spontaneously due to competing atomic-scale interactions3, the control of which would enable a top-down approach for designing tunable intrinsic heterostructures. This is particularly attractive for correlated electron materials, where spontaneous heterostructures strongly affect the interplay between charge and spin degrees of freedom4. Here we report high-resolution neutron spectroscopy on the prototypical strongly correlated metal CeRhIn5, revealing competition between magnetic frustration and easy-axis anisotropy—a well-established mechanism for generating spontaneous superstructures5. Because the observed easy-axis anisotropy is field-induced and anomalously large, it can be controlled efficiently with small magnetic fields. The resulting field-controlled magnetic superstructure is closely tied to the formation of superconducting6 and electronic nematic textures7 in CeRhIn5, suggesting that in situ tunable heterostructures can be realized in correlated electron materials.

Tunable emergent heterostructures in a prototypical correlated metal

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

Fobes, D. M.; Zhang, S.; Lin, S. -Z.

We report at the interface between two distinct materials, desirable properties, such as superconductivity, can be greatly enhanced1, or entirely new functionalities may emerge. Similar to in artificially engineered heterostructures, clean functional interfaces alternatively exist in electronically textured bulk materials. Electronic textures emerge spontaneously due to competing atomic-scale interactions, the control of which would enable a top-down approach for designing tunable intrinsic heterostructures. This is particularly attractive for correlated electron materials, where spontaneous heterostructures strongly affect the interplay between charge and spin degrees of freedom. Here we report high-resolution neutron spectroscopy on the prototypical strongly correlated metal CeRhIn 5, revealingmore » competition between magnetic frustration and easy-axis anisotropy—a well-established mechanism for generating spontaneous superstructures. Because the observed easy-axis anisotropy is field-induced and anomalously large, it can be controlled efficiently with small magnetic fields. Finally, the resulting field-controlled magnetic superstructure is closely tied to the formation of superconducting and electronic nematic textures in CeRhIn 5, suggesting that in situ tunable heterostructures can be realized in correlated electron materials.« less

Self-organized microstructures induced by MeV ion beam on silicon surface

NASA Astrophysics Data System (ADS)

Ahmad, Muthanna

2017-02-01

Micro patterning of self organized structure on silicon surface is induced by ion implantation of energetic (MeV) copper ions. This work reports for the first time the ability of using energetic ions for producing highly ordered ripples and dots of micro sizes. The experiments are realized at the Tandem ion beam accelerator (3 MV) at the IBA laboratory of the Atomic Energy Commission of Syria. Similarly to nano patterning formed by slow ions, the formation of micro patterned structures dots and ripples is observed to be depending on the angle of ion beam incidence, energy and ion fluence. The observation of such microstructures formation is limited to a range of ion energies (few MeV) at fluence higher than 1.75 × 1017 ion cm-2. The patterned surface layer is completely amorphousized by the ion implantation. Shadowing effect is observed in the formation of microripples and superstructures in the top of ripples. The superstructure develops new morphology that is not observed before. This morphology has butterfly shape with symmetry in its structure.

Origin of the Giant Honeycomb Network of Quinones on Cu(111)

NASA Astrophysics Data System (ADS)

Einstein, T. L.; Kim, Kwangmoo; Wyrick, Jon; Cheng, Zhihai; Bartels, Ludwig; Berland, Kristian; Hyldgaard, Per

2011-03-01

We discuss the factors that lead to the amazing regular giant honeycomb network formed by quinones on Cu(111). Using a related lattice gas model with many characteristic energies, we can reproduce many experimental features. These models require a long-range attraction, which can be attributed to indirect interactions mediated by the Shockley surface state of Cu(111). However, Wyrick's preceding talk gave evidence that the network self-selects for the size of the pore rather than for the periodicity of the superstructure, suggesting that confined states are the key ingredient. We discuss this phenomenon in terms of the magic numbers of 2D quantum dots. We also report calculations of the effects of anthraquinones (AQ) in modifying the surface states by considering a superlattice of AQ chains with various separations. We discuss implications of these results for tuning the electronic states and, thence, superstructures. Supported by (TLE) NSF CHE 07-50334 & UMD MRSEC DMR 05-20471, (JW & LB) NSF CHE NSF CHE 07-49949, (KB & PH) Swedish Vetenskapsrådet VR 621-2008-4346.

Correlations of crystallographic defects and anisotropy with magnetotransport properties in Fe x TaS 2 single crystals ( 0.23 ≤ x ≤ 0.35 )

DOE PAGES

Chen, Chih-Wei; Chikara, Shalinee; Zapf, Vivien S.; ...

2016-08-02

Very large magnetoresistance discovered in single crystals of the ferromagnetic Fe-intercalated transition metal dichalcogenide, Fe 0.28TaS 2 was attributed to the deviation of the Fe concentration from commensurate values (x = 1/4 or 1/3), which caused magnetic moment misalignments. Here we report a study of Fe xTaS 2 crystals with 0:23 ≤ x ≤ 0:35, demonstrating that crystallographic defects lead to spin disorder, which correlates with magneto-transport properties such as switching magnetic fi eld HS, magnetoresistance MR, and even zero-field resistivity ρ0 and temperature coefficient A in ρ(T) = ρ 0 + AT 2: The ordering temperature T C andmore » Weiss temperature θ W are maximized at the superstructure composition x = 1/4, while H s, MR, ρ 0, and A are minimum. Conversely, at a composition intermediate between the superstructure compositions x = 1/4 and 1/3, the corresponding magneto-transport properties reach local maxima.« less

Magnetic Superstructure and Metal-Insulator Transition in Mn-Substituted Sr3 Ru 2 O 7

NASA Astrophysics Data System (ADS)

Hossain, M. A.; Zhu, Z. H.; Bohnenbuck, B.; Chuang, Y.-D.; Yoshida, Y.; Hussain, Z.; Keimer, B.; Elfimov, I. S.; Sawatzky, G. A.; Damascelli, A.

2011-03-01

We present a temperature-dependent resonant elastic soft x-ray scattering (REXS) study of the metal-insulator transition in Sr 3 (Ru 1-x Mn x)2 O7 , performed at both Ru and Mn L -edges. Resonant magnetic superstructure reflections together with ab-initio density functional theory calculations identify the ground state as a spin checkerboard with blocks of 4 spins up and 4 spins down. Based on modelling of the REXS intensity from randomly distributed Mn impurities, we establish the inhomogeneous nature of the metal-insulator transition, with an effective percolation threshold corresponding to an anomalously low x ~ 0.05 Mn substitution. Perhaps more important, our results suggest that the same checkerboard instability might be present already in the parent compound Sr 3 Ru 2 O7 . In collaboration with: A.G. Cruz Gonzalez, J.D. Denlinger (Berkeley) I. Zegkinoglou, M.W. Haverkort (MPI) J. Geck, D.G. Hawthorn (UBC) R. Mathieu, Y. Tokura, S. Satow, H. Takagi (Tokyo) H.-H. Wu and C. Schussler-Langeheine (Cologne).

Tunable emergent heterostructures in a prototypical correlated metal

DOE PAGES

Fobes, D. M.; Zhang, S.; Lin, S. -Z.; ...

2018-03-26

We report at the interface between two distinct materials, desirable properties, such as superconductivity, can be greatly enhanced1, or entirely new functionalities may emerge. Similar to in artificially engineered heterostructures, clean functional interfaces alternatively exist in electronically textured bulk materials. Electronic textures emerge spontaneously due to competing atomic-scale interactions, the control of which would enable a top-down approach for designing tunable intrinsic heterostructures. This is particularly attractive for correlated electron materials, where spontaneous heterostructures strongly affect the interplay between charge and spin degrees of freedom. Here we report high-resolution neutron spectroscopy on the prototypical strongly correlated metal CeRhIn 5, revealingmore » competition between magnetic frustration and easy-axis anisotropy—a well-established mechanism for generating spontaneous superstructures. Because the observed easy-axis anisotropy is field-induced and anomalously large, it can be controlled efficiently with small magnetic fields. Finally, the resulting field-controlled magnetic superstructure is closely tied to the formation of superconducting and electronic nematic textures in CeRhIn 5, suggesting that in situ tunable heterostructures can be realized in correlated electron materials.« less

Correlations of crystallographic defects and anisotropy with magnetotransport properties in Fe x TaS 2 single crystals ( 0.23 ≤ x ≤ 0.35 )

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

Chen, Chih-Wei; Chikara, Shalinee; Zapf, Vivien S.

Very large magnetoresistance discovered in single crystals of the ferromagnetic Fe-intercalated transition metal dichalcogenide, Fe 0.28TaS 2 was attributed to the deviation of the Fe concentration from commensurate values (x = 1/4 or 1/3), which caused magnetic moment misalignments. Here we report a study of Fe xTaS 2 crystals with 0:23 ≤ x ≤ 0:35, demonstrating that crystallographic defects lead to spin disorder, which correlates with magneto-transport properties such as switching magnetic fi eld HS, magnetoresistance MR, and even zero-field resistivity ρ0 and temperature coefficient A in ρ(T) = ρ 0 + AT 2: The ordering temperature T C andmore » Weiss temperature θ W are maximized at the superstructure composition x = 1/4, while H s, MR, ρ 0, and A are minimum. Conversely, at a composition intermediate between the superstructure compositions x = 1/4 and 1/3, the corresponding magneto-transport properties reach local maxima.« less

First-principles study of intermetallic phase stability in the ternary Ti-Al-Nb alloy system

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

Asta, M.; Ormeci, A.; Wills, J.M.

The stability of bcc-based phases in the Ti-Al-Nb alloy system has been studied from first-principles using a combination of ab-initio total energy and cluster variation method (CVM) calculations. Total energies have been computed for 18 binary and ternary bcc superstructures in order to determine low temperature ordering tendencies. From the results of these calculations a set of effective cluster interaction parameters have been derived. These interaction parameters are required input for CVM computations of alloy thermodynamic properties. The CVM has been used to study the effect of composition on finite-temperature ordering tendencies and site preferences for bcc-based phases. Strong orderingmore » tendencies are observed for binary Nb-Al and Ti-Al bcc phases as well as for ternary alloys with compositions near Ti{sub 2}AlNb. For selected superstructures we have also analyzed structural stabilities with respect to tetragonal distortions which transform the bcc into an fcc lattice. Instabilities with respect to such distortions are found to exist for binary but not ternary bcc compounds.« less

Programmable DNA tile self-assembly using a hierarchical sub-tile strategy.

PubMed

Shi, Xiaolong; Lu, Wei; Wang, Zhiyu; Pan, Linqiang; Cui, Guangzhao; Xu, Jin; LaBean, Thomas H

2014-02-21

DNA tile based self-assembly provides a bottom-up approach to construct desired nanostructures. DNA tiles have been directly constructed from ssDNA and readily self-assembled into 2D lattices and 3D superstructures. However, for more complex lattice designs including algorithmic assemblies requiring larger tile sets, a more modular approach could prove useful. This paper reports a new DNA 'sub-tile' strategy to easily create whole families of programmable tiles. Here, we demonstrate the stability and flexibility of our sub-tile structures by constructing 3-, 4- and 6-arm DNA tiles that are subsequently assembled into 2D lattices and 3D nanotubes according to a hierarchical design. Assembly of sub-tiles, tiles, and superstructures was analyzed using polyacrylamide gel electrophoresis and atomic force microscopy. DNA tile self-assembly methods provide a bottom-up approach to create desired nanostructures; the sub-tile strategy adds a useful new layer to this technique. Complex units can be made from simple parts. The sub-tile approach enables the rapid redesign and prototyping of complex DNA tile sets and tiles with asymmetric designs.

Influence of conformational changes on spin crossover properties and superstructure formation in 2D coordination polymers [Fe(hbtz)2(RCN)2](ClO4)2.

PubMed

Książek, Maria; Kusz, Joachim; Białońska, Agata; Bronisz, Robert; Weselski, Marek

2015-11-14

2D structurally related iron(ii) coordination networks {[Fe(hbtz)2(RCN)2](ClO4)2}∞ featuring, besides tetrazol-2-yl rings in the first coordination sphere, also axially coordinated propionitrile or allyl cyanide molecules (R = C3H5-, 1; R = C2H5-, 2) were synthesized. Thermally induced spin crossover (SCO) in 1 takes place in two poorly resolved stages (T(1)1/2(↓) = T(1)1/2(↑) = 198 K, T(2)1/2(↓) = 170 K, T(2)1/2(↑) = 171 K) whereas in 2 complete and relatively gradual one step SCO (T1/2(↓) = T1/2(↑) = 160 K) occurs. Diversification of the SCO properties of the complexes originates from the ability of coordinated allyl cyanide in 1 to undergo conformational alterations, which is not observed for propionitrile molecules in 2. SCO in 1 is accompanied by a non-monotonic change of the contribution of allyl cyanide conformers which is related to reconstruction of the network of intermolecular contacts established between polymeric layers. The coordination network 1 exhibits extraordinary elasticity and in the second stage SCO, accompanied by conformational changes of allyl cyanide, triggers a crystallographic phase transition which leads to the formation of a superstructure. What is important, the formation of the superstructure is not caused by long range ordering of HS and LS iron(ii) ions. The structural alteration is associated with corrugation of the polymeric skeleton and disappearance of nitrile disorder. Irradiation of a single crystal of 1 at 15 K with laser light (520 nm) allowed producing a novel low temperature HS phase of 1 in which, contrary to the high temperature HS phase, disordering of anion and allyl cyanide molecules is not observed and the corrugated nature of the polymeric layer, characteristic of the LS phase, is preserved.

Enhanced thermophysical properties via PAO superstructure

NASA Astrophysics Data System (ADS)

Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

2017-01-01

For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Enhanced thermophysical properties via PAO superstructure.

PubMed

Pournorouz, Zahra; Mostafavi, Amirhossein; Pinto, Aditya; Bokka, Apparao; Jeon, Junha; Shin, Donghyun

2017-12-01

For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Role of Absorbing Nanocrystal Cores in Soft Photonic Crystals: A Spectroscopy and SANS Study.

PubMed

Rauh, Astrid; Carl, Nico; Schweins, Ralf; Karg, Matthias

2018-01-23

Periodic superstructures of plasmonic nanoparticles have attracted significant interest because they can support coupled plasmonic modes, making them interesting for plasmonic lasing, metamaterials, and as light-management structures in thin-film optoelectronic devices. We have recently shown that noble metal hydrogel core-shell colloids allow for the fabrication of highly ordered 2-dimensional plasmonic lattices that show surface lattice resonances as the result of plasmonic/diffractive coupling (Volk, K.; Fitzgerald, J. P. S.; Ruckdeschel, P.; Retsch, M.; König, T. A. F.; Karg, M. Reversible Tuning of Visible Wavelength Surface Lattice Resonances in Self-Assembled Hybrid Monolayers. Adv. Optical Mater. 2017, 5, 1600971, DOI: 10.1002/adom.201600971). In the present work, we study the photonic properties and structure of 3-dimensional crystalline superstructures of gold hydrogel core-shell colloids and their pitted counterparts without gold cores. We use far-field extinction spectroscopy to investigate the optical response of these superstructures. Narrow Bragg peaks are measured, independently of the presence or absence of the gold cores. All crystals show a significant reduction in low-wavelength scattering. This leads to a significant enhancement of the plasmonic properties of the samples prepared from gold-nanoparticle-containing core-shell colloids. Plasmonic/diffractive coupling is not evident, which we mostly attribute to the relatively small size of the gold cores limiting the effective coupling strength. Small-angle neutron scattering is applied to study the crystal structure. Bragg peaks of several orders clearly assignable to an fcc arrangement of the particles are observed for all crystalline samples in a broad range of volume fractions. Our results indicate that the nanocrystal cores do not influence the overall crystallization behavior or the crystal structure. These are important prerequisites for future studies on photonic materials built from core-shell particles, in particular, the development of new photonic materials from plasmonic nanocrystals.

46 CFR 173.085 - General subdivision requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... elimination of the required inner bottom is allowed if— (1) The inner bottom would interfere with the mission.... (k) Each port light in a space located below the freeboard deck, as defined in § 42.13-15(i) of this chapter, or in a space within an enclosed superstructure must be fitted with a hinged inside dead cover...

46 CFR 173.085 - General subdivision requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... elimination of the required inner bottom is allowed if— (1) The inner bottom would interfere with the mission.... (k) Each port light in a space located below the freeboard deck, as defined in § 42.13-15(i) of this chapter, or in a space within an enclosed superstructure must be fitted with a hinged inside dead cover...

46 CFR 173.085 - General subdivision requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... elimination of the required inner bottom is allowed if— (1) The inner bottom would interfere with the mission.... (k) Each port light in a space located below the freeboard deck, as defined in § 42.13-15(i) of this chapter, or in a space within an enclosed superstructure must be fitted with a hinged inside dead cover...

46 CFR 173.085 - General subdivision requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... elimination of the required inner bottom is allowed if— (1) The inner bottom would interfere with the mission.... (k) Each port light in a space located below the freeboard deck, as defined in § 42.13-15(i) of this chapter, or in a space within an enclosed superstructure must be fitted with a hinged inside dead cover...

46 CFR 173.085 - General subdivision requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... elimination of the required inner bottom is allowed if— (1) The inner bottom would interfere with the mission.... (k) Each port light in a space located below the freeboard deck, as defined in § 42.13-15(i) of this chapter, or in a space within an enclosed superstructure must be fitted with a hinged inside dead cover...

6. VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CENTRAL PIER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW OF THE EASTERN BRIDGE ELEVATION, SHOWING CENTRAL PIER AND ASSOCIATED SUPERSTRUCTURE, AND CANTILEVERED NORTHERN TRUSS SECTION. NOTE THE JOIN BETWEEN EYE-BAR (LEFT) AND RIVETED CHANNEL (RIGHT) LOWER BRIDGE CHORDS AT CENTER LEFT OF PHOTOGRAPH. FACING NORTH. - Coverts Crossing Bridge, Spanning Mahoning River along Township Route 372 (Covert Road), New Castle, Lawrence County, PA

Ultra-high performance fiber-reinforced concrete (UHPFRC) for infrastructure rehabilitation : volume 1 : evaluation of ultra high strength concrete (UHSC) in joints of bridge girders.

DOT National Transportation Integrated Search

2017-03-01

Joints are often considered as the weak link in a structure and often deterioration of the structure initiates from the : joints. Joints transfer the stresses from super-structure to sub-structure and in this process are subjected to large : transfer...

10. "TEST STAND 15, AIR FORCE FLIGHT TEST CENTER." ca. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. "TEST STAND 1-5, AIR FORCE FLIGHT TEST CENTER." ca. 1958. Test Area 1-115. Original is a color print, showing Test Stand 1-5 from below, also showing the superstructure of TS1-4 at left. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Leuhman Ridge near Highways 58 & 395, Boron, Kern County, CA

Comparative durability of timber bridges in the USA

Treesearch

James P. Wacker; Brian K. Brashaw

2017-01-01

As engineers begin to utilize life-cycle-cost design approaches for timber bridges, there is a necessity for more reliable data about their durability and expected service life. This paper summarizes a comprehensive effort to assess the current condition of more than one hundred timber highway bridge superstructures throughout the United States. This national study was...

Field performance of stress-laminated highway bridges constructed with glued laminated timber

Treesearch

J.P. Wacker

2004-01-01

This paper summarizes the field performance of three stress-laminated deck timber bridges located in Wisconsin, New York, and Arizona. The deck superstructures of these single-span highway bridges is comprised of full-span glued laminated timber (glulam) beam laminations manufactured with southern pine, hem fir/red maple combination, and/or Douglas fir lumber species....

Nondestructive assessment of timber bridges using a vibration-based method

Treesearch

Xiping Wang; James P. Wacker; Robert J. Ross; Brian K. Brashaw

2005-01-01

This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship...

A National Plan for a Use-Oriented Foreign Language System. NFLC Position Papers.

ERIC Educational Resources Information Center

Lambert, Richard D.

The significant progress made in the United States' foreign language education system in recent decades is not enough. If the current system is to expand adult foreign language competency and use, both a change of perspective and a new organizational superstructure are necessary to serve those needs more directly, which in turn demands a…

Applied Research Centres at South African Universities. The Relationship between 'Base' Internal Structures and Network 'Superstructures'

ERIC Educational Resources Information Center

Cooper, David

2005-01-01

This article considers the way in which applied research centres and units at South African higher education institutions enhance their networks with industry, government and community organizations. The findings from 12 case studies of research groupings at higher education institutions in Cape Town support the author's argument for a more…

46 CFR 72.05-10 - Type, location, and construction of fire control bulkheads and decks.

Code of Federal Regulations, 2011 CFR

2011-10-01

..., and deckhouses shall be constructed of steel or other equivalent metal construction of appropriate scantlings. (b) The hull, superstructure, and deck houses shall be subdivided by suitable structural steel or... the deck. (1) Bulkheads or decks of the “A” Class shall be composed of steel or equivalent metal...

Smart timber bridge on geosynthetic reinforced soil (GRS) abutments

Treesearch

Adam Senalik; James P. Wacker; Travis K. Hosteng; John Hermanson

2017-01-01

Recently, Buchanan County, Iowa, has cooperated with the U.S. Federal Highway Administration (FHWA), USDA Forest Service, Forest Products Laboratory (FPL), and Iowa State University’s Bridge Engineering Center (ISU–BEC) to initiate a project involving the construction and monitoring of a glued-laminated (glulam) timber superstructure on geosynthetic reinforced soil (...

Field performance of timber bridges. 14, Dean, Hibbsville, and Decatur stress-laminated deck bridges

Treesearch

P. D. Hilbrich Lee; M. A. Ritter; S. Golston; K. Hinds

1984-01-01

The Dean, Hibbsville, and Decatur bridges were constructed in southern Iowa during 1994. Each bridge is a simple-span, stress-laminated deck superstructure, approximately 7.3 m (24 ft) long, constructed from eastern cottonwood lumber. The performance of each bridge was monitored for approximately 2 years, beginning shortly after installation. Monitoring involved...

Service life assessment of timber highway bridges in USA climate zones

Treesearch

James P. Wacker; Brian K. Brashaw; Thomas G. Williamson; P. David Jones; Matthew S. Smith; Travis K. Hosteng; David L. Strahl; Lola E. Coombe; V.J. Gopu

2014-01-01

As engineers begin to estimate life-cycle costs and sustainable design approaches for timber bridges, there is a need for more reliable data about their durability and expected service life. This paper summarizes a comprehensive effort to assess the current condition of more than one hundred timber highway bridge superstructures throughout the United States. This...

387. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

387. D.E.M., Delineator December 1932 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; TOWERS 2, 3, 5 & 6; BRACING DETAILS - LOWER DECK; CONTRACT NO. 6; DRAWING NO. 27 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

367. J.W.G., Delineator August 1933 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

367. J.W.G., Delineator August 1933 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; PIER NO. 5; GENERAL PLAN & ELEVATION; CONTRACT NO. 2; SUP. DRAWING NO. 10A - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Quantifying enzymatic lysis: estimating the combined effects of chemistry, physiology and physics.

PubMed

Mitchell, Gabriel J; Nelson, Daniel C; Weitz, Joshua S

2010-10-04

The number of microbial pathogens resistant to antibiotics continues to increase even as the rate of discovery and approval of new antibiotic therapeutics steadily decreases. Many researchers have begun to investigate the therapeutic potential of naturally occurring lytic enzymes as an alternative to traditional antibiotics. However, direct characterization of lytic enzymes using techniques based on synthetic substrates is often difficult because lytic enzymes bind to the complex superstructure of intact cell walls. Here we present a new standard for the analysis of lytic enzymes based on turbidity assays which allow us to probe the dynamics of lysis without preparing a synthetic substrate. The challenge in the analysis of these assays is to infer the microscopic details of lysis from macroscopic turbidity data. We propose a model of enzymatic lysis that integrates the chemistry responsible for bond cleavage with the physical mechanisms leading to cell wall failure. We then present a solution to an inverse problem in which we estimate reaction rate constants and the heterogeneous susceptibility to lysis among target cells. We validate our model given simulated and experimental turbidity assays. The ability to estimate reaction rate constants for lytic enzymes will facilitate their biochemical characterization and development as antimicrobial therapeutics.

Synthesis of hollow spherical calcium phosphate nanoparticles using polymeric nanotemplates

NASA Astrophysics Data System (ADS)

Tjandra, Wiliana; Ravi, Palaniswamy; Yao, Jia; Tam, Kam C.

2006-12-01

Poly(methylmethacrylate)-block-poly(methacrylic acid) (PMMA-b-PMAA) copolymer was synthesized by an atom transfer radical polymerization (ATRP) technique. The block copolymer was employed as a template for the controlled precipitation of calcium phosphate from aqueous solution at different pH values. A Ca2+ ion selective electrode was used to study the interactions between Ca2+ ions and the polymer, which indicated a possible weak interaction between Ca2+ and un-ionized MAA segments at pH~4.0 in addition to electrostatic interaction between Ca2+ and ionized MAA segments at higher pH. An interesting structure representing that of a superstructure consisting of hybrid nano-filaments was observed by the transmission electron microscope at pH~4.0. The filaments originated from a core of similar size to primary polymer aggregates, suggesting that cooperative interactions at a local level between dissolving calcium phosphate clusters and disassembling polymer segments are responsible for the secondary growth process. A hollow spherical morphology was obtained at pH~7.0 and 9.0. Such calcium phosphate/polymer monohybrids with complex morphologies are interesting and might be useful as novel drug delivery carriers, ceramics precursors, reinforcing fillers or biomedical implants.

Self-assembly concepts for multicompartment nanostructures

NASA Astrophysics Data System (ADS)

Gröschel, André H.; Müller, Axel H. E.

2015-07-01

Compartmentalization is ubiquitous to many biological and artificial systems, be it for the separate storage of incompatible matter or to isolate transport processes. Advancements in the synthesis of sequential block copolymers offer a variety of tools to replicate natural design principles with tailor-made soft matter for the precise spatial separation of functionalities on multiple length scales. Here, we review recent trends in the self-assembly of amphiphilic block copolymers to multicompartment nanostructures (MCNs) under (semi-)dilute conditions, with special emphasis on ABC triblock terpolymers. The intrinsic immiscibility of connected blocks induces short-range repulsion into discrete nano-domains stabilized by a third, soluble block or molecular additive. Polymer blocks can be synthesized from an arsenal of functional monomers directing self-assembly through packing frustration or response to various fields. The mobility in solution further allows the manipulation of self-assembly processes into specific directions by clever choice of environmental conditions. This review focuses on practical concepts that direct self-assembly into predictable nanostructures, while narrowing particle dispersity with respect to size, shape and internal morphology. The growing understanding of underlying self-assembly mechanisms expands the number of experimental concepts providing the means to target and manipulate progressively complex superstructures.

Organization of inorganic nanomaterials via programmable DNA self-assembly and peptide molecular recognition.

PubMed

Carter, Joshua D; LaBean, Thomas H

2011-03-22

An interesting alternative to top-down nanofabrication is to imitate biology, where nanoscale materials frequently integrate organic molecules for self-assembly and molecular recognition with ordered, inorganic minerals to achieve mechanical, sensory, or other advantageous functions. Using biological systems as inspiration, researchers have sought to mimic the nanoscale composite materials produced in nature. Here, we describe a combination of self-assembly, molecular recognition, and templating, relying on an oligonucleotide covalently conjugated to a high-affinity gold-binding peptide. After integration of the peptide-coupled DNA into a self-assembling superstructure, the templated peptides recognize and bind gold nanoparticles. In addition to providing new ways of building functional multinanoparticle systems, this work provides experimental proof that a single peptide molecule is sufficient for immobilization of a nanoparticle. This molecular construction strategy, combining DNA assembly and peptide recognition, can be thought of as programmable, granular, artificial biomineralization. We also describe the important observation that the addition of 1-2% Tween 20 surfactant to the solution during gold particle binding allows the gold nanoparticles to remain soluble within the magnesium-containing DNA assembly buffer under conditions that usually lead to the aggregation and precipitation of the nanoparticles.

Insights into the multi-equilibrium, superstructure system based on β-cyclodextrin and a highly water soluble guest.

PubMed

De Paula, Elgte Elmin B; De Sousa, Frederico B; Da Silva, Júlio César C; Fernandes, Flaviana R; Melo, Maria Norma; Frézard, Frédéric; Grazul, Richard M; Sinisterra, Rubén D; Machado, Flávia C

2012-12-15

Pentamidine isethionate (PNT) is an antiprotozoal active in many cases of leishmaniasis, despite the present limitations including high toxicity and parenteral administration. In the present work, a PNT encapsulation strategy into β-cyclodextrin cavity at 1:1 and 2:1 (βCD:PNT) molar ratios was used in order to improve the drug's physical and chemical properties. Combining thermodynamic and structural approaches such as isothermal titration calorimetry (ITC), electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance ((1)H NMR, and ROESY) the inclusion process and the thermodynamics parameters were identified. ITC and ESI-MS experimental data suggest the simultaneous formation of different supramolecular complexes in solution. Moreover, NMR data are in accordance with these results, suggesting a deep inclusion of PNT into the βCD cavity, through correlations observed in 2D ROESY contour maps. The systems were also characterized by FTIR, TG/DTA and SEM. These techniques indicate the formation of inclusion complex in the solid state. In vivo PNT activity was evaluated orally in mice. The inclusion complex showed a significant reduction of parasite load compared to free PNT. Copyright © 2012 Elsevier B.V. All rights reserved.

Monitoring the performance of timber bridges over the long term

Treesearch

James P. Wacker; Marc R. Joyal; Joseph F. Murphy; Xiping Wang

2007-01-01

Timber bridges are often viewed by engineers as less durable than steel or concrete structures. However, they remain a durable and economical option along secondary roads in many rural areas of the country. With well over 75,000 bridges listed by the Federal Highway Administration’s National Bridge Inventory as having timber superstructures as of 2002, they represent...

Nondestructive assessment of single-span timber bridges using a vibration- based method

Treesearch

Xiping Wang; James P. Wacker; Angus M. Morison; John W. Forsman; John R. Erickson; Robert J. Ross

2005-01-01

This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship...

Estimating bridge stiffness using a forced-vibration technique for timber bridge health monitoring

Treesearch

James P. Wacker; Xiping Wang; Brian Brashaw; Robert J. Ross

2006-01-01

This paper describes an effort to refine a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the frequency response of several simple-span, sawn timber beam (with plank deck) bridges located in St. Louis County, Minnesota. Static load deflections were also measured to...

Novel Nanometric Superstructures for Radiation and Magnetic Sensing

DTIC Science & Technology

2007-05-22

AAO Anodic aluminum oxide AFM Atomic force microscope AFRL Air...Ni nanowires in a 2 µm AAO film after aluminum oxide was partially dissolved; (c) part of the Bi nanowires in a 25 µm AAO template after aluminum ...conditions [R3]. In this process, after removing the thick aluminum oxide film obtained from the first long anodization , the aluminum surface

An Oceanographic and Climatological Atlas of Bristol Bay

DTIC Science & Technology

1987-10-01

36 Forecasting Method ................................ 38 SUPERSTRUCTURE ICING.............................. 41 WIND...slicks and risk general advection of oil by large-scale ice move- analysis to coastal regions were computed. ment, and specific advection of oil by the...tide 1) Fetch wind (speed and direction) from tables or other sources. Forecast time of a surface map analysis of pressure highest range based on loss of

2. VIEW OF WASH TANKS Skins are brought in through ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW OF WASH TANKS Skins are brought in through hatches, seen on rear wall, and washed of blood and flesh in redwood tanks, with wooden grates to hold skins down in water. Superstructure and screening on tanks are a later alteration, unrelated to this process. - Sealing Plant, St. George Island, Pribilof Islands, Saint George, Aleutians West Census Area, AK

Influence of wind turbine foundation

NASA Technical Reports Server (NTRS)

Yee, S. T.

1978-01-01

The 200 kW Mod-0A wind turbine was modeled using a 3 lumped mass-spring system for the superstructure and a rotational spring for the foundation and supporting soil. Natural frequencies were calculated using soil elastic moduli varying from 3000 to 22,400 p.s.i. The reduction in natural frequencies from the rigid foundation case ranged up to 20 percent.

75 FR 3416 - Fisheries in the Western Pacific; Pelagic Fisheries; Vessel Identification Requirements

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-21

... other registration number) on the port and starboard sides of the deckhouse or hull, and on an...) to display its IRCS on the port and starboard sides of the hull or superstructure, and on a deck... port and starboard sides of the deckhouse or hull, and on an appropriate weather deck, so as to be...

Field performance of timber bridges. 11, Spearfish Creek stress-laminated box-beam bridge

Treesearch

J. P. Wacker; M. A. Ritter; K. Stanfill-McMillan

The Spearfish Creek bridge was constructed in 1992 in Spearfish, South Dakota. It is a single-span, stress-laminated, box-beam superstructure. Performance of the bridge is being monitored for 5 years, beginning at installation. This report summarizes results for the first 3-1/2 years of monitoring and includes information on the design, construction, and field...

Field performance of timber bridges. 15, Pueblo County, Colorado, stress-laminated deck bridge

Treesearch

L. E. Hislop

The Pueblo County 204B bridge was constructed in March 1990 in Pueblo, Colorado, as a demonstration bridge under the USDA Forest Service Timber Bridge Initiative. The stress-laminated deck superstructure is approximately 10 m long, 9 m wide, and 406 mm deep, with a skew of 10 degrees. Performance monitoring was conducted for 3 years, beginning at...

Designing timber bridge superstructures : a comparison of U.S. and Canadian bridge codes.

Treesearch

James Scott Groenier; James P. Wacker

2008-01-01

Several changes relating to timber bridges have been incorporated into the AASHTO-LRFD Bridge Design Specifications recently. In addition, the Federal Highway Administration is strongly encouraging an LRFD-based design approach for all new bridges in the United States. The Bridge Design Code in Canada was one of the first to adopt the limit states design philosophy,...

Light-Driven Chiral Molecular Motors for Passive Agile Filters

DTIC Science & Technology

2014-05-20

liquid crystal , we fabricated the self-organized, phototubable 3D photonic superstructure, i.e. photoresponsive monodisperse cholesteric liquid...systems for applications. Here the new light-driven chiral molecular switch and upconversion nanoparticles, doped in a liquid crystal media, were...the bottom-up nanofabrication of intelligent molecular devices. Light-driven chiral molecular switches or motors in liquid crystal (LC) media that

Field performance of timber bridges. 6, Hoffman Run stress-laminated deck bridge

Treesearch

M. A. Ritter; P. D. Hilbrich Lee; G. J. Porter

The Hoffman Run bridge, located just outside Dahoga, Pennsylvania, was constructed in October 1990. The bridge is a simple-span, single-lane, stress-laminated deck superstructure that is approximately 26 ft long and 16 ft wide. It is the second stress-laminated timber bridge to be constructed of hardwood lumber in Pennsylvania. The performance of the bridge was...

363. A.C.S., Delineator March 1934 STATE OF CALIFORNIA; DEPARTMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

363. A.C.S., Delineator March 1934 STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; CONTRACT NO. 6A; SUPERSTRUCTURE - WEST BAY CROSSING; SAN FRANCISCO ANCHORAGE; AMERICAN BRIDGE CO.; AMBRIDGE PLANT; ORDER NO. G4866; SHEET NO E3 - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

371. A.J.M. and D.L.S., Delineators April 1934. STATE OF CALIFORNIA; ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

371. A.J.M. and D.L.S., Delineators April 1934. STATE OF CALIFORNIA; DEPARTMENT OF PUBLIC WORKS; SAN FRANCISCO - OAKLAND BAY BRIDGE; SUPERSTRUCTURE - WEST BAY CROSSING; PIER NO. 4; VERTICAL SECTIONS; CONTRACT NO. 2; SUP. DRAWING NO. 17A - San Francisco Oakland Bay Bridge, Spanning San Francisco Bay, San Francisco, San Francisco County, CA

Nb2OsB2, with a new twofold superstructure of the U3Si2 type: Synthesis, crystal chemistry and chemical bonding

NASA Astrophysics Data System (ADS)

Mbarki, Mohammed; Touzani, Rachid St.; Fokwa, Boniface P. T.

2013-07-01

The new ternary metal-rich boride, Nb2OsB2, was synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. The compound was characterized from single-crystal X-ray data and EDX measurements. It crystallizes as a new superstructure (space group P4/mnc, no. 128) of the tetragonal U3Si2-structure type with lattice parameters a=5.922(1) Å and c=6.879(2) Å. All of the B atoms are involved in B2 dumbbells with B-B distances of 1.89(4) Å. Structure relaxation using VASP (Vienna ab intio Simulation Package) has confirmed the space group and the lattice parameters. According to electronic structure calculations (TB-LMTO-ASA), the homoatomic B-B interactions are optimized and very strong, but relatively strong heteroatomic Os-B, Nb-B and Nb-Os bonds are also found: These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of this new phase. The density of state at the Fermi level predicts metallic behavior, as expected, from this metal-rich boride.

Chemically stable Au nanorods as probes for sensitive surface enhanced scattering (SERS) analysis of blue BIC ballpoint pens

NASA Astrophysics Data System (ADS)

Alyami, Abeer; Saviello, Daniela; McAuliffe, Micheal A. P.; Cucciniello, Raffaele; Mirabile, Antonio; Proto, Antonio; Lewis, Liam; Iacopino, Daniela

2017-08-01

Au nanorods were used as an alternative to commonly used Ag nanoparticles as Surface Enhanced Raman Scattering (SERS) probes for identification of dye composition of blue BIC ballpoint pens. When used in combination with Thin Layer Chromatography (TLC), Au nanorod colloids allowed identification of the major dye components of the BIC pen ink, otherwise not identifiable by normal Raman spectroscopy. Thanks to their enhanced chemical stability compared to Ag colloids, Au nanorods provided stable and reproducible SERS signals and allowed easy identification of phthalocyanine and triarylene dyes in the pen ink mixture. These findings were supported by FTIR and MALDI analyses, also performed on the pen ink. Furthermore, the self-assembly of Au nanorods into large area ordered superstructures allowed identification of BIC pen traces. SERS spectra of good intensity and high reproducibility were obtained using Au nanorod vertical arrays, due to the high density of hot spots and morphological reproducibility of these superstructures. These results open the way to the employment of SERS for fast screening analysis and for quantitative analysis of pens and faded pens which are relevant for the fields of forensic and art conservation sciences.

Macro-retentive replaceable veneers on crowns and fixed dental prostheses: a new approach in implant-prosthodontics.

PubMed

Schweiger, Josef; Neumeier, Peter; Stimmelmayr, Michael; Beuer, Florian; Edelhoff, Daniel

2013-04-01

Implant-supported prosthetic restorations with veneered crowns and fixed dental prostheses are a proven, scientifically accepted treatment concept in fixed prosthodontics. However, in this area of indication there is a comparatively high technical complication rate, which occurs mainly in the area of the superstructure in the form of minor or major chipping of the veneering material. Various studies have shown that purely implant-supported restorations are subjected to higher loading than those on natural abutment teeth due to the special biomechanical conditions. A possible approach to prevent technical complications is to create higher stability for the implant superstructure through the use of high-strength materials. This would, however, result in undiminished overloading being transmitted to the implant components and could cause increased technical and biological complications. This article describes a new procedure for the use of replaceable veneers made from high-performance polymer material on modified implant abutments. By storing digital datasets for the veneer section, it can be replaced easily and quickly if it becomes worn or is fractured. A reduction in the stresses for the implant components and biological structures under the polymer is also to be expected due the material properties of polymers.