Synthesis and properties of hemicelluloses-based semi-IPN hydrogels.

Science.gov (United States)

Peng, Feng; Guan, Ying; Zhang, Bing; Bian, Jing; Ren, Jun-Li; Yao, Chun-Li; Sun, Run-Cang

2014-04-01

Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9 wt% sodium chloride solutions was up to 1085 g g(-1) and 87 g g(-1), respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization and swelling-deswelling properties of wheat straw cellulose based semi-IPNs hydrogel.

Science.gov (United States)

Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu

2014-07-17

A novel wheat straw cellulose-g-poly(potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was prepared by polymerizing wheat straw and an aqueous solution of acrylic acid (AA), and further semi-interpenetrating with PVA occurred during the chemosynthesis. The swelling and deswelling properties of WSC-g-PKA/PVA semi-IPNs hydrogel and WSC-g-PKA hydrogel were studied and compared in various pH solutions, salt solutions, temperatures, particle sizes and ionic strength. The results indicated that both hydrogels had the largest swelling capacity at pH=6, and the effect of ions on the swelling of hydrogels was in the order: Na(+)>K(+)>Mg(2+)>Ca(2+). The Schott's pseudo second order model can be effectively used to evaluate swelling kinetics of hydrogels. Moreover, the semi-IPNs hydrogel had improved swelling-deswelling properties compared with that of WSC-g-PKA hydrogel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Proton conducting semi-IPN based on Nafion and crosslinked poly(AMPS) for direct methanol fuel cell

International Nuclear Information System (INIS)

Cho, Ki-Yun; Jung, Ho-Young; Shin, Seung-Shik; Choi, Nam-Soon; Sung, Shi-Joon; Park, Jung-Ki; Choi, Jong-Ho; Park, Kyung-Won; Sung, Yung-Eun

2004-01-01

For direct methanol fuel cell, the proton conducting membrane based on semi-interpenetrating polymer networks (IPNs) of Nafion and crosslinked poly(AMPS) was prepared and characterized. The modification of Nafion with crosslinked poly(AMPS) such as hydrocarbon polymer changed the state of water in membranes. Without a significant increase of the membrane resistance, the semi-IPNs demonstrated a reduction of the methanol permeability, comparing to the native Nafion. And the maximum power density of AMPS60 increased as much as 22.2% compared with Nafion

Novel pH-sensitive IPNs of polyacrylamide-g-gum ghatti and sodium alginate for gastro-protective drug delivery.

Science.gov (United States)

Boppana, Rashmi; Krishna Mohan, G; Nayak, Usha; Mutalik, Srinivas; Sa, Biswanath; Kulkarni, Raghavendra V

2015-04-01

This article reports the development of pH-sensitive interpenetrating polymer network (IPN) microbeads using polyacrylamide-grafted-gum ghatti (PAAm-g-GG) and sodium alginate (SA) for gastro-protective controlled delivery of ketoprofen. We have synthesized PAAm-grafted-GG copolymer under microwave irradiation using cerric ammonium nitrate as reaction initiator; further, the PAAm-g-GG was converted to pH-sensitive copolymer through alkaline hydrolysis. Sophisticated instrumentation techniques were used to characterize PAAm-g-GG. The IPN microbeads of PAAm-g-GG and SA, pre-loaded with ketoprofen were prepared by dual crosslinking using Ca(2+) ions and glutaraldehyde (GA). The IPN microbeads demonstrated excellent pH-sensitive behavior as noted in the pulsatile swelling test and scanning electron microscopy. IPN microbeads also showed larger amount of drug release in buffer solution of pH 7.4 as compared to drug release in solution of pH 1.2. The in vivo pharmacokinetic, pharmacodynamic and stomach histopathology studies conducted on wistar rats confirmed the pH-sensitive controlled release of ketoprofen; IPN microbeads retarded the drug release in stomach resulting in reduced adverse effects of ketoprofen. Copyright © 2015 Elsevier B.V. All rights reserved.

Printing continuously graded interpenetrating polymer networks of acrylate/epoxy by manipulating cationic network formation during stereolithography

Directory of Open Access Journals (Sweden)

W. Li

2016-12-01

Full Text Available Ultra-violet (UV laser assisted stereolithography is used to print graded interpenetrating polymer networks (IPNs by controlling network formation. Unlike the traditional process where structural change in IPNs is achieved by varying the feeding ratio of monomers or polymer precursors, in this demonstration property is changed by controlled termination of network formation. A photo-initiated process is used to construct IPNs by a combination of radical and cationic network formation in an acrylate/epoxy system. The extent of the cationic network formation is used to control the final properties of the system. Rapid-Scan Fourier Transformation Infrared Spectroscopy (RS-FTIR is used to track the curing kinetics of the two networks and identify key parameters to control the final properties. Atomic force microscopy (AFM and differential scanning calorimetry (DSC confirm the formation of homogenous IPNs, whereas nano-indentation indicates that properties vary with the extent of cationic network formation. The curing characteristics are used to design and demonstrate printing of graded IPNs that show two orders of magnitude variation in mechanical properties in the millimeter scale.

IPNS-I chopper spectrometers

International Nuclear Information System (INIS)

Price, D.L.; Carpenter, J.M.; Pelizzari, C.A.; Sinha, S.K.; Bresof, I.; Ostrowski, G.E.

1982-01-01

We briefly describe the layout and operation of the two chopper experiments at IPNS-I. The recent measurement on solid 4 He by Hilleke et al. provides examples of time-of-flight data from the Low Resolution Chopper Spectrometer

SANS from interpenetrating polymer networks

International Nuclear Information System (INIS)

Markotsis, M.G.; Burford, R.P.; Knott, R.B.; Australian Nuclear Science and Technology Organisation, Menai, NSW; Hanley, T.L.; CRC for Polymers,; Australian Nuclear Science and Technology Organisation, Menai, NSW; Papamanuel, N.

2003-01-01

Full text: Interpenetrating polymer networks (IPNs) have been formed by combining two polymeric systems in order to gain enhanced material properties. IPNs are a combination of two or more polymers in network form with one network polymerised and/or crosslinked in the immediate presence of the other(s).1 IPNs allow better blending of two or more crosslinked networks. In this study two sets of IPNs were produced and their microstructure studied using a variety of techniques including small angle neutron scattering (SANS). The first system combined a glassy polymer (polystyrene) with an elastomeric polymer (SBS) with the glassy polymer predominating, to give a high impact plastic. The second set of IPNs contained epichlorohydrin (CO) and nitrile rubber (NBR), and was formed in order to produce novel materials with enhanced chemical and gas barrier properties. In both cases if the phase mixing is optimised the probability of controlled morphologies and synergistic behaviour is increased. The PS/SBS IPNs were prepared using sequential polymerisation. The primary SBS network was thermally crosslinked, then the polystyrene network was polymerised and crosslinked using gamma irradiation to avoid possible thermal degradation of the butadiene segment of the SBS. Tough transparent systems were produced with no apparent thermal degradation of the polybutadiene segments. The epichlorohydrin/nitrile rubber IPNs were formed by simultaneous thermal crosslinking reactions. The epichlorohydrin network was formed using lead based crosslinker, while the nitrile rubber was crosslinked by peroxide methods. The use of two different crosslinking systems was employed in order to achieve independent crosslinking thus resulting in an IPN with minimal grafting between the component networks. SANS, Transmission electron microscopy (TEM), and atomic force microscopy (AFM) were used to examine the size and shape of the phase domains and investigate any variation with crosslinking level and

Life test of DMFC using poly(ethylene glycol)bis(carboxymethyl)ether plasticized PVA/PAMPS proton-conducting semi-IPNs

Energy Technology Data Exchange (ETDEWEB)

Qiao, Jinli [National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Central 5, Tsukuba, Ibaraki 305-8565 (Japan); New Energy Technology Research Center, Tongji University, Shanghai 201804 (China); Ikesaka, Shinya; Saito, Morihiro; Kuwano, Jun [Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, 12-1 Ichigayafunagawara-machi, Shinjuku-ku, Tokyo 162-0826 (Japan); Okada, Tatsuhiro [National Institute of Advanced Industrial Science and Technology, Higashi 1-1-1, Central 5, Tsukuba, Ibaraki 305-8565 (Japan)

2007-08-15

A novel, low-cost proton-conducting semi-IPN (semi-interpenetrating polymer network) has been successfully prepared from PVA/PAMPS (poly(vinyl alcohol) and poly(2-acrylamindo-2-methyl-1-propanesulfonic acid))blends by incorporating poly(ethylene glycol)bis(carboxymethyl)ether (PEGBCME) as a novel plasticizer. Although, the polymer is based on a relatively low content of PAMPS as a component of ion conducting sites, the resulting semi-IPN exhibited high proton conductivity (0.1 S cm{sup -1}) at 25 C, which afforded a higher power density of 51 mW cm{sup -2} at 80 C. A striking feature is that a long-term initial performance is achieved with a 130 h of stable fuel cell operation in DMFC mode due to effectively suppressed methanol crossover. This is a new record for a fully hydrocarbon membrane in DMFC, seeing that the PVA-PAMPS proton-conducting semi-IPNs are made simply of aliphatic skeletons. (author)

Morfologia de hidrogéis-ipn termo-sensíveis e ph-responsivos para aplicação como biomaterial na cultura de células Morphology of temperature-sensitive and ph-responsive ipn-hydrogels for application as biomaterial for cell growth

Directory of Open Access Journals (Sweden)

Adley F. Rubira

2009-06-01

Full Text Available No presente trabalho, foram sintetizados hidrogéis com ambas as propriedades, termo-sensíveis e pH-responsivos, pela formação de redes de alginato de cálcio (alginato-Ca dentro de redes de poli(N-Isopropil Acrilamida (PNIPAAm, resultando em um sistema IPN (sistema de redes poliméricas interpenetradas. Através das análises por microscopia de varredura eletrônica (MEV e ensaios de intumescimento foi possível observar que os hidrogéis IPN exibiram forte contração quando aquecidos acima da LCST (temperatura critica inferior de solubilização da PNIPAAm, ou seja, acima de temperaturas de 30-35 ºC. Observou-se ainda que devido à contração do hidrogel, houve uma diminuição significativa nos tamanhos de poros os quais foram observados pelas micrografias. Observou-se também que no intervalo de pH estudado os hidrogéis de IPN sofreram significativa variação da estrutura com a variação desse parâmetro. Tal efeito foi atribuído à presença de grupos químicos carregados com alginato, os quais possuem carga elétrica negativa. Os resultados indicaram que o hidrogel formado por alginato-Ca e PNIPAAm possuíram características especificas após variação de pH e temperatura, e que tais características são derivadas dos compostos individuais envolvidos na síntese. Nesse caso, as propriedades de alginato-Ca e PNIPAAm livres foram preservadas dentro do hidrogel. Tal hidrogel ficou mais resistente à aplicação de uma tensão de compressão. Como conclusão, observou-se que os hidrogéis apresentaram morfologia característica para variações controladas de pH e temperatura, podendo ser eficientemente aplicados como biomaterial na cultura de células.In the present investigation, hydrogels with pH-responsive and temperature-sensitive properties were obtained by formation of alginate-Ca network inside the PNIPAAm network resulting in an interpenetrated network system (IPN. From scanning electron microscopy (SEM images and water

Intense Pulsed Neutron Source progress report for 1991

International Nuclear Information System (INIS)

1991-01-01

The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne's ZING-P and ZING-P' prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and ''in press'' articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications

Intense Pulsed Neutron Source progress report for 1991

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

The IPNS Progress Report 10th Anniversary Edition is being published in recognition of the first ten years of successful IPNS operation. To emphasize the significance of this milestone, we wanted this report to stand apart from the previous IPNS Progress Reports, and the best way to do this, we thought, was to make the design and organization of the report significantly different. In their articles, authors were asked to emphasize not only advances made since IPNS began operating but also the groundwork that was laid at its predecessor facilities - Argonne`s ZING-P and ZING-P` prototype pulsed neutron sources and CP-5 reactor. Each article stands as a separate chapter in the report, since each represents a particular instrument or class of instruments, system, technique, or area of research. In some cases, contributions were similar to review articles in scientific journals, complete with extensive lists of references. Ten-year cumulative lists of members of IPNS committees and of scientists who have visited or done experiments at IPNS were assembled. A list of published and ``in press`` articles in journals, books, and conference proceedings, resulting from work done at IPNS during the past ten years, was compiled. And archival photographs of people and activities during the ten-year history of IPNS were located and were used liberally throughout the report. The titles of the chapters in this report are: accelerator; computer; radiation effects; powder; stress; single crystal; superconductivity; amorphous; small angle; reflection; quasielastic; inelastic; inelastic magnetic; deep inelastic; user program; the future; and publications.

Thermal and Ablative Properties of Ipns and Composites of High Ortho Resole Resin and Difurfurylidene Acetone

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Tariq S. NAJIM

2008-12-01

Full Text Available High ortho resole resin was prepared by condensation of phenol with excess of formaldehyde in the presence of magnesium oxide as catalyst. Reaction of furfuraldehyde with acetone in basic medium led to difurfurylidene acetone (DFA. Their interpenetrating polymer network (IPNS were obtained by the reaction of predetermined quantities of difurfurylidene acetone and high ortho resole using p-toluene sulphonic acid (PTSA as curing agent. The thermal behavior of the resins was studied using thermogravimetry (TG under ambient and nitrogen atmospheres over a temperature range of (25-1000 Cº. It was observed that the IPN of 20% DFA – 80% resole has higher thermal stability than that of resole alone and the decomposition temperature was higher by 80 Cº. This behavior was attributed to highly cross linked structure and thermally stable backbone of ploy difurfurylidene acetone due to formation of ladder structure.Impregnation of chopped fiber glass type (E with the polymeric solutions was used to prepare their composites, and the ablative properties were investigated according to ASTM E-285 –80. It was observed that the IPN of (DFA- resol perform better than the resole composite alone.

Tailoring the mechanical properties by molecular integration of flexible and stiff polymer networks.

Science.gov (United States)

Wan, Haixiao; Shen, Jianxiang; Gao, Naishen; Liu, Jun; Gao, Yangyang; Zhang, Liqun

2018-03-28

Designing a multiple-network structure at the molecular level to tailor the mechanical properties of polymeric materials is of great scientific and technological importance. Through the coarse-grained molecular dynamics simulation, we successfully construct an interpenetrating polymer network (IPN) composed of a flexible polymer network and a stiff polymer network. First, we find that there is an optimal chain stiffness for a single network (SN) to achieve the best stress-strain behavior. Then we turn to study the mechanical behaviors of IPNs. The result shows that the stress-strain behaviors of the IPNs appreciably exceed the sum of that of the corresponding single flexible and stiff network, which highlights the advantage of the IPN structure. By systematically varying the stiffness of the stiff polymer network of the IPNs, optimal stiffness also exists to achieve the best performance. We attribute this to a much larger contribution of the non-bonded interaction energy. Last, the effect of the component concentration ratio is probed. With the increase of the concentration of the flexible network, the stress-strain behavior of the IPNs is gradually enhanced, while an optimized concentration (around 60% molar ration) of the stiff network occurs, which could result from the dominant role of the enthalpy rather than the entropy. In general, our work is expected to provide some guidelines to better tailor the mechanical properties of the IPNs made of a flexible network and a stiff network, by manipulating the stiffness of the stiff polymer network and the component concentration ratio.

STUDY ON THE SYNTHESIS AND STRUCTURE OF MACRORETICULAR BEAD PAN/PVC IPN RESINS

Institute of Scientific and Technical Information of China (English)

LI Yanfeng; ZHUO Renxi

1993-01-01

Macroreticular bead PAN/PVC IPN reans with cyano and chloro groups were synthesized by interpenetrating polymerization of acrylonitrile, or acrylonitrile and divinylbenzene into a macroporous polyvinyl chloride bead. The composition and structure of the bead IPN resins have been investigated by means of FT-IR, NMR, SEM, mercury porosimetry and elemental analysis. During the process of interpenetrating polymerization, the chain propagation obeys Bernoullian statistical law, and no grafting polymerization has been observed. The content of cyano group in the resulting IPN resins can be adjusted by the amount of acrylonitrile added. The morphology of the IPN resins basically resembles that of the polyvinyl chloride bead,whereas the pore structures vary to a certain degree

IPNS data acquisition system

International Nuclear Information System (INIS)

Worlton, T.G.; Crawford, R.K.; Haumann, J.R.; Daly, R.

1983-01-01

The IPNS Data Acquisition System (DAS) was designed to be reliable, flexible, and easy to use. It provides unique methods of acquiring Time-of-Flight neutron scattering data and allows collection, storage, display, and analysis of very large data arrays with a minimum of user input. Data can be collected from normal detectors, linear position-sensitive detectors, and/or area detectors. The data can be corrected for time-delays and can be time-focussed before being binned. Corrections to be made to the data and selection of inputs to be summed are entirely software controlled, as are the time ranges and resolutions for each detector element. Each system can be configured to collect data into millions of channels. Maximum continuous data rates are greater than 2000 counts/sec with full corrections, or 16,000 counts/sec for the simpler binning scheme used with area detectors. Live displays of the data may be made as a function of time, wavevector, wavelength, lattice spacing, or energy. In most cases the complete data analysis can be done on the DAS host computer. The IPNS DAS became operational for four neutron scattering instruments in 1981 and has since been expanded to seven instruments

International Production Networks: The Role of East Asia

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Marina Gamilovna Mazitova

2017-03-01

Full Text Available The authors propose a concept of international production integration which considers international production networks (IPNs as multi-dimensional structures with relational links and consisting of chains (goods, value creation, etc., characterized by linear connections. Formation and functioning of IPNs are subject to economies of scale and are well described by the theory of fragmentation. When analyzing the functioning of IPNs considerable attention needs to be devoted to the relative composition of trade flows they generate with respect to inter- and intra-industry trade. The authors classify production networks by their spatial scale into two types: regional and global. Then the researchers verify the hypothesis that the majority of East Asian IPNs are global. This hypothesis is confirmed using the analysis of foreign trade and investment flows. The analysis of foreign trade statistics of individual countries (China, Cambodia and Vietnam and certain industries (textiles, clothing and leather using the regional trade intensity index (RTII shows that the prevailing part of IPNs in mentioned countries as well as in selected sectors are global IPNs, that is, the hypothesis is fully confirmed. At the same time RTII dynamics demonstrates that a growing number of China's IPNs are turning towards the global type; on the contrary, a growing number of Cambodia's IPNs are transforming to the regional type; and there are two opposite trends in Vietnam: a growing number of IPNs in textiles, clothing and leather goods are tend towards the regional type but when considering the industry as a whole a growing number of IPNs are becoming global. The majority of East Asian IPNs in textiles, clothing and leather goods are global due to the fact that these networks are controlled by global brands (mainly of European and American origin

Carbohydrate polymer based pH-sensitive IPN microgels: Synthesis, characterization and drug release characteristics

Energy Technology Data Exchange (ETDEWEB)

Eswaramma, S. [Polymer Biomaterial Design and Synthesis Laboratory, Department of Chemistry, Yogi Vemana University, Kadapa, Andhra Pradesh, 516003 (India); Reddy, N. Sivagangi [Advanced Nanomaterials Lab, Department of Polymer Science and Engineering, Pusan National University, Busan, 46241 (Korea, Republic of); Rao, K.S.V. Krishna, E-mail: ksvkr@yogivemanauniversity.ac.in [Polymer Biomaterial Design and Synthesis Laboratory, Department of Chemistry, Yogi Vemana University, Kadapa, Andhra Pradesh, 516003 (India)

2017-07-01

pH-sensitive interpenetrating polymer network (IPN) microgels of chitosan (CS) and guargum-g-poly((2-dimethylamino)ethylmethacrylate) (GG-g-PDMAEMA) were developed by emulsion crosslinking method using glutaraldehyde as a crosslinker. In this regard, primarily guargum (GG) is grafted with (2-dimethylamino)ethylmethacrylate (DMAEMA) followed by blended with CS to prepare various microgel formulations. These microgels were treated as responsive drug carriers for an anticancer agent, 5-fluorouracil (5-FU). The maximum % encapsulation efficiency was found to be 81. Fourier transform infrared analysis was used to investigate the formation of graft copolymer (GG-g-PDMAEMA), chemical structure of microgels as well as the chemical interactions of drug molecules with the polymer matrix. The surface morphological studies and average particle size were examined by scanning electron microscopy. The average size of microgels is 130 ± 20 μm. Thermal behavior and molecular distribution of 5-FU within the polymer matrix were confirmed from thermogravimetric analysis and X-ray diffraction experiments. The pH-sensitive swelling behavior of IPN microgels was investigated in different pH solutions. To study the release profile of 5-FU, in vitro release profiles were performed in both pH 1.2 and 7.4. The release kinetics showed pH- dependent drug release and IPN microgels exhibited an excellent controlled release pattern for 5-FU over a period of more than 24 h. The release mechanism was analyzed by evaluating the release data using different empirical equations. - Highlights: • poly((2-dimethylamino)ethylmethacrylate) was grafted on to guargum backbone. • pH-responsive IPN microgels were developed from chitosan and graft copolymer. • Microgels were treated as responsive drug carriers for an anticancer agent, 5-fluorouracil. • Swelling and drug release studies were greatly dependent on pH.

Carbohydrate polymer based pH-sensitive IPN microgels: Synthesis, characterization and drug release characteristics

International Nuclear Information System (INIS)

Eswaramma, S.; Reddy, N. Sivagangi; Rao, K.S.V. Krishna

2017-01-01

pH-sensitive interpenetrating polymer network (IPN) microgels of chitosan (CS) and guargum-g-poly((2-dimethylamino)ethylmethacrylate) (GG-g-PDMAEMA) were developed by emulsion crosslinking method using glutaraldehyde as a crosslinker. In this regard, primarily guargum (GG) is grafted with (2-dimethylamino)ethylmethacrylate (DMAEMA) followed by blended with CS to prepare various microgel formulations. These microgels were treated as responsive drug carriers for an anticancer agent, 5-fluorouracil (5-FU). The maximum % encapsulation efficiency was found to be 81. Fourier transform infrared analysis was used to investigate the formation of graft copolymer (GG-g-PDMAEMA), chemical structure of microgels as well as the chemical interactions of drug molecules with the polymer matrix. The surface morphological studies and average particle size were examined by scanning electron microscopy. The average size of microgels is 130 ± 20 μm. Thermal behavior and molecular distribution of 5-FU within the polymer matrix were confirmed from thermogravimetric analysis and X-ray diffraction experiments. The pH-sensitive swelling behavior of IPN microgels was investigated in different pH solutions. To study the release profile of 5-FU, in vitro release profiles were performed in both pH 1.2 and 7.4. The release kinetics showed pH- dependent drug release and IPN microgels exhibited an excellent controlled release pattern for 5-FU over a period of more than 24 h. The release mechanism was analyzed by evaluating the release data using different empirical equations. - Highlights: • poly((2-dimethylamino)ethylmethacrylate) was grafted on to guargum backbone. • pH-responsive IPN microgels were developed from chitosan and graft copolymer. • Microgels were treated as responsive drug carriers for an anticancer agent, 5-fluorouracil. • Swelling and drug release studies were greatly dependent on pH.

Electroactive semi-interpenetrating polymer networks architecture with tunable IR reflectivity

Science.gov (United States)

Chevrot, C.; Teyssié, D.; Verge, P.; Goujon, L.; Tran-Van, F.; Vidal, F.; Aubert, P. H.; Peralta, S.; Sauques, L.

2011-04-01

A promising alternative of multi-layered devices showing electrochromic properties results from the design of a self-supported semi-interpenetrating polymer network (semi-IPN) including an electronic conductive polymer (ECP) formed within. The formation of the ECP in the network has already been described by oxidative polymerization using iron trichloride as an oxidant and leading to conducting semi-IPN with mixed electronic and ionic conductivities as well as convenient mechanical properties. This presentation relates to the elaboration of such semi-IPN using polyethyleneoxide (PEO) network or a PEO/NBR (Nitrile Butadiene Rubber) IPN in which a linear poly (3,4-ethylenedioxythiophene) (PEDOT) is formed symmetrically and selectively as very thin layers very next to the two main faces of the film matrix. PEO/PEDOT semi-IPNs lead to interesting optical reflective properties in the IR between 0.8 and 25 μm. Reflectance contrasts up to 35 % is observed when, after swelling in an ionic liquid, a low voltage is applied between the two main faces of the film. However the low flexibility and brittleness of the film and a slow degradation in air at temperature up from 60°C prompted to replace the PEO matrix by a flexible PEO/NBR IPN one. Indeed, the combination of NBR and PEO in an IPN leads to materials possessing flexible properties, good ionic conductivity at 25°C as well as a better resistance to thermal ageing. Finally, NBR/PEO/PEDOT semi-IPNs allow observing comparable reflectance contrast in the IR range than those shown by PEO/PEDOT semi-IPNs.

Synthesis and characterization of p and n dopable interpenetrating polymer networks for organic photovoltaic devices

International Nuclear Information System (INIS)

Lav, T.X.; Tran-Van, F.; Vidal, F.; Peralta, S.; Chevrot, C.; Teyssie, D.; Grazulevicius, J.V.; Getautis, V.; Derbal, H.; Nunzi, J.-M.

2008-01-01

Interpenetrating polymer networks (IPN) based on carbazole derivatives and diacrylate perylene are synthesized in two steps via an in-situ process. From a spin-coated thin film of a mixture of the two precursors, the diacrylate perylene is first photopolymerized to form a network in the presence of the carbazole derivative which is then electropolymerized to elaborate the IPN. Electrochemical characterizations show that the carbazole and perylene are electroactive inside the film which confirm the p and n dopable properties of the IPN. AFM images of the IPNs show a homogenous and smooth surface, compared to single network, which indicate a high quality of association of each network which should allow an efficient p/n bulk heterojunction

Synthesis and characterization of p and n dopable interpenetrating polymer networks for organic photovoltaic devices

Energy Technology Data Exchange (ETDEWEB)

Lav, T.X. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France); Tran-Van, F. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France)], E-mail: francois.tran-van@u-cergy.fr; Vidal, F.; Peralta, S.; Chevrot, C.; Teyssie, D. [Laboratoire de Physicochimie des Polymeres et des Interfaces, EA 2528 Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex (France); Grazulevicius, J.V.; Getautis, V. [Faculty of Chemical Technology, Kaunas University of Technology, Radvilenu Plentas 19, LT 50254 (Lithuania); Derbal, H.; Nunzi, J.-M. [PPF Cellules Solaires Photovoltaiques Plastiques - Laboratoire POMA, UMR-CNRS 6136, Universite d' Angers, 2 bd Lavoisier, 49045 Angers (France)

2008-08-30

Interpenetrating polymer networks (IPN) based on carbazole derivatives and diacrylate perylene are synthesized in two steps via an in-situ process. From a spin-coated thin film of a mixture of the two precursors, the diacrylate perylene is first photopolymerized to form a network in the presence of the carbazole derivative which is then electropolymerized to elaborate the IPN. Electrochemical characterizations show that the carbazole and perylene are electroactive inside the film which confirm the p and n dopable properties of the IPN. AFM images of the IPNs show a homogenous and smooth surface, compared to single network, which indicate a high quality of association of each network which should allow an efficient p/n bulk heterojunction.

Synthesis and Characterization of pH and Thermo Dual-Responsive Hydrogels with a Semi-IPN Structure Based on N-Isopropylacrylamide and Itaconamic Acid.

Science.gov (United States)

Rwei, Syang-Peng; Tuan, Huynh Nguyen Anh; Chiang, Whe-Yi; Way, Tun-Fun

2018-04-28

A series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated in this study. Linear copolymer poly( N -isopropylacrylamide-co-itaconamic acid) p(NIPAM-co-IAM), which is formed by copolymerization of N -isopropylacrylamide (NIPAM) and itaconamic acid (IAM, 4-amino-2-ethylene-4-oxobutanoic acid), was introduced into a solution of NIPAM to form a series of pH and thermo dual-responsive p(NIPAM-co-IAM)/pNIPAM semi-IPN hydrogels by free radical polymerization. The structural, morphological, chemical, and physical properties of the linear copolymer and semi-IPN hydrogels were investigated. The semi-IPN hydrogel showed high thermal stability according to thermal gravimetric analyzer (TGA). Scanning electronic microscopy (SEM) images showed that the pore size was in the range of 119~297 µm and could be controlled by the addition ratio of the linear copolymer in the semi-IPN structure. The addition of linear copolymer increased the fracture strain from 57.5 ± 2.9% to 91.1 ± 4.9% depending on the added amount, while the compressive modulus decreased as the addition increased. Moreover, the pH and thermo dual-responsive properties were investigated using differential scanning calorimetry (DSC) and monitoring the swelling behavior of the hydrogels. In deionized (DI) water, the equilibrium swelling ratio of the hydrogels decreased as the temperature increased from 20 °C to 50 °C, while it varied in various pH buffer solutions. In addition, the swelling and deswelling rates of the hydrogels also significantly increased. The results indicate that the novel pH-thermo dual-responsive semi-IPN hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application.

Sample-related peripheral equipment at IPNS

International Nuclear Information System (INIS)

Bohringer, D.E.; Crawford, R.K.

1985-01-01

This paper describes samples environment equipment provided by IPNS to visiting users and staff scientists. Of the twelve horizontal neutron beam stations, (ten now operational, two under construction) all use one or more form of such support equipment. An in-house support group devotes a significant fraction of its time to development, calibration, and maintenance of this equipment

Dose assessment of an accidental exposure at IPNS

International Nuclear Information System (INIS)

Torres, M.M.C.

1996-01-01

Seven different methods were used to estimate the dose rate to a female worker who was accidentally exposed in the neutron PHOENIX beamline at the IPNS. Theoretical and measured entrance dose rates ranged from 550 mrem/min to 2,850 mrem/min. Theoretical estimates were based on a Monte Carlo simulation of a spectrum provided by IPNS (Crawford Spectrum). Dose measurements were made with TLDs on phantoms and with ionization chambers in a water phantom. Estimates of the whole body total effective dose equivalent (TEDE) rate ranged from 5.2 mrem/min to 840 mrem/min. Assumed and measured quality factors ranged from 2.6 to 11.8. Cytogenic analyses of blood samples detected no positive exposure. The recommended TEDE rate was 158 mrem/min. The TEDE was 750 mrem

3rd Interplanetary Network Gamma-Ray Burst Website

Science.gov (United States)

Hurley, Kevin

1998-05-01

We announce the opening of the 3rd Interplanetary Network web site at http://ssl.berkeley.edu/ipn3/index.html This site presently has four parts: 1. A bibliography of over 3000 publications on gamma-ray bursts, 2. IPN data on all bursts triangulated up to February 1998, 3. A master list showing which spacecraft observed which bursts, 4. Preliminary IPN data on the latest bursts observed.

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2

International Nuclear Information System (INIS)

1996-01-01

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source's first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ''in press' articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1

International Nuclear Information System (INIS)

Marzec, B.

1996-01-01

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source's first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ''in press' articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 1

Energy Technology Data Exchange (ETDEWEB)

Marzec, B. [ed.

1996-05-01

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the authors have made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

Intense Pulsed Neutron Source: Progress report 1991--1996. 15. Anniversary edition -- Volume 2

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-05-01

The 15th Anniversary Edition of the IPNS Progress Report is being published in recognition of the Intense Pulsed Neutron Source`s first 15 years of successful operation as a user facility. To emphasize the importance of this milestone, the author shave made the design and organization of the report significantly different from previous IPNS Progress Reports. This report consists of two volumes. For Volume 1, authors were asked to prepare articles that highlighted recent scientific accomplishments at IPNS, from 1991 to present; to focus on and illustrate the scientific advances achieved through the unique capabilities of neutron studies performed by IPNS users; to report on specific activities or results from an instrument; or to focus on a body of work encompassing different neutron-scattering techniques. Articles were also included on the accelerator system, instrumentation, computing, target, and moderators. A list of published and ``in press` articles in journals, books, and conference proceedings, resulting from work done at IPNS since 1991, was compiled. This list is arranged alphabetically according to first author. Publication references in the articles are listed by last name of first author and year of publication. The IPNS experimental reports received since 1991 are compiled in Volume 2. Experimental reports referenced in the articles are listed by last name of first author, instrument designation, and experiment number.

Preparation and characterization of shape memory composite foams with interpenetrating polymer networks

International Nuclear Information System (INIS)

Yao, Yongtao; Zhou, Tianyang; Yang, Cheng; Leng, Jinsong; Liu, Yanju

2016-01-01

The present study reports a feasible approach of fabricating shape memory composite foams with an interpenetrating polymer network (IPN) based on polyurethane (PU) and shape memory epoxy resin (SMER) via a simultaneous polymerization technique. The PU component is capable of constructing a foam structure and the SMER is grafted on the PU network to offer its shape memory property in the final IPN foams. A series of IPN foams without phase separation were produced due to good compatibility and a tight chemical interaction between PU and SMER components. The relationships of the geometry of the foam cell were investigated via varying compositions of PU and SMER. The physical property and shape memory property were also evaluated. The stimulus temperature of IPN shape memory composite foams, glass temperature (T g ), could be tunable by varying the constituents and T g of PU and SMER. The mechanism of the shape memory effect of IPN foams has been proposed. The shape memory composite foam with IPN developed in this study has the potential to extend its application field. (paper)

Thermo-sensitive and swelling properties of cellouronic acid sodium/poly (acrylamide-co-diallyldimethylammonium chloride) semi-IPN.

Science.gov (United States)

Zhang, Heng; Gao, Xin; Chen, Keli; Li, Hui; Peng, Lincai

2018-02-01

In current study, cellouronic acid sodium (CAS), obtained from bagasse pith, has been introduced into poly(acrylamide-co-diallyldimethylammonium chloride) (poly(AM-co-DAC)) network to form novel thermo-sensitive semi-IPNs. The structure and morphology of the hydrogels were proved by Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effects of CAS content, initiator charge, cross-linker dosage and swelling-medium property on the thermo-responsive water absorptivity were investigated in detail. The results elucidated that the prepared gels exhibited a thermo-sensibility with an upper critical solution temperature (UCST) and a high water-absorbency. And the values of UCST and equilibrium swelling ratio largely depended on the inner structure of the semi-IPNs and the external solvent property. It was also revealed that the swelling process conformed to the Schott's pseudo second order model and diffusion type was non-Fickian diffusion. The value of activation energy for this polyelectrolyte was found to be 8.74kJ/mol. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dose assessment of an accidental exposure at the IPNS

International Nuclear Information System (INIS)

Campos Torres, M.M.

1995-02-01

Seven different methods were used to estimate the dose rate to a female worker who was accidentally exposed in the neutron PHOENIX beamline at the IPNS. Theoretical and measured entrance dose ranged from 550 mrem/min to 2850 mrem/min. Theoretical estimates were based on a Monte Carlo simulation of a spectrum provided by IPNS (Crawford Spectrum). Dose measurements were made with TLDs on phantoms and with ionization chambers in a water phantom. Estimates of the whole body total effective dose equivalent (TEDE) rate ranged from 5.2 mrem/min to 840 mrem/min. Assumed and measured quality factors ranged from 2.6 to 11.8. Cytogenetic analyses of blood samples detected no positive exposure. The recommended TEDE rate was 158 mrem/min. The TEDE was 750 mrem

Interpenetrating Polymer Networks as Innovative Drug Delivery Systems

Directory of Open Access Journals (Sweden)

Alka Lohani

2014-01-01

Full Text Available Polymers have always been valuable excipients in conventional dosage forms, also have shown excellent performance into the parenteral arena, and are now capable of offering advanced and sophisticated functions such as controlled drug release and drug targeting. Advances in polymer science have led to the development of several novel drug delivery systems. Interpenetrating polymer networks (IPNs have shown superior performances over the conventional individual polymers and, consequently, the ranges of applications have grown rapidly for such class of materials. The advanced properties of IPNs like swelling capacity, stability, biocompatibility, nontoxicity and biodegradability have attracted considerable attention in pharmaceutical field especially in delivering bioactive molecules to the target site. In the past few years various research reports on the IPN based delivery systems showed that these carriers have emerged as a novel carrier in controlled drug delivery. The present review encompasses IPNs, their types, method of synthesis, factors which affects the morphology of IPNs, extensively studied IPN based drug delivery systems, and some natural polymers widely used for IPNs.

IPN's of Acrylic Acid and N-Isopropylacrylamide by Gamma and Electron Beam Irradiation

International Nuclear Information System (INIS)

Burillo, G.

2006-01-01

In recent years, temperature and pH sensitive hydrogels have been investigated widely because of their unique properties and versatile applications in medicine and biotechnology, as well as drug delivery. However a serious limitation of hydrogels in many applications is the low mechanical strength of such gels when highly swollen. To overcome this problem, sensitive hydrogels were prepared with satisfactory mechanical properties as a semi-interpenetranting network, where one of them is a mechanically stable polymer. In this work temperature sensitive monomer N-isopropylacrylamide (NIPAAm) and a pH sensitive monomer, acrylic acid (AAc) were prepared as an interpenetranting network by a sequential method. Poly (AAc) hydrogels were prepared in glass tubes 3 mm inner diameter, at room temperature from an aqueous solutions 50%vol under argon atmosphere, and irradiated with a Co 6 0 gamma source, at doses from 5 to 30 kGy and dose rate of 3 kGy/h. Poly (AAc) hydrogels were also prepared by electron beam irradiation with a Van de Graaff at a dose rate of 19.4 kGy/min, and radiation doses from 10 to 30 kGy. After polymerization and crosslinking, the gels were washed in water during 48 h, and dried in vacuo to constant weight. Poly (NIPAAm) as secondary gel was synthetized directly within the primary gels in aqueous solution with the croslinker N, N' methylenebisacrylamide (BIS), the accelerator N,N,N , N tetramethyl ethylenediamidne TMEDA, and potasium persulfate as initiator. Equilibrium swelling properties of hydrogels were studied in pH 2.2-8 range and temperature 10-45degree; LCST and pH critic point of the IPN's were determined; the composition of the interpenetrating network was measured by elemental analysis, and the morphological structure characterized by SEM. The volume of the cells of PAAC hydrogels decreased with increase in radiation dose, their mechanic hardness increased and they lost elasticity. The interpenetrating networks of samples with PAAc irradiated

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

International Nuclear Information System (INIS)

Wang, Ming-Qiu; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-01-01

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via N-Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni–P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni–P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

Energy Technology Data Exchange (ETDEWEB)

Wang, Ming-Qiu, E-mail: mqwang1514@163.com; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-07-15

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via N-Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni–P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni–P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Electroless plating of PVC plastic through new surface modification method applying a semi-IPN hydrogel film

Science.gov (United States)

Wang, Ming-Qiu; Yan, Jun; Du, Shi-Guo; Li, Hong-Guang

2013-07-01

A novel palladium-free surface activation process for electroless nickel plating was developed. This method applied a semi-Interpenetrating Polymer Network (semi-IPN) hydrogel film to modify the poly(vinyl chloride) (PVC) surface by chemical bonds. The activation process involved the formation of semi-IPN hydrogel film on the PVC surface and the immobilization of catalyst for electroless plating linking to the pretreated substrate via Nsbnd Ni chemical bond. The hydrogel layer was used as the chemisorption sites for nickel ions, and the catalyst could initiate the subsequent electroless nickel plating onto the PVC surface. Finally, a Ni-P layer was deposited on the nickel-activated PVC substrate by electroless plating technique. The composition and morphology of nickel-plated PVC foils were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results of SEM and XRD show that a compact and continuous Ni-P layer with amorphous nickel phase is formed on the PVC surface. EDS shows that the content of the nickel and the phosphorus in the deposits is 89.4 wt.% and 10.6 wt.%, respectively.

Evaluation of Fibrin-Based Interpenetrating Polymer Networks as Potential Biomaterials for Tissue Engineering

Directory of Open Access Journals (Sweden)

Olfat Gsib

2017-12-01

Full Text Available Interpenetrating polymer networks (IPNs have gained great attention for a number of biomedical applications due to their improved properties compared to individual components alone. In this study, we investigated the capacity of newly-developed naturally-derived IPNs as potential biomaterials for tissue engineering. These IPNs combine the biologic properties of a fibrous fibrin network polymerized at the nanoscale and the mechanical stability of polyethylene oxide (PEO. First, we assessed their cytotoxicity in vitro on L929 fibroblasts. We further evaluated their biocompatibility ex vivo with a chick embryo organotypic culture model. Subcutaneous implantations of the matrices were subsequently conducted on nude mice to investigate their biocompatibility in vivo. Our preliminary data highlighted that our biomaterials were non-cytotoxic (viability above 90%. The organotypic culture showed that the IPN matrices induced higher cell adhesion (across all the explanted organ tissues and migration (skin, intestine than the control groups, suggesting the advantages of using a biomimetic, yet mechanically-reinforced IPN-based matrix. We observed no major inflammatory response up to 12 weeks post implantation. All together, these data suggest that these fibrin-based IPNs are promising biomaterials for tissue engineering.

Predicting the catalytic sites of isopenicillin N synthase (IPNS ...

African Journals Online (AJOL)

Isopenicillin N synthase (IPNS) related Non-haem iron-dependent oxygenases and oxidases (NHIDOX) demonstrated a striking structural conservativeness, even with low protein sequence homology. It is evident that these enzymes have an architecturally similar catalytic centre with active ligands lining the reactive pocket.

Interpenetrating networks of two conducting polymers

DEFF Research Database (Denmark)

Winther-Jensen, Bjørn; West, Keld

2005-01-01

Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings, and beca......Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings......, and because its reaction products can be removed efficiently after the formation of the composite. Several combinations of polymers are demonstrated, and the versatility of the proposed method allows extensions to a wide range of conjugated polymers. The IPNs show optical and electrochemical characteristics......, which are sums of the characteristics from the participating conducting polymers....

IPNS distributed-processing data-acquisition system

International Nuclear Information System (INIS)

Haumann, J.R.; Daly, R.T.; Worlton, T.G.; Crawford, R.K.

1981-01-01

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a major new user-oriented facility which has come on line for basic research in neutron scattering and neutron radiation damage. This paper describes the distributed-processing data-acquisition system which handles data collection and instrument control for the time-of-flight neutron-scattering instruments. The topics covered include the overall system configuration, each of the computer subsystems, communication protocols linking each computer subsystem, and an overview of the software which has been developed

Evaluation of structural integrity of IPNS-I and ZING-P' targets

International Nuclear Information System (INIS)

Carpenter, J.; Ahmed, H.; Loomis, B.; Ball, J.; Ewing, T.; Bailey, J.; D'Souza, A.F.

1982-12-01

This report discusses the design, production, and evaluation of clad uranium-alloy targets that function as spallation neutron sources in the ZING-P' and IPNS-I facilities with a pulsed (10 to 30 Hz), 500-MeV proton beam. The methodology and results of theoretical nuclear-particle transport, heat transport, and stress analyses that were used in the development of a design for the targets are described. The production of a zirconium-clad uranium-alloy cylinder for ZING-P' and Zircaloy-2-clad uranium-alloy discs for IPNS-I is discussed with particular attention to the procedural details. The theoretical analyses were verified by measuring the thermal and mechanical response of the clad uranium under conditions designed to simulate the operations of the pulsed-neutron sources

Channeling experiments at IPNE Cyclotron

Energy Technology Data Exchange (ETDEWEB)

Constantin, F; Dumitru, M; Ivan, A [Cyclotron Laboratory, Institute of Atomic Physics, Institute of Physics and Nuclear Engineering, R-76900 Bucharest, P.O.Box MG-6, (Romania)

1992-01-01

Channeling experiments have been performed at the I.P.N.E Cyclotron using a 3 MeV alpha beam. A slide system cut the beam up to 5 minutes spatial resolution with a maximum 60 nA beam current on the target. The two-axis goniometer, fully computer-controlled, moves the target, a silicon wafer, with 2.5 minute resolution, while an alpha particle sensitive solid state detector, monitors the backscattered particle fluence. In the first stage, channeling appears to be a simple, fast and reliable method for precise monocrystal orientation. A reduction of the host yield by a factor of two allowed impurities and defects to be studied. (Author).

IPN and AFI collaboration balance. The SIS source (Crysis)

International Nuclear Information System (INIS)

Goldstein, C.

1985-01-01

The fabrication and development of a source with confined electron beam (EBIS) is the result of a collaboration between IPN (Institut de Physique Nucleaire) and AFI (Forskningstitutet for Atom-fysik) First tests have confirmed the good operation of the whole elements. A critical balance is made, and conclusions are drawn [fr

A 3D Porous Gelatin-Alginate-Based-IPN Acts as an Efficient Promoter of Chondrogenesis from Human Adipose-Derived Stem Cells

OpenAIRE

Dinescu, Sorina; Galateanu, Bianca; Radu, Eugen; Hermenean, Anca; Lungu, Adriana; Stancu, Izabela Cristina; Jianu, Dana; Tumbar, Tudorita; Costache, Marieta

2015-01-01

Cartilage has limited regeneration potential. Thus, there is an imperative need to develop new strategies for cartilage tissue engineering (CTE) amenable for clinical use. Recent CTE approaches rely on optimal cell-scaffold interactions, which require a great deal of optimization. In this study we attempt to build a novel gelatin- (G-) alginate- (A-) polyacrylamide (PAA) 3D interpenetrating network (IPN) with superior performance in promoting chondrogenesis from human adipose-derived stem cel...

Rules of origin and development of regional production network in ...

International Development Research Centre (IDRC) Digital Library (Canada)

Simpler Rules of Origin (RoO) with product specific rules can act as a catalyst in trade even if tariff rates are not low. Sector specific restrictiveness across trade agreements are assessed, in view of potential growth of International production networks (IPN). RoO is shown to play a significant role in promoting IPN.

Studies of neutron irradiation effects at IPNS-REF

International Nuclear Information System (INIS)

Kirk, M.A.

1983-09-01

Neutron irradiation effects studies at the Radiation Effects Facility (REF) at the Intense Pulsed Neutron Source (IPNS) located at Argonne National Laboratory (ANL) are reviewed. A brief history of the development of this user facility is followed by an overview of the scientific program. Experiments unique to a spallation neutron source are covered in more detail. Future direction of research at this facility is suggested

Soft hydrogels interpenetrating silicone – a polymer network for drug releasing medical devices

DEFF Research Database (Denmark)

Steffensen, Søren Langer; Merete H., Vestergaard,; Møller, Eva Horn

2016-01-01

such a sophisticated material by forming an interpenetrating polymer network (IPN) material through modification of silicone elastomers with a poly(2-hydroxyethyl methacrylate) (PHEMA)-based hydrogel. IPN materials with a PHEMA content in the range of 13%–38% (w/w) were synthesized by using carbon dioxide...

The Electroluminescence Mechanism of Solution-Processed TADF Emitter 4CzIPN Doped OLEDs Investigated by Transient Measurements

Directory of Open Access Journals (Sweden)

Peng Wang

2016-10-01

Full Text Available High efficiency, solution-processed, organic light emitting devices (OLEDs, using a thermally-activated delayed fluorescent (TADF emitter, 1,2,3,5-tetrakis(carbazol-9-yl-4,6-dicyanobenzene (4CzIPN, are fabricated, and the transient electroluminescence (EL decay of the device with a structure of [ITO/PEDOT: PSS/4CzIPN 5 wt % doped 4,40-N,N0-dicarbazolylbiphenyl(CBP/bis-4,6-(3,5-di-4-pyridylphenyl-2-methylpyrimidine (B4PyMPM/lithium fluoride (LiF/Al], is systematically studied. The results shed light on the dominant operating mechanism in TADF-based OLEDs. Electroluminescence in the host–guest system is mainly produced from the 4CzIPN emitter, rather than the exciplex host materials.

Interpenetrated polymer networks based on commercial silicone elastomers and ionic networks with high dielectric permittivity and self-healing properties

DEFF Research Database (Denmark)

Ogliani, Elisa; Yu, Liyun; Skov, Anne Ladegaard

the applicability. One method used to avoid this limitation is to increase the dielectric permittivity of the material in order to improve the actuation response at a given field. Recently, interpenetrating polymer networks (IPNs) based on covalently cross-linked commercial silicone elastomers and ionic networks...... from amino- and carboxylic acid- functional silicones have been designed[2] (Figure 1). This novel system provides both the mechanical stability and the high breakdown strength given by the silicone part of the IPNs and the high permittivity and the softening effect of the ionic network. Thus......,1 Hz), and the commercial elastomers RT625 and LR3043/30 provide thebest viscoelastic properties to the systems, since they maintain low viscous losses upon addition of ionic network. The values ofthe breakdown strength in all cases remain higher than that of the reference pure PDMS network (ranging...

UV-radiation curing of simultaneous interpenetrating polymer network hydrogels for enhanced heavy metal ion removal

International Nuclear Information System (INIS)

Wang, Jingjing; Liu, Fang

2012-01-01

Highlights: ► Simultaneous IPN hydrogels were prepared by hybrid photopolymerization of AM and DVE-3. ► The synergistic complexation was found in the adsorption studies. ► The simultaneous IPN hydrogels could be used as fast-responsive and renewable sorbent materials. - Abstract: Simultaneous interpenetrating polymer network (IPN) hydrogels have been prepared by UV-initiated polymerization of a mixture of acrylamide (AM) and triethylene glycol divinyl ether (DVE-3). The consumption of each monomer upon UV-irradiation was monitored in situ by real-time infrared (RTIR) spectroscopy. The acrylamide monomer AM was shown to polymerize faster and more extensively than the vinyl ether monomer DVE-3, which was further consumed upon storage of the sample in the dark, due to the living character of the cationic polymerization. The IPN hydrogels were used to remove heavy metal ions from aqueous solution under the non-competitive condition. The effects of pH values of the feed solution and the DVE-3 content in the formulation on the adsorption capacity were investigated. The results indicated that the adsorption capacity of the IPN hydrogels increased with the pH values and DVE-3 content in the formulation. Furthermore, the synergistic complexation of metal ions with two polymer networks in the IPN was found in the adsorption studies. Adsorption kinetics and regeneration studies suggested that the IPN hydrogels could be used as fast-responsive and renewable sorbent materials in heavy metal removing processes.

Dielectric elastomers, with very high dielectric permittivity, based on silicone and ionic interpenetrating networks

DEFF Research Database (Denmark)

Yu, Liyun; Madsen, Frederikke Bahrt; Hvilsted, Søren

2015-01-01

permittivity and the Young's modulus of the elastomer. One system that potentially achieves this involves interpenetrating polymer networks (IPNs), based on commercial silicone elastomers and ionic networks from amino- and carboxylic acid-functional silicones. The applicability of these materials as DEs...... are obtained while dielectric breakdown strength and Young's modulus are not compromised. These good overall properties stem from the softening effect and very high permittivity of ionic networks – as high as ε′ = 7500 at 0.1 Hz – while the silicone elastomer part of the IPN provides mechanical integrity...

Tuning mechanical performance of poly(ethylene glycol) and agarose interpenetrating network hydrogels for cartilage tissue engineering.

Science.gov (United States)

Rennerfeldt, Deena A; Renth, Amanda N; Talata, Zsolt; Gehrke, Stevin H; Detamore, Michael S

2013-11-01

Hydrogels are attractive for tissue engineering applications due to their incredible versatility, but they can be limited in cartilage tissue engineering applications due to inadequate mechanical performance. In an effort to address this limitation, our team previously reported the drastic improvement in the mechanical performance of interpenetrating networks (IPNs) of poly(ethylene glycol) diacrylate (PEG-DA) and agarose relative to pure PEG-DA and agarose networks. The goal of the current study was specifically to determine the relative importance of PEG-DA concentration, agarose concentration, and PEG-DA molecular weight in controlling mechanical performance, swelling characteristics, and network parameters. IPNs consistently had compressive and shear moduli greater than the additive sum of either single network when compared to pure PEG-DA gels with a similar PEG-DA content. IPNs withstood a maximum stress of up to 4.0 MPa in unconfined compression, with increased PEG-DA molecular weight being the greatest contributing factor to improved failure properties. However, aside from failure properties, PEG-DA concentration was the most influential factor for the large majority of properties. Increasing the agarose and PEG-DA concentrations as well as the PEG-DA molecular weight of agarose/PEG-DA IPNs and pure PEG-DA gels improved moduli and maximum stresses by as much as an order of magnitude or greater compared to pure PEG-DA gels in our previous studies. Although the viability of encapsulated chondrocytes was not significantly affected by IPN formulation, glycosaminoglycan (GAG) content was significantly influenced, with a 12-fold increase over a three-week period in gels with a lower PEG-DA concentration. These results suggest that mechanical performance of IPNs may be tuned with partial but not complete independence from biological performance of encapsulated cells. © 2013 Elsevier Ltd. All rights reserved.

Evaluation of structural integrity of IPNS-I and ZING-P' targets

Energy Technology Data Exchange (ETDEWEB)

Carpenter, J.; Ahmed, H.; Loomis, B.; Ball, J.; Ewing, T.; Bailey, J.; D' Souza, A.F.

1982-12-01

This report discusses the design, production, and evaluation of clad uranium-alloy targets that function as spallation neutron sources in the ZING-P' and IPNS-I facilities with a pulsed (10 to 30 Hz), 500-MeV proton beam. The methodology and results of theoretical nuclear-particle transport, heat transport, and stress analyses that were used in the development of a design for the targets are described. The production of a zirconium-clad uranium-alloy cylinder for ZING-P' and Zircaloy-2-clad uranium-alloy discs for IPNS-I is discussed with particular attention to the procedural details. The theoretical analyses were verified by measuring the thermal and mechanical response of the clad uranium under conditions designed to simulate the operations of the pulsed-neutron sources.

Glass transition temperatures of microphase separated semi-interpenetrating polymer networks of polystyrene-inter-poly(cross)-2-ethylhexyl-methacrylate

NARCIS (Netherlands)

de Graaf, L.A.; de Graaf, Leontine A.; Möller, Martin; Moller, M.

1995-01-01

The glass transition temperature of semi-interpenetrating polymer networks (semi-IPNs) of atactic polystyrene (PS) in crosslinked methacrylates was studied by systematic variation of the morphology, that is domain size, continuity and concentration in the domains. Semi-IPNs were prepared from

3D printing of an interpenetrating network hydrogel material with tunable viscoelastic properties.

Science.gov (United States)

Bootsma, Katherine; Fitzgerald, Martha M; Free, Brandon; Dimbath, Elizabeth; Conjerti, Joe; Reese, Greg; Konkolewicz, Dominik; Berberich, Jason A; Sparks, Jessica L

2017-06-01

Interpenetrating network (IPN) hydrogel materials are recognized for their unique mechanical properties. While IPN elasticity and toughness properties have been explored in previous studies, the factors that impact the time-dependent stress relaxation behavior of IPN materials are not well understood. Time-dependent (i.e. viscoelastic) mechanical behavior is a critical design parameter in the development of materials for a variety of applications, such as medical simulation devices, flexible substrate materials, cellular mechanobiology substrates, or regenerative medicine applications. This study reports a novel technique for 3D printing alginate-polyacrylamide IPN gels with tunable elastic and viscoelastic properties. The viscoelastic stress relaxation behavior of the 3D printed alginate-polyacrylamide IPN hydrogels was influenced most strongly by varying the concentration of the acrylamide cross-linker (MBAA), while the elastic modulus was affected most by varying the concentration of total monomer material. The material properties of our 3D printed IPN constructs were consistent with those reported in the biomechanics literature for soft tissues such as skeletal muscle, cardiac muscle, skin and subcutaneous tissue. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preparation and Properties of a Novel Semi-IPN Slow-Release Fertilizer with the Function of Water Retention.

Science.gov (United States)

Xiang, Yang; Ru, Xudong; Shi, Jinguo; Song, Jiang; Zhao, Haidong; Liu, Yaqing; Guo, Dongdong; Lu, Xin

2017-12-20

A new semi-interpenetrating polymer network (semi-IPN) slow-release fertilizer (SISRF) with water absorbency, based on the kaolin-g-poly(acrylic acid-co-acrylic amide) (kaolin-g-P(AA-co-AM)) network and linear urea-formaldehyde oligomers (UF), was prepared by solution polymerization. Nutrients phosphorus and potassium were supplied by adding dipotassium hydrogen phosphate during the preparation process. The structure and properties of SISRF were characterized by various characterization methods. SISRF showed excellent water absorbency of 68 g g -1 in tap water. The slow-release behavior of nutrients and water-retention capacity of SISRF were also measured. Meanwhile, the swelling kinetics was well described by a pseudo-second-order kinetics model. Results suggested the formation of SISRF with simultaneously good slow-release and water-retention capacity, which was expected to apply in modern agriculture and horticulture.

IPNS grooved, solid methane moderator

International Nuclear Information System (INIS)

Carpenter, J.M.; Schulke, A.W.; Scott, T.L.; Wozniak, D.G.; Benson, B.E.; Leyda, B.D.

1985-01-01

There are two motives for using cold moderators in pulsed neutron sources, to provide higher fluxes of long-wavelength neutrons, and to extend the epithermal range with its short pulse structure to lower energies. For both these purposes solid methane, operated at the lowest possible temperatures, is the best material we know of. Two problems accompany the use of solid methane in high power sources, namely heat transport in view of the low thermal conductivity of solid methane, and deterioration due to radiation damage. We have designed a system suitable to operate in IPNS, subject to nuclear heating of about 25 W, which incorporates an aluminum foam matrix to conduct the heat from within the moderator. We report the results of the first few months' operation and of a few tests that we have performed

Effective connectivity gateways to the Theory of Mind network in processing communicative intention.

Science.gov (United States)

Tettamanti, Marco; Vaghi, Matilde M; Bara, Bruno G; Cappa, Stefano F; Enrici, Ivan; Adenzato, Mauro

2017-07-15

An Intention Processing Network (IPN), involving the medial prefrontal cortex, precuneus, bilateral posterior superior temporal sulcus, and temporoparietal junctions, plays a fundamental role in comprehending intentions underlying action goals. In a previous fMRI study, we showed that, depending on the linguistic or extralinguistic (gestural) modality used to convey the intention, the IPN is complemented by activation of additional brain areas, reflecting distinct modality-specific input gateways to the IPN. These areas involve, for the linguistic modality, the left inferior frontal gyrus (LIFG), and for the extralinguistic modality, the right inferior frontal gyrus (RIFG). Here, we tested the modality-specific gateway hypothesis, by using DCM to measure inter-regional functional integration dynamics between the IPN and LIFG/RIFG gateways. We found strong evidence of a well-defined effective connectivity architecture mediating the functional integration between the IPN and the inferior frontal cortices. The connectivity dynamics indicate a modality-specific propagation of stimulus information from LIFG to IPN for the linguistic modality, and from RIFG to IPN for the extralinguistic modality. Thus, we suggest a functional model in which the modality-specific gateways mediate the structural and semantic decoding of the stimuli, and allow for the modality-specific communicative information to be integrated in Theory of Mind inferences elaborated through the IPN. Copyright © 2017 Elsevier Inc. All rights reserved.

Evaluating the mechanical properties of E-Glass fiber/carbon fiber reinforced interpenetrating polymer networks

Directory of Open Access Journals (Sweden)

G. Suresh

2015-02-01

Full Text Available A series of vinyl ester and polyurethane interpenetrating polymer networks were prepared by changing the component ratios of VER (Vinyl ester and PU (Polyurethane and the polymerization process was confirmed with Fourier Transform infrared spectroscopy. IPN (Inter Penetrating Polymer Network - VER/PU reinforced Glass and carbon fiber composite laminates were made using the Hand lay up technique. The Mechanical properties of the E-glass and carbon fiber specimens were compared from tests including Tensile, Compressive, Flexural, ILSS (Inter Laminar Shear Strength, Impact & Head Deflection Test (HDT. The IPN Reinforced Carbon fiber specimen showed better results in all the tests than E-Glass fibre reinforced IPN laminate with same thickness of the specimen, according to ASTM standards. It was found that the combination of 60%VER and 40%PU IPN exhibits better impact strength and maximum elongation at break, but at the slight expense of mechanical properties such as tensile, compressive, flexural, ILSS properties. The morphology of the unreinforced and reinforced composites was analyzed with help of scanning electron microscopy.

The Interplanetary Network Supplement to the Fermi GBM Catalog - An AO-2 and AO-3 Guest Investigator Project

Science.gov (United States)

Hurley, K.; Briggs, M.; Connaughton, V.; Meegan, C.; von Kienlin, A.; Rau, A.; Zhang, X.; Golenetskii, S.; Aptekar, R.; Mazets, E.;

New instruments at IPNS: POSY II and SAD II

International Nuclear Information System (INIS)

Crawford, R.K.; Felcher, G.P.; Kleb, R.; Epperson, J.E.; Thiyagarajan, P.

1988-01-01

Three new instruments are currently in varying degrees of development/construction at IPNS. One of these, the Glass, Liquid, and Amorphous Materials Diffractometer (GLAD) is the subject of a separate paper in these Proceedings, and so will not be discussed further here. The other two, a second neutron reflectometer (POSY II) and a second small-angle diffractometer (SAD II) are described briefly below. 5 refs., 1 fig., 1 tab

Interpenetrating polymer networks based on polyol modified castor ...

Indian Academy of Sciences (India)

Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC–PU) and poly[2-hydroxyethylmethacrylate] (PHEMA) were synthesized using benzoyl peroxide as initiator and N,N-methylene bis acrylamide as crosslinker. GC–PU/PHEMA interpenetrating polymer networks were obtained by ...

Segmental dynamics in poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks: structural relaxation experiments

International Nuclear Information System (INIS)

Ribelles, J L Gomez; Duenas, J M Meseguer; Cabanilles, C Torregrosa; Pradas, M Monleon

2003-01-01

The miscibility of poly(methyl acrylate)-poly(methyl methacrylate) sequential interpenetrating polymer networks (IPNs) has been studied by probing the conformational mobility of the component polymer chains. These IPNs exhibit the phenomenon of forced compatibilization. In a conventional heating differential scanning calorimetry (DSC) thermogram, the highly cross-linked IPN shows a single glass transition which covers a temperature interval of around 100 d eg C; in contrast, loosely cross-linked IPNs show two glass transitions. The conformational mobility in these IPNs is studied by subjecting them to isothermal annealings at temperatures in the region of the glass transition and below it. The DSC scans measured after these treatments allow one to determine the temperature interval in which the sample is out of thermodynamic equilibrium but keeps enough conformational mobility to relax during the isothermal annealing in such a way that the enthalpy loss is measurable with the sensitivity of a conventional DSC. The results allow one to reach some conclusions about the compositional distribution of the IPN on the nanometre scale

Interpenetrating polymer networks from acetylene terminated materials

Science.gov (United States)

Connell, J. W.; Hergenrother, P. M.

1989-01-01

As part of a program to develop high temperature/high performance structural resins for aerospace applications, the chemistry and properties of a novel class of interpenetrating polymer networks (IPNs) were investigated. These IPNs consist of a simple diacetylenic compound (aspartimide) blended with an acetylene terminated arylene ether oligomer. Various compositional blends were prepared and thermally cured to evaluate the effect of crosslink density on resin properties. The cured IPNs exhibited glass transition temperatures ranging from 197 to 254 C depending upon the composition and cure temperature. The solvent resistance, fracture toughness and coefficient of thermal expansion of the cured blends were related to the crosslink density. Isothermal aging of neat resin moldings, adhesive and composite specimens showed a postcure effect which resulted in improved elevated temperature properties. The chemistry, physical and mechanical properties of these materials will be discussed.

IPNS time-of-flight single crystal diffractometer

International Nuclear Information System (INIS)

Schultz, A.J.; Teller, R.G.; Williams, J.M.

1983-01-01

The single crystal diffractometer (SCD) at the Argonne Intense Pulsed Neutron Source (IPNS) utilizes the time-of-flight (TOF) Laue technique to provide a three-dimensional sampling of reciprocal space during each pulse. The instrument contains a unique neutron position-sensitive 6 Li-glass scintillation detector with an active area of 30 x 30 cm. The three-dimensional nature of the data is very useful for fast, efficient measurement of Bragg intensities and for the studies of superlattice and diffuse scattering. The instrument was designed to achieve a resolution of 2% or better (R = δQ/Q) with 2 THETA > 60 0 and lambda > 0.7A

Thermoplastic elastomer IPNs using radiation methods

International Nuclear Information System (INIS)

Burford, R.P.; Shirodkar, B.D.

2000-01-01

Full text: Styrene swollen, cross-linked TPEs can be thermally processed to give a new class of sequential interpenetrating polymer network (IPN). There are however certain limitations with this procedure, particularly in relation to the thermally initiated polymerization, including: the microscopic texture of the original TPE may be modified, the butadiene component of the TPE may thermally oxidize, safety concerns with monomer vapors at elevated temperatures exist; the concentration of monomer in the swollen TPE may change and be uneven. The method cannot be readily extended to the use of a volatile second monomer, such as butadiene or isoprene. Gamma radiation crosslinking allows uniform penetration and ambient temperatures. We used the multifunctional cross-linker, TMPTA, as this has been shown to work well under these conditions with styrene. Peroxide cross-linked Solprene 475 was swollen in inhibitor-free styrene containing 0, 10 and 33% by weight TMPTA and irradiated at 3 kGy/hr for total doses ranging typically from 50 to 1000 kGy. Hardnesses (Durometer Shore D) increased from 50 to plateau at about 65 units, and tensile strengths are ∼ 10-15 MPa. Initial data indicates breaking strains in the range 20 to 90%. A key observation is that the products were of uniform hardness and appearance, in contrast to many of the thermally prepared materials in the past, which also showed yellowing due to polybutadiene oxidation. Products were stained with osmium tetroxide, ultramicrotomed and observed by TEM. The morphologies of the new materials are more uniform than before, with less evidence of orientation. The previous structures were typically of swollen styrene rich rods in a butadiene matrix, whereas here the TEMs reveal a spongelike texture

Physical properties of a high molecular weight hydroxyl-terminated polydimethylsiloxane modified castor oil based polyurethane/epoxy interpenetrating polymer network composites

Science.gov (United States)

Chen, Shoubing; Wang, Qihua; Wang, Tingmei

2011-06-01

A series of polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The effects of HTPDMS content on the phase structure, damping properties and the glass transition temperature ( Tg) of the HTPDMS-modified PU/EP IPN composites were studied by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of the composites increased with the increase of HTPDMS content. The tensile strength and impact strength of the IPN composites were also significantly improved, especially when the HTPDMS content was 10%. The modified IPN composites were expected to be used as structural damping materials in the future.

Novel 3D porous semi-IPN hydrogel scaffolds of silk sericin and poly(N-hydroxyethyl acrylamide for dermal reconstruction

Directory of Open Access Journals (Sweden)

S. Ross

2017-09-01

Full Text Available In this work, a novel semi-interpenetrating polymer network (semi-IPN hydrogel scaffold based on silk sericin (SS and poly(N-hydroxyethyl acrylamide (PHEA was successfully fabricated via conventional free-radical polymerization. The porous structure of the scaffolds was introduced using a lyophilization technique and the effect of cross-linker (XL on morphology, gelation time and physical properties of hydrogel scaffold was first studied. The results show that using low cross-linker content (0.125, 0.25 and 0.5 wt% XL produced flexible scaffolds and appropriate gelation times for fabricating the scaffold. Therefore, the polymerization system with a constant percentage of XL at 0.5 wt% was chosen to study further the effect of SS on the physical properties and cell culture of the scaffolds. It was observed that the hydrogel scaffold of PHEA without SS (PHEA/SS-0 had no cell proliferation, whereas hydrogel scaffolds with SS enhanced cell viability when compared to the positive control. The sample of PHEA/SS at 1.25 wt% of SS and 0.5 wt% of cross-linker was the most suitable for HFF-1 cells to migrate and cell proliferation due to possessing a connective porous structure, along with silk sericin. The results proved that this novel porous semi-IPN hydrogel has the potential to be used as dermal reconstruction scaffold.

Silk Fibroin/Polyvinyl Pyrrolidone Interpenetrating Polymer Network Hydrogels

Directory of Open Access Journals (Sweden)

Dajiang Kuang

2018-02-01

Full Text Available Silk fibroin hydrogel is an ideal model as biomaterial matrix due to its excellent biocompatibility and used in the field of medical polymer materials. Nevertheless, native fibroin hydrogels show poor transparency and resilience. To settle these drawbacks, an interpenetrating network (IPN of hydrogels are synthesized with changing ratios of silk fibroin/N-Vinyl-2-pyrrolidonemixtures that crosslink by H2O2 and horseradish peroxidase. Interpenetrating polymer network structure can shorten the gel time and the pure fibroin solution gel time for more than a week. This is mainly due to conformation from the random coil to the β-sheet structure changes of fibroin. Moreover, the light transmittance of IPN hydrogel can be as high as more than 97% and maintain a level of 90% within a week. The hydrogel, which mainly consists of random coil, the apertures inside can be up to 200 μm. Elastic modulus increases during the process of gelation. The gel has nearly 95% resilience under the compression of 70% eventually, which is much higher than native fibroin gel. The results suggest that the present IPN hydrogels have excellent mechanical properties and excellent transparency.

Calculation of beam neutralization in the IPNS-Upgrade RCS

International Nuclear Information System (INIS)

Chae, Yong-Chul.

1995-01-01

The author calculated the neutralization of circulating beam in this report. In the calculation it is assumed that all electrons liberated from the background molecules due to the collisional processes are trapped in the potential well of the proton beam. Including the dependence of ionization cross sections on the kinetic energy of the incident particle, the author derived the empirical formula for beam neutralization as a function of time and baseline vacuum pressure, which is applicable to the one acceleration cycle of the IPNS-Upgrade RCS

Self-assembled interpenetrating networks by orthogonal self assembly of surfactants and hydrogelators

NARCIS (Netherlands)

Brizard, Aurelie M.; Stuart, Marc C. A.; van Esch, Jan H.

2009-01-01

Interpenetrating networks (IPN) consist of two or more networks of different components which are entangled on a molecular scale and cannot be separated without breaking at least one of the networks. They are of great technological interest because they allow the blending of two or more otherwise

The IPNS rietveld analysis software package for TOF [time-of-flight] powder diffraction data: Recent developments

International Nuclear Information System (INIS)

Rotella, F.J.; Richardson, J.W. Jr.

1987-01-01

A system of FORTRAN programs for the analysis of time-of-flight (TOF) neutron powder diffraction data via the Rietveld method at IPNS has been modified recently, making it possible to analyze data that exhibit diffraction maxima broadened due to anisotropic strain and that can be modeled by individual atomic anharmonic thermal vibrations. The observation of noncrystalline scattering in data from some powder samples has led to the development of software to fit such scattering by a function related to a radial distribution function through Fourier-filtering techniques. The ''user friendliness'' of the IPNS Rietveld package has been enhanced by the development of ''RIETVELD,'' a menu-based VAX/VMS command language routine for interactive file manipulation and program execution

Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

Energy Technology Data Exchange (ETDEWEB)

Koetzle, Thomas F. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)], E-mail: tkoetzle@anl.gov; Piccoli, Paula M.B.; Schultz, Arthur J. [IPNS Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2009-02-21

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a {beta}-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS)

Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

Science.gov (United States)

Koetzle, Thomas F.; Piccoli, Paula M. B.; Schultz, Arthur J.

2009-02-01

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H⋯O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).

Single-crystal neutron diffraction studies of hydrogen-bonded systems: Two recent examples from IPNS

International Nuclear Information System (INIS)

Koetzle, Thomas F.; Piccoli, Paula M.B.; Schultz, Arthur J.

2009-01-01

Beginning with work in the 1950s at the first generation of research reactors, studies of hydrogen-bonded systems have been a prime application for single-crystal neutron diffraction. The range of systems studied was extended in the 1960s and 1970s, with the advent of high flux reactor sources, and beginning around 1980 studies at pulsed neutron sources have made increasingly important contributions. Recently at the Argonne Intense Pulsed Neutron Source (IPNS), working with collaborators, we completed two studies of hydrogen-bonded systems that will serve to illustrate topics of current interest. In the first study, on andrographolide, an active diterpenoid natural product, our neutron diffraction results definitively characterize the hydrogen-bonding interactions. The second IPNS study is on tetraacetylethane (TAE), a β-diketone enol system with a very short, strong intramolecular O-H...O hydrogen bond. At IPNS, we have determined the neutron crystal structure of TAE at five temperatures between 20 and 298 K to investigate changes in the structure with temperature and to probe for disorder. Despite the successes illustrated by the two examples presented here and by many other studies, at present applications of single-crystal neutron diffraction continue to be extremely flux limited and constrained by the requirement for mm-size crystals for many problems. These limitations are being addressed through the realization of powerful instruments at a new generation of pulsed neutron sources, including in the USA the TOPAZ and MaNDi single-crystal diffractometers that are under development at the Spallation Neutron Source (SNS).

Analysis of a drum chopper for use on a new small angle diffractometer at IPNS

International Nuclear Information System (INIS)

Crawford, R.K.; Epperson, J.E.; Thiyagarajan, P.; Carpenter, J.M.

1990-01-01

Light-weight drum choppers rotating at 15 Hz have been in use on the IPNS powder diffractometers for several years, where they serve to eliminate the delayed-neutron background from much of the spectral region of interest. Monte Carlo simulations indicate that a similar chopper operated at 15 Hz should do an excellent job of delayed-neutron removal in the new small-angle diffractometer being designed at IPNS. The simulations also show that when the same chopper is operated at 7.5 Hz it performs quite successfully as a frame-elimination chopper, effectively eliminating neutrons from alternate pulses and allowing extension of the useful wavelength range of the instrument to ∼28 Angstrom. Thus the incorporation of such a chopper should add considerably to the range and flexibility of the new instrument. 7 refs., 9 figs

Structure and properties of semi-interpenetrating network hydrogel based on starch.

Science.gov (United States)

Zhu, Baodong; Ma, Dongzhuo; Wang, Jian; Zhang, Shuang

2015-11-20

Starch-g-P(acrylic acid-co-acrylamide)/PVA semi-interpenetrating network (semi-IPN) hydrogels were prepared by aqueous solution polymerization method. Starch grafting copolymerization reaction, semi-IPN structure and crystal morphology were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The PVA in the form of partial crystallization distributing in the gel matrix uniformly were observed by Field emission scanning electron microscope (FESEM). The space network structure, finer microstructure and pore size in the interior of hydrogel were presented by biomicroscope. The results demonstrated that absorption ratio of water and salt generated different degree changes with the effect of PVA. In addition, the mechanical strength of hydrogel was improved. Copyright © 2015 Elsevier Ltd. All rights reserved.

The InterPlanetary Network Supplement to the Second Fermi GBM Catalog of Cosmic Gamma-Ray Bursts

Energy Technology Data Exchange (ETDEWEB)

Hurley, K. [University of California, Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Svinkin, D. S. [Ioffe Institute, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Pal’shin, V. D. [Vedeneeva 2-31, St. Petersburg (Russian Federation); Briggs, M. S.; Meegan, C. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Connaughton, V. [Universities Space Research Association, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Goldsten, J. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Boynton, W.; Fellows, C.; Harshman, K. [University of Arizona, Department of Planetary Sciences, Tucson, Arizona 85721 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Rau, A.; Kienlin, A. von, E-mail: khurley@ssl.berkeley.edu [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, Garching, D-85748 (Germany); and others

2017-04-01

InterPlanetary Network (IPN) data are presented for the gamma-ray bursts in the second Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 462 bursts in that catalog between 2010 July 12 and 2012 July 11, 428, or 93%, were observed by at least 1 other instrument in the 9-spacecraft IPN. Of the 428, the localizations of 165 could be improved by triangulation. For these bursts, triangulation gives one or more annuli whose half-widths vary between about 2.′3° and 16°, depending on the peak flux, fluence, time history, arrival direction, and the distance between the spacecraft. We compare the IPN localizations with the GBM 1 σ , 2 σ , and 3 σ error contours and find good agreement between them. The IPN 3 σ error boxes have areas between about 8 square arcminutes and 380 square degrees, and are an average of 2500 times smaller than the corresponding GBM 3 σ localizations. We identify four bursts in the IPN/GBM sample whose origins were given as “uncertain,” but may in fact be cosmic. This leads to an estimate of over 99% completeness for the GBM catalog.

Hidrogéis semi-IPN baseados em rede de alginato-Ca2+ com PNIPAAm entrelaçado: propriedades hidrofílicas, morfológicas e mecânicas Semi-IPN hydrogels based on alginate-Ca2+ network and PNIPAAm: hydrophilic, morphological and mechanical properties

Directory of Open Access Journals (Sweden)

Márcia R. de Moura

2008-06-01

Full Text Available Neste trabalho, a termossensibilidade dos hidrogéis do tipo semi-IPN baseados em rede de alginato-Ca2+com poli(N-isopropil acrilamida (PNIPAAm entrelaçado, com diferentes teores de alginato e de PNIPAAm, foi caracterizada por meio de medidas de grau de intumescimento (Q, microscopia eletrônica de varredura (MEV e propriedades mecânicas [tensão máxima de compressão (σ, densidade aparente de reticulação (νe e módulo de elasticidade (E]. Os valores de Q variam inversamente com νe. Para o parâmetro νe contribuem as concentrações de retículos alginato-Ca2+ e de cadeias de PNIPAAm. Hidrogéis com maiores valores de Q possuem maiores poros. Resultados de propriedades mecânicas demonstraram que hidrogéis com maior νe apresentam maior rigidez e resistência à compressão, sendo este efeito mais intenso acima da LCST do PNIPAAm. O controle dessas propriedades nesses hidrogéis termos-sensíveis torna esses materiais potencialmente viáveis para aplicação em sistemas carreadores para liberação controlada e/ou prolongada de fármacos e substratos para crescimento e cultura de célula.In this study, the thermosensitivity of semi-IPN hydrogels based on alginate-Ca2+ network and having PNIPAAm entangled was characterized by swelling degree (Q, scanning electron microscopy (SEM and mechanical properties [compressive stress (σ, apparent cross-linking density (νe and modulus of elasticity (E]. The Q values change inversely to the νe ones. The concentrations of the alginate-Ca2+ cross-linking and of the PNIPAAm chains contribute to the νe parameter. Higher values of Q correlate to larger pores size in the hydrogel. Hydrogels richer in alginate and PNIPAAm were more rigid, highly resistant to deformation because of their higher compressive modulus of elasticity. This is more intense at temperatures above the LCST of PNIPAAm in water (32-35 °C. The control of thermosensitive properties by tailoring the alginate-Ca2+/PNIPAAm ratio and

The upgrade of intense pulsed neutron source (IPNS) through the change of coolant and reflector

CERN Document Server

Baek, I C; Iverson, E B

2002-01-01

The current intense pulsed neutron source (IPNS) depleted uranium target is cooled by light water. The inner reflector material is graphite and the outer reflector material is beryllium. The presence of H sub 2 O in the target moderates neutrons and leads to a higher absorption loss in the target than is necessary. D sub 2 O coolant in the small quantities required minimizes this effect. We have studied the possible improvement in IPNS beam fluxes that would result from changing the coolant from H sub 2 O to D sub 2 O and the inner reflector from graphite to beryllium. Neutron intensities were calculated for directions normal to the viewed surface of each moderator for four different cases of combinations of target coolant and reflector materials. The simulations reported here were performed using the MCNPX (version 2.1.5) computer program. Our results show that substantial gains in neutron beam intensities can be achieved by appropriate combination of target coolant and reflector materials. The combination o...

GLAD: The IPNS (Intense Pulsed Neutron Source) Glass, Liquid, and Amorphous materials Diffractometer

International Nuclear Information System (INIS)

Crawford, R.K.; Price, D.L.; Haumann, J.R.; Kleb, R.; Montague, D.G.; Carpenter, J.M.; Susman, S.; Dejus, R.J.

1989-01-01

A number of years of experience in diffraction from amorphous materials has now been accumulated at various pulsed neutron sources. Workshops t IPNS and elsewhere have distilled some of this experience to provide a set of criteria for a new diffractometer dedicated to an optimized for structural studies of amorphous materials. This paper discusses the instrument GLAD (Glass, Liquid, and Amorphous Materials Diffractometer) which has been designed to meet these criteria and is now being built at IPNS. This instrument involves the use of relatively short-wavelength neutrons and a sophisticated neutron detection and acquisition system. A preliminary, simplified version of the instrument has been constructed while the final version is still under design, in order to develop the data acquisition and analysis techniques and to develop methods for collection of data with adequate quality (low background) at short wavelengths. This paper will briefly outline the final instrument envisioned and its calculated performance, but will focus mostly on the details of the detection/acquisition system and the calibration and data collection procedures which have been developed. The brief operating experience which has been gained to data with the preliminary instrument version will also be summarized. 6 refs., 12 figs

Análisis de las competencias informacionales en la comunidad académica del CICIMAR-IPN

Directory of Open Access Journals (Sweden)

Teresa de Jesús Barriga Ramírez

2015-04-01

Full Text Available Objetivo. Caracterizar la competencias informacionales de la comunidad académica y los bibliotecarios del CICIMAR-IPN. Métodos. Se aplicó una encuesta la cual fue complementada con entrevistas a los directivos y coordinadores de los programas de posgrado del centro. Resultados. Se identificaron diversas falencias en la comunidad, como: la necesidad de fomento del uso de las tecnologías de información y comunicación entre los docentes e investigadores; la difusión y reconocimiento de las normas de propiedad intelectual entre los estudiantes; y el desarrollo de competencias directivas y pedagógicas para la transmitisión de conocimientos entre los bibliotecarios. Conclusiones. Se evidencia la necesidad de crear un programa de alfabetización informacional para la comunidad académica del CICIMAR-IPN, que contribuya a la generación y transferencia de conocimientos para promover su excelencia.

Semi-interpenetrating networks based on POLY(N-isopropyl acrilamide and POLY(N-vinylpyrrolidone

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Žugić Dragana

2007-01-01

Full Text Available Three series of semi-interpenetrating polymer networks based on cross-linked poly(N-isopropylacrylamide, PNIPA, and 1, 2 and 3 wt% of linear poly(N-vinylpyrrolidone, PVP, were synthesized in order to improve the mechanical properties of PNIPA gels. The effect of the incorporation of the linear PVP polymer into the temperature responsive networks on the phase transition temperature, swelling behavior and mechanical properties was studied. Polymer networks with four different crosslinking densities were prepared with various molar ratios (25/1 to 100/1 of the monomer (N-isopropylacrylamide to the cross linker (N,N'-methylene-bisacrylamide. The hydrogels were characterized by determination of the equilibrium degree of swelling at 25 °C, the dynamic shear modulus and the effective crosslinking density, as well as the ultimate hydrogel properties, such as the tensile strength and elongation at break. Furthermore, the deswelling kinetics of the hydrogels was also studied by measuring their water retention capacity. The inclusion of the linear hydrophilic PVP in the PNIPA networks increased the equilibrium degree of swelling, the highest values of which were obtained for samples with 2 and 3 wt% of PVP and the NIPA/MBA molar ratio of 75/1 and 100/1. The highest reinforcement effect, evaluated from the ratio of G'red(semi-IPN to G'red(PNIPA, was obtained by incorporation of 2 wt% PVP. The tensile strength of the semi-IPNs reinforced with linear PVP was higher than that of the PNIPA networks. The elongation at break of these semi-IPNs varied between 22 and 55%, which are 22^11% larger than those for single PNIPA networks. The tensile measurements confirmed that the presence of 2 wt% of the linear polymer significantly reinforced the PNIPA network.

Interpenetrating network hydrogel membranes of sodium alginate and poly(vinyl alcohol) for controlled release of prazosin hydrochloride through skin.

Science.gov (United States)

Kulkarni, Raghavendra V; Sreedhar, V; Mutalik, Srinivas; Setty, C Mallikarjun; Sa, Biswanath

2010-11-01

Interpenetrating network (IPN) hydrogel membranes of sodium alginate (SA) and poly(vinyl alcohol) (PVA) were prepared by solvent casting method for transdermal delivery of an anti-hypertensive drug, prazosin hydrochloride. The prepared membranes were thin, flexible and smooth. The X-ray diffraction studies indicated the amorphous dispersion of drug in the membranes. Differential scanning calorimetric analysis confirmed the IPN formation and suggests that the membrane stiffness increases with increased concentration of glutaraldehyde (GA) in the membranes. All the membranes were permeable to water vapors depending upon the extent of cross-linking. The in vitro drug release study was performed through excised rat abdominal skin; drug release depends on the concentrations of GA in membranes. The IPN membranes extended drug release up to 24 h, while SA and PVA membranes discharged the drug quickly. The primary skin irritation and skin histopathology study indicated that the prepared IPN membranes were less irritant and safe for skin application. Copyright © 2010 Elsevier B.V. All rights reserved.

Development of visible-light responsive and mechanically enhanced "smart" UCST interpenetrating network hydrogels.

Science.gov (United States)

Xu, Yifei; Ghag, Onkar; Reimann, Morgan; Sitterle, Philip; Chatterjee, Prithwish; Nofen, Elizabeth; Yu, Hongyu; Jiang, Hanqing; Dai, Lenore L

2017-12-20

An interpenetrating polymer network (IPN), chlorophyllin-incorporated environmentally responsive hydrogel was synthesized and exhibited the following features: enhanced mechanical properties, upper critical solution temperature (UCST) swelling behavior, and promising visible-light responsiveness. Poor mechanical properties are known challenges for hydrogel-based materials. By forming an interpenetrating network between polyacrylamide (PAAm) and poly(acrylic acid) (PAAc) polymer networks, the mechanical properties of the synthesized IPN hydrogels were significantly improved compared to hydrogels made of a single network of each polymer. The formation of the interpenetrating network was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), the analysis of glass transition temperature, and a unique UCST responsive swelling behavior, which is in contrast to the more prevalent lower critical solution temperature (LCST) behaviour of environmentally responsive hydrogels. The visible-light responsiveness of the synthesized hydrogel also demonstrated a positive swelling behavior, and the effect of incorporating chlorophyllin as the chromophore unit was observed to reduce the average pore size and further enhance the mechanical properties of the hydrogel. This interpenetrating network system shows potential to serve as a new route in developing "smart" hydrogels using visible-light as a simple, inexpensive, and remotely controllable stimulus.

Non-monotonic reorganization of brain networks with Alzheimer’s disease progression

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Hyoungkyu eKim

2015-06-01

Full Text Available Background: Identification of stage-specific changes in brain network of patients with Alzheimer’s disease (AD is critical for rationally designed therapeutics that delays the progression of the disease. However, pathological neural processes and their resulting changes in brain network topology with disease progression are not clearly known. Methods: The current study was designed to investigate the alterations in network topology of resting state fMRI among patients in three different clinical dementia rating (CDR groups (i.e., CDR = 0.5, 1, 2 and amnestic mild cognitive impairment (aMCI and age-matched healthy subject groups. We constructed cost networks from these 5 groups and analyzed their network properties using graph theoretical measures.Results: The topological properties of AD brain networks differed in a non-monotonic, stage-specific manner. Interestingly, local and global efficiency and betweenness of the network were rather higher in the aMCI and AD (CDR 1 groups than those of prior stage groups. The number, location, and structure of rich-clubs changed dynamically as the disease progressed.Conclusions: The alterations in network topology of the brain are quite dynamic with AD progression, and these dynamic changes in network patterns should be considered meticulously for efficient therapeutic interventions of AD.

Instrument hardware and software upgrades at IPNS

International Nuclear Information System (INIS)

Worlton, Thomas; Hammonds, John; Mikkelson, D.; Mikkelson, Ruth; Porter, Rodney; Tao, Julian; Chatterjee, Alok

2006-01-01

IPNS is in the process of upgrading their time-of-flight neutron scattering instruments with improved hardware and software. The hardware upgrades include replacing old VAX Qbus and Multibus-based data acquisition systems with new systems based on VXI and VME. Hardware upgrades also include expanded detector banks and new detector electronics. Old VAX Fortran-based data acquisition and analysis software is being replaced with new software as part of the ISAW project. ISAW is written in Java for ease of development and portability, and is now used routinely for data visualization, reduction, and analysis on all upgraded instruments. ISAW provides the ability to process and visualize the data from thousands of detector pixels, each having thousands of time channels. These operations can be done interactively through a familiar graphical user interface or automatically through simple scripts. Scripts and operators provided by end users are automatically included in the ISAW menu structure, along with those distributed with ISAW, when the application is started

COMPLEX NETWORKS IN CLIMATE SCIENCE: PROGRESS, OPPORTUNITIES AND CHALLENGES

Data.gov (United States)

National Aeronautics and Space Administration — COMPLEX NETWORKS IN CLIMATE SCIENCE: PROGRESS, OPPORTUNITIES AND CHALLENGES KARSTEN STEINHAEUSER, NITESH V. CHAWLA, AND AUROOP R. GANGULY Abstract. Networks have...

The IPNS second harmonic RF upgrade

International Nuclear Information System (INIS)

Middendorf, M.E.; Brumwell, F.R.; Dooling, J.C.; Horan, D.; Kustom, R.L.; Lien, M.K.; McMichael, G.E.; Moser, M.R.; Nassiri, A.; Wang, S.

2008-01-01

The intense pulsed neutron source (IPNS) rapid cycling synchrotron (RCS) is used to accelerate protons from 50 MeV to 450 MeV, at a repetition rate of 30 Hz. The original ring design included two identical rf systems, each consisting of an accelerating cavity, cavity bias supply, power amplifiers and low-level analog electronics. The original cavities are located 180 degrees apart in the ring and provide a total peak accelerating voltage of ∼21 kV over the 2.21-MHz to 5.14-MHz revolution frequency sweep. A third rf system has been constructed and installed in the RCS. The third rf system is capable of operating at the fundamental revolution frequency for the entire acceleration cycle, providing an additional peak accelerating voltage of up to ∼11 kV, or at the second harmonic of the revolution frequency for the first ∼4 ms of the acceleration cycle, providing an additional peak voltage of up to ∼11 kV for bunch shape control. We describe here the hardware implementation and operation to date of the third rf cavity in the second harmonic mode.

Thermosensitive Behavior and Antibacterial Activity of Cotton Fabric Modified with a Chitosan-poly(N-isopropylacrylamide Interpenetrating Polymer Network Hydrogel

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Boxiang Wang

2016-03-01

Full Text Available To increase the themosensitive behavior and antibacterial activity of cotton fabric, a series of poly (N-isopropylacrylamide/chitosan (PNIPAAm/Cs hydrogels was synthesized by interpenetrating polymer network (IPN technology using a redox initiator. The IPN PNIPAAm/Cs hydrogel was characterized by Fourier transform infrared spectroscopy (FT-IR, differential scanning calorimetry (DSC, and thermogravimetric analysis (TGA. The results indicated that the IPN PNIPAAm/Cs hydrogel has a lower critical solution temperature (LCST at 33 °C. The IPN hydrogel was then used to modify cotton fabric using glutaric dialdehyde (GA as a crosslinking agent following a double-dip-double-nip process. The results demonstrated that the modified cotton fabric showed obvious thermosensitive behavior and antibacterial activity. The contact angle of the modified cotton fabric has a sharp rise around 33 °C, and the modified cotton fabric showed an obvious thermosensitive behavior. The bacterial reduction of modified cotton fabric against Staphylococcus aureus (S. aureus and Escherichia coli (E. coli were more than 99%. This study presents a valuable route towards smart textiles and their applications in functional clothing.

Interpenetrating Polymer Network Hydrogels Based on Gelatin and PVA by Biocompatible Approaches: Synthesis and Characterization

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Eltjani-Eltahir Hago

2013-01-01

Full Text Available In this work, a new approach was introduced to prepare interpenetrating polymer network PVA/GE hydrogels by cross-linking of various concentration gelatin in the presence of transglutaminase enzyme by using the freezing-thawing cycles technique. The effects of freezing-thawing cycles on the properties of morphological characterization, gel fraction, swelling, mechanical, and MTT assay were investigated. The IPN PVA/GE hydrogels showed excellent physical and mechanical Properties. MTT assay data and the fibroblasts culture also showed excellent biocompatibility and good proliferation. This indicates that the IPN hydrogels are stable enough for various biomedical applications.

Synthesis and characterization of sulfonic acid membranes based on interpenetrating polymer networks for application in fuel cells; Sintese e caracterizacao de membranas sulfonadas baseadas em redes polimericas interpenetrantes para aplicacao em celulas a combustivel

Energy Technology Data Exchange (ETDEWEB)

Blanco, Lyzed Toloza; Loureiro, Felipe A.M.; Rocco, Ana Maria [Grupo de Materiais Condutores e Energia, Escola de Quimica, Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)], e-mail: amrocco@eq.ufrj.br; Pereira, Robson Pacheco [Instituto de Ciencias Exatas, Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil)

2011-07-01

In the present work, the synthesis and characterization of sulfonic membranes based on interpenetrating polymer networks (IPN). In order to obtain such systems, the diglycidyl ether of bisphenol A (DGEBA) was polymerized in presence of polyethyleneimine (PEI). These membranes were submitted to sulfonation reactions, originating IPN-SO{sub 3}H membranes. The characterization by FTIR evidenced the formation of a Semi-IPN structure, while sulfonation reactions resulted in systems containing -SO{sub 3}H groups covalently bonded to the chains. The membranes exhibited water retention up to 200 degree C, in a temperature range sufficient for application in PEMFC under hydration. (author)

Influence of Ethylene Glycol Methacrylate to the Hydration and Transition Behaviors of Thermo-Responsive Interpenetrating Polymeric Network Hydrogels

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Bing Li

2018-01-01

Full Text Available The influence of ethylene glycol methacrylate (EGMA to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm, and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 and 18.5:1.5 in the thermo-responsive alginate-Ca2+/P(NIPAAm-co-EGMA IPN hydrogels. Due to the more hydrophilicity and high flexibility of EGMA, the IPN hydrogels exhibited higher lower critical solution temperature (LCST and lower glass transition temperature (Tg when the ratio of EGMA increases. The swelling/deswelling kinetics of the IPN hydrogels could be controlled by adjusting the NIPAAm/EGMA molar ratio. A faster water uptake rate and a slower water loss rate could be realized by increase the amount of EGMA in the IPN hydrogel (the shrinking rate constant was decreased from 0.01207 to 0.01195 and 0.01055 with the changing of NIPAAm/EGMA ratio from 20:0, 19.5:0.5 to 18.5:1.5. By using 2-Isopropylthioxanthone (ITX as a photo initiator, the obtained alginate-Ca2+/P(NIPAAm-co-EGMA360 IPN hydrogels were successfully immobilized on cotton fabrics. The surface and cross section of the hydrogel were probed by scanning electron microscopy (SEM. They all exhibited a porous structure, and the pore size was increased with the amount of EGMA. Moreover, the LCST values of the fabric-grafted hydrogels were close to those of the pure IPN hydrogels. Their thermal sensitivity remained unchanged. The cotton fabrics grafted with hydrogel turned out to be much softer with the continuous increase of EGMA amount. Therefore, compared with alginate-Ca2+/PNIPAAm hydrogel, alginate-Ca2+/P(NIPAAm-co-EGMA360 hydrogel is a more promising candidate for wound dressing in the field of biomedical textile.

Novel composite membrane coated with a poly(diallyldimethylammonium chloride)/urushi semi-interpenetrating polymer network for non-aqueous redox flow battery application

Science.gov (United States)

Cho, Eunhae; Won, Jongok

2016-12-01

Novel composite membranes of a semi-interpenetrating network (semi-IPN) coated on the surfaces of a porous Celgard 2400 support are prepared and investigate for application in a non-aqueous redox flow battery (RFB). A natural polymer, urushi, is used for the matrix because of its high mechanical robustness, and poly(diallyldimethylammonium chloride) (PDDA) provides anionic exchange sites. The PDDA/urushi (P/U) semi-IPN film is prepared by the photo polymerization of urushiol in the presence of PDDA. The thin layer composed of the P/U semi-IPN on the porous support provides selectivity while maintaining the ion conductivity. The coulombic and energy efficiencies increase with increasing amounts of PDDA in the P/U semi-IPN layer, and the values reach 69.5% and 42.5%, respectively, for the one containing 40 wt% of PDDA. These values are substantially higher than those of the Neosepta AHA membrane and the Celgard membrane, indicating that the selective layer reduces the crossover of the redox active species through the membrane. This result implies that the formation of composite membranes using semi-IPN selective layers on the dimensionally stable porous membrane enable the successful use of a non-aqueous RFB for future energy storage systems.

Taste masking of ofloxacin and formation of interpenetrating polymer network beads for sustained release

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A. Michael Rajesh

2017-08-01

Full Text Available The objective of this study was to carry out taste masking of ofloxacin (Ofl by ion exchange resins (IERs followed by sustained release of Ofl by forming interpenetrating polymer network (IPN beads. Drug-resin complexes (DRCs with three different ratios of Ofl to IERs (1:1, 1:2, 1:4 were prepared by batch method and investigated for in vivo and in vitro taste masking. DRC of methacrylic acid-divinyl benzene (MD resin and Ofl prepared at a ratio of 1:4 was used to form IPN beads. IPN beads of MD 1:4 were prepared by following the ionic cross-linking method using sodium carboxymethyl xanthan gum (SCMXG and SCMXG-sodium carboxymethyl cellulose (SCMXG-SCMC. IPN beads were characterized with FT-IR and further studied on sustained release of Ofl at different pH. In vivo taste masking carried out by human volunteers showed that MD 1:4 significantly reduced the bitterness of Ofl. Characterization studies such as FT-IR, DSC, P-XRD and taste masking showed that complex formation took place between drug and resin. In vitro study at gastric pH showed complete release of drug from MD 1:4 within 30 min whereas IPN beads took 5 h at gastric pH and 10 h at salivary pH for the complete release of drug. As the crosslinking increased the release kinetics changed into non-Fickian diffusion to zero-order release mechanism. MD 1:4 showed better performance for the taste masking of Ofl and IPNs beads prepared from it were found useful for the sustained release of Ofl at both the pH, indicating a versatile drug delivery system.

Development of semi- and grafted interpenetrating polymer networks based on poly(ethylene glycol) diacrylate and collagen.

Science.gov (United States)

Madaghiele, Marta; Marotta, Francesco; Demitri, Christian; Montagna, Francesco; Maffezzoli, Alfonso; Sannino, Alessandro

2014-12-30

The objective of this work was to develop composite hydrogels based on poly(ethylene glycol) diacrylate (PEGDA) and collagen (Coll), potentially useful for biomedical applications. Semi-interpenetrating polymer networks (semi-IPNs) were obtained by photo-stabilizing aqueous solutions of PEGDA and acrylic acid (AA), in the presence of collagen. Further grafting of the collagen macromolecules to the PEGDA/poly(AA) network was achieved by means of a carbodiimide-mediated crosslinking reaction. The resulting hydrogels were characterized in terms of swelling capability, collagen content and mechanical properties. The grafting procedure was found to significantly improve the mechanical stability of the IPN hydrogels, due to the establishment of covalent bonding between the PEGDA/poly(AA) and the collagen networks. The suitability of the composite hydrogels to be processed by means of stereolithography (SLA) was also investigated, toward creating biomimetic constructs with complex shapes, which might be useful either as platforms for tissue engineering applications or as tissue mimicking phantoms.

IPN hydrogels based on PNIPAAm and PVA-Ma networks: characterization through measure of LCST, swelling ratio and mechanical properties - doi: 10.4025/actascitechnol.v34i2.15019

OpenAIRE

Wenceslau, Adriana Cristina; Universidade Estadual de Maringá - UEM; Rubira, Adley Forti; Universidade Estadual de Maringá - UEM; Muniz, Edvani Curti; UEM, Maringá, Paraná

2011-01-01

IPN hydrogels based on chemically modified poly(vinyl alcohol) (or PVA-Ma), with different degrees of substitution (DS), and poly(N-isopropylacrylamide) (or PNIPAAm) were obtained and characterized through measures of LCST, swelling ratio and mechanical properties. Linear PVA-Ma with several DS were obtained through the chemical reaction of PVA with glycidyl methacrylate (GMA). The DS of various PVA-Ma were determined through 1H NMR spectroscopy. Two steps were used for preparation the PVA-Ma...

Generando vinculación académica en el IPN entre el nivel medio superior y superior en unidades de aprendizaje de básicas

OpenAIRE

Gil Balderrama, Sara Beatríz; Pérez Bussó, Carlos Eduardo

2016-01-01

El Instituto Politécnico Nacional (IPN) en el estado de Guanajuato presenta, como muchas instituciones educativas un enorme filtro de abandono y deserción en los primeros semestres del nivel superior. En este trabajo, presentamos una experiencia docente en el CECyT 174, una escuela del nivel medio superior del I.P.N. en la ciudad de León, Guanajuato, México. Este reporte es el trabajo desarrollado por los autores intentando que la labor académica contribuya a reducir la brecha existente entre...

Grafting of Interpenetrating Networks of Two Stimuli-responsive Polymers onto PP

International Nuclear Information System (INIS)

Ruiz, J. C.

2006-01-01

In this work a new strategy was used to prepare interpenetrating polymer networks (IPNs) of two 'stimuli-responsive' polymers: a thermosensitive poly N-isopropylacrylamide (PNIPAAm) and pH sensitive poly acrylic acid (PAAc), the last grafted onto PP films. IPNs are a combination of two or more polymers in network form, which are mixed together (not chemically but physically), with al least one such polymer polymerized and/or crosslinked in the immediate presence of the other(s). The 'stimuli-responsive' polymers, also called 'smart' polymers, exhibit relatively large and sharp physical or chemical changes in response to small physical or chemical stimuli. These polymers are being used as hydrogels or copolymers for technical applications in chemical and mechanical engineering systems such as mass separation, chemical valves, temperature or pH indicators, biomedical and drug delivery systems. For these applications a rapid response and good mechanical properties are necessary. Formerly when PNIPAAm and PAAc were chemically combined their sensitivity was often altered or eliminated and their copolymer had poor mechanical properties. Attempts to solve this problem by creating IPN's with a reduced gel size or by using a macro-porous structure were successful in preserving sensitivity but failed to produce adequate mechanical properties. The object of this paper is to improve the past results of using a binary graft of PNIPAAm and PAAc onto poly(tetrafluoroethylene) PTFE. Poly acrylic acid was grafted onto polypropylene films (with good mechanical properties) by gamma radiation in air (pre-irradiation method), then these grafts were crosslinked using any of the next two methods: The first one, the grafted film in water and argon atmosphere by gamma radiation; and the second one, in the same conditions, but adding a crosslinking agent N, N'-methylenebisacrylamide (MBAAm). The second network was carried out in situ, in the cross-linked PAAc grafted onto PP films, by

Status of the intense pulsed neutron source

International Nuclear Information System (INIS)

Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

1988-01-01

IPNS is not unique in having concerns about the level of funding, and the future looks good despite these concerns. This report details the progress made at IPNS during the last two years. Other papers in these proceedings discuss in detail the status of the enriched uranium Booster target, the two instruments that are under construction, GLAD and POSY II, and a proposal for research on an Advanced Pulsed Neutron Source (ASPUN) that has been submitted to the Department of Energy (DOE). Further details on IPNS are available in the IPNS Progress Report 1987--1988, available by writing the IPNS Division Office. 9 refs., 3 tabs

Interpenetrating polymer networks based on cyanate ester and fluorinated ethynyl-terminated imide oligomers

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Y. Wen

2017-12-01

Full Text Available Highly soluble fluorinated ethynyl-terminated imide (FETI oligomers were prepared via a conventional one-step method in m-cresol, using 4, 4′-(hexafluoroisopropylidene diphthalic anhydride and 2, 2′-bis(trifluoromethyl benzidine as the monomers, and ethynylphthalic anhydride as the end-capper; then interpenetrating polymer networks (IPN were formulated from FETI oligomers and bisphenol A dicyanate ester (BADCy through a solvent-free procedure, and their thermal, mechanical, and dielectric properties were fully characterized. The curing mechanism was studied by model reactions using nitrogen nuclear magnetic resonance. As evidenced by differential scanning calorimetry analysis and rheological measurements, the FETI/BADCy blends exhibited lower curing temperature and shorter gelation time in comparison with pure BADCy due to the catalytic effects of ethynyl and residue amic acid groups. The properties of IPNs were fully compared with those of polycyanurate, and the results revealed that the incorporation of FETI into cyanate ester resins could significantly improve the toughness, glass transition temperatures, mechanical and dielectric properties of the resultant IPNs.

Development and optimization of locust bean gum and sodium alginate interpenetrating polymeric network of capecitabine.

Science.gov (United States)

Upadhyay, Mansi; Adena, Sandeep Kumar Reddy; Vardhan, Harsh; Pandey, Sureshwar; Mishra, Brahmeshwar

2018-03-01

The objective of the study was to develop interpenetrating polymeric network (IPN) of capecitabine (CAP) using natural polymers locust bean gum (LBG) and sodium alginate (NaAlg). The IPN microbeads were optimized by Box-Behnken Design (BBD) to provide anticipated particle size with good drug entrapment efficiency. The comparative dissolution profile of IPN microbeads of CAP with the marketed preparation proved an excellent sustained drug delivery vehicle. Ionotropic gelation method utilizing metal ion calcium (Ca 2+ ) as a cross-linker was used to prepare IPN microbeads. The optimization study was done by response surface methodology based Box-Behnken Design. The effect of the factors on the responses of optimized batch was exhibited through response surface and contour plots. The optimized batch was analyzed for particle size, % drug entrapment, pharmacokinetic study, in vitro drug release study and further characterized by FTIR, XRD, and SEM. To study the water uptake capacity and hydrodynamic activity of the polymers, swelling studies and viscosity measurement were performed, respectively. The particle size and % drug entrapment of the optimized batch was 494.37 ± 1.4 µm and 81.39 ± 2.9%, respectively, closer to the value predicted by Minitab 17 software. The in vitro drug release study showed sustained release of 92% for 12 h and followed anomalous drug release pattern. The derived pharmacokinetic parameters of optimized batch showed improved results than pure CAP. Thus, the formed IPN microbeads of CAP proved to be an effective extended drug delivery vehicle for the water soluble antineoplastic drug.

Characterization of nanocellulose reinforced semi-interpenetrating polymer network of poly(vinyl alcohol) & polyacrylamide composite films.

Science.gov (United States)

Mandal, Arup; Chakrabarty, Debabrata

2015-12-10

Semi-interpenetrating polymer network (semi-IPN) of poly(vinyl alcohol)/polyacrylamide was reinforced with various doses of nanocellulose. The different composite films thus prepared were characterized with respect to their mechanical, thermal, morphological and barrier properties. The composite film containing 5 wt.% of nanocellulose showed the highest tensile strength. The semi-interpenetrating polymer network of poly(vinyl alcohol)/polyacrylamide; and its various composites with nanocellulose were almost identical in their thermal stability. Each of the composites however exhibited much superior stability with respect to the linear poly(vinyl alcohol) and crosslinked polyacrylamide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited phase separated morphology where agglomerates of nanocellulose were found to be dispersed in the matrix of the semi-IPN. The moisture vapor transmission rate (MVTR) was the lowest for the film containing 5 wt.% of nanocellulose. Copyright © 2015 Elsevier Ltd. All rights reserved.

Performance Evaluation of Peer-to-Peer Progressive Download in Broadband Access Networks

Science.gov (United States)

Shibuya, Megumi; Ogishi, Tomohiko; Yamamoto, Shu

P2P (Peer-to-Peer) file sharing architectures have scalable and cost-effective features. Hence, the application of P2P architectures to media streaming is attractive and expected to be an alternative to the current video streaming using IP multicast or content delivery systems because the current systems require expensive network infrastructures and large scale centralized cache storage systems. In this paper, we investigate the P2P progressive download enabling Internet video streaming services. We demonstrated the capability of the P2P progressive download in both laboratory test network as well as in the Internet. Through the experiments, we clarified the contribution of the FTTH links to the P2P progressive download in the heterogeneous access networks consisting of FTTH and ADSL links. We analyzed the cause of some download performance degradation occurred in the experiment and discussed about the effective methods to provide the video streaming service using P2P progressive download in the current heterogeneous networks.

Examination of disks from the IPNS depleted uranium target

International Nuclear Information System (INIS)

Strain, R.V.; Carpenter, J.M.

1995-10-01

This report describes the results of examining the Zircaloy-2 clad depleted uranium disks from the Intense Pulse Neutron Source (IPNS) Target. That target operated from August, 1981 to June, 1988 and from September, 1991 to September, 1992 at 450 MeV, pulsing at 30 Hz with a time average proton current of about 15 microA. The target was removed from service when the presence of fission products ( 135 Xe) in the coolant cover gas indicated a failure in the Zircaloy-2 cladding. Altogether, the target had absorbed about 240 mA hours of proton current, and endured between 50,000 and 100,000 thermal cycles. The purpose of the examination was to assess the condition of the disks and determine the cause of the cladding failure. The results of visual, gamma ray scanning, and destructive metallurgical examination of two disks are described

IPN Polysiloxane-Epoxy Resin for High Temperature Coatings: Structure Effects on Layer Performance after 450 °C Treatment

Directory of Open Access Journals (Sweden)

Simone Giaveri

2017-11-01

Full Text Available Coatings for high temperatures (HT > 400 °C are obtained from interpenetrating polymer network (IPN binders formed by simultaneous polymerization of silicone and epoxide pre-polymers. A ceramic layer; mainly composed of silica and fillers; remains on the metal surface after a thermal treatment at 450 °C. The layer adhesion and the inorganic filler’s distribution have been investigated by, firstly, exchanging the organic substituents (methyl and phenyl of the silicone chains and, secondly, by adding conductive graphene nanoplatelets with the aim to assure a uniform distribution of heat during the thermal treatment. The results are evidence that different substituent ratios affect the polymer initial layout. The adhesion tests of paint formulations are analysed and were related to instrumental analyses performed using glow discharge optical emission spectroscopy (GDOES; thermal analyses (TG/DTA and DSC; electron microscopy with energy dispersive X-ray analysis (SEM-EDX. A greater resistance to powdering using phenyl groups instead of methyl ones; and an improved distribution of fillers due to graphene nanoplatelet addition; is evidenced.

THE INTERPLANETARY NETWORK RESPONSE TO LIGO GW150914

Energy Technology Data Exchange (ETDEWEB)

Hurley, K. [University of California, Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D. [Ioffe Physical Technical Institute, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Boynton, W. [University of Arizona, Department of Planetary Sciences, Tucson, AZ 85721 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Rau, A.; Kienlin, A. von; Zhang, X. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, Garching, D-85748 Germany (Germany); Connaughton, V.; Meegan, C. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Cline, T.; Gehrels, N., E-mail: khurley@ssl.berkeley.edu [NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771 (United States)

2016-09-20

We have performed a blind search for a gamma-ray transient of arbitrary duration and energy spectrum around the time of the LIGO gravitational-wave event GW150914 with the six-spacecraft interplanetary network (IPN). Four gamma-ray bursts were detected between 30 hr prior to the event and 6.1 hr after it, but none could convincingly be associated with GW150914. No other transients were detected down to limiting 15–150 keV fluences of roughly 5 ×10{sup −8}–5 × 10{sup −7} erg cm{sup −2}. We discuss the search strategies and temporal coverage of the IPN on the day of the event and compare the spatial coverage to the region where GW150914 originated. We also report the negative result of a targeted search for the Fermi -GBM event reported in conjunction with GW150914.

Polycaprolactone diacrylate crosslinked biodegradable semi-interpenetrating networks of polyacrylamide and gelatin for controlled drug delivery

International Nuclear Information System (INIS)

Jaiswal, Maneesh; Koul, Veena; Dinda, Amit K; Gupta, Asheesh

2010-01-01

A biodegradable semi-interpenetrating hydrogel network (semi-IPN) of polyacrylamide and gelatin was prepared using polycaprolactone diacrylate (mol. wt ∼ 640) as a crosslinker. The drug-polymer interaction and IPN formation were investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and thermal gravimetric analysis (TGA). Scanning electron micrographs of lyophilized matrices revealed porous internal structure with varying pore sizes under equilibrium hydrated conditions, depending upon formulation composition. pH-dependent swelling and degradation was enhanced with increasing gelatin content and decreasing crosslinker concentration (Cs). Compression modulus (CM) (at 20% strain) increased significantly from 23 ± 1.4 to 75 ± 2.7 kPa (p 0 C). Fitting of drug release data in the Korsmeyer-Peppas model suggested sustained release behavior up to 10 days with a combination of diffusion and erosion mechanism (0.5 t /M ∞ ≤ 0.6). The newly developed porous, biodegradable and elastic semi-IPNs may serve as an ideal matrix for controlled drug release and wound healing applications. The possibilities can be explored for pharmaceutical and tissue engineering applications.

Interpenetrating polymer networks based on polyol modified castor ...

Indian Academy of Sciences (India)

Unknown

glycerol modification of castor oil results in more crosslinked and stiffer IPNs possessing better mechanical properties over that of unmodified castor oil polyurethane/. PHEMA IPNs. 3.5 Chemical resistance. The percentage weight loss of IPNs were determined in. H2SO4, CH3COOH, HCl, HNO3, NaCl and NaOH etc and.

Two years of real progress in European HEP networking: A CERN perspective

International Nuclear Information System (INIS)

Carpenter, B.E.; Fluckiger, F.; Gerard, J.M.; Lord, D.; Segal, B.

1987-01-01

The last two years have been marked by real progress in networking in HEP. Home-made developments, studies and plans have given way to the use of real networks involving hundreds of HEP and other computers and based on externally produced software and hardware. Within the last year, the first generation of industrial software products following some of the international standards for networking have become available. Related developments are taking place in networking for on-line systems and indeed the LEP experiments are distinguished by their heavy and crucial reliance on both local and wide-area networks. This paper describes the progress made at CERN since the last two years and looks at perspectives for the future. (orig.)

Binary Systematic Network Coding for Progressive Packet Decoding

OpenAIRE

Jones, Andrew L.; Chatzigeorgiou, Ioannis; Tassi, Andrea

2015-01-01

We consider binary systematic network codes and investigate their capability of decoding a source message either in full or in part. We carry out a probability analysis, derive closed-form expressions for the decoding probability and show that systematic network coding outperforms conventional net- work coding. We also develop an algorithm based on Gaussian elimination that allows progressive decoding of source packets. Simulation results show that the proposed decoding algorithm can achieve ...

Intense pulsed neutron source (IPNS) at Argonne National Laboratory (ANL): a status report as of June, 1982

International Nuclear Information System (INIS)

Carpenter, J.M.; Potts, C.W.; Lander, G.H.

1983-01-01

In this status report a general overview is given of the IPNS program. The facility has been operating since August 1981 and in a routine way for outside users since November 1981. The accelerator performance has been exceptional. Most instruments are now operational, or nearly so. For details of the individual instruments and experimental program the reader is referred to papers later in these proceedings

Alginate-polyvinyl alcohol based interpenetrating polymer network for prolonged drug therapy, Optimization and in-vitro characterization.

Science.gov (United States)

Anwar, Hina; Ahmad, Mahmood; Minhas, Muhammad Usman; Rehmani, Sahrish

2017-06-15

A new natural and synthetic polymeric blend to form interpenetrating polymer network (IPN) hydrogels was synthesized utilizing sodium alginate and PVA as polymers by free radical polymerization employing 2-Acylamido-2-methylpropane-sulfonic acid as monomer (AMPS) and tramadol HCl as model drug through 3 2 level full factorial design to evaluate the impact of selected independent factors i.e. polymer (sodium alginate) and monomer (AMPS) contents on swelling index at 18th hour, percent drug release at 18th hour, time required for 80% drug release and drug entrapment efficiency as dependent variables. FTIR, SEM, sol-gel analysis, equilibrium swelling studies and in-vitro release kinetics were performedfor in-vitro characterization of formulated IPN hydrogels. In-vitro studies carried out at pH 1.2 and pH 7.4 revealed pH independent swelling and drug release from polymeric IPN, providing controlled drug release for an extended period of time with improved entrapment efficiency, thereby concluding that this polymeric blend may be a promising system for the prolonged drug delivery. Copyright © 2017 Elsevier Ltd. All rights reserved.

IPNS upgrade: A feasibility study

International Nuclear Information System (INIS)

1995-04-01

Many of Argonne National Laboratory's (ANL's) scientific staff members were very active in R ampersand D work related to accelerator-based spoliation sources in the 1970s and early 1980s. In 1984, the Seitz/Eastman Panel of the National Academy of Sciences reviewed U.S. materials science research facilities. One of the recommendations of this panel was that the United States build a reactor-based steady-state source, the Advanced Neutron Source (ANS), at Oak Ridge National Laboratory. Subsequently, R ampersand D activities related to the design of an accelerator-based source assumed a lower priority. The resumption of pulsed-source studies in this country started simultaneously with design activities in Europe aimed at the European Spallation Source (ESS). The European Community funded a workshop in September 1991 to define the parameters of the ESS. Participants in this workshop included both accelerator builders and neutron source users. A consortium of European countries has proposed to build a 5-MW pulsed source, and a feasibility study is currently under way. Soon after the birth of the ESS, a small group at ANL set about bringing themselves up to date on pulsed-source information since 1984 and studied the feasibility of upgrading ANL's Intense Pulsed Neutron Source (IPNS) to 1 MW by means of a rapidly cycling synchrotron that could be housed, along with its support facilities, in existing buildings. In early 1993, the Kohn panel recommended that (1) design and construction of the ANS should be completed according to the proposed project schedule and (2) development of competitive proposals for cost-effective design and construction of a 1-MW pulsed spallation source should be authorized immediately

IPNS upgrade: A feasibility study

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-04-01

Many of Argonne National Laboratory`s (ANL`s) scientific staff members were very active in R&D work related to accelerator-based spoliation sources in the 1970s and early 1980s. In 1984, the Seitz/Eastman Panel of the National Academy of Sciences reviewed U.S. materials science research facilities. One of the recommendations of this panel was that the United States build a reactor-based steady-state source, the Advanced Neutron Source (ANS), at Oak Ridge National Laboratory. Subsequently, R&D activities related to the design of an accelerator-based source assumed a lower priority. The resumption of pulsed-source studies in this country started simultaneously with design activities in Europe aimed at the European Spallation Source (ESS). The European Community funded a workshop in September 1991 to define the parameters of the ESS. Participants in this workshop included both accelerator builders and neutron source users. A consortium of European countries has proposed to build a 5-MW pulsed source, and a feasibility study is currently under way. Soon after the birth of the ESS, a small group at ANL set about bringing themselves up to date on pulsed-source information since 1984 and studied the feasibility of upgrading ANL`s Intense Pulsed Neutron Source (IPNS) to 1 MW by means of a rapidly cycling synchrotron that could be housed, along with its support facilities, in existing buildings. In early 1993, the Kohn panel recommended that (1) design and construction of the ANS should be completed according to the proposed project schedule and (2) development of competitive proposals for cost-effective design and construction of a 1-MW pulsed spallation source should be authorized immediately.

Taste masking of ciprofloxacin by ion-exchange resin and sustain release at gastric-intestinal through interpenetrating polymer network

Directory of Open Access Journals (Sweden)

A. Michael Rajesh

2015-07-01

Full Text Available The aim of the study was to taste mask ciprofloxacin (CP by using ion-exchange resins (IERs followed by sustain release of CP by forming interpenetrating polymer network (IPN. IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised. Drug-resin complexes (DRCs with three different ratios of drug to IERs (1:1, 1:2, 1:4 were prepared & evaluated for taste masking by following in vivo and in vitro methods. Human volunteers graded ADC 1:4, acrylic acid-divinyl benzene (ADC-3 resin as tasteless. Characterization studies such as FTIR, SEM, DSC, P-XRD differentiated ADC 1:4, from physical mixture (PM 1:4 and confirmed the formation of complex. In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid (SGF i.e. pH 1.2. IPN beads were prepared with ADC 1:4 by using sodium alginate (AL and sodium alginate-chitosan (AL-CS for sustain release of CP at SGF pH and followed by simulated intestinal fluid (SIF i.e. pH 7.4. FTIR spectra confirmed the formation of IPN beads. The release of CP was sustain at SGF pH (75%. The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.

Adsorption of ammonium and phosphate by feather protein based semi-interpenetrating polymer networks hydrogel as a controlled-release fertilizer.

Science.gov (United States)

Su, Yuan; Liu, Jia; Yue, Qinyan; Li, Qian; Gao, Baoyu

2014-01-01

A new feather protein-grafted poly(potassium acrylate)/polyvinyl alcohol (FP-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) hydrogel was produced through graft copolymerization with FP as a basic macromolecular skeletal material, acrylic acid as a monomer and PVA as a semi-IPNs polymer. The adsorption of ammonium and phosphate ions from aqueous solution using the new hydrogel as N and P controlled-release fertilizer with water-retention capacity was studied. The effects of pH value, concentration, contact time and ion strength on NH4+ and PO3-4 removal by FP-g-PKA/PVA semi-IPNs hydrogel were investigated using batch adsorption experiments. The results indicated that the hydrogel had high adsorption capacities and fast adsorption rates for NH4+ and PO3-4 in wide pH levels ranging from 4.0 to 9.0. Kinetic analysis presented that both NH4+ and PO3-4 removal were closely fitted with the pseudo-second-order model. Furthermore, the adsorption isotherms of hydrogel were best represented by the Freundlich model. The adsorption-desorption experimental results showed the sustainable stability of FP-g-PKA/PVA semi-IPNs hydrogel for NH4+ and PO3-4 removal. Overall, FP-g-PKA/PVA could be considered as an efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer.

Russian section of GGOS: Network status and progress

Directory of Open Access Journals (Sweden)

A. Ipatov

2017-03-01

Full Text Available Establishment of the Russian section in the framework of Global Geodetic Observing System (GGOS is under progress. New components of “Quasar” network observatories, which are included into GGOS global network as core stations, are presented. Recent developments include: two new generation radio telescopes with 13 m antennas at Badary and Zelenchukskaya observatories, water vapor radiometers installed at all observatories and software correlator at the Institute of Applied Astronomy. New and potential developments within other networks belonging to different agencies are also considered in the context of widening of Russian section activity in GGOS project. The paper gives a short overview of status, new components and plans, concerning 5 sub-networks of Federal Agency of Scientific Organizations, Roskosmos, Rosstandard, and Rosreestr. Short overview of the plans on creating Data and Analysis Distributed Center is also given.

Biodegradation study of enzymatically catalyzed interpenetrating polymer network: Evaluation of agrochemical release and impact on soil fertility

Directory of Open Access Journals (Sweden)

Saruchi

2016-03-01

Full Text Available A novel interpenetrating polymer network (IPN has been synthesized through enzymatic initiation using lipase as initiator, glutaraldehyde as cross-linker, acrylic acid as primary monomer and acrylamide as secondary monomer. Biodegradability of synthesized interpenetrating polymer network was studied through soil burial and composting methods. Synthesized hydrogel was completely degraded within 70 days using composting method, while it was 86.03% degraded within 77 days using soil burial method. This was confirmed by Fourier transform Infrared spectroscopy (FTIR and Scanning electron microscopy (SEM techniques. Synthesized interpenetrating polymer network hydrogel was used as a device for controlled release of urea and also act as water releasing device. Their impact on soil fertility and plant growth was also studied. The initial diffusion coefficient has a greater value than the later diffusion coefficient indicating a higher fertilizer release rate during the early stage. Fertilizer release kinetic was also studied which showed Non-Fickian diffusion behavior, as the rate of fertilizer release was comparable to the relaxation time of the synthesized matrix. Synthesized IPN enhance the water uptake capacity up to 6.2% and 7.2% in sandy loam and clay soil, respectively.

Understanding interpenetrating-polymer-network-like porous nitrile butadiene rubber hybrids by their long-period miscibility

International Nuclear Information System (INIS)

Zhang, Jihua; Wang, Lifeng; Zhao, Yunfeng

2013-01-01

Highlights: • Hydrogen bonds are introduced into NBR to develop its IPN-like porous hybrids. • NBR is partly miscible with AO-60. • AO-60 possesses the viscoelastic behavior resembling that of polymers. • Phase separation aggravates and AO-60 crystallizes in the durations. • The porous hybrids may have potential damping applications. - Abstract: In this article, tetrakis [methylene-3-(3, 5-di-tert-butyl-4-hydroxy phenyl) propionyloxy] methane (AO-60) with hydrogen bonds was designed to interpenetrate into the chemical crosslinking bonds of nitrile butadiene rubber (NBR) and then porous materials were prepared. Scanning electron microscopy (SEM), atomic force microscopy (AFM) images and dynamic mechanical analyses (DMA) demonstrate that NBR is partly miscible with AO-60 which induces the micro-pores and interpenetrating-polymer-network (IPN)-like phase morphology in the hybrids. The wide double tan δ peak in DMA curve displays that AO-60 possesses similar viscoelastic behaviors to polymers which come from supramolecular interactions between polar groups of NBR chains and hydroxyl (OH) groups of AO-60. To further understand the supramolecular abilities of AO-60 in the rubber, the long-period observations for their miscibility are conducted. With the increase of durations, the hydrogen bond network from AO-60 is weakened. The phase separation between AO-60 and NBR is aggravated and even extremely few AO-60 crystallizes which develops multi-scale porous morphology in the hybrids. It is believed that these findings can serve as a guide for the designs of the IPN-like hybrids with small molecule substances and their applications of damping materials

Data acquisition and control system for the IPNS time-of-flight neutron scattering instruments

International Nuclear Information System (INIS)

Daly, R.T.; Haumann, J.R.; Kraimer, M.R.; Lenkszus, F.R.; Lidinsky, W.P.; Morgan, C.B.; Rutledge, L.L.; Rynes, P.E.; Tippie, J.W.

1979-01-01

The Argonne Intense Pulsed Neutron System (IPNS-I) presently under construction at Argonne National Laboratory will include a number of neutron scattering instruments. This study investigates the data acquisition requirements of these instruments and proposes three alternative multiprocessor systems which will satisfy these requirements. All proposals are star configurations with a super-mini as the central node or HOST. The first proposal is based on front-ends composed of two or more 16-bit microcomputers, the second proposal is based on front ends consisting of a combination of a mini and microcomputers, and the third is based on a minicomputer with an intelligent CAMAC controller

Implementation of a dosimetry service for the occupationally exposed personnel of the ESFM-IPN; Implementacion de un servicio de dosimetria para el personal ocupacionalmente expuesto de la ESFM-IPN

Energy Technology Data Exchange (ETDEWEB)

Hernandez A, Y. [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico); Sanchez R, A. A. [IPN, Escuela Superior de Fisica y Matematicas, U. P. Adolfo Lopez Mateos, Edif. 9, 07738 Mexico D. F. (Mexico); Ceron R, P. V.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia y Tecnologia Avanzada, Unidad Legaria, Av. Legaria No. 694, 11500 Mexico D. F. (Mexico); Vega C, H. R., E-mail: yamani.hernandez@cnsns.gob.mx [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

2014-10-15

Because the ionizing radiations handling implies a risk for the health, is necessary to take a control of the radiation quantity that the occupationally exposed personnel receives during their daily work with ionizing radiations. For this purpose there are several types of dosimetry and companies that provide the service, but taking advantage that the Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional (ESFM-IPN) possesses a thermoluminescence equipment (Tl) was decided to develop a personnel dosimetry service for gammas, with thermoluminescent glasses of type TLD-100. First one carries out a glasses characterization, for which the glasses were washed with a methyl alcohol solution, without rubbing them for not damaging them; after the drying, they were subjected to a temperature of 400 C during one hour and later on 100 grades C for two hours in order to erasing them the bottom information that they could have. 200 glasses were exposed to gamma radiation coming from a Cobalt 60 source property of ESFM-IPN in order to selecting the glasses that had a response whose precision was inside a standard deviation. Of this characterization 80 dosimeters were selected that had better response according to the obtained readings as well as of their shine curves. These selected TLD-100 glasses were irradiated to different dose of gamma radiation and with those readings it was built a dose response curve in m R against readings of electric load in pick Coulombs (pCou). The response curve was a direct line or calibration curve. As final exercise some glasses of this selected lot were subjected to irradiation dose not known by the person that carried out the readings and this way was proven that the results were appropriate with the calibration curve. Finally these dosimeters were placed in port-dosimeters and erased guides of dosimeters, of equipment use and dosimeters lecture were also elaborated. (Author)

Semi-Interpenetrating Polymer Networks with Predefined Architecture for Metal Ion Fluorescence Monitoring

Directory of Open Access Journals (Sweden)

Kyriakos Christodoulou

2016-11-01

Full Text Available The development of new synthetic approaches for the preparation of efficient 3D luminescent chemosensors for transition metal ions receives considerable attention nowadays, owing to the key role of the latter as elements in biological systems and their harmful environmental effects when present in aquatic media. In this work, we describe an easy and versatile synthetic methodology that leads to the generation of nonconjugated 3D luminescent semi-interpenetrating amphiphilic networks (semi-IPN with structure-defined characteristics. More precisely, the synthesis involves the encapsulation of well-defined poly(9-anthrylmethyl methacrylate (pAnMMA (hydrophobic, luminescent linear polymer chains within a covalent poly(2-(dimethylaminoethyl methacrylate (pDMAEMA hydrophilic polymer network, derived via the 1,2-bis-(2-iodoethoxyethane (BIEE-induced crosslinking process of well-defined pDMAEMA linear chains. Characterization of their fluorescence properties demonstrated that these materials act as strong blue emitters when exposed to UV irradiation. This, combined with the presence of the metal-binding tertiary amino functionalities of the pDMAEMA segments, allowed for their applicability as sorbents and fluorescence chemosensors for transition metal ions (Fe3+, Cu2+ in solution via a chelation-enhanced fluorescence-quenching effect promoted within the semi-IPN network architecture. Ethylenediaminetetraacetic acid (EDTA-induced metal ion desorption and thus material recyclability has been also demonstrated.

3D CAD model of the subcritical nuclear reactor of IPN; Modelo CAD 3D del reactor nuclear subcritico del IPN

Energy Technology Data Exchange (ETDEWEB)

Pahuamba V, F. de J.; Delfin L, A.; Gomez T, A. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Ibarra R, G.; Del Valle G, E.; Sanchez R, A., E-mail: narehc@hotmail.com [IPN, Escuela Superior de Fisica y Matematicas, Av. IPN, Edif. 9, Unidad Profesional Adolfo Lopez Mateos, San Pedro Zacatenco, 07738 Ciudad de Mexico (Mexico)

2016-09-15

The three-dimensional (3D) CAD model of the subcritical reactor Chicago model 9000 of Instituto Politecnico Nacional (IPN) allows obtaining a 3D view with the dimensions of each of its components, such as: natural uranium cylindrical rods, fuel elements, hexagonal reactor core arrangement, cylindrical stainless steel tank containing the core, fuel element support grids and reactor water cleaning system. As a starting point for the development of the model, the Chicago model 9000 subcritical reactor manual provided by the manufacturer was used, the measurement and verification of the components to adapt the geometric, physical and mechanical characteristics was carried out and materials standards were used to obtain a design that allows to elaborate a new manual according to the specifications. In addition, the 3D models of the building of the Advanced Physics Laboratory, neutron generator, cobalt source and the corridors connecting to the subcritical reactor facility were developed, allowing an animated ride, developed by computer-aided design software. The manual provided by the company Nuclear Chicago, dates from the year 1959 and presents diverse deviations in the design and dimensions of the reactor components. The model developed; in addition to supporting the development of the new manual represents a learning tool to visualize the reactor components. (Author)

Radiation preparation of interpenetrating polymer networks

International Nuclear Information System (INIS)

Sheikh, N.; Ahmadi, M.; Afshar Taromi, F.

2002-01-01

Sequential interpenetrating polymer netwoks were prepared using gamma radiation. Styrene-butadiene rubber (SBR) and polymethyl methacrylate (PMMA) were used as elastomer and plastomer components respectively. Dicumyl peroxide (DCP) and ethylene glycol dimethacrylate (EGDMA) were also used as the curing agent of SBR and crosslinker for MMA monomer. The resulting IPNs were characterized by evaluating their mechanical properties. The effect of the amount of DCP on the final properties of product was examined. It was found that amount of curing agent had an important role on the properties of obtained IPNS. The results of the mechanical properties of IPNs showed very good synergistic behavior. (Author)

Status of the intense pulsed neutron source

International Nuclear Information System (INIS)

Brown, B.S.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

1989-01-01

Since 1981 the average proton currents at IPNS has increased substantially. The reliability has averaged 91%. The moderator has changed from a room temperature polyethylene to cryogenic methane. This report details progress made at IPNS (Intense Pulsed Neutron Source) during the last two years. The topics discussed are the operating status of the accelerator systems, other accelerator activities (such as, IPNS participation in SDI), instrumentation operating at IPNS, chopper development at IPNS, data acquisition, Booster target, moderators and examples of recent scientific results. The ever increasing instrument capability, the Booster target and the very active involvement with the scientific user community guarantees a productive scientific future at IPNS. 9 figs., 3 tabs

Abnormal-induced theta activity supports early directed-attention network deficits in progressive MCI.

Science.gov (United States)

Deiber, Marie-Pierre; Ibañez, Vicente; Missonnier, Pascal; Herrmann, François; Fazio-Costa, Lara; Gold, Gabriel; Giannakopoulos, Panteleimon

2009-09-01

The electroencephalography (EEG) theta frequency band reacts to memory and selective attention paradigms. Global theta oscillatory activity includes a posterior phase-locked component related to stimulus processing and a frontal-induced component modulated by directed attention. To investigate the presence of early deficits in the directed attention-related network in elderly individuals with mild cognitive impairment (MCI), time-frequency analysis at baseline was used to assess global and induced theta oscillatory activity (4-6Hz) during n-back working memory tasks in 29 individuals with MCI and 24 elderly controls (EC). At 1-year follow-up, 13 MCI patients were still stable and 16 had progressed. Baseline task performance was similar in stable and progressive MCI cases. Induced theta activity at baseline was significantly reduced in progressive MCI as compared to EC and stable MCI in all n-back tasks, which were similar in terms of directed attention requirements. While performance is maintained, the decrease of induced theta activity suggests early deficits in the directed-attention network in progressive MCI, whereas this network is functionally preserved in stable MCI.

Noise Reduction and Correction in the IPNS Linac ESEM

Science.gov (United States)

Dooling, J. C.; Brumwell, F. R.; Donley, L.; McMichael, G. E.; Stipp, V. F.

2004-11-01

The Energy Spread and Energy Monitor (ESEM) is an on-line, non-intrusive diagnostic used to characterize the output beam from the 200-MHz, 50-MeV IPNS linac. The energy spread is determined from a 3-size, longitudinal emittance measurement; whereas the energy is derived from time of flight (TOF) analysis. Signals are detected on 50-ohm, stripline beam position monitors (BPMs) terminated in their characteristic impedance. Each BPM is constructed with four striplines: top, bottom, left and right. The ESEM signals are taken from the bottom stripline in four separate BPM locations in the 50-MeV transport line between the linac and the synchrotron. Deterministic linac noise is sampled before and after the 70-microsecond macropulse. The noise phasor is vectorially subtracted from the beam signal. Noise subtraction is required at several frequencies, especially the fundamental and fifth harmonics (200 MHz and 1 GHz). It is also necessary to correct for attenuation and dispersion in the co-axial signal cables. Presently, the analysis assumes a single particle distribution to determine energy and energy spread. Work is on-going to allow for more realistic longitudinal distributions to be included in the analysis.

Behavior of ionic conducting IPN actuators in simulated space conditions

Science.gov (United States)

Fannir, Adelyne; Plesse, Cédric; Nguyen, Giao T. M.; Laurent, Elisabeth; Cadiergues, Laurent; Vidal, Frédéric

2016-04-01

The presentation focuses on the performances of flexible all-polymer electroactive actuators under space-hazardous environmental factors in laboratory conditions. These bending actuators are based on high molecular weight nitrile butadiene rubber (NBR), poly(ethylene oxide) (PEO) derivative and poly(3,4-ethylenedioxithiophene) (PEDOT). The electroactive PEDOT is embedded within the PEO/NBR membrane which is subsequently swollen with an ionic liquid as electrolyte. Actuators have been submitted to thermal cycling test between -25 to 60°C under vacuum (2.4 10-8 mbar) and to ionizing Gamma radiations at a level of 210 rad/h during 100 h. Actuators have been characterized before and after space environmental condition ageing. In particular, the viscoelasticity properties and mechanical resistance of the materials have been determined by dynamic mechanical analysis and tensile tests. The evolution of the actuation properties as the strain and the output force have been characterized as well. The long-term vacuuming, the freezing temperature and the Gamma radiations do not affect significantly the thermomechanical properties of conducting IPNs actuators. Only a slight decrease on actuation performances has been observed.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network.

Science.gov (United States)

Aasi, J; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J S; Ast, S; Aston, S M; Astone, P; Aufmuth, P; Augustus, H; Aulbert, C; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Baune, C; Bavigadda, V; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Biwer, C; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Calderón Bustillo, J; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castaldi, G; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, D E; Clark, J A; Clayton, J H; Cleva, F; Coccia, E; Cohadon, P-F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Costa, C A; Coughlin, M W; Coulon, J-P; Countryman, S; Couvares, P; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Croce, R P; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Cutler, C; Dahl, K; Dal Canton, T; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; DeBra, D; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Dolique, V; Dominguez, E; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H-B; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Favata, M; Fazi, D; Fehrmann, H; Fejer, M M; Feldbaum, D; Feroz, F; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Finn, L S; Fiori, I; Fisher, R P; Flaminio, R; Fournier, J-D; Franco, S; Frasca, S; Frasconi, F; Frede, M; Frei, Z; Freise, A; Frey, R; Fricke, T T; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gair, J R; Gammaitoni, L; Gaonkar, S; Garufi, F; Gehrels, N; Gemme, G; Gendre, B; Genin, E; Gennai, A; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gleason, J; Goetz, E; Goetz, R; Gondan, L; González, G; Gordon, N; Gorodetsky, M L; Gossan, S; Goßler, S; Gouaty, R; Gräf, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greenhalgh, R J S; Gretarsson, A M; Groot, P; Grote, H; Grover, K; Grunewald, S; Guidi, G M; Guido, C J; Gushwa, K; Gustafson, E K; Gustafson, R; Ha, J; Hall, E D; Hamilton, W; Hammer, D; Hammond, G; Hanke, M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Harms, J; Harry, G M; Harry, I W; Harstad, E D; Hart, M; Hartman, M T; Haster, C-J; Haughian, K; Heidmann, A; Heintze, M; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Hofman, D; Holt, K; Hopkins, P; Horrom, T; Hoske, D; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Huerta, E; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Idrisy, A; Ingram, D R; Inta, R; Islas, G; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; Haris, K; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kaufer, S; Kaur, T; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Keppel, D G; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N G; Kim, N; Kim, S; Kim, Y-M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, D Nanda; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lam, P K; Landry, M; Lantz, B; Larson, S; Lasky, P D; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, J; Lee, P J; Leonardi, M; Leong, J R; Leonor, I; Le Roux, A; Leroy, N; Letendre, N; Levin, Y; Levine, B; Lewis, J; Li, T G F; Libbrecht, K; Libson, A; Lin, A C; Littenberg, T B; Lockerbie, N A; Lockett, V; Lodhia, D; Loew, K; Logue, J; Lombardi, A L; Lopez, E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J; Lubinski, M J; Lück, H; Lundgren, A P; Ma, Y; Macdonald, E P; MacDonald, T; Machenschalk, B; MacInnis, M; Macleod, D M; Magaña-Sandoval, F; Magee, R; Mageswaran, M; Maglione, C; Mailand, K; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Manca, G M; Mandel, I; Mandic, V; Mangano, V; Mangini, N M; Mansell, G; Mantovani, M; Marchesoni, F; Marion, F; Márka, S; Márka, Z; Markosyan, A; Maros, E; Marque, J; Martelli, F; Martin, I W; Martin, R M; Martinelli, L; Martynov, D; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Matichard, F; Matone, L; Mavalvala, N; May, G; Mazumder, N; Mazzolo, G; McCarthy, R; McClelland, D E; McGuire, S C; McIntyre, G; McIver, J; McLin, K; Meacher, D; Meadors, G D; Mehmet, M; Meidam, J; Meinders, M; Melatos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C; Meyer, M S; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Mikhailov, E E; Milano, L; Miller, J; Minenkov, Y; Mingarelli, C M F; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moe, B; Moggi, A; Mohan, M; Mohapatra, S R P; Moraru, D; Moreno, G; Morgado, N; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, C L; Mueller, G; Mukherjee, S; Mullavey, A; Munch, J; Murphy, D; Murray, P G; Mytidis, A; Nagy, M F; Nardecchia, I; Naticchioni, L; Nayak, R K; Necula, V; Nelemans, G; Neri, I; Neri, M; Newton, G; Nguyen, T; Nielsen, A B; Nissanke, S; Nitz, A H; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Ochsner, E; O'Dell, J; Oelker, E; Oh, J J; Oh, S H; Ohme, F; Omar, S; Oppermann, P; Oram, R; O'Reilly, B; Ortega, W; O'Shaughnessy, R; Osthelder, C; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Padilla, C; Pai, A; Palashov, O; Palomba, C; Pan, H; Pan, Y; Pankow, C; Paoletti, F; Papa, M A; Paris, H; Pasqualetti, A; Passaquieti, R; Passuello, D; Pedraza, M; Pele, A; Penn, S; Perreca, A; Phelps, M; Pichot, M; Pickenpack, M; Piergiovanni, F; Pierro, V; Pinard, L; Pinto, I M; Pitkin, M; Poeld, J; Poggiani, R; Poteomkin, A; Powell, J; Prasad, J; Predoi, V; Premachandra, S; Prestegard, T; Price, L R; Prijatelj, M; Privitera, S; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; Pürrer, M; Qin, J; Quetschke, V; Quintero, E; Quitzow-James, R; Raab, F J; Rabeling, D S; Rácz, I; Radkins, H; Raffai, P; Raja, S; Rajalakshmi, G; Rakhmanov, M; Ramet, C; Ramirez, K; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Recchia, S; Reed, C M; Regimbau, T; Reid, S; Reitze, D H; Reula, O; Rhoades, E; Ricci, F; Riesen, R; Riles, K; Robertson, N A; Robinet, F; Rocchi, A; Roddy, S B; Rolland, L; Rollins, J G; Romano, R; Romanov, G; Romie, J H; Rosińska, D; Rowan, S; Rüdiger, A; Ruggi, P; Ryan, K; Salemi, F; Sammut, L; Sandberg, V; Sanders, J R; Sankar, S; Sannibale, V; Santiago-Prieto, I; Saracco, E; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Savage, R; Scheuer, J; Schilling, R; Schilman, M; Schmidt, P; Schnabel, R; Schofield, R M S; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Shaddock, D A; Shah, S; Shahriar, M S; Shaltev, M; Shao, Z; Shapiro, B; Shawhan, P; Shoemaker, D H; Sidery, T L; Siellez, K; Siemens, X; Sigg, D; Simakov, D; Singer, A; Singer, L; Singh, R; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, R J E; Smith-Lefebvre, N D; Son, E J; Sorazu, B; Souradeep, T; Staley, A; Stebbins, J; Steinke, M; Steinlechner, J; Steinlechner, S; Stephens, B C; Steplewski, S; Stevenson, S; Stone, R; Stops, D; Strain, K A; Straniero, N; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Susmithan, S; Sutton, P J; Swinkels, B; Tacca, M; Talukder, D; Tanner, D B; Tao, J; Tarabrin, S P; Taylor, R; Tellez, G; Thirugnanasambandam, M P; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, V; Tokmakov, K V; Tomlinson, C; Tonelli, M; Torres, C V; Torrie, C I; Travasso, F; Traylor, G; Tse, M; Tshilumba, D; Tuennermann, H; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Beuzekom, M; van den Brand, J F J; Van Den Broeck, C; van der Sluys, M V; van Heijningen, J; van Veggel, A A; Vass, S; Vasúth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Viceré, A; Vincent-Finley, R; Vinet, J-Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Vousden, W D; Vyachanin, S P; Wade, A R; Wade, L; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, M; Wang, X; Ward, R L; Was, M; Weaver, B; Wei, L-W; Weinert, M; Weinstein, A J; Weiss, R; Welborn, T; Wen, L; Wessels, P; West, M; Westphal, T; Wette, K; Whelan, J T; White, D J; Whiting, B F; Wiesner, K; Wilkinson, C; Williams, K; Williams, L; Williams, R; Williams, T D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Wolovick, N; Worden, J; Wu, Y; Yablon, J; Yakushin, I; Yam, W; Yamamoto, H; Yancey, C C; Yang, H; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J-P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, H; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Aptekar, R L; Atteia, J L; Cline, T; Connaughton, V; Frederiks, D D; Golenetskii, S V; Hurley, K; Krimm, H A; Marisaldi, M; Pal'shin, V D; Palmer, D; Svinkin, D S; Terada, Y; von Kienlin, A

2014-07-04

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by the Interplanetary Network

Science.gov (United States)

Aasi, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Acernese, F.; Blackbum, L.; Camp, J. B.; Gehrels, N.; Graff, P. B.;

A 3D Porous Gelatin-Alginate-Based-IPN Acts as an Efficient Promoter of Chondrogenesis from Human Adipose-Derived Stem Cells

Directory of Open Access Journals (Sweden)

Sorina Dinescu

2015-01-01

Full Text Available Cartilage has limited regeneration potential. Thus, there is an imperative need to develop new strategies for cartilage tissue engineering (CTE amenable for clinical use. Recent CTE approaches rely on optimal cell-scaffold interactions, which require a great deal of optimization. In this study we attempt to build a novel gelatin- (G- alginate- (A- polyacrylamide (PAA 3D interpenetrating network (IPN with superior performance in promoting chondrogenesis from human adipose-derived stem cells (hADSCs. We show that our G-A-PAA scaffold is capable of supporting hADSCs proliferation and survival, with no apparent cytotoxic effect. Moreover, we find that after exposure to prochondrogenic conditions a key transcription factor known to induce chondrogenesis, namely, Sox9, is highly expressed in our hADSCs/G-A-PAA bioconstruct, along with cartilage specific markers such as collagen type II, CEP68, and COMP extracellular matrix (ECM components. These data suggest that our G-A-PAA structural properties and formulation might enable hADSCs conversion towards functional chondrocytes. We conclude that our novel G-A-PAA biomatrix is a good candidate for prospective in vivo CTE applications.

Characterisation of the IPNE Bonner sphere spectrometer by comparison with the PTB system

International Nuclear Information System (INIS)

Alevra, A.V.; Plostinaru, V.D.

2002-01-01

An existing set of Bonner spheres of the Institute for Physics and Nuclear Engineering in Bucharest has been modified following the PTB design for application of an 3 He-filled SP9 counter. By simple interpolations of the fluence responses of the PTB spheres, a preliminary fluence response matrix could be established for the IPNE Bonner sphere set. For further adjustments of the preliminary responses and for validation of the final fluence response matrix of the Romanian Bonner sphere spectrometer, calibration measurements with a reference 252 Cf neutron source and joint measurements, including the PTB Bonner sphere spectrometer, were performed in a few neutron fields differing substantially in their spectral distributions. It is estimated that the integral neutron fluences and dose-equivalent values can now be determined with the Romanian spectrometer with uncertainties of about ±4% and ±8%, respectively

Implementation of a dosimetry service for the occupationally exposed personnel of the ESFM-IPN

International Nuclear Information System (INIS)

Hernandez A, Y.; Sanchez R, A. A.; Ceron R, P. V.; Rivera M, T.; Vega C, H. R.

2014-10-01

Because the ionizing radiations handling implies a risk for the health, is necessary to take a control of the radiation quantity that the occupationally exposed personnel receives during their daily work with ionizing radiations. For this purpose there are several types of dosimetry and companies that provide the service, but taking advantage that the Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional (ESFM-IPN) possesses a thermoluminescence equipment (Tl) was decided to develop a personnel dosimetry service for gammas, with thermoluminescent glasses of type TLD-100. First one carries out a glasses characterization, for which the glasses were washed with a methyl alcohol solution, without rubbing them for not damaging them; after the drying, they were subjected to a temperature of 400 C during one hour and later on 100 grades C for two hours in order to erasing them the bottom information that they could have. 200 glasses were exposed to gamma radiation coming from a Cobalt 60 source property of ESFM-IPN in order to selecting the glasses that had a response whose precision was inside a standard deviation. Of this characterization 80 dosimeters were selected that had better response according to the obtained readings as well as of their shine curves. These selected TLD-100 glasses were irradiated to different dose of gamma radiation and with those readings it was built a dose response curve in m R against readings of electric load in pick Coulombs (pCou). The response curve was a direct line or calibration curve. As final exercise some glasses of this selected lot were subjected to irradiation dose not known by the person that carried out the readings and this way was proven that the results were appropriate with the calibration curve. Finally these dosimeters were placed in port-dosimeters and erased guides of dosimeters, of equipment use and dosimeters lecture were also elaborated. (Author)

Effects of imperfections on the dynamic aperture and closed orbit of the IPNS Upgrade synchrotron

International Nuclear Information System (INIS)

Lessner, E.; Chae, Y.C.; Kim, S.

1995-01-01

Magnet imperfections and misalignments are analyzed in terms of their effects on the dynamic aperture and closed orbit of the IPNS Upgrade synchrotron. The dynamic aperture is limited primarily by the presence of chromaticity-correcting sextupoles. With the sextupoles energized to the values required to adjust the chromaticities to zero, further reductions of the dynamic aperture caused by dipole strength and roll errors, quadrupole strength and alignment errors, and higher-order multipole errors are studied by tracking. Design specifications for the dipole corrector magnets are obtained and the dynamic aperture is studied before and after correction of the closed orbit. The use of harmonic-correcting sextupoles to reduce the amplitude-dependent tune shifts driven by the chromaticity-correcting sextupoles is investigated

Cerebello-thalamo-cortical networks predict positive symptom progression in individuals at ultra-high risk for psychosis

Directory of Open Access Journals (Sweden)

Jessica A. Bernard

2017-01-01

Full Text Available Prospective longitudinal evaluation of adolescents at ultra-high-risk (UHR for the development of psychosis enables an enriched neurodevelopmental perspective of disease progression in the absence of many of the factors that typically confound research with formally psychotic patients (antipsychotic medications, drug/alcohol dependence. The cerebellum has been linked to cognitive dysfunction and symptom severity in schizophrenia and recent work from our team suggests that it is a promising target for investigation in UHR individuals as well. However, the cerebellum and cerebello-thalamo-cortical networks have not been investigated developmentally or with respect to disease progression in this critical population. Further, to date, the types of longitudinal multimodal connectivity studies that would substantially inform our understanding of this area have not yet been conducted. In the present investigation 26 UHR and 24 healthy control adolescents were administered structured clinical interviews and scanned at baseline and then again at 12-month time points to investigate both functional and structural connectivity development of cerebello-thalamo-cortical networks in conjunction with symptom progression. Our results provide evidence of abnormal functional and structural cerebellar network development in the UHR group. Crucially, we also found that cerebello-thalamo-cortical network development and connectivity at baseline are associated with positive symptom course, suggesting that cerebellar networks may be a biomarker of disease progression. Together, these findings provide support for neurodevelopmental models of psychotic disorders and suggest that the cerebellum and respective networks with the cortex may be especially important for elucidating the pathophysiology of psychosis and highlighting novel treatment targets.

The impact of calcium carbonate as pore forming agent and drug entrapment method towards drug dissolution mechanism of amoxicillin trihydrate encapsulated by chitosan-methyl cellulose semi-IPN hydrogel for floating drug delivery system

Science.gov (United States)

Dewantara, Fauzi; Budianto, Emil

2018-04-01

Chitosan-methyl cellulose semi-IPN hydrogel is used as floating drug delivery system, and calcium carbonate also added as pore forming agent. The hydrogel network arranged by not only using biopolymer chitosan and methyl cellulose, but also the crosslink agent that is glutaraldehyde. Amoxicillin trihydrate entrapped into the polymer network with two different method, in situ loading and post loading. Furthermore both method has been tested for drug entrapment efficiency along with drug dissolution test, and the result for drug entrapment efficiency is in situ loading method has highest value of 100%, compared to post loading method which has value only 71%. Moreover, at the final time of drug dissolution test shows in situ loading method has value of 96% for total accumulative of drug dissolution, meanwhile post loading method has 72%. The value of drug dissolution test from both method is used for analyzing drug dissolution mechanism of amoxicillin trihydrate from hydrogel network with four mathematical drug mechanism models as parameter. The polymer network encounter destructive degradation causes by acid solution which used as dissolution medium, and the level of degradation is observed with optical microscope. However the result shows that degradation of the polymer network doesn't affect drug dissolution mechanism directly. Although the pore forming agent causes the pore inside the hydrogel network create interconnection and it was quite influential to drug dissolution mechanism. Interconnected pore is observed with Scanning Electron Microscope (SEM) and shows that the amount and area of interconnected pore inside the hydrogel network is increasing as drug dissolution goes on.

Intégration d'actionneurs à base de polymères conducteurs électroniques pour des applications aux microsystèmes

OpenAIRE

Khaldi , Alexandre

2012-01-01

The aim of this work is the realization of new microactuators based on electronicconducting polymer (ECP) for a flapping wing nano-aerial vehicle.Two Interpenetrating Polymer Networks (IPNs) PEO/PTHF(polyethyleneoxide/polytetrahydrofurane) and PEO/NBR (polyethyleneoxide/NitrileButadiene Rubber) were synthesized and characterized. By controlling the synthesis of these IPNs, a phase co-continuity of the two networks could be obtained. This work has enabled the production of materials combining ...

Progress on the Development of Future Airport Surface Wireless Communications Network

Science.gov (United States)

Kerczewski, Robert J.; Budinger, James M.; Brooks, David E.; Franklin, Morgan; DeHart, Steve; Dimond, Robert P.; Borden, Michael

2009-01-01

Continuing advances in airport surface management and improvements in airport surface safety are required to enable future growth in air traffic throughout the airspace, as airport arrival and departure delays create a major system bottleneck. These airport management and safety advances will be built upon improved communications, navigation, surveillance, and weather sensing, creating an information environment supporting system automation. The efficient movement of the digital data generated from these systems requires an underlying communications network infrastructure to connect data sources with the intended users with the required quality of service. Current airport surface communications consists primarily of buried copper or fiber cable. Safety related communications with mobile airport surface assets occurs over 25 kHz VHF voice and data channels. The available VHF spectrum, already congested in many areas, will be insufficient to support future data traffic requirements. Therefore, a broadband wireless airport surface communications network is considered a requirement for the future airport component of the air transportation system. Progress has been made on defining the technology and frequency spectrum for the airport surface wireless communications network. The development of a test and demonstration facility and the definition of required testing and standards development are now underway. This paper will review the progress and planned future work.

The Indigenous Phenology Network: Engage, Observe, and Adapt to Change

Science.gov (United States)

Miller, B. W.; Davíd-Chavez, D. M.; Elevitch, C.; Hamilton, A.; Hatfield, S. C.; Jones, K. D.; Rabin, R.; Rosemartin, A.; Souza, M. K.; Sparrow, E.

2017-12-01

The Indigenous Phenology Network (IPN) is a grassroots organization whose participants are interested in understanding changes to seasonality and timing of life cycle events, and forecasting impacts to lands and species of importance to native peoples. The group focuses on building relationships, ensuring benefit to indigenous communities, and integrating indigenous and western knowledge systems. The IPN's work is guided by the Relational Doctrine, a set of principles founded on the notion that all things are connected. This multimedia presentation and dialogue will bring together IPN members and their experiences in diverse communities and landscapes facing impacts from a changing climate and extreme weather events. Impacts on water supply, vegetation, wildlife, and living conditions, and ideas for minimizing and responding to the projected impacts of continued change will be discussed in the context of multi-generational, place-based traditional knowledge and community resilience. Scalable, community-based gardens, for example, provide a sustainable source of traditional, locally grown food, most valuable in times of disaster when supplies from the outside world are unavailable. Following the concept of Victory Gardens, the model of small-scale agroforestry (VICTree Gardens - Virtually Interconnected Community Tree Gardens), being implemented in Hawaii, has the potential to provide a diverse diet of food grown in very limited space. Gardens build resilience by connecting people with each other, with local food, and with nature. We envision community-based projects which will apply local, multi-generational knowledge to adapt the gardens to changing environments. Going forward, direct observation of garden conditions can be combined with satellite and ground-based measurements of environmental conditions, such as soil moisture, soil and air temperature, precipitation, and phenology, to further assess and manage these gardens in the context of the surrounding

Polycaprolactone diacrylate crosslinked biodegradable semi-interpenetrating networks of polyacrylamide and gelatin for controlled drug delivery

Energy Technology Data Exchange (ETDEWEB)

Jaiswal, Maneesh; Koul, Veena [Centre for Biomedical Engineering, Indian Institute of Technology, New Delhi 110016 (India); Dinda, Amit K [Department of Pathology, All India Institute of Medical Sciences, New Delhi 110029 (India); Gupta, Asheesh, E-mail: veenak_iitd@yahoo.co [Department of Biochemical Pharmacology, Defense Institute of Physiology and Allied Sciences, Ministry of Defense, New Delhi 110059 (India)

2010-12-15

A biodegradable semi-interpenetrating hydrogel network (semi-IPN) of polyacrylamide and gelatin was prepared using polycaprolactone diacrylate (mol. wt {approx} 640) as a crosslinker. The drug-polymer interaction and IPN formation were investigated by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and thermal gravimetric analysis (TGA). Scanning electron micrographs of lyophilized matrices revealed porous internal structure with varying pore sizes under equilibrium hydrated conditions, depending upon formulation composition. pH-dependent swelling and degradation was enhanced with increasing gelatin content and decreasing crosslinker concentration (Cs). Compression modulus (CM) (at 20% strain) increased significantly from 23 {+-} 1.4 to 75 {+-} 2.7 kPa (p < 0.02) with increasing Cs (from 0.5 to 2.0 mol%), while it decreased from 162 {+-} 6.4 to 23 {+-} 1.4 kPa (p < 0.05) with decreasing PAm/G ratio. Cell viability studies by MTT assay showed excellent cytocompatibility of matrices with fibroblast L929 cells. Curcumin, a hydrophobic phytochemical, was loaded by a diffusion method and its release profile was investigated in 4% w/v aqueous BSA solution at 75 rpm (at 37 {+-} 0.2 {sup 0}C). Fitting of drug release data in the Korsmeyer-Peppas model suggested sustained release behavior up to 10 days with a combination of diffusion and erosion mechanism (0.5 < n < 1.0; M{sub t}/M{sub {infinity} {<=}} 0.6). The newly developed porous, biodegradable and elastic semi-IPNs may serve as an ideal matrix for controlled drug release and wound healing applications. The possibilities can be explored for pharmaceutical and tissue engineering applications.

3D CAD model of the subcritical nuclear reactor of IPN

International Nuclear Information System (INIS)

Pahuamba V, F. de J.; Delfin L, A.; Gomez T, A.; Ibarra R, G.; Del Valle G, E.; Sanchez R, A.

2016-09-01

The three-dimensional (3D) CAD model of the subcritical reactor Chicago model 9000 of Instituto Politecnico Nacional (IPN) allows obtaining a 3D view with the dimensions of each of its components, such as: natural uranium cylindrical rods, fuel elements, hexagonal reactor core arrangement, cylindrical stainless steel tank containing the core, fuel element support grids and reactor water cleaning system. As a starting point for the development of the model, the Chicago model 9000 subcritical reactor manual provided by the manufacturer was used, the measurement and verification of the components to adapt the geometric, physical and mechanical characteristics was carried out and materials standards were used to obtain a design that allows to elaborate a new manual according to the specifications. In addition, the 3D models of the building of the Advanced Physics Laboratory, neutron generator, cobalt source and the corridors connecting to the subcritical reactor facility were developed, allowing an animated ride, developed by computer-aided design software. The manual provided by the company Nuclear Chicago, dates from the year 1959 and presents diverse deviations in the design and dimensions of the reactor components. The model developed; in addition to supporting the development of the new manual represents a learning tool to visualize the reactor components. (Author)

Control of Metastatic Progression by microRNA Regulatory Networks

Science.gov (United States)

Pencheva, Nora; Tavazoie, Sohail F.

2015-01-01

Aberrant microRNA (miRNA) expression is a defining feature of human malignancy. Specific miRNAs have been identified as promoters or suppressors of metastatic progression. These miRNAs control metastasis through divergent or convergent regulation of metastatic gene pathways. Some miRNA regulatory networks govern cell-autonomous cancer phenotypes, while others modulate the cell-extrinsic composition of the metastatic microenvironment. The use of small RNAs as probes into the molecular and cellular underpinnings of metastasis holds promise for the identification of candidate genes for potential therapeutic intervention. PMID:23728460

Study of castor oil polyurethane - poly(methyl methacrylate semi-interpenetrating polymer network (SIPN reaction parameters using a 2³ factorial experimental design

Directory of Open Access Journals (Sweden)

Fernanda Oliveira Vieira da Cunha

2004-12-01

Full Text Available In this work was employed a 2³ factorial experiment design to evaluate the castor oil polyurethane-poly(methyl methacrylate semi-IPN synthesis. The reaction parameters used as independent variables were NCO/OH molar ratio, polyurethane polymerization time and methyl methacrylate (MMA content. The semi-IPNs were cured over 28 h using two thermal treatments. The polymers were characterized by infrared and Raman spectroscopy, thermal analysis and swelling profiles in n-hexane. The glass transition temperature (Tg and the swelling were more affect by the NCO/OH molar ratio variation. The semi-IPNs showed Tg from - 27 to - 6 °C and the swelling range was from 3 to 22%, according to the crosslink density. The IPN mechanical properties were dependent on the cure temperature and MMA content in it. Lower elastic modulus values were observed in IPNs cured at room temperature.

Identification of unstable network modules reveals disease modules associated with the progression of Alzheimer's disease.

Directory of Open Access Journals (Sweden)

Masataka Kikuchi

Full Text Available Alzheimer's disease (AD, the most common cause of dementia, is associated with aging, and it leads to neuron death. Deposits of amyloid β and aberrantly phosphorylated tau protein are known as pathological hallmarks of AD, but the underlying mechanisms have not yet been revealed. A high-throughput gene expression analysis previously showed that differentially expressed genes accompanying the progression of AD were more down-regulated than up-regulated in the later stages of AD. This suggested that the molecular networks and their constituent modules collapsed along with AD progression. In this study, by using gene expression profiles and protein interaction networks (PINs, we identified the PINs expressed in three brain regions: the entorhinal cortex (EC, hippocampus (HIP and superior frontal gyrus (SFG. Dividing the expressed PINs into modules, we examined the stability of the modules with AD progression and with normal aging. We found that in the AD modules, the constituent proteins, interactions and cellular functions were not maintained between consecutive stages through all brain regions. Interestingly, the modules were collapsed with AD progression, specifically in the EC region. By identifying the modules that were affected by AD pathology, we found the transcriptional regulation-associated modules that interact with the proteasome-associated module via UCHL5 hub protein, which is a deubiquitinating enzyme. Considering PINs as a system made of network modules, we found that the modules relevant to the transcriptional regulation are disrupted in the EC region, which affects the ubiquitin-proteasome system.

A green approach to prepare silver nanoparticles loaded gum acacia/poly(acrylate) hydrogels.

Science.gov (United States)

Bajpai, S K; Kumari, Mamta

2015-09-01

In this work, gum acacia (GA)/poly(sodium acrylate) semi-interpenetrating polymer networks (Semi-IPN) have been fabricated via free radical initiated aqueous polymerization of monomer sodium acrylate (SA) in the presence of dissolved Gum acacia (GA), using N,N'-methylenebisacrylamide (MB) as cross-linker and potassium persulphate (KPS) as initiator. The semi-IPNs, synthesized, were characterized by various techniques such as X-ray diffraction (XRD), thermo gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The dynamic water uptake behavior of semi-IPNs was investigated and the data were interpreted by various kinetic models. The equilibrium swelling data were used to evaluate various network parameters. The semi-IPNs were used as template for the in situ preparation of silver nanoparticles using extract of Syzygium aromaticum (clove). The formation of silver nanoparticles was confirmed by surface plasmon resonance (SPR), XRD and transmission electron microscopy (TEM). Finally, the antibacterial activity of GA/poly(SA)/silver nanocomposites was tested against E. coli. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of the physical parameters of the nuclear subcritical assembly Chicago 9000 of the IPN using the Serpent code; Determinacion de los parametros fisicos del conjunto subcritico nuclear Chicago 9000 del IPN usando el codigo SERPENT

Energy Technology Data Exchange (ETDEWEB)

Arriaga R, L.; Del Valle G, E. [IPN, Escuela Superior de Fisica y Matematicas, Av. Instituto Politecnico Nacional s/n, U.P. Adolfo Lopez Mateos, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico); Gomez T, A. M., E-mail: guten_tag_04@hotmail.com [ININ, Departamento de Sistemas Nucleares, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

2013-10-15

For the Serpent code was developed the three-dimensional model corresponding to the nuclear subcritical assembly (S A) Chicago 9000 of the Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional (ESFM-IPN). The model includes: a) the core, formed by 312 aluminum pipes that contain 5 nuclear fuel rods (natural uranium in metallic form), b) the multi-perforated plates where they penetrate the inferior part of each pipe to be able to remain in vertical form, c) water, acting as moderator and reflector, and d) the recipient lodging to the core. The pipes arrangement is hexagonal although the transversal section of the recipient that lodges to the core is circular. The entrance file for the Serpent code was generated with the data provided by the manual of the S A use about the composition and density of the fuel rods and others obtained in direct form of the rods, as the interior and external diameter, mass and height. Of the obtained physical parameters, those more approached to that reported in the manual of the subcritical assembly are the effective multiplication factor and the reproduction factor η. The differences can be because the description of the fuel rods provided by the manual of the S A use do not correspond those that are physically in the S A core. This difference consists on the presence of a circular central channel of 1.245 diameter centimeters in each fuel rod. The fuel rods reported in the mentioned manual do not have that channel. Although the obtained results are encouraging, we want to continue improving the model to incorporate in this the detectors, defined this way by the Serpent code, which could determine the existent neutrons flux in diverse points of interest like the axial or radial aligned points and to compare these with those that are obtained in an experimental way when a generating neutrons source (Pu-Be) is introduced. Added to this effort the cross sections for each unitary cell will be determined, so that

Argonne National Laboratory high-performance network support of APS experiments

International Nuclear Information System (INIS)

Knott, M.J.; McMahon, R.J.

1995-01-01

Under the Scientific Facilities Initiative, IPNS is planning to double its operation to 32 weeks/yr. Additional scientific and technical support staff will be added for the greatly expanded user program. The IPNS Upgrade Feasibility Study was published in April 1995 and is a thoroughly documented study on a 1-MW pulsed spallation neutron source at Argonne, including cost and schedule. A new booster target ( 235 U-Mo alloy) has been designed that will increase the neutron flux by a factor of ∼3 and construction will begin soon. A new small angle diffractometer (SAND) is in the final stages of commissioning, a prototype inelastic scattering spectrometer for Chemical Excitations (CHEX) was recently constructed and an upgraded quasielastic spectrometer (QENS) has been designed. IPNS has gained considerable operating experience with solid methane moderators, including controlled heating at periodic intervals in order to anneal the accumulated radiation induced stored energy

Argonne National Laboratory high-performance network support of APS experiments

Energy Technology Data Exchange (ETDEWEB)

Knott, M.J.; McMahon, R.J.

1995-12-31

Under the Scientific Facilities Initiative, IPNS is planning to double its operation to 32 weeks/yr. Additional scientific and technical support staff will be added for the greatly expanded user program. The IPNS Upgrade Feasibility Study was published in April 1995 and is a thoroughly documented study on a 1-MW pulsed spallation neutron source at Argonne, including cost and schedule. A new booster target ({sup 235}U-Mo alloy) has been designed that will increase the neutron flux by a factor of {approximately}3 and construction will begin soon. A new small angle diffractometer (SAND) is in the final stages of commissioning, a prototype inelastic scattering spectrometer for Chemical Excitations (CHEX) was recently constructed and an upgraded quasielastic spectrometer (QENS) has been designed. IPNS has gained considerable operating experience with solid methane moderators, including controlled heating at periodic intervals in order to anneal the accumulated radiation induced stored energy.

Thermosetting polyimide resin matrix composites with interpenetrating polymer networks for precision foil resistor chips based on special mechanical performance requirements

Energy Technology Data Exchange (ETDEWEB)

Wang, X.Y., E-mail: wxy@tju.edu.cn [School of Electronic Information Engineering, Tianjin University, Tianjin 300072 (China); Ma, J.X.; Li, C.G. [School of Electronic Information Engineering, Tianjin University, Tianjin 300072 (China); Wang, H.X. [ZHENGHE electronics Co., Ltd, Jining 272023 (China)

2014-04-01

Highlights: • Macromolecular materials were chosen to modify thermosetting polyimide (TSPI). • The formation of IPN structure in TSPI composite polymers was discussed. • The special mechanical properties required were the main study object. • The desired candidate materials should have proper hardness and toughness. • The specific mechanical data are quantitatively determined by experiments. - Abstract: Based on interpenetrating networks (IPNs) different macromolecular materials such as epoxy, phenolic, and silicone resin were chosen to modify thermosetting polyimide (TSPI) resin to solve the lack of performance when used for protecting precision foil resistor chips. Copolymerization modification, controlled at curing stage, was used to prepare TSPI composites considering both performance and process requirements. The mechanical properties related to trimming process were mainly studied due to the special requirements of the regularity of scratch edges caused by a tungsten needle. The analysis on scratch edges reveals that the generation and propagation of microcracks caused by scratching together with crack closure effect may lead to regular scratch traces. Experiments show that the elongation at break of TSPI composites is the main reason that determines the special mechanical properties. The desired candidate materials should have proper hardness and toughness, and the specific mechanical data are that the mean elongation at break and tensile strength of polymer materials are in the range of 9.2–10.4% and 100–107 MPa, respectively. Possible reasons for the effect of the modifiers chosen on TSPI polymers, the reaction mechanisms on modified TSPI resin and the IPN structure in TSPI composite polymers were discussed based on IR and TG analysis.

Thermosetting polyimide resin matrix composites with interpenetrating polymer networks for precision foil resistor chips based on special mechanical performance requirements

International Nuclear Information System (INIS)

Wang, X.Y.; Ma, J.X.; Li, C.G.; Wang, H.X.

2014-01-01

Highlights: • Macromolecular materials were chosen to modify thermosetting polyimide (TSPI). • The formation of IPN structure in TSPI composite polymers was discussed. • The special mechanical properties required were the main study object. • The desired candidate materials should have proper hardness and toughness. • The specific mechanical data are quantitatively determined by experiments. - Abstract: Based on interpenetrating networks (IPNs) different macromolecular materials such as epoxy, phenolic, and silicone resin were chosen to modify thermosetting polyimide (TSPI) resin to solve the lack of performance when used for protecting precision foil resistor chips. Copolymerization modification, controlled at curing stage, was used to prepare TSPI composites considering both performance and process requirements. The mechanical properties related to trimming process were mainly studied due to the special requirements of the regularity of scratch edges caused by a tungsten needle. The analysis on scratch edges reveals that the generation and propagation of microcracks caused by scratching together with crack closure effect may lead to regular scratch traces. Experiments show that the elongation at break of TSPI composites is the main reason that determines the special mechanical properties. The desired candidate materials should have proper hardness and toughness, and the specific mechanical data are that the mean elongation at break and tensile strength of polymer materials are in the range of 9.2–10.4% and 100–107 MPa, respectively. Possible reasons for the effect of the modifiers chosen on TSPI polymers, the reaction mechanisms on modified TSPI resin and the IPN structure in TSPI composite polymers were discussed based on IR and TG analysis

Utilization of the intense pulsed neutron source (IPNS) at Argonne National Laboratory for neutron activation analysis

International Nuclear Information System (INIS)

Heinrich, R.R.; Greenwood, L.R.; Popek, R.J.; Schulke, A.W. Jr.

1983-01-01

The Intense Pulsed Neutron Source (IPNS) neutron scattering facility (NSF) has been investigated for its applicability to neutron activation analysis. A polyethylene insert has been added to the vertical hole VT3 which enhances the thermal neutron flux by a factor of two. The neutron spectral distribution at this position has been measured by the multiple-foil technique which utilized 28 activation reactions and the STAYSL computer code. The validity of this spectral measurement was tested by two irradiations of National Bureau of Standards SRM-1571 (orchard leaves), SRM-1575 (pine needles), and SRM-1645 (river sediment). The average thermal neutron flux for these irradiations normalized to 10 μamp proton beam is 4.0 x 10 11 n/cm 2 -s. Concentrations of nine trace elements in each of these SRMs have been determined by gamma-ray spectrometry. Agreement of measured values to certified values is demonstrated to be within experiment error

Neutron scattering measurements from cryogenic ammonia: a progress report

International Nuclear Information System (INIS)

Carpenter, J.; Micklich, B.; Zanotti, J.M.

2004-01-01

We survey the results of an earlier study of the inelastic scattering from solid ammonia, and report the results of a preliminary experiment carried out at the ∝100 μeV-resolution quasielastic scattering spectrometer QENS at IPNS. (orig.)

Observations of electrons in the Intense Pulse Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS)

International Nuclear Information System (INIS)

Dooling, J.C.; Brumwell, F.R.; Czyz, W.S.; Harkay, K.C.; Lien, M.K.; McMichael, G.E.

2004-01-01

In the process of accelerating protons from 50 to 450 MeV at 30 Hz, low-energy electrons are generated within the IPNS RCS vacuum chamber. Electrons from background gas stripping are detected using an Ionization Profile Monitor (IPM) to generate integrated, horizontal charge distributions of the single-harmonic bunch during acceleration. Recently, a Retarding Field Analyzer (RFA) was installed in the RCS to look for evidence of beam-induced multipacting by measuring the electrons ejected by the space charge of the beam. A wide-band, high-gain transimpedance amplifier has been built to observe time structure in the electron signal detected with the RFA. Though a noisy power supply prevented full I-V characteristics from being obtained, interesting features are observed; especially, after the period of phase modulation between the rf cavities that is deliberately introduced during the cycle. The phase modulation generates a longitudinal quadrupole oscillation in the bunch, which is believed to enhance beam stability. Preliminary results indicate that electron multipacting is not significant in the RCS. The effects of background gas neutralization are considered and details of the RFA measurements are presented.

Systems-level organization of non-alcoholic fatty liver disease progression network

Directory of Open Access Journals (Sweden)

K. Shubham

2017-10-01

Full Text Available Non-Alcoholic Fatty Liver Disease (NAFLD is a hepatic metabolic disorder that is commonly associated with sedentary lifestyle and high fat diets. NAFLD is prevalent in individuals with obesity, insulin resistance and Type 2 Diabetes (T2D. The clinical spectrum of NAFLD ranges from simple steatosis to Non-Alcoholic Steatohepatitis (NASH with fibrosis, which can progress to cirrhosis and hepatocellular carcinoma.The pathogenesis of NAFLD is complex, involving crosstalk between multiple organs, cell-types, and environmental and genetic factors. Dysfunction of White Adipose Tissue (WAT plays a central role in the development of NAFLD and other metabolic disorders. WAT is an active endocrine organ that regulates whole-body energy homeostasis, lipid metabolism, insulin sensitivity and food intake by secreting biologically active molecules (lipokines, adipokines and cytokines. WAT dynamically reacts to nutrient excess or deprivation by remodelling the number (called hyperplasia and/or size (called hypertrophy of adipocytes to store fat or supply nutrients to other tissues by lipolysis, respectively. Adipose tissue remodelling is also accompanied by changes in the composition or function of stromal vascular cells and ECM. The major objective of our study was to identify and characterize the metabolic and signaling modules associated with the progression of NAFLD in the VAT. We performed Weighted Gene Co-expression Network Analysis (WGCNA to organize microarray data obtained from the VAT of patients at different stages of NAFLD into functional modules. In order to obtain insights into the metabolism and its regulation at the genome scale, a co-expression network of metabolic genes in the Human Metabolic Network (HMR2 was constructed and compared with the co-expression network constructed based on all the varying genes. We also used the prior network information on adipocyte metabolism (GEM to verify and extract reporter metabolites. Our analysis revealed

Gelatin-carboxymethyl tamarind gum biocomposites: In vitro characterization & anti-inflammatory pharmacodynamics

Energy Technology Data Exchange (ETDEWEB)

Jana, Sougata, E-mail: janapharmacy@rediffmail.com; Banerjee, Abhisek; Sen, Kalyan Kumar; Maiti, Sabyasachi

2016-12-01

In this study, gelatin and carboxymethyl tamarind gum (CTG) were chemically cross-linked to control the delivery of aceclofenac from their interpenetrating network (IPNs). Infrared spectra, thermal and X-ray data supported that drug and polymer was compatible in the composite hydrogels. Irregularly shaped IPN microstructures were seen under field emission scanning electron microscope (FE-SEM). IPN system was capable of entrapping about 96% of the drug fed. CTG in IPN structures suppressed the drug release rate in HCl solution (pH 1.2); however extended the same in phosphate buffer solution (pH 6.8). The drug release was controlled by polymer chain relaxation/swelling and simple diffusion in vitro. The anti-inflammatory activity of drug-loaded biocomposites lasted over 7 h in albino rats, thus suggesting their potential as an anti-inflammatory therapeutics. - Highlights: • Novel gelatin-carboxymethyl tamarind gum biocomposites was synthesized. • FTIR, thermal and X-ray study ensured compatibility between drug and polymers. • FE-SEM image revealed irregular shape of the IPN microstructures. • In vivo anti-inflammatory pharmacodynamics in rat model was encouraging.

Radiation synthesis and characterization of network structure of natural/synthetic double-network superabsorbent polymers

International Nuclear Information System (INIS)

Sen, M.; Hayrabolulu, H.

2011-01-01

Complete text of publication follows. Superabsorbent polymers (SAPs) are moderately cross linked, 3-D, hydrophilic network polymers that can absorb and conserve considerable amounts of aqueous fluids even under certain heat or pressure. Because of the unique properties superior to conventional absorbents, SAPs have found potential application in many fields such as hygienic products, disposable diapers, horticulture, gel actuators, drug-delivery systems, as well as water-blocking tapes coal dewatering, water managing materials for the renewal of arid and desert environment, etc. In recent years, naturally available resources, such as polysaccharides have drawn considerable attention for the preparation of SAPs. Since the mechanical properties of polysaccharide based natural polymers are low, researchers have mostly focused on natural/synthetic polymer/monomer mixtures to obtain novel SAPs. The aim of this study is to synthesize and characterization of network structure of novel double-network (DN) hydrogels as a SAP. Hydrogels with high mechanical strength have been prepared by radiation induced polymerization and crosslink of acrylic acid sodium salt in the presence of natural polymer locust bean gum. Liquid retention capacities and absorbency under load (AUL) analysis of synthesized SAPs was performed at different temperatures in water and synthetic urine solution, in order to determine their SAP character. For the characterization of network structure of the semi-IPN hydrogels, the average molecular weight between cross links (M c ) were evaluated by using uniaxial compression and oscillatory dynamical mechanical analyses and the advantage and disadvantage of these two technique for the characterization of network structures were compared.

Progressively Disrupted Brain Functional Connectivity Network in Subcortical Ischemic Vascular Cognitive Impairment Patients.

Science.gov (United States)

Sang, Linqiong; Chen, Lin; Wang, Li; Zhang, Jingna; Zhang, Ye; Li, Pengyue; Li, Chuanming; Qiu, Mingguo

2018-01-01

Cognitive impairment caused by subcortical ischemic vascular disease (SIVD) has been elucidated by many neuroimaging studies. However, little is known regarding the changes in brain functional connectivity networks in relation to the severity of cognitive impairment in SIVD. In the present study, 20 subcortical ischemic vascular cognitive impairment no dementia patients (SIVCIND) and 20 dementia patients (SIVaD) were enrolled; additionally, 19 normal controls were recruited. Each participant underwent a resting-state functional MRI scan. Whole-brain functional networks were analyzed with graph theory and network-based statistics (NBS) to study the functional organization of networks and find alterations in functional connectivity among brain regions. After adjustments for age, gender, and duration of formal education, there were significant group differences for two network functional organization indices, global efficiency and local efficiency, which decreased (NC > SIVCIND > SIVaD) as cognitive impairment worsened. Between-group differences in functional connectivity (NBS corrected, p  impairment worsened, with an increased number of decreased connections between brain regions. We also observed more reductions in nodal efficiency in the prefrontal and temporal cortices for SIVaD than for SIVCIND. These findings indicated a progressively disrupted pattern of the brain functional connectivity network with increased cognitive impairment and showed promise for the development of reliable biomarkers of network metric changes related to cognitive impairment caused by SIVD.

Progress on the IPNS Enriched Uranium Booster Target

International Nuclear Information System (INIS)

Knox, A.E.; Carpenter, J.M.; Bailey, J.L.

1986-09-01

We describe the Enriched Uranium Booster Target designed for use in Argonne's Intense Pulsed Neutron Source. This report contains a general description of the system, and descriptions of the thermal-hydraulic and loss-of-coolant accident analyses, of the neutronic, criticality and power density calculations, of the assessment of radiation and thermal cycling growth, and of the disk fabrication methods. We also describe the calculations of radionuclide buildup and the related hazards analysis and our calculations of the temperature and stress profiles in the disks, and briefly allude to considerations of security and safeguards

Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life.

Science.gov (United States)

Khan, Aftab A; Al-Kheraif, Abdulaziz A; Al-Shehri, Abdullah M; Säilynoja, Eija; Vallittu, Pekka K

2018-02-01

This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as "stage 1-5". To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (Pprepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pilot study of dynamic Bayesian networks approach for fault diagnostics and accident progression prediction in HTR-PM

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yunfei; Tong, Jiejuan; Zhang, Liguo, E-mail: lgzhang@tsinghua.edu.cn; Zhang, Qin

2015-09-15

Highlights: • Dynamic Bayesian network is used to diagnose and predict accident progress in HTR-PM. • Dynamic Bayesian network model of HTR-PM is built based on detailed system analysis. • LOCA Simulations validate the above model even if part monitors are lost or false. - Abstract: The first high-temperature-reactor pebble-bed demonstration module (HTR-PM) is under construction currently in China. At the same time, development of a system that is used to support nuclear emergency response is in progress. The supporting system is expected to complete two tasks. The first one is diagnostics of the fault in the reactor based on abnormal sensor measurements obtained. The second one is prognostic of the accident progression based on sensor measurements obtained and operator actions. Both tasks will provide valuable guidance for emergency staff to take appropriate protective actions. Traditional method for the two tasks relies heavily on expert judgment, and has been proven to be inappropriate in some cases, such as Three Mile Island accident. To better perform the two tasks, dynamic Bayesian networks (DBN) is introduced in this paper and a pilot study based on the approach is carried out. DBN is advantageous in representing complex dynamic systems and taking full consideration of evidences obtained to perform diagnostics and prognostics. Pearl's loopy belief propagation (LBP) algorithm is recommended for diagnostics and prognostics in DBN. The DBN model of HTR-PM is created based on detailed system analysis and accident progression analysis. A small break loss of coolant accident (SBLOCA) is selected to illustrate the application of the DBN model of HTR-PM in fault diagnostics (FD) and accident progression prognostics (APP). Several advantages of DBN approach compared with other techniques are discussed. The pilot study lays the foundation for developing the nuclear emergency response supporting system (NERSS) for HTR-PM.

3D Printed Silicone–Hydrogel Scaffold with Enhanced Physicochemical Properties

DEFF Research Database (Denmark)

Mohanty, Soumyaranjan; Alm, Martin; Hemmingsen, Mette

2016-01-01

is currently a huge challenge. The goal of this work was to fabricate a tissue engineering scaffold from clinically approved materials with the capability of delivering biomolecules and direct cell fate. We have used a simple 3D printing approach, that combines polymer casting with supercritical fluid...... technology to produce 3D interpenetrating polymer network (IPN) scaffold of silicone-poly(2-hydroxyethyl methacrylate)-co-poly(ethylene glycol) methyl ether acrylate (pHEMA-co-PEGMEA). The pHEMA-co-PEGMEA IPN materials were employed to support growth of human mesenchymal stem cells (hMSC), resulting in high...... cell viability and metabolic activity over a 3 weeks period. In addition, the IPN scaffolds support 3D tissue formation inside the porous scaffold with well spread cell morphology on the surface of the scaffold. As a proof of concept, sustained doxycycline (DOX) release from pHEMA-co-PEGMEA IPN...

Informe de investigación sobre deserción escolar mediante jerarquización de factores en la UPIIG, del IPN en Silao, Guanajuato

OpenAIRE

Luis Felipe A. El Sahili González

2011-01-01

La presente investigación se realizó en la Upiig (Unidad Profesional Interdisciplinaria de Ingeniería en Guanajuato), perteneciente al IPN, entre el 5 y el 16 de octubre de 2009. La intención de esta investigación consistió en indagar los principales factores de deserción, en un primer momento, en opinión de todos los actores alrededor del proceso educativo, así como posteriormente aplicar una escala jerarquizada para valorar dichos factores. La forma de lograrlo fue a través de la opinión de...

Gum ghatti based novel electrically conductive biomaterials: A study of conductivity and surface morphology

Directory of Open Access Journals (Sweden)

S. Kalia

2014-04-01

Full Text Available Gum ghatti-cl-poly(acrylamide-aniline interpenetrating network (IPN was synthesized by a two-step aqueous polymerization method, in which aniline monomer was absorbed into the network of gum ghatti-cl-poly(acrylamide and followed by a polymerization reaction between aniline monomers. Initially, semi-IPN based on acrylamide and gum ghatti was prepared by free-radical copolymerization in aqueous media with optimized process parameters, using N,N'-methylenebis-acrylamide, as cross-linker and ammonium persulfate, as an initiator system. Optimum reaction conditions affording maximum percentage swelling were: solvent [mL] =12, Acrylamide (AAm [mol•L–1] = 1.971, Ammonium peroxydisulfate (APS [mol•L–1] = 0.131•10–1, N,N'-methylene-bis-acrylamide (MBA [mol•L–1] = 0.162•10–1, reaction time [min] = 210, temperature [°C] = 100 and pH = 7.0. The resulting IPN was doped with different protonic acids. The effect of the doping has been investigated on the conductivity and surface morphology of the IPN hydrogel. The maximum conductivity was observed with 1.5N HClO4 concentration. The morphological, structural and electrical properties of the candidate polymers were studied using scanning electron micrscopy (SEM, Fourier transform infrared spectroscopy FTIR and two-probe method, respectively.

The time-of-flight small-angle neutron diffractometer (SAD) at IPNS, Argonne National Laboratory

International Nuclear Information System (INIS)

Thiyagarajan, P.; Epperson, J.E.; Crawford, R.K.; Carpenter, J.M.; Klippert, T.E.; Wozniak, D.G.

1997-01-01

The design, development and performance of the time-of-flight (TOF) small-angle diffractometer (SAD) at the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory are described. Similar TOF-SANS instruments are in operation at the pulsed neutron sources at Los Alamos National Laboratory, USA, at Rutherford Appleton Laboratory, England, and at KEK, Japan. These instruments have an advantage by comparison with their steady-state counterparts in that a relatively wide range of momentum transfer (q) can be monitored in a single experiment without the need to alter the collimation or the sample-to-detector distance. This feature makes SANS experiments easy and very effective for studying systems such as those undergoing phase transitions under different conditions, samples that cannot be easily reproduced for repetitive experiments, and systems under high temperature, pressure or shear. Three standard samples are used to demonstrate that the quality of the SANS data from SAD is comparable with those from other established steady-state SANS facilities. Two examples are given to illustrate that the wide q region accessible in a single measurement at SAD is very effective for following the time-dependent phase transitions in paraffins and temperature- and pressure-dependent phase transitions in model biomembranes. (orig.)

Determination of the physical parameters of the nuclear subcritical assembly Chicago 9000 of the IPN using the Serpent code

International Nuclear Information System (INIS)

Arriaga R, L.; Del Valle G, E.; Gomez T, A. M.

2013-10-01

For the Serpent code was developed the three-dimensional model corresponding to the nuclear subcritical assembly (S A) Chicago 9000 of the Escuela Superior de Fisica y Matematicas del Instituto Politecnico Nacional (ESFM-IPN). The model includes: a) the core, formed by 312 aluminum pipes that contain 5 nuclear fuel rods (natural uranium in metallic form), b) the multi-perforated plates where they penetrate the inferior part of each pipe to be able to remain in vertical form, c) water, acting as moderator and reflector, and d) the recipient lodging to the core. The pipes arrangement is hexagonal although the transversal section of the recipient that lodges to the core is circular. The entrance file for the Serpent code was generated with the data provided by the manual of the S A use about the composition and density of the fuel rods and others obtained in direct form of the rods, as the interior and external diameter, mass and height. Of the obtained physical parameters, those more approached to that reported in the manual of the subcritical assembly are the effective multiplication factor and the reproduction factor η. The differences can be because the description of the fuel rods provided by the manual of the S A use do not correspond those that are physically in the S A core. This difference consists on the presence of a circular central channel of 1.245 diameter centimeters in each fuel rod. The fuel rods reported in the mentioned manual do not have that channel. Although the obtained results are encouraging, we want to continue improving the model to incorporate in this the detectors, defined this way by the Serpent code, which could determine the existent neutrons flux in diverse points of interest like the axial or radial aligned points and to compare these with those that are obtained in an experimental way when a generating neutrons source (Pu-Be) is introduced. Added to this effort the cross sections for each unitary cell will be determined, so that

Primary progressive aphasia: A dementia of the language network

Directory of Open Access Journals (Sweden)

Marsel Mesulam

Full Text Available ABSTRACT Primary progressive aphasia (PPA is a clinical syndrome diagnosed when three core criteria are met. First, there should be a language impairment (i.e., aphasia that interferes with the usage or comprehension of words. Second, the neurological work-up should determine that the disease is neurodegenerative, and therefore progressive. Third, the aphasia should arise in relative isolation, without equivalent deficits of comportment or episodic memory. The language impairment can be fluent or non-fluent and may or may not interfere with word comprehension. Memory for recent events is preserved although memory scores obtained in verbally mediated tests may be abnormal. Minor changes in personality and behavior may be present but are not the leading factors that bring the patient to medical attention or that limit daily living activities. This distinctive clinical pattern is most conspicuous in the initial stages of the disease, and reflects a relatively selective atrophy of the language network, usually located in the left hemisphere. There are different clinical variants of PPA, each with a characteristic pattern of atrophy. The underlying neuropathological diseases are heterogeneous and can include Alzheimer's disease as well as frontotemporal lobar degeneration. The clinician's task is to recognize PPA and differentiate it from other neurodegenerative phenotypes, use biomarkers to surmise the nature of the underlying neuropathology, and institute the most fitting multimodal interventions.

Processing and Dynamic Failure Characterization of Novel Impact Absorbing Transparent Interpenetrating Polymer Networks (t-IPN)

Science.gov (United States)

2014-02-01

samples were placed into the oven for the same curing treatment as before. The scanning electron microscope (SEM) photo in Figure 19 shows a typical...Interpenetrating Polymer Networks with Polyurethane and Methacrylate-based Polymers,’ S. A . Bird , PhD Dissertation, Department of Polymer and Fiber Engineering...Jajam, H. V. Tippur, S. A . Bird , and M. L. Auad, Proceedings of the 50th SES Annual Technical Meeting and ASME-AMD Summer Meeting, Providence, RI

The GRB coordinates network (GCN): A status report

International Nuclear Information System (INIS)

Barthelmy, S. D.; Takeshima, T.; Butterworth, P.; Cline, T. L.; Gehrels, N.; Marshall, F.; Connaughton, V.; Kippen, R. M.; Kouveliotou, C.; Robinson, C. R.

1998-01-01

A review of the GRB Coordinates Network (GCN) will be given. The GCN has recently replaced the BATSE Coordinates Distribution Network (BACODINE), maintaining all of BACODINE's original capabilities and services, but also providing new sources of GRB location information. These are: (1) source locations using the MSFC LOCBURST algorithm, (2) the Rossi-XTE detections (PCA and ASM), (3) the Interplanetary Network (IPN) locations, and (4) CGRO-COMPTEL locations. These new sources of locations are available for distribution in the minutes-to-hours-to-days time delay ranges, and they also have increasingly and significantly reduced error boxes, thus providing a broad range of time delays and error box sizes to fit within the observing capabilities of a broad range of follow-up instruments in the radio, optical, and TeV gamma-ray bands. Extreme-UV transients from ALEXIS are also now distributed. For all sources of location information, all the distribution methods are available (Internet Socket, E-mail, Alpha-numeric and Numeric Pagers, and Phone/modem) and several filters. Sites can choose which sources to receive and what filters to be applied. The GCN web site has been expanded to include a globally inclusive table of locations, light-curves, and fluence information which is automatically updated in real-time

Carbon Reduction Strategies Based on an NW Small-World Network with a Progressive Carbon Tax

Directory of Open Access Journals (Sweden)

Bin Wu

2017-09-01

Full Text Available There is an increasingly urgent need to reduce carbon emissions. Devising effective carbon tax policies has become an important research topic. It is necessary to explore carbon reduction strategies based on the design of carbon tax elements. In this study, we explore the effect of a progressive carbon tax policy on carbon emission reductions using the logical deduction method. We apply experience-weighted attraction learning theory to construct an evolutionary game model for enterprises with different levels of energy consumption in an NW small-world network, and study their strategy choices when faced with a progressive carbon tax policy. The findings suggest that enterprises that adopt other energy consumption strategies gradually transform to a low energy consumption strategy, and that this trend eventually spreads to the entire system. With other conditions unchanged, the rate at which enterprises change to a low energy consumption strategy becomes faster as the discount coefficient, the network externality, and the expected adjustment factor increase. Conversely, the rate of change slows as the cost of converting to a low energy consumption strategy increases.

Rossi X-Ray Timing Explorer All-Sky Monitor Localization of SGR 1627-41

Science.gov (United States)

Smith, Donald A.; Bradt, Hale V.; Levine, Alan M.

1999-07-01

The fourth unambiguously identified soft gamma repeater (SGR), SGR 1627-41, was discovered with the BATSE instrument on 1998 June 15. Interplanetary Network (IPN) measurements and BATSE data constrained the location of this new SGR to a 6° segment of a narrow (19") annulus. We present two bursts from this source observed by the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer. We use the ASM data to further constrain the source location to a 5' long segment of the BATSE/IPN error box. The ASM/IPN error box lies within 0.3 arcmin of the supernova remnant G337.0-0.1. The probability that a supernova remnant would fall so close to the error box purely by chance is ~5%.

Healthy brain connectivity predicts atrophy progression in non-fluent variant of primary progressive aphasia.

Science.gov (United States)

Mandelli, Maria Luisa; Vilaplana, Eduard; Brown, Jesse A; Hubbard, H Isabel; Binney, Richard J; Attygalle, Suneth; Santos-Santos, Miguel A; Miller, Zachary A; Pakvasa, Mikhail; Henry, Maya L; Rosen, Howard J; Henry, Roland G; Rabinovici, Gil D; Miller, Bruce L; Seeley, William W; Gorno-Tempini, Maria Luisa

2016-10-01

Neurodegeneration has been hypothesized to follow predetermined large-scale networks through the trans-synaptic spread of toxic proteins from a syndrome-specific epicentre. To date, no longitudinal neuroimaging study has tested this hypothesis in vivo in frontotemporal dementia spectrum disorders. The aim of this study was to demonstrate that longitudinal progression of atrophy in non-fluent/agrammatic variant primary progressive aphasia spreads over time from a syndrome-specific epicentre to additional regions, based on their connectivity to the epicentre in healthy control subjects. The syndrome-specific epicentre of the non-fluent/agrammatic variant of primary progressive aphasia was derived in a group of 10 mildly affected patients (clinical dementia rating equal to 0) using voxel-based morphometry. From this region, the inferior frontal gyrus (pars opercularis), we derived functional and structural connectivity maps in healthy controls (n = 30) using functional magnetic resonance imaging at rest and diffusion-weighted imaging tractography. Graph theory analysis was applied to derive functional network features. Atrophy progression was calculated using voxel-based morphometry longitudinal analysis on 34 non-fluent/agrammatic patients. Correlation analyses were performed to compare volume changes in patients with connectivity measures of the healthy functional and structural speech/language network. The default mode network was used as a control network. From the epicentre, the healthy functional connectivity network included the left supplementary motor area and the prefrontal, inferior parietal and temporal regions, which were connected through the aslant, superior longitudinal and arcuate fasciculi. Longitudinal grey and white matter changes were found in the left language-related regions and in the right inferior frontal gyrus. Functional connectivity strength in the healthy speech/language network, but not in the default network, correlated with

IPN - Orsay Report of activity 1998-1999. Division of Research; IPN - Orsay. Rapport d'activity 1998-1999. Division de Recherche

Energy Technology Data Exchange (ETDEWEB)

Morlet, Marcel; Willis, Alain [eds.; Institut de Physique Nucleaire, 91406 Orsay cedex (France)

2000-01-12

The main direction of research of the Institute of Nuclear Physics at Orsay was the physics of nuclei far from stability line. The high value of the results obtained is due mainly to development of MUST detectors, LISE3 and SPEG spectrometers and use of large size germanium crystals. Important findings in radioactivity, elastic and inelastic scattering, in transfer reactions (in {sup 11}Be for the first time), Coulomb excitation and use of on-line gamma labelling technique, especially applied to neutron rich nuclei around N=20 and 28, are mentioned. Collaborations to projects like EXOGAM, VAMOS, LISE2000 at GANIL as well as the studies on nuclei around {sup 132}Sn at ISOLDE are reviewed. Very promising appear the results obtained with hot nuclei, produced in heavy ion collisions at 30-200 MeV/n and with the new nuclear species produced in relativistic heavy ion collisions. The studies on hadrons in nuclear matter conducted at CERN LHC and GSI at Darmstadt concerned mainly the quark-gluon plasma. The results on J/{psi} suppression obtained by NA50 collaboration appear to signal this state. The studies on hadron structure with the GRAAL experiment at ESRF opened the domain of strange baryon resonances. This second volume of the IPN-Orsay Report of activity has the following content: 1. Nuclear structure far from stability. 1.1. Exotic nuclei-secondary beams of radioactive ions. 1.2. On line spectroscopy. 2. High excitation energy nuclear states. 3. Nuclear matter and nucleus-nucleus collisions. 3,1. Physics of waste management. 3.2. Hot nuclei. 3.3 Ultra-relativistic collisions. 4. Hadronic physics. 4.1. Meson production. 4.2. Hadronic physics with electromagnetic probe. 5. Radiochemistry. 5.1. Study related to radioactive waste management. 5.1.1. Matrix to immobilize actinide compounds. 5.1.2. Thorium cycle. 5.1.3. Study of solid/solution interfaces. 5.1.4. Solution chemistry of some long life fission products. 5.2. Solution chemistry of lanthanides and actinides. 5

RXTE All-Sky Monitor Localization of SGR 1627-41

Science.gov (United States)

Smith, D. A.; Bradt, H. V.; Levine, A. M.

1999-09-01

The fourth unambiguously identified Soft Gamma Repeater (SGR), SGR 1627--41, was discovered with the BATSE instrument on 1998 June 15 (Kouveliotou et al. 1998). Interplanetary Network (IPN) measurements and BATSE data constrained the location of this new SGR to a 6(deg) segment of a narrow (19('') ) annulus (Hurley et al. 1999; Woods et al. 1998). We report on two bursts from this source observed by the All-Sky Monitor (ASM) on RXTE. We use the ASM data to further constrain the source location to a 5(') long segment of the BATSE/IPN error box. The ASM/IPN error box lies within 0.3(') of the supernova remnant (SNR) G337.0--0.1. The probability that a SNR would fall so close to the error box purely by chance is ~ 5%.

Proton conductive membranes based on poly (styrene-co-allyl alcohol semi-IPN

Directory of Open Access Journals (Sweden)

Felipe Augusto Moro Loureiro

2014-01-01

Full Text Available The optimization of fuel cell materials, particularly polymer membranes, for PEMFC has driven the development of methods and alternatives to achieve systems with more adequate properties to this application. The sulfonation of poly (styrene-co-allyl alcohol (PSAA, using sulfonating agent:styrene ratios of 2:1, 1:1, 1:2, 1:4, 1:6, 1:8 and 1:10, was previously performed to obtain proton conductive polymer membranes. Most of those membranes exhibited solubility in water with increasing temperature and showed conductivity of approximately 10-5 S cm-1. In order to optimize the PSAA properties, especially decreasing its solubility, semi-IPN (SIPN membranes are proposed in the present study. These membranes were obtained from the diglycidyl ether of bisphenol A (DGEBA, curing reactions in presence of DDS (4,4-diaminodiphenyl sulfone and PSAA. Different DGEBA/PSAA weight ratios were employed, varying the PSAA concentration between 9 and 50% and keeping the mass ratio of DGEBA:DDS as 1:1. The samples were characterized by FTIR and by electrochemical impedance spectroscopy. Unperturbed bands of PSAA were observed in the FTIR spectra of membranes, suggesting that chemical integrity of the polymer is maintained during the synthesis. In particular, bands involving C-C stretching (1450 cm-1, C=C (aromatic, ~ 3030 cm-1 and C-H (2818 and 2928 cm-1 were observed, unchanged after the synthesis. The disappearance or reduction of the intensity of the band at 916 cm-1, attributed to the DGEBA epoxy ring, is evidenced for all samples, indicating the epoxy ring opening and the DGEBA crosslinking. Conductivity of H3PO4 doped membranes increases with temperature, reaching 10-4 S cm-1.

Performance and biocompatibility of extremely tough alginate/polyacrylamide hydrogels.

Science.gov (United States)

Darnell, Max C; Sun, Jeong-Yun; Mehta, Manav; Johnson, Christopher; Arany, Praveen R; Suo, Zhigang; Mooney, David J

2013-11-01

Although hydrogels now see widespread use in a host of applications, low fracture toughness and brittleness have limited their more broad use. As a recently described interpenetrating network (IPN) of alginate and polyacrylamide demonstrated a fracture toughness of ≈ 9000 J/m(2), we sought to explore the biocompatibility and maintenance of mechanical properties of these hydrogels in cell culture and in vivo conditions. These hydrogels can sustain a compressive strain of over 90% with minimal loss of Young's Modulus as well as minimal swelling for up to 50 days of soaking in culture conditions. Mouse mesenchymal stem cells exposed to the IPN gel-conditioned media maintain high viability, and although cells exposed to conditioned media demonstrate slight reductions in proliferation and metabolic activity (WST assay), these effects are abrogated in a dose-dependent manner. Implantation of these IPN hydrogels into subcutaneous tissue of rats for 8 weeks led to mild fibrotic encapsulation and minimal inflammatory response. These results suggest the further exploration of extremely tough alginate/PAAM IPN hydrogels as biomaterials. © 2013 Elsevier Ltd. All rights reserved.

Transformation to problem and project based learning

DEFF Research Database (Denmark)

Kolmos, Anette

2006-01-01

During the last ten years, Engineering Education has undergone tremendous changes. A lot of these changes were caused by external and internal factors. The external factors such as government policy concerning resources, and educational and quality assurance policies are rather simple to describe......). Particularly five Engineering University Colleges have undergone changes towards PBL. The Pedagogical Network for Danish Engineering Education (IPN) has been one of the central agents in the change processes for engineering education in Denmark. IPN has been responsible for staff and faculty development...

Formation of semi-IPN membrane composed of crosslinked SPS-[PVdF-co-HFP/Nafion] for application in DMFC: A fine tuning between crosslinker and initiator

Energy Technology Data Exchange (ETDEWEB)

Kumar, Piyush; Kundu, Patit Paban, E-mail: ppk923@yahoo.com

2015-08-15

The semi-interpenetrating (semi-IPN) membrane composed of crosslinked sulfonated polystyrene (SPS) within the host blend of PVdF-co-HFP (Polyvinylidenefluoride-co-hexafluoropropylene) and Nafion has already been tested as a promising polymer electrolyte membrane (PEM) in terms of improved water uptake, proton conductivity and electrical efficiency for application in the direct methanol fuel cell (DMFC). These desired results have generated further curiosity about a fine tuning between the contents of divinyl benzene (DVB) as a crosslinker and azobisisobutyronitrile (AIBN) as an initiator for the optimization of PEM characteristics. It has been observed that an increase in AIBN content leads to an acceptable degree of water uptake, swelling ratio and proton conductivity in PEM, while higher DVB content causes declined methanol crossover, leading to higher membrane selectivity. These two opposing effects are optimized in terms of proton conductivity, tensile strength and membrane selectivity for the membrane consisting of 0.4 wt% of AIBN and 1.2 wt% of DVB. Moreover, the maximum power density obtained for the membrane having optimum selectivity is 56 mW cm{sup −2}, when analyzed at 90 °C. These results indicate that one can achieve a high power density in comparison to Nafion by fine tuning the contents of initiator and cross-linker during the synthesis of the semi-IPN membrane. - Graphical abstract: Display Omitted - Highlights: • PEM composed of 0.4/1.2 wt% of AIBN/DVB produced best result. • Lower methanol crossover (1.02 × 10{sup −6} cm{sup 2} s{sup −1}) compare to Nafion-117. • Higher membrane selectivity i.e 3.05 × 10{sup 4} Ss cm{sup −3} was obtained. • A maximum power density of 56 mW cm{sup −2} was obtained at 90 °C.

Formation of semi-IPN membrane composed of crosslinked SPS-[PVdF-co-HFP/Nafion] for application in DMFC: A fine tuning between crosslinker and initiator

International Nuclear Information System (INIS)

Kumar, Piyush; Kundu, Patit Paban

2015-01-01

The semi-interpenetrating (semi-IPN) membrane composed of crosslinked sulfonated polystyrene (SPS) within the host blend of PVdF-co-HFP (Polyvinylidenefluoride-co-hexafluoropropylene) and Nafion has already been tested as a promising polymer electrolyte membrane (PEM) in terms of improved water uptake, proton conductivity and electrical efficiency for application in the direct methanol fuel cell (DMFC). These desired results have generated further curiosity about a fine tuning between the contents of divinyl benzene (DVB) as a crosslinker and azobisisobutyronitrile (AIBN) as an initiator for the optimization of PEM characteristics. It has been observed that an increase in AIBN content leads to an acceptable degree of water uptake, swelling ratio and proton conductivity in PEM, while higher DVB content causes declined methanol crossover, leading to higher membrane selectivity. These two opposing effects are optimized in terms of proton conductivity, tensile strength and membrane selectivity for the membrane consisting of 0.4 wt% of AIBN and 1.2 wt% of DVB. Moreover, the maximum power density obtained for the membrane having optimum selectivity is 56 mW cm −2 , when analyzed at 90 °C. These results indicate that one can achieve a high power density in comparison to Nafion by fine tuning the contents of initiator and cross-linker during the synthesis of the semi-IPN membrane. - Graphical abstract: Display Omitted - Highlights: • PEM composed of 0.4/1.2 wt% of AIBN/DVB produced best result. • Lower methanol crossover (1.02 × 10 −6 cm 2 s −1 ) compare to Nafion-117. • Higher membrane selectivity i.e 3.05 × 10 4 Ss cm −3 was obtained. • A maximum power density of 56 mW cm −2 was obtained at 90 °C

IPN - Orsay Report of activity 1998-1999. Division of Research; IPN - Orsay. Rapport d'activity 1998-1999. Division de Recherche

Energy Technology Data Exchange (ETDEWEB)

Morlet, Marcel; Willis, Alain [eds.] [Institut de Physique Nucleaire, 91406 Orsay cedex (France)

2000-01-12

The main direction of research of the Institute of Nuclear Physics at Orsay was the physics of nuclei far from stability line. The high value of the results obtained is due mainly to development of MUST detectors, LISE3 and SPEG spectrometers and use of large size germanium crystals. Important findings in radioactivity, elastic and inelastic scattering, in transfer reactions (in {sup 11}Be for the first time), Coulomb excitation and use of on-line gamma labelling technique, especially applied to neutron rich nuclei around N=20 and 28, are mentioned. Collaborations to projects like EXOGAM, VAMOS, LISE2000 at GANIL as well as the studies on nuclei around {sup 132}Sn at ISOLDE are reviewed. Very promising appear the results obtained with hot nuclei, produced in heavy ion collisions at 30-200 MeV/n and with the new nuclear species produced in relativistic heavy ion collisions. The studies on hadrons in nuclear matter conducted at CERN LHC and GSI at Darmstadt concerned mainly the quark-gluon plasma. The results on J/{psi} suppression obtained by NA50 collaboration appear to signal this state. The studies on hadron structure with the GRAAL experiment at ESRF opened the domain of strange baryon resonances. This second volume of the IPN-Orsay Report of activity has the following content: 1. Nuclear structure far from stability. 1.1. Exotic nuclei-secondary beams of radioactive ions. 1.2. On line spectroscopy. 2. High excitation energy nuclear states. 3. Nuclear matter and nucleus-nucleus collisions. 3,1. Physics of waste management. 3.2. Hot nuclei. 3.3 Ultra-relativistic collisions. 4. Hadronic physics. 4.1. Meson production. 4.2. Hadronic physics with electromagnetic probe. 5. Radiochemistry. 5.1. Study related to radioactive waste management. 5.1.1. Matrix to immobilize actinide compounds. 5.1.2. Thorium cycle. 5.1.3. Study of solid/solution interfaces. 5.1.4. Solution chemistry of some long life fission products. 5.2. Solution chemistry of lanthanides and actinides. 5

Design and Evaluation of Chitosan-Based Novel pH- Sensitive Drug ...

African Journals Online (AJOL)

Method: pH sensitive interpenetrating network (IPN) cefixime microspheres based on chitosan, its grafted copolymer, and hydrolyzed grafted copolymer were prepared by precipitation and .... hydrochloric acid, glutaradehyde, acetic acid and.

Aliphatic amine cured PDMS–epoxy interpenetrating network ...

Indian Academy of Sciences (India)

Unknown

Tg, heat-distortion temperature and reduced the percentage weight loss with ... The siliconized epoxy IPN, with better impact and thermal resistance, ... However, these materials also deteriorate ... the method of compounding remains the state of the art. ... geneity and to ascertain any chemical change during storage.

The Ulysses supplement to the Granat/WATCH catalog of cosmic gamma-ray bursts

DEFF Research Database (Denmark)

Hurley, K.; Lund, Niels; Brandt, Søren Kristian

2000-01-01

We present third Interplanetary Network (IPN) localization data for 56 gamma-ray bursts in the Granat/WATCH catalog that occurred between 1990 November and 1994 September. These localizations are obtained by triangulation using various combinations of spacecraft and instruments in the IPN, which ...... consisted of Ulysses, BATSE, Pioneer Venus Orbiter, Mars Observer, WATCH, and PHEBUS. The intersections of the triangulation annuli with the WATCH error circles produce error boxes with areas as small as 16 arcmin(2), reducing the sizes of the error circles by factors of up to 800....

Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

Energy Technology Data Exchange (ETDEWEB)

Hsu, Chia-Wen [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Ma, Chen-Chi M., E-mail: ccma@che.nthu.edu.tw [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Tan, Chung-Sung [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Li, Hsun-Tien [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

2015-07-15

The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ{sub 1}) and 753.6 h (ζ{sub 2}) at 55 °C. The ζ{sub 1} of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ{sub 2} can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. - Highlights: • The cured network conformations of DGEBA–PMSE hybrids were studied using DMA. • The structural relaxation behaviours of DGEBA–PMSE hybrids were studied using PALS. • The cured DGEBA–PMSE hybrids were interpenetrating polymer networks (IPNs). • PALS studies provided a quantitative demonstration of relaxation behaviours. • Double additive exponential model effectively predicted the relaxation times of hybrids.

Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

International Nuclear Information System (INIS)

Hsu, Chia-Wen; Ma, Chen-Chi M.; Tan, Chung-Sung; Li, Hsun-Tien

2015-01-01

The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ 1 ) and 753.6 h (ζ 2 ) at 55 °C. The ζ 1 of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ 2 can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. - Highlights: • The cured network conformations of DGEBA–PMSE hybrids were studied using DMA. • The structural relaxation behaviours of DGEBA–PMSE hybrids were studied using PALS. • The cured DGEBA–PMSE hybrids were interpenetrating polymer networks (IPNs). • PALS studies provided a quantitative demonstration of relaxation behaviours. • Double additive exponential model effectively predicted the relaxation times of hybrids

Novel blends of acrylonitrile butadiene rubber and polyurethane-silica hybrid networks

Directory of Open Access Journals (Sweden)

X. P. Wang

2012-07-01

Full Text Available Novel blends of acrylonitrile butadiene rubber (NBR and polyurethane-silica (PU-SiO2 hybrid networks have been prepared by melt blending. The PU-SiO2 hybrid networks were formed via the reaction of NCO groups of NCO-terminated PU prepolymer and OH groups of SiO2 in the absence of an external crosslinking agent (i.e. alcohols and amines during the curing process of NBR. Both in the neat PU-SiO2 system and the NBR/(PU-SiO2 system, the NCO-terminated PU prepolymer could be crosslinked by SiO2 to form PU-SiO2 hybrid networks. The effects of PU-SiO2 introduction into the NBR, on the properties of the resulting blends were studied. It was found that the vulcanization was activated by the incorporation of PU-SiO2. Transmission electronic microscopy (TEM studies indicated that the interpenetration and entanglement structures between NBR and PU-SiO2 increased with increasing PU-SiO2 content and the quasi-interpenetrating polymer networks (quasi-IPN structures were formed when the PU-SiO2 was 50 wt% in the NBR/(PU-SiO2 systems. The microstructures formed in the blends led to good compatibility between NBR and PU-SiO2 and significantly improved the mechanical properties, abrasion resistance and flex-fatigue life of the blends.

Swelling and Shrinking Properties of Thermo-Responsive Polymeric Ionic Liquid Hydrogels with Embedded Linear pNIPAAM

Directory of Open Access Journals (Sweden)

Simon Gallagher

2014-03-01

Full Text Available In this study, varying concentrations of linear pNIPAAM have been incorporated for the first time into a thermo-responsive polymeric ionic liquid (PIL hydrogel, namely tributyl-hexyl phosphonium 3-sulfopropylacrylate (P-SPA, to produce semi-interpenetrating polymer networks. The thermal properties of the resulting hydrogels have been investigated along with their thermo-induced shrinking and reswelling capabilities. The semi-interpenetrating networks (IPN hydrogels were found to have improved shrinking and reswelling properties compared with their PIL counterpart. At elevated temperatures (50–80 °C, it was found that the semi-IPN with the highest concentration of hydrophobic pNIPAAM exhibited the highest shrinking percentage of ~40% compared to the conventional P-SPA, (27%. This trend was also found to occur for the reswelling measurements, with semi-IPN hydrogels producing the highest reswelling percentage of ~67%, with respect to its contracted state. This was attributed to an increase in water affinity due to the presence of hydrophilic pNIPAAM. Moreover, the presence of linear pNIPAAM in the polymer matrix leads to improved shrinking and reswelling response compared to the equivalent PIL.

Progressive gender differences of structural brain networks in healthy adults: a longitudinal, diffusion tensor imaging study.

Directory of Open Access Journals (Sweden)

Yu Sun

Full Text Available Sexual dimorphism in the brain maturation during childhood and adolescence has been repeatedly documented, which may underlie the differences in behaviors and cognitive performance. However, our understanding of how gender modulates the development of structural connectome in healthy adults is still not entirely clear. Here we utilized graph theoretical analysis of longitudinal diffusion tensor imaging data over a five-year period to investigate the progressive gender differences of brain network topology. The brain networks of both genders showed prominent economical "small-world" architecture (high local clustering and short paths between nodes. Additional analysis revealed a more economical "small-world" architecture in females as well as a greater global efficiency in males regardless of scan time point. At the regional level, both increased and decreased efficiency were found across the cerebral cortex for both males and females, indicating a compensation mechanism of cortical network reorganization over time. Furthermore, we found that weighted clustering coefficient exhibited significant gender-time interactions, implying different development trends between males and females. Moreover, several specific brain regions (e.g., insula, superior temporal gyrus, cuneus, putamen, and parahippocampal gyrus exhibited different development trajectories between males and females. Our findings further prove the presence of sexual dimorphism in brain structures that may underlie gender differences in behavioral and cognitive functioning. The sex-specific progress trajectories in brain connectome revealed in this work provide an important foundation to delineate the gender related pathophysiological mechanisms in various neuropsychiatric disorders, which may potentially guide the development of sex-specific treatments for these devastating brain disorders.

Progressive gender differences of structural brain networks in healthy adults: a longitudinal, diffusion tensor imaging study.

Science.gov (United States)

Sun, Yu; Lee, Renick; Chen, Yu; Collinson, Simon; Thakor, Nitish; Bezerianos, Anastasios; Sim, Kang

2015-01-01

Sexual dimorphism in the brain maturation during childhood and adolescence has been repeatedly documented, which may underlie the differences in behaviors and cognitive performance. However, our understanding of how gender modulates the development of structural connectome in healthy adults is still not entirely clear. Here we utilized graph theoretical analysis of longitudinal diffusion tensor imaging data over a five-year period to investigate the progressive gender differences of brain network topology. The brain networks of both genders showed prominent economical "small-world" architecture (high local clustering and short paths between nodes). Additional analysis revealed a more economical "small-world" architecture in females as well as a greater global efficiency in males regardless of scan time point. At the regional level, both increased and decreased efficiency were found across the cerebral cortex for both males and females, indicating a compensation mechanism of cortical network reorganization over time. Furthermore, we found that weighted clustering coefficient exhibited significant gender-time interactions, implying different development trends between males and females. Moreover, several specific brain regions (e.g., insula, superior temporal gyrus, cuneus, putamen, and parahippocampal gyrus) exhibited different development trajectories between males and females. Our findings further prove the presence of sexual dimorphism in brain structures that may underlie gender differences in behavioral and cognitive functioning. The sex-specific progress trajectories in brain connectome revealed in this work provide an important foundation to delineate the gender related pathophysiological mechanisms in various neuropsychiatric disorders, which may potentially guide the development of sex-specific treatments for these devastating brain disorders.

Interpenetrating network ceramic-resin composite dental restorative materials.

Science.gov (United States)

Swain, M V; Coldea, A; Bilkhair, A; Guess, P C

2016-01-01

This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications. Initially the basis of interpenetrating network materials is defined along with placing them into a materials science perspective. This involves identifying potential advantages of such structures beyond that of the individual materials or simple mixing of the components. Observations from a number of recently published papers on this class of materials are summarized. These include the strength, fracture toughness, hardness and damage tolerance, namely to pointed and blunt (spherical) indentation as well as to burr adjustment. In addition a summary of recent results of crowns subjected to simulated clinical conditions using a chewing simulator are presented. These results are rationalized on the basis of existing theoretical considerations. The currently available ceramic-resin IPN material for clinical application is softer, exhibits comparable strength and fracture toughness but with substantial R-curve behavior, has lower E modulus and is more damage tolerant than existing glass-ceramic materials. Chewing simulation observations with crowns of this material indicate that it appears to be more resistant to sliding/impact induced cracking although its overall contact induced breakage load is modest. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Concept of polymer alloy electrolytes: towards room temperature operation of lithium-polymer batteries

International Nuclear Information System (INIS)

Noda, Kazuhiro; Yasuda, Toshikazu; Nishi, Yoshio

2004-01-01

Polymer alloy technique is very powerful tool to tune the ionic conductivity and mechanical strength of polymer electrolyte. A semi-interpenetrating polymer network (semi-IPN) polymer alloy electrolyte, composed of non-cross-linkable siloxane-based polymer and cross-linked 3D network polymer, was prepared. Such polymer alloy electrolyte has quite high ionic conductivity (more than 10 -4 Scm -1 at 25 o C and 10 -5 Scm -1 at -10 o C) and mechanical strength as a separator film with a wide electrochemical stability window. A lithium metal/semi-IPN polymer alloy solid state electrolyte/LiCoO 2 cell demonstrated promising cycle performance with room temperature operation of the energy density of 300Wh/L and better rate performance than conventional PEO based lithium polymer battery ever reported

Perilipin Expression Reveals Adipogenic Potential of hADSCs inside Superporous Polymeric Cellular Delivery Systems

Directory of Open Access Journals (Sweden)

Sorina Dinescu

2014-01-01

Full Text Available Recent progress in tissue engineering and regenerative medicine envisages the use of cell-scaffold bioconstructs to best mimic the natural in vivo microenvironment. Our aim was not only to develop novel 3D porous scaffolds for regenerative applications by the association of gelatin (G, alginate (A, and polyacrylamide (PAA major assets but also to evaluate their in vitro potential to support human adipose-derived stem cells (hADSCs adipogenesis. G-A-PAA biomatrix investigated in this work is an interesting substrate combining the advantages of the three individual constituents, namely, biodegradability of G, hydrophilicity of A and PAA, superior elasticity at compression with respect to the G-A and PAA controls, and the capacity to generate porous scaffolds. hADSCs inside these novel interpenetrating polymer networks (IPNs were able to populate the entire scaffold structure and to display their characteristic spindle-like shape as a consequence of a good interaction with G component of the matrices. Additionally, hADSCs proved to display the capacity to differentiate towards mature adipocytes, to accumulate lipids inside their cytoplasm, and to express perilipin late adipogenic marker inside novel IPNs described in this study. On long term, this newly designed biomatrix aims to represent a stem cell delivery system product dedicated for modern regenerative strategies.

Primary progressive aphasia and the evolving neurology of the language network.

Science.gov (United States)

Mesulam, M-Marsel; Rogalski, Emily J; Wieneke, Christina; Hurley, Robert S; Geula, Changiz; Bigio, Eileen H; Thompson, Cynthia K; Weintraub, Sandra

2014-10-01

Primary progressive aphasia (PPA) is caused by selective neurodegeneration of the language-dominant cerebral hemisphere; a language deficit initially arises as the only consequential impairment and remains predominant throughout most of the course of the disease. Agrammatic, logopenic and semantic subtypes, each reflecting a characteristic pattern of language impairment and corresponding anatomical distribution of cortical atrophy, represent the most frequent presentations of PPA. Such associations between clinical features and the sites of atrophy have provided new insights into the neurology of fluency, grammar, word retrieval, and word comprehension, and have necessitated modification of concepts related to the functions of the anterior temporal lobe and Wernicke's area. The underlying neuropathology of PPA is, most commonly, frontotemporal lobar degeneration in the agrammatic and semantic forms, and Alzheimer disease (AD) pathology in the logopenic form; the AD pathology often displays atypical and asymmetrical anatomical features consistent with the aphasic phenotype. The PPA syndrome reflects complex interactions between disease-specific neuropathological features and patient-specific vulnerability. A better understanding of these interactions might help us to elucidate the biology of the language network and the principles of selective vulnerability in neurodegenerative diseases. We review these aspects of PPA, focusing on advances in our understanding of the clinical features and neuropathology of PPA and what they have taught us about the neural substrates of the language network.

Learning oncogenetic networks by reducing to mixed integer linear programming.

Science.gov (United States)

Shahrabi Farahani, Hossein; Lagergren, Jens

2013-01-01

Cancer can be a result of accumulation of different types of genetic mutations such as copy number aberrations. The data from tumors are cross-sectional and do not contain the temporal order of the genetic events. Finding the order in which the genetic events have occurred and progression pathways are of vital importance in understanding the disease. In order to model cancer progression, we propose Progression Networks, a special case of Bayesian networks, that are tailored to model disease progression. Progression networks have similarities with Conjunctive Bayesian Networks (CBNs) [1],a variation of Bayesian networks also proposed for modeling disease progression. We also describe a learning algorithm for learning Bayesian networks in general and progression networks in particular. We reduce the hard problem of learning the Bayesian and progression networks to Mixed Integer Linear Programming (MILP). MILP is a Non-deterministic Polynomial-time complete (NP-complete) problem for which very good heuristics exists. We tested our algorithm on synthetic and real cytogenetic data from renal cell carcinoma. We also compared our learned progression networks with the networks proposed in earlier publications. The software is available on the website https://bitbucket.org/farahani/diprog.

BACODINE/3rd Interplanetary Network burst localization

International Nuclear Information System (INIS)

Hurley, K.; Barthelmy, S.; Butterworth, P.; Cline, T.; Sommer, M.; Boer, M.; Niel, M.; Kouveliotou, C.; Fishman, G.; Meegan, C.

1996-01-01

Even with only two widely separated spacecraft (Ulysses and GRO), 3rd Interplanetary Network (IPN) localizations can reduce the areas of BATSE error circles by two orders of magnitude. Therefore it is useful to disseminate them as quickly as possible following BATSE bursts. We have implemented a system which transmits the light curves of BACODINE/BATSE bursts directly by e-mail to UC Berkeley immediately after detection. An automatic e-mail parser at Berkeley watches for these notices, determines the Ulysses crossing time window, and initiates a search for the burst data on the JPL computer as they are received. In ideal cases, it is possible to retrieve the Ulysses data within a few hours of a burst, generate an annulus of arrival directions, and e-mail it out to the astronomical community by local nightfall. Human operators remain in this loop, but we are developing a fully automated routine which should remove them, at least for intense events, and reduce turn-around times to an absolute minimum. We explain the current operations, the data types used, and the speed/accuracy tradeoffs

IPN. Annual progress report. 1 Sep 1984 - 30 Aug 1985

International Nuclear Information System (INIS)

1985-01-01

This report presents the work of the year 1985 of research in the Division of experimental physics of the Institute of Nuclear Physics in Orsay, the activities are conducted in six axes: nuclear structure, high excitation energy nuclear states, heavy ion collision phenomena, intermediate energy nuclear physics, radiochemistry and perinuclear research. The second part presents the studies of the theoretical physics division of the Institute for Nuclear Physics in Orsay in 1985. The different research axes are the following: nuclear physics, intermediate energy nuclear physics, elementary particles. A compilation of publications of meetings of the year is finally given [fr

WOOD HEMICELLULOSE/CHITOSAN-BASED SEMI-INTERPENETRATING NETWORK HYDROGELS: MECHANICAL, SWELLING AND CONTROLLED DRUG RELEASE PROPERTIES

Directory of Open Access Journals (Sweden)

Muzaffer Ahmet Karaaslan

2010-04-01

Full Text Available The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose, and glucose. The effects of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study, and the ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid.

SCIENTIFIC PROGRESS OF THE MC-PAD NETWORK

CERN Document Server

Aguilar, J; Ambalathankandy, P; Apostolakis, J; Arora, R; Balog, T; Behnke, T; Beltrame, P; Bencivenni, G; Caiazza, S; Dong, J; Heller, M; Heuser, J; Idzik, M; Joram, C; Klanner, R; Koffeman, E; Korpar, S; Kramberger, G; Lohmann, W; Milovanović, M; Miscetti, S; Moll, M; Novgorodova, O; Pacifico, N; Pirvutoiu, C; Radu, R; Rahman, S; Rohe, T; Ropelewski, L; Roukoutakis, F; Schmidt, C; Schön, R; Sibille, J; Tsagri, M; Turala, M; Van Beuzekom, M; Verheyden, R; Villa, M; Zappon, F; Zawiejski, L; Zhang, J

2013-01-01

MC-PAD is a multi-site Initial Training Network on particle detectors in physics experiments. It comprises nine academic participants, three industrial partners and two associated academic partners. 17 recruited Early Stage and 5 Experienced Researchers have performed their scientific work in the network. The research and development work of MC-PAD is organized in 12 work packages, which focus on a large variety of aspects of particle detector development, electronics as well as simulation and modelling. The network was established in November 2008 and lasted until October 2012 (48 months). This report describes the R&D activities and highlights the main results achieved during this period.

Stress relaxing hyaluronic acid-collagen hydrogels promote cell spreading, fiber remodeling, and focal adhesion formation in 3D cell culture.

Science.gov (United States)

Lou, Junzhe; Stowers, Ryan; Nam, Sungmin; Xia, Yan; Chaudhuri, Ovijit

2018-02-01

The physical and architectural cues of the extracellular matrix (ECM) play a critical role in regulating important cellular functions such as spreading, migration, proliferation, and differentiation. Natural ECM is a complex viscoelastic scaffold composed of various distinct components that are often organized into a fibrillar microstructure. Hydrogels are frequently used as synthetic ECMs for 3D cell culture, but are typically elastic, due to covalent crosslinking, and non-fibrillar. Recent work has revealed the importance of stress relaxation in viscoelastic hydrogels in regulating biological processes such as spreading and differentiation, but these studies all utilize synthetic ECM hydrogels that are non-fibrillar. Key mechanotransduction events, such as focal adhesion formation, have only been observed in fibrillar networks in 3D culture to date. Here we present an interpenetrating network (IPN) hydrogel system based on HA crosslinked with dynamic covalent bonds and collagen I that captures the viscoelasticity and fibrillarity of ECM in tissues. The IPN hydrogels exhibit two distinct processes in stress relaxation, one from collagen and the other from HA crosslinking dynamics. Stress relaxation in the IPN hydrogels can be tuned by modulating HA crosslinker affinity, molecular weight of the HA, or HA concentration. Faster relaxation in the IPN hydrogels promotes cell spreading, fiber remodeling, and focal adhesion (FA) formation - behaviors often inhibited in other hydrogel-based materials in 3D culture. This study presents a new, broadly adaptable materials platform for mimicking key ECM features of viscoelasticity and fibrillarity in hydrogels for 3D cell culture and sheds light on how these mechanical and structural cues regulate cell behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

IPN - Orsay Report of activity 1998-1999. Division of Research

International Nuclear Information System (INIS)

Morlet, Marcel; Willis, Alain

2000-01-01

The main direction of research of the Institute of Nuclear Physics at Orsay was the physics of nuclei far from stability line. The high value of the results obtained is due mainly to development of MUST detectors, LISE3 and SPEG spectrometers and use of large size germanium crystals. Important findings in radioactivity, elastic and inelastic scattering, in transfer reactions (in 11 Be for the first time), Coulomb excitation and use of on-line gamma labelling technique, especially applied to neutron rich nuclei around N=20 and 28, are mentioned. Collaborations to projects like EXOGAM, VAMOS, LISE2000 at GANIL as well as the studies on nuclei around 132 Sn at ISOLDE are reviewed. Very promising appear the results obtained with hot nuclei, produced in heavy ion collisions at 30-200 MeV/n and with the new nuclear species produced in relativistic heavy ion collisions. The studies on hadrons in nuclear matter conducted at CERN LHC and GSI at Darmstadt concerned mainly the quark-gluon plasma. The results on J/ψ suppression obtained by NA50 collaboration appear to signal this state. The studies on hadron structure with the GRAAL experiment at ESRF opened the domain of strange baryon resonances. This second volume of the IPN-Orsay Report of activity has the following content: 1. Nuclear structure far from stability. 1.1. Exotic nuclei-secondary beams of radioactive ions. 1.2. On line spectroscopy. 2. High excitation energy nuclear states. 3. Nuclear matter and nucleus-nucleus collisions. 3,1. Physics of waste management. 3.2. Hot nuclei. 3.3 Ultra-relativistic collisions. 4. Hadronic physics. 4.1. Meson production. 4.2. Hadronic physics with electromagnetic probe. 5. Radiochemistry. 5.1. Study related to radioactive waste management. 5.1.1. Matrix to immobilize actinide compounds. 5.1.2. Thorium cycle. 5.1.3. Study of solid/solution interfaces. 5.1.4. Solution chemistry of some long life fission products. 5.2. Solution chemistry of lanthanides and actinides. 5

Disrupted Brain Network in Progressive Mild Cognitive Impairment Measured by Eigenvector Centrality Mapping is Linked to Cognition and Cerebrospinal Fluid Biomarkers.

Science.gov (United States)

Qiu, Tiantian; Luo, Xiao; Shen, Zhujing; Huang, Peiyu; Xu, Xiaojun; Zhou, Jiong; Zhang, Minming

2016-10-18

Mild cognitive impairment (MCI) is a heterogeneous condition associated with a high risk of progressing to Alzheimer's disease (AD). Although functional brain network alterations have been observed in progressive MCI (pMCI), the underlying pathological mechanisms of network alterations remain unclear. In the present study, we evaluated neuropsychological, imaging, and cerebrospinal fluid (CSF) data at baseline across a cohort of: 21 pMCI patients, 33 stable MCI (sMCI) patients, and 29 normal controls. Fast eigenvector centrality mapping (fECM) based on resting-state functional MRI (rsfMRI) was used to investigate brain network organization differences among these groups, and we further assessed its relation to cognition and AD-related pathology. Our results demonstrated that pMCI had decreased eigenvector centrality (EC) in left temporal pole and parahippocampal gyrus, and increased EC in left middle frontal gyrus compared to sMCI. In addition, compared to normal controls, patients with pMCI showed decreased EC in right hippocampus and bilateral parahippocampal gyrus, and sMCI had decreased EC in right middle frontal gyrus and superior parietal lobule. Correlation analysis showed that EC in the left temporal pole was related to Wechsler Memory Scale-Revised Logical Memory (WMS-LM) delay score (r = 0.467, p = 0.044) and total tau (t-tau) level in CSF (r = -0.509, p = 0.026) in pMCI. Our findings implicate EC changes of different brain network nodes in the prognosis of pMCI and sMCI. Importantly, the association between decreased EC of brain network node and pathological changes may provide a deeper understanding of the underlying pathophysiology of pMCI.

Progress and lessons learned from water-quality monitoring networks

Science.gov (United States)

Myers, Donna N.; Ludtke, Amy S.

2017-01-01

Stream-quality monitoring networks in the United States were initiated and expanded after passage of successive federal water-pollution control laws from 1948 to 1972. The first networks addressed information gaps on the extent and severity of stream pollution and served as early warning systems for spills. From 1965 to 1972, monitoring networks expanded to evaluate compliance with stream standards, track emerging issues, and assess water-quality status and trends. After 1972, concerns arose regarding the ability of monitoring networks to determine if water quality was getting better or worse and why. As a result, monitoring networks adopted a hydrologic systems approach targeted to key water-quality issues, accounted for human and natural factors affecting water quality, innovated new statistical methods, and introduced geographic information systems and models that predict water quality at unmeasured locations. Despite improvements, national-scale monitoring networks have declined over time. Only about 1%, or 217, of more than 36,000 US Geological Survey monitoring sites sampled from 1975 to 2014 have been operated throughout the four decades since passage of the 1972 Clean Water Act. Efforts to sustain monitoring networks are important because these networks have collected information crucial to the description of water-quality trends over time and are providing information against which to evaluate future trends.

Recent Progress in Some Active Topics on Complex Networks

International Nuclear Information System (INIS)

Gu, J; Zhu, Y; Wang, Q A; Guo, L; Jiang, J; Chi, L; Li, W; Cai, X

2015-01-01

Complex networks have been extensively studied across many fields, especially in interdisciplinary areas. It has since long been recognized that topological structures and dynamics are important aspects for capturing the essence of complex networks. The recent years have also witnessed the emergence of several new elements which play important roles in network study. By combining the results of different research orientations in our group, we provide here a review of the recent advances in regards to spectral graph theory, opinion dynamics, interdependent networks, graph energy theory and temporal networks. We hope this will be helpful for the newcomers of those fields to discover new intriguing topics. (paper)

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science; Volume 31; Issue 2. Studies on in vitro release of CPM from semi-interpenetrating polymer network (IPN) composed of chitosan and glutamic acid. K Kumari P P Kundu. Polymers Volume 31 Issue 2 April 2008 pp 159-167 ...

Keratin sponge/hydrogel II, active agent delivery

Science.gov (United States)

Keratin sponge/hydrogels from oxidation and reduction hydrolysis of fine and coarse wool fibers were formed to behave as cationic hydrogels to swell and release active agents in the specific region of the gastro-intestinal (GI) tract. Their porous, interpenetrating networks (IPN) were effective for...

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres.

Science.gov (United States)

Bhattacharya, Shiv Sankar; Mazahir, Farhan; Banerjee, Subham; Verma, Anurag; Ghosh, Amitava

2013-10-15

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application. Copyright © 2013 Elsevier Ltd. All rights reserved.

Progressive Disintegration of Brain Networking from Normal Aging to Alzheimer Disease: Analysis of Independent Components of 18F-FDG PET Data.

Science.gov (United States)

Pagani, Marco; Giuliani, Alessandro; Öberg, Johanna; De Carli, Fabrizio; Morbelli, Silvia; Girtler, Nicola; Arnaldi, Dario; Accardo, Jennifer; Bauckneht, Matteo; Bongioanni, Francesca; Chincarini, Andrea; Sambuceti, Gianmario; Jonsson, Cathrine; Nobili, Flavio

2017-07-01

Brain connectivity has been assessed in several neurodegenerative disorders investigating the mutual correlations between predetermined regions or nodes. Selective breakdown of brain networks during progression from normal aging to Alzheimer disease dementia (AD) has also been observed. Methods: We implemented independent-component analysis of 18 F-FDG PET data in 5 groups of subjects with cognitive states ranging from normal aging to AD-including mild cognitive impairment (MCI) not converting or converting to AD-to disclose the spatial distribution of the independent components in each cognitive state and their accuracy in discriminating the groups. Results: We could identify spatially distinct independent components in each group, with generation of local circuits increasing proportionally to the severity of the disease. AD-specific independent components first appeared in the late-MCI stage and could discriminate converting MCI and AD from nonconverting MCI with an accuracy of 83.5%. Progressive disintegration of the intrinsic networks from normal aging to MCI to AD was inversely proportional to the conversion time. Conclusion: Independent-component analysis of 18 F-FDG PET data showed a gradual disruption of functional brain connectivity with progression of cognitive decline in AD. This information might be useful as a prognostic aid for individual patients and as a surrogate biomarker in intervention trials. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Synthesis and characterization of poly (n-butyl acrylate)-poly (methyl methacrylate) latex interpenetrating polymer networks by radiation-induced seeded emulsion polymerization

Energy Technology Data Exchange (ETDEWEB)

Yu Haibo [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Peng Jing [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)], E-mail: jpeng@pku.edu.cn; Zhai Maolin; Li Jiuqiang; Wei Genshuan [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Qiao Jinliang [Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); SINOPEC Beijing Research Institute of Chemical Industry, Beijing 100013 (China)

2007-11-15

A series of latex interpenetrating polymer networks (LIPNs) were prepared via a two-stage emulsion polymerization of methyl methacrylate (MMA) or mixture of MMA and n-butyl acrylate (n-BA) on crosslinked poly(n-butyl acrylate)(PBA) seed latex using {sup 60}Co {gamma}-ray radiation. The particles of resultant latex were produced with diameters between 150 and 250 nm. FTIR spectra identified the formation of crosslinked copolymers of PMMA or P(MMA-co-BA). Dynamic light scattering (DLS) showed that with increasing n-BA concentration in second-stage monomers, the particle size of LIPN increased. Transmission electron microscope(TEM) photographs showed that the morphology of resultant acrylate interpenetrating polymer network (IPN) latex varied from the distinct core-shell structure to homogenous particle structure with the increase of n-BA concentration, and the morphology was mainly controlled by the miscibility between crosslinked PBA seed and second-stage copolymers and polarity of P(MMA-co-BA)copolymers. In addition, differential scanning calorimeter (DSC) measurements indicated the existence of reinforced miscibility between PBA seed and P(MMA-co-BA)copolymer in prepared LIPNs.

Synthesis and characterization of castor oil based polyurethane ...

Indian Academy of Sciences (India)

Unknown

Abstract. A series of interpenetrating polymer networks (IPNs) of castor oil based polyurethane/polyacrylo- nitrile (PU/PAN: 80/20, 60/40, 50/50, 40/60 and 20/80) were synthesized by condensation reaction of castor oil with methylene diisocyanate and acrylonitrile, employing benzoyl peroxide (BPO) and ethylene glycol ...

A Progress Review on Soot Experiments and Modeling in the Engine Combustion Network (ECN)

KAUST Repository

Skeen, Scott A.

2016-04-05

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

A Progress Review on Soot Experiments and Modeling in the Engine Combustion Network (ECN)

KAUST Repository

Skeen, Scott A.; Manin, Julien; Pickett, Lyle M.; Cenker, Emre; Bruneaux, Gilles; Kondo, Katsufumi; Aizawa, Tets; Westlye, Fredrik; Dalen, Kristine; Ivarsson, Anders; Xuan, Tiemin; Garcia-Oliver, Jose M; Pei, Yuanjiang; Som, Sibendu; Hu, Wang; Reitz, Rolf D.; Lucchini, Tommaso; D'Errico, Gianluca; Farrace, Daniele; Pandurangi, Sushant S.; Wright, Yuri M.; Chishty, Muhammad Aqib; Bolla, Michele; Hawkes, Evatt

2016-01-01

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered.

Optical Subsystems for Next Generation Access Networks

DEFF Research Database (Denmark)

Lazaro, J.A; Polo, V.; Schrenk, B.

2011-01-01

Recent optical technologies are providing higher flexibility to next generation access networks: on the one hand, providing progressive FTTx and specifically FTTH deployment, progressively shortening the copper access network; on the other hand, also opening fixed-mobile convergence solutions...... in next generation PON architectures. It is provided an overview of the optical subsystems developed for the implementation of the proposed NG-Access Networks....

Interdisciplinary and physics challenges of network theory

Science.gov (United States)

Bianconi, Ginestra

2015-09-01

Network theory has unveiled the underlying structure of complex systems such as the Internet or the biological networks in the cell. It has identified universal properties of complex networks, and the interplay between their structure and dynamics. After almost twenty years of the field, new challenges lie ahead. These challenges concern the multilayer structure of most of the networks, the formulation of a network geometry and topology, and the development of a quantum theory of networks. Making progress on these aspects of network theory can open new venues to address interdisciplinary and physics challenges including progress on brain dynamics, new insights into quantum technologies, and quantum gravity.

Recent Progress of Seismic Observation Networks in Japan

Science.gov (United States)

Okada, Y.

2013-04-01

Before the occurrence of disastrous Kobe earthquake in 1995, the number of high sensitivity seismograph stations operated in Japan was nearly 550 and was concentrated in the Kanto and Tokai districts, central Japan. In the wake of the Kobe earthquake, Japanese government has newly established the Headquarters for Earthquake Research Promotion and started the reconstruction of seismic networks to evenly cover the whole Japan. The basic network is composed of three seismographs, i.e. high sensitivity seismograph (Hi-net), broadband seismograph (F-net), and strong motion seismograph (K-NET). A large majority of Hi-net stations are also equipped with a pair of strong motion sensors at the bottom of borehole and the ground surface (KiK-net). A plenty of high quality data obtained from these networks are circulated at once and is producing several new seismological findings as well as providing the basis for the Earthquake Early Warning system. In March 11, 2011, "Off the Pacific coast of Tohoku Earthquake" was generated with magnitude 9.0, which records the largest in the history of seismic observation in Japan. The greatest disaster on record was brought by huge tsunami with nearly 20 thousand killed or missing people. We are again noticed that seismic observation system is quite poor in the oceanic region compared to the richness of it in the inland region. In 2012, NIED has started the construction of ocean bottom seismic and tsunami observation network along the Japan Trench. It is planned to layout 154 stations with an average spacing of 30km, each of which is equipped with an accelerometer for seismic observation and a water pressure gauge for tsunami observation. We are expecting that more rapid and accurate warning of earthquake and tsunami becomes possible by this observing network.

Recent Progress of Seismic Observation Networks in Japan

International Nuclear Information System (INIS)

Okada, Y

2013-01-01

Before the occurrence of disastrous Kobe earthquake in 1995, the number of high sensitivity seismograph stations operated in Japan was nearly 550 and was concentrated in the Kanto and Tokai districts, central Japan. In the wake of the Kobe earthquake, Japanese government has newly established the Headquarters for Earthquake Research Promotion and started the reconstruction of seismic networks to evenly cover the whole Japan. The basic network is composed of three seismographs, i.e. high sensitivity seismograph (Hi-net), broadband seismograph (F-net), and strong motion seismograph (K-NET). A large majority of Hi-net stations are also equipped with a pair of strong motion sensors at the bottom of borehole and the ground surface (KiK-net). A plenty of high quality data obtained from these networks are circulated at once and is producing several new seismological findings as well as providing the basis for the Earthquake Early Warning system. In March 11, 2011, 'Off the Pacific coast of Tohoku Earthquake' was generated with magnitude 9.0, which records the largest in the history of seismic observation in Japan. The greatest disaster on record was brought by huge tsunami with nearly 20 thousand killed or missing people. We are again noticed that seismic observation system is quite poor in the oceanic region compared to the richness of it in the inland region. In 2012, NIED has started the construction of ocean bottom seismic and tsunami observation network along the Japan Trench. It is planned to layout 154 stations with an average spacing of 30km, each of which is equipped with an accelerometer for seismic observation and a water pressure gauge for tsunami observation. We are expecting that more rapid and accurate warning of earthquake and tsunami becomes possible by this observing network.

Progressively expanded neural network for automatic material identification in hyperspectral imagery

Science.gov (United States)

Paheding, Sidike

The science of hyperspectral remote sensing focuses on the exploitation of the spectral signatures of various materials to enhance capabilities including object detection, recognition, and material characterization. Hyperspectral imagery (HSI) has been extensively used for object detection and identification applications since it provides plenty of spectral information to uniquely identify materials by their reflectance spectra. HSI-based object detection algorithms can be generally classified into stochastic and deterministic approaches. Deterministic approaches are comparatively simple to apply since it is usually based on direct spectral similarity such as spectral angles or spectral correlation. In contrast, stochastic algorithms require statistical modeling and estimation for target class and non-target class. Over the decades, many single class object detection methods have been proposed in the literature, however, deterministic multiclass object detection in HSI has not been explored. In this work, we propose a deterministic multiclass object detection scheme, named class-associative spectral fringe-adjusted joint transform correlation. Human brain is capable of simultaneously processing high volumes of multi-modal data received every second of the day. In contrast, a machine sees input data simply as random binary numbers. Although machines are computationally efficient, they are inferior when comes to data abstraction and interpretation. Thus, mimicking the learning strength of human brain has been current trend in artificial intelligence. In this work, we present a biological inspired neural network, named progressively expanded neural network (PEN Net), based on nonlinear transformation of input neurons to a feature space for better pattern differentiation. In PEN Net, discrete fixed excitations are disassembled and scattered in the feature space as a nonlinear line. Each disassembled element on the line corresponds to a pattern with similar features

Integrating Networking into ATLAS

CERN Document Server

Mc Kee, Shawn Patrick; The ATLAS collaboration

2018-01-01

Networking is foundational to the ATLAS distributed infrastructure and there are many ongoing activities related to networking both within and outside of ATLAS. We will report on the progress in a number of areas exploring ATLAS's use of networking and our ability to monitor the network, analyze metrics from the network, and tune and optimize application and end-host parameters to make the most effective use of the network. Specific topics will include work on Open vSwitch for production systems, network analytics, FTS testing and tuning, and network problem alerting and alarming.

Progress and challenges in the computational prediction of gene function using networks [v1; ref status: indexed, http://f1000r.es/SqmJUM

Directory of Open Access Journals (Sweden)

Paul Pavlidis

2012-09-01

Full Text Available In this opinion piece, we attempt to unify recent arguments we have made that serious confounds affect the use of network data to predict and characterize gene function. The development of computational approaches to determine gene function is a major strand of computational genomics research. However, progress beyond using BLAST to transfer annotations has been surprisingly slow. We have previously argued that a large part of the reported success in using "guilt by association" in network data is due to the tendency of methods to simply assign new functions to already well-annotated genes. While such predictions will tend to be correct, they are generic; it is true, but not very helpful, that a gene with many functions is more likely to have any function. We have also presented evidence that much of the remaining performance in cross-validation cannot be usefully generalized to new predictions, making progressive improvement in analysis difficult to engineer. Here we summarize our findings about how these problems will affect network analysis, discuss some ongoing responses within the field to these issues, and consolidate some recommendations and speculation, which we hope will modestly increase the reliability and specificity of gene function prediction.

Preparation of wheat straw based superabsorbent resins and their applications as adsorbents for ammonium and phosphate removal.

Science.gov (United States)

Liu, Jia; Su, Yuan; Li, Qian; Yue, Qinyan; Gao, Baoyu

2013-09-01

A novel wheat straw cellulose-g-poly (potassium acrylate)/polyvinyl alcohol (WSC-g-PKA/PVA) semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) was prepared by graft copolymerization. The structure and performance of the WSC-g-PKA/PVA semi-IPNs SAR was studied and compared with those of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) SAR. The effects of various experimental parameters such as solution pH, concentration, contact time and ion strength on NH4(+) and PO4(3-) removal from solutions were investigated. Equilibrium isotherm data of adsorption of both NH4(+) and PO4(3-) were well fitted to the Freundlich model. Kinetic analysis showed that the pseudo-second-order kinetic model was more suitable for describing the whole adsorption process of NH4(+) and PO4(3-) on SARs. Overall, WSC-g-PKA/PVA semi-IPNs SAR showed better properties in comparison with WSC-g-PKA SAR and it could be considered as one efficient material for the removal and recovery of nitrogen and phosphorus with the agronomic reuse as a fertilizer. Copyright © 2013 Elsevier Ltd. All rights reserved.

Heterogeneous cellular networks

CERN Document Server

Hu, Rose Qingyang

2013-01-01

A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

Propuesta de un proyecto de política pública de vinculación, entre las unidades académicas de educación superior del IPN con las empresas, que coadyuven al desarrollo económico de México

OpenAIRE

Olguín Nicolás, Raquel

2013-01-01

Esta investigación tuvo como objetivo proponer un proyecto de política pública de vinculación, entre las unidades académicas de educación superior del IPN con las empresas, que coadyuven al desarrollo de México, que sirva como un sustento y plataforma sólida para la creación de la infraestructura industrial necesaria para que México inicie su desarrollo económico a través de la diversificación de la producción de bienes y servicios que posean alto valor agregado y le pueda dar competitividad ...

The afterglow of the short/intermediate-duration gamma-ray burst GRB 000301C: A jet at z=2.04

DEFF Research Database (Denmark)

Jensen, B.L.; Fynbo, J.U.; Gorosabel, J.

2001-01-01

We present Ulysses and NEAR data from the detection of the short or intermediate duration (2 s) gamma-ray burst GRB 000301C (2000 March 1.41 UT). The gamma-ray burst (GRB) was localised by the Inter Planetary Network (IPN) and RXTE to an area of similar to 50 arcmin(2). A fading optical counterpa...

Francis Wayland Parker's Morning Exercise and the Progressive Movement

Science.gov (United States)

Schmitt, Natalie Crohn

2010-01-01

In the progressive era, the distinguished political scientist Robert Putnam explains, progressives invested heavily in "social capital," that is, in the stock of active connections, social networks, shared values, norms of reciprocity, trustworthiness, and friendship that bind people together (Putnam 2000, 395). They were, he argues,…

Advancing functional dysconnectivity and atrophy in progressive supranuclear palsy

Directory of Open Access Journals (Sweden)

Jesse A. Brown

2017-01-01

Full Text Available Progressive supranuclear palsy syndrome (PSP-S results from neurodegeneration within a network of brainstem, subcortical, frontal and parietal cortical brain regions. It is unclear how network dysfunction progresses and relates to longitudinal atrophy and clinical decline. In this study, we evaluated patients with PSP-S (n = 12 and healthy control subjects (n = 20 at baseline and 6 months later. Subjects underwent structural MRI and task-free functional MRI (tf-fMRI scans and clinical evaluations at both time points. At baseline, voxel based morphometry (VBM revealed that patients with mild-to-moderate clinical symptoms showed structural atrophy in subcortex and brainstem, prefrontal cortex (PFC; supplementary motor area, paracingulate, dorsal and ventral medial PFC, and parietal cortex (precuneus. Tf-fMRI functional connectivity (FC was examined in a rostral midbrain tegmentum (rMT-anchored intrinsic connectivity network that is compromised in PSP-S. In healthy controls, this network contained a medial parietal module, a prefrontal-paralimbic module, and a subcortical-brainstem module. Baseline FC deficits in PSP-S were most severe in rMT network integrative hubs in the prefrontal-paralimbic and subcortical-brainstem modules. Longitudinally, patients with PSP-S had declining intermodular FC between the subcortical-brainstem and parietal modules, while progressive atrophy was observed in subcortical-brainstem regions (midbrain, pallidum and posterior frontal (perirolandic cortex. This suggested that later-stage subcortical-posterior cortical change may follow an earlier-stage subcortical-anterior cortical disease process. Clinically, patients with more severe baseline impairment showed greater subsequent prefrontal-parietal cortical FC declines and posterior frontal atrophy rates, while patients with more rapid longitudinal clinical decline showed coupled prefrontal-paralimbic FC decline. VBM and FC can augment disease monitoring in PSP

IPN

Indian Academy of Sciences (India)

WINTEC

glutamic acid was prepared in 2% acetic acid solution, extruded as droplets through a syringe to alkali– methanol solution and the precipitated beads were crosslinked using .... and cold (25°C) water and it generally took two to three.

Wood hemicellulose/chitosan-based semi-interpenetrating network hydrogels : mechanical swelling and controlled drug release properties

Science.gov (United States)

Ahmet M. Karaaslan; Mandla A. Tshabalala; Gisela Buschle-Diller

2010-01-01

The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose, and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the...

Clinical application of CT and CT-guided percutaneous transthoracic needle biopsy in patients with indeterminate pulmonary nodules

Energy Technology Data Exchange (ETDEWEB)

Cardoso, Luciana Vargas; Souza Júnior, Arthur Soares, E-mail: fabianonatividade@terra.com.br [Rio Preto-Ultra-X Radiological Diagnosis Institute, São José do Rio Preto, SP (Brazil)

2014-07-15

Objective: To investigate the clinical application of CT and CT-guided percutaneous transthoracic needle biopsy (CT-PTNB) in patients with indeterminate pulmonary nodules (IPNs). Methods: We retrospectively studied 113 patients with PNs undergoing CT and CT-PTNB. Variables such as gender, age at diagnosis, smoking status, CT findings, and CT-PTNB techniques were analyzed. Data analysis was performed with the Student's t-test for independent samples the chi-square test, and normal approximation test for comparison of two proportions. Results: Of the 113 patients studied, 68 (60.2%) were male and 78 (69%) were smokers. The diameter of malignant lesions ranged from 2.6 cm to 10.0 cm. Most of the IPNs (85%) were located in the peripheral region. The biopsied IPNs were found to be malignant in 88 patients (77.8%) and benign in 25 (22.2%). Adenocarcinoma was the most common malignant tumor, affecting older patients. The IPN diameter was significantly greater in patients with malignant PNs than in those with benign IPNs (p < 0.001). Having regular contour correlated significantly with an IPN being benign (p = 0.022), whereas spiculated IPNs and bosselated IPNs were more often malignant (in 50.7% and 28.7%, respectively). Homogeneous attenuation and necrosis were more common in patients with malignant lesions (51.9% and 26.9%, respectively). Conclusions: In our sample, CT and CT-PTNB were useful in distinguishing between malignant and benign IPNs. Advanced age and smoking were significantly associated with malignancy. Certain CT findings related to IPNs (larger diameter, spiculated borders, homogeneous attenuation, and necrosis) were associated with malignancy. (author)

Interpenetrating polymer network hydrogels based on poly(2-hydroxyethyl methacrylate): morphology effects on formation, swelling, optical, and mechanical properties

Czech Academy of Sciences Publication Activity Database

Dušková-Smrčková, Miroslava; Sadakbayeva, Zhansaya; Steinhart, Miloš; Šturcová, Adriana; Pfleger, Jiří; Dušek, Karel

2017-01-01

Roč. 254, 20 August (2017), s. 40 ISSN 0065-7727. [ACS National Meeting & Exposition /254./. 20.08.2017-24.08.2017, Washington] Institutional support: RVO:61389013 Keywords : IPN * poly(2-hydroxyethyl methacrylate) * hydrogel Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science

Effects of pore CaCO3 form agencies on dissolution mechanisms of amoxicillin drugs encapsulated in hydrogels full-IPN chitosan N-vinyl caprolactam

Science.gov (United States)

Budianto, Emil; Fauzia, Maghfira

2018-04-01

The administration of amoxicillin trihydrate in Helicobacter pylori infection is not effective enough because the conventional preparations used have a short retention time in the stomach. To overcome this problem, amoxicillin trihydrate was encapsulated into the floating drug delivery matrix-matrix. In this study, the full-ipn acetaldehyde crosslinked hydrogel (N-vinyl caprolactam) was synthesized with a 10% CaCO3 pore forming agent and then encapsulated on amoxicillin trihydrate and studied the mechanism of drug dissolution with its kinetic kinetics approach. The K-PNVCL Hydrogel produces optimal properties which are then loaded with amoxicillin trihydrate in situ and post loading. In this research, we have got the percentage of swelling, floating time, the efficiency of in situ and post loading 873%; 3.15 minutes; 99.8% and 99.4%. The dissolution test was performed on amoxicillin trihydrate which had been encapsulated K-PNVCL hydrogel in vitro at pH 1.2 resulting in 94.5% for in situ loading and 98.5% for post loading. Results of the kinetics of drug release for post loading and in situ loading methods tend to follow the Higuchi model kinetics. The drug release mechanism occurs by Fickian diffusion. Proof of drug release mechanism from K-PNVCL hydrogel matrix is further done by Scanning Electron Microscope (SEM) instrument.

Water permeability, hybrid layer long-term integrity and reaction mechanism of a two-step adhesive system.

Science.gov (United States)

Grégoire, Geneviève; Dabsie, Firas; Delannée, Mathieu; Akon, Bernadette; Sharrock, Patrick

2010-07-01

Our aim was to investigate the reaction mechanism of formation of the hybrid layer by a HEMA-containing self-etch adhesive and to study fluid filtration, contact angle and interfacial ultrastructure by SEM following a 1 year ageing period. Acidic behaviour and chemical interactions between Silorane System Adhesive and dentine were studied by potentiometric titrations, atomic absorption spectroscopy and infrared spectroscopy. The hydrophilicity of the adhesive was evaluated using the sessile drop method and dentine permeability by hydraulic conductance. The morphological study of the dentine/adhesive system interface was conducted using SEM. The Silorane System Adhesive behaved as a multi-acid with several different pK(a) values. When the adhesive was in contact with dentine, the acid was progressively consumed and calcium ions were released. The acrylate substituted phosphonate bound strongly to apatite crystals. The polyacrylic acid copolymer reacted with calcium ions and formed an interpenetrating polymer network (IPN). Water contact angle measurements showed rapid spreading on primer (angles reached 15 degrees at 30s) and larger contact angles when the Silorane bonding layer was added (from over 60 degrees to 44 degrees ). A thick, homogeneous hybrid layer was observed both initially and after 1 year of ageing, with a corresponding hydraulic conductance of -48.50% initially and -52.07% at 12 months. The Silorane System Adhesive is capable of both dissolving calcium ions and binding to apatite surfaces. The results showed the hydrophilicity of the adhesive, which formed an IPN-like hybrid layer that conserved adequate impermeability over a 1-year period. Copyright 2010 Elsevier Ltd. All rights reserved.

Progression of Diabetic Capillary Occlusion: A Model.

Directory of Open Access Journals (Sweden)

Xiao Fu

2016-06-01

Full Text Available An explanatory computational model is developed of the contiguous areas of retinal capillary loss which play a large role in diabetic maculapathy and diabetic retinal neovascularization. Strictly random leukocyte mediated capillary occlusion cannot explain the occurrence of large contiguous areas of retinal ischemia. Therefore occlusion of an individual capillary must increase the probability of occlusion of surrounding capillaries. A retinal perifoveal vascular sector as well as a peripheral retinal capillary network and a deleted hexagonal capillary network are modelled using Compucell3D. The perifoveal modelling produces a pattern of spreading capillary loss with associated macular edema. In the peripheral network, spreading ischemia results from the progressive loss of the ladder capillaries which connect peripheral arterioles and venules. System blood flow was elevated in the macular model before a later reduction in flow in cases with progression of capillary occlusions. Simulations differing only in initial vascular network structures but with identical dynamics for oxygen, growth factors and vascular occlusions, replicate key clinical observations of ischemia and macular edema in the posterior pole and ischemia in the retinal periphery. The simulation results also seem consistent with quantitative data on macular blood flow and qualitative data on venous oxygenation. One computational model applied to distinct capillary networks in different retinal regions yielded results comparable to clinical observations in those regions.

INVESTIGATION OF PRIMORDIAL BLACK HOLE BURSTS USING INTERPLANETARY NETWORK GAMMA-RAY BURSTS

Energy Technology Data Exchange (ETDEWEB)

Ukwatta, T. N. [Director' s Postdoctoral Fellow, Space and Remote Sensing (ISR-2), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hurley, K. [University of California, Berkeley, Space Sciences Laboratory, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); MacGibbon, J. H. [Department of Physics, University of North Florida, Jacksonville, FL 32224 (United States); Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal' shin, V. D. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Goldsten, J. [Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 (United States); Boynton, W. [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); Kozyrev, A. S. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Rau, A.; Kienlin, A. von; Zhang, X. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, Postfach 1312, Garching, D-85748 (Germany); Connaughton, V. [University of Alabama in Huntsville, NSSTC, 320 Sparkman Drive, Huntsville, AL 35805 (United States); Yamaoka, K. [Department of Physics and Mathematics, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara, Kanagawa 229-8558 (Japan); Ohno, M. [Department of Physics, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ohmori, N. [Department of Applied Physics, University of Miyazaki, 1-1 Gakuen kibanadai-nishi, Miyazaki-shi, Miyazaki 889-2192 (Japan); Feroci, M. [INAF/IAPS-Roma, via Fosso del Cavaliere 100, I-00133, Roma (Italy); Frontera, F., E-mail: tilan@lanl.gov [Department of Physics and Earth Science, University of Ferrara, via Saragat 1, I-44122 Ferrara (Italy); and others

2016-07-20

The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 10{sup 13}–10{sup 18} cm (7–10{sup 5} au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

Building clinical networks: a developmental evaluation framework.

Science.gov (United States)

Carswell, Peter; Manning, Benjamin; Long, Janet; Braithwaite, Jeffrey

2014-05-01

Clinical networks have been designed as a cross-organisational mechanism to plan and deliver health services. With recent concerns about the effectiveness of these structures, it is timely to consider an evidence-informed approach for how they can be developed and evaluated. To document an evaluation framework for clinical networks by drawing on the network evaluation literature and a 5-year study of clinical networks. We searched literature in three domains: network evaluation, factors that aid or inhibit network development, and on robust methods to measure network characteristics. This material was used to build a framework required for effective developmental evaluation. The framework's architecture identifies three stages of clinical network development; partner selection, network design and network management. Within each stage is evidence about factors that act as facilitators and barriers to network growth. These factors can be used to measure progress via appropriate methods and tools. The framework can provide for network growth and support informed decisions about progress. For the first time in one place a framework incorporating rigorous methods and tools can identify factors known to affect the development of clinical networks. The target user group is internal stakeholders who need to conduct developmental evaluation to inform key decisions along their network's developmental pathway.

Development of natural rubber membranes for separation of methyl tert-butyl ether and methanol

International Nuclear Information System (INIS)

Nur Azrini Ramlee; Ghazali Mohd Nawawi; Khairul Zaman Dahlan

2010-01-01

As a new commercial process, membrane separation raises significant expectations in the process plant of the future and therefore this research was being initiated to develop and characterize pervaporation membrane based on natural rubber (NR). Natural Rubber SMR-L grade which was supplied by Malaysia Rubber Research Institute (MRRI) was used for the development of the membranes via interpenetrating polymer network (IPN) techniques. Polystyrene (PS) was used to modify the natural rubber to further improve their mechanical and chemical properties. The membranes were prepared with various blend ratios of natural rubber, polystyrene and divinyl benzene as cross linker with constant 1 % of dicumyl peroxide as the initiator. The developed membranes were then characterized to study the functional group presence, membranes morphology, crosslink density, tear strength, adsorption of the membranes and pervaporation separation of Methyl-Tert-Butyl-Ether (MTBE) and Methanol. Pervaporation process was conducted by using varies of MTBE concentration 10, 30, 50 and 70 wt % and at differ operation temperature, 25 degree Celsius and 55 degree Celsius. Separation performance of IPN NR/ PS membranes were based on the presented permeation flux and separation factor. Examination through Fourier Transform Infrared Spectroscopy (FTIR), determined crosslink density and tear strength, 6 series of IPN NR/ PS membranes were successfully developed using natural rubber. Observation from Scanning Electron Microscopy (SEM) showed that the membranes were dense and appropriated for the pervaporation process application. From the pervaporation of MTBE and Methanol, IPN NR/ PS membranes of series D4N30 shown low permeation flux of MTBE but high separation factor while D2N70 membranes was vice versa for both temperature of 25 degree Celsius and 55 degree Celsius. (author)

Study protocol for a prospective cohort study examining the predictive potential of dynamic symptom networks for the onset and progression of psychosis: the Mapping Individual Routes of Risk and Resilience (Mirorr) study.

Science.gov (United States)

Booij, Sanne H; Wichers, Marieke; de Jonge, Peter; Sytema, Sjoerd; van Os, Jim; Wunderink, Lex; Wigman, Johanna T W

2018-01-21

Our current ability to predict the course and outcome of early psychotic symptoms is limited, hampering timely treatment. To improve our understanding of the development of psychosis, a different approach to psychopathology may be productive. We propose to reconceptualise psychopathology from a network perspective, according to which symptoms act as a dynamic, interconnected system, impacting on each other over time and across diagnostic boundaries to form symptom networks. Adopting this network approach, the Mapping Individual Routes of Risk and Resilience study aims to determine whether characteristics of symptom networks can predict illness course and outcome of early psychotic symptoms. The sample consists of n=100 participants aged 18-35 years, divided into four subgroups (n=4×25) with increasing levels of severity of psychopathology, representing successive stages of clinical progression. Individuals representing the initial stage have a relatively low expression of psychotic experiences (general population), whereas individuals representing the end stage are help seeking and display a psychometric expression of psychosis, putting them at ultra-high risk for transition to psychotic disorder. At baseline and 1-year follow-up, participants report their symptoms, affective states and experiences for three consecutive months in short, daily questionnaires on their smartphone, which will be used to map individual networks. Network parameters, including the strength and directionality of symptom connections and centrality indices, will be estimated and associated to individual differences in and within-individual progression through stages of clinical severity and functioning over the next 3 years. The study has been approved by the local medical ethical committee (ABR no. NL52974.042.15). The results of the study will be published in (inter)national peer-reviewed journals, presented at research, clinical and general public conferences. The results will assist

Network biology: Describing biological systems by complex networks. Comment on "Network science of biological systems at different scales: A review" by M. Gosak et al.

Science.gov (United States)

Jalili, Mahdi

2018-03-01

I enjoyed reading Gosak et al. review on analysing biological systems from network science perspective [1]. Network science, first started within Physics community, is now a mature multidisciplinary field of science with many applications ranging from Ecology to biology, medicine, social sciences, engineering and computer science. Gosak et al. discussed how biological systems can be modelled and described by complex network theory which is an important application of network science. Although there has been considerable progress in network biology over the past two decades, this is just the beginning and network science has a great deal to offer to biology and medical sciences.

An Expedient Study on Back-Propagation (BPN) Neural Networks for Modeling Automated Evaluation of the Answers and Progress of Deaf Students' That Possess Basic Knowledge of the English Language and Computer Skills

Science.gov (United States)

Vrettaros, John; Vouros, George; Drigas, Athanasios S.

This article studies the expediency of using neural networks technology and the development of back-propagation networks (BPN) models for modeling automated evaluation of the answers and progress of deaf students' that possess basic knowledge of the English language and computer skills, within a virtual e-learning environment. The performance of the developed neural models is evaluated with the correlation factor between the neural networks' response values and the real value data as well as the percentage measurement of the error between the neural networks' estimate values and the real value data during its training process and afterwards with unknown data that weren't used in the training process.

Tourism-planning network knowledge dynamics

DEFF Research Database (Denmark)

Dredge, Dianne

2014-01-01

This chapter explores the characteristics and functions of tourism networks as a first step in understanding how networks facilitate and reproduce knowledge. A framework to progress understandings of knowledge dynamics in tourism networks is presented that includes four key dimensions: context......, network agents, network boundaries and network resources. A case study of the development of the Next Generation Tourism Handbook (Queensland, Australia), a policy initiative that sought to bring tourism and land use planning knowledge closer together is presented. The case study illustrates...... that the tourism policy and land use planning networks operate in very different spheres and that context, network agents, network boundaries and network resources have a significant influence not only on knowledge dynamics but also on the capacity of network agents to overcome barriers to learning and to innovate....

Synthesis and characterization of a polymeric material based on gum arabic by gamma radiation for purification of water

International Nuclear Information System (INIS)

Ibrahim, K. M. A.

2012-07-01

The objective of this study is to prepare interpenetrating polymer net works to be used in adsorption of heavy metal from water. (Gum Arabic (GA)/ acrylamide (AAm)) interpenetrating polymer net works (IPN) have been prepared at different compositions where Acrylamide varies between 5, 10, 15, and 20% w/w Gum Arabic solution. The percent conversion was determined gravimetrically. The swelling result of ( GA/AAm) IPN hydrogels in solutions of desired ph at a temperature of 25 O showed maximum swelling in water at ph 4.75 and the diffusion of water within ( GA/AAM) IPN hydrogels was found to be of non-fickian character at the stage of swelling. The maximum weight loss temperature and half life temperature for GA, PAAM and (GA/AAm) INP hydrogels were found from the thermal analysis. The results showed that the weight loss of hydrogels is 374 o C . This degree was between gum arabic 317 o C and acrylamide 400 o C . In the adsorption experiments, the efficiency of (GA/AAm) IPN hydrogels to adsorb cooper ions from water was studied. (GA/AAm) IPN hydrogels showed maximum adsorption for different aqueous solutions of copper at ph 5.00. Adsorption isotherm was constructed for (GA/AAm) IPN copper ion. Linear type in adsorption classification system was found. The complexation between GA and copper solution was investigated and their complex stoichiometries were calculated. The result shows that the percent of gum arabic to copper ions is 2:1 the spectroscopic analysis of copper, GA, AAM and (GA/AAm) IPN hydrogels was performed. The optimum ratio used to synthesize (IPN) hydrogels was found to be: Gum Arabic 30% and Acrylamide between 10% and 15% and the best dose is 10 kGy. The efficiency of the (IPN) hydrogels to adsorb heavy metal ions found to be 47 mg/g of hydrogels.(Author)

Intense pulsed neutron source status report

International Nuclear Information System (INIS)

Brown, B.S.; Bohringer, D.E.; Brumwell, F.R.; Carpenter, J.M.; Crawford, R.K.; Rauchas, A.V.; Schulke, A.W.; Worlton, T.G.

1991-01-01

The status and future plans of IPNS will be reviewed. At the celebration of our 10th anniversary in 7 months, IPNS will have performed over 2000 experiments and has over 230 scientists visiting IPNS annually. Plans for a new spallation source concept using a fixed field alternating gradient synchrotron will be presented. (author)

Hierarchical spatial organization of geographical networks

International Nuclear Information System (INIS)

Travencolo, Bruno A N; Costa, Luciano da F

2008-01-01

In this work, we propose a hierarchical extension of the polygonality index as the means to characterize geographical planar networks. By considering successive neighborhoods around each node, it is possible to obtain more complete information about the spatial order of the network at progressive spatial scales. The potential of the methodology is illustrated with respect to synthetic and real geographical networks

GNS3 network simulation guide

CERN Document Server

Welsh, Chris

2013-01-01

GNS3 Network Simulation Guide is an easy-to-follow yet comprehensive guide which is written in a tutorial format helping you grasp all the things you need for accomplishing your certification or simulation goal. If you are a networking professional who wants to learn how to simulate networks using GNS3, this book is ideal for you. The introductory examples within the book only require minimal networking knowledge, but as the book progresses onto more advanced topics, users will require knowledge of TCP/IP and routing.

Network information improves cancer outcome prediction.

Science.gov (United States)

Roy, Janine; Winter, Christof; Isik, Zerrin; Schroeder, Michael

2014-07-01

Disease progression in cancer can vary substantially between patients. Yet, patients often receive the same treatment. Recently, there has been much work on predicting disease progression and patient outcome variables from gene expression in order to personalize treatment options. Despite first diagnostic kits in the market, there are open problems such as the choice of random gene signatures or noisy expression data. One approach to deal with these two problems employs protein-protein interaction networks and ranks genes using the random surfer model of Google's PageRank algorithm. In this work, we created a benchmark dataset collection comprising 25 cancer outcome prediction datasets from literature and systematically evaluated the use of networks and a PageRank derivative, NetRank, for signature identification. We show that the NetRank performs significantly better than classical methods such as fold change or t-test. Despite an order of magnitude difference in network size, a regulatory and protein-protein interaction network perform equally well. Experimental evaluation on cancer outcome prediction in all of the 25 underlying datasets suggests that the network-based methodology identifies highly overlapping signatures over all cancer types, in contrast to classical methods that fail to identify highly common gene sets across the same cancer types. Integration of network information into gene expression analysis allows the identification of more reliable and accurate biomarkers and provides a deeper understanding of processes occurring in cancer development and progression. © The Author 2012. Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Software Defined Networking for Next Generation Converged Metro-Access Networks

Science.gov (United States)

Ruffini, M.; Slyne, F.; Bluemm, C.; Kitsuwan, N.; McGettrick, S.

2015-12-01

While the concept of Software Defined Networking (SDN) has seen a rapid deployment within the data center community, its adoption in telecommunications network has progressed slowly, although the concept has been swiftly adopted by all major telecoms vendors. This paper presents a control plane architecture for SDN-driven converged metro-access networks, developed through the DISCUS European FP7 project. The SDN-based controller architecture was developed in a testbed implementation targeting two main scenarios: fast feeder fiber protection over dual-homed Passive Optical Networks (PONs) and dynamic service provisioning over a multi-wavelength PON. Implementation details and results of the experiment carried out over the second scenario are reported in the paper, showing the potential of SDN in providing assured on-demand services to end-users.

Multi-state supernetworks: recent progress and prospects

Directory of Open Access Journals (Sweden)

Feixiong Liao

2014-02-01

Full Text Available Supernetworks have long been adopted to address multi-dimensional choice problems, which are thorny to solve for classic singular networks. Originated from combining transport mode and route choice into a multi-modal network, supernetworks have been extended into multi-state networks to include activity-travel scheduling, centered around activity-based models of travel demand. A key feature of the network extensions is that multiple choice facets pertaining to conducting a full activity program can be modeled in a consistent and integrative fashion. Thus, interdependencies and constraints between related choice facets can be readily captured. Given this advantage of integrity, the modeling of supernetwork has become an emerging topic in transportation research. This paper summarizes the recent progress in modeling multi-state supernetworks and discusses future prospects.

The B-MYB transcriptional network guides cell cycle progression and fate decisions to sustain self-renewal and the identity of pluripotent stem cells.

Science.gov (United States)

Zhan, Ming; Riordon, Daniel R; Yan, Bin; Tarasova, Yelena S; Bruweleit, Sarah; Tarasov, Kirill V; Li, Ronald A; Wersto, Robert P; Boheler, Kenneth R

2012-01-01

Embryonic stem cells (ESCs) are pluripotent and have unlimited self-renewal capacity. Although pluripotency and differentiation have been examined extensively, the mechanisms responsible for self-renewal are poorly understood and are believed to involve an unusual cell cycle, epigenetic regulators and pluripotency-promoting transcription factors. Here we show that B-MYB, a cell cycle regulated phosphoprotein and transcription factor critical to the formation of inner cell mass, is central to the transcriptional and co-regulatory networks that sustain normal cell cycle progression and self-renewal properties of ESCs. Phenotypically, B-MYB is robustly expressed in ESCs and induced pluripotent stem cells (iPSCs), and it is present predominantly in a hypo-phosphorylated state. Knockdown of B-MYB results in functional cell cycle abnormalities that involve S, G2 and M phases, and reduced expression of critical cell cycle regulators like ccnb1 and plk1. By conducting gene expression profiling on control and B-MYB deficient cells, ChIP-chip experiments, and integrative computational analyses, we unraveled a highly complex B-MYB-mediated transcriptional network that guides ESC self-renewal. The network encompasses critical regulators of all cell cycle phases and epigenetic regulators, pluripotency transcription factors, and differentiation determinants. B-MYB along with E2F1 and c-MYC preferentially co-regulate cell cycle target genes. B-MYB also co-targets genes regulated by OCT4, SOX2 and NANOG that are significantly associated with stem cell differentiation, embryonic development, and epigenetic control. Moreover, loss of B-MYB leads to a breakdown of the transcriptional hierarchy present in ESCs. These results coupled with functional studies demonstrate that B-MYB not only controls and accelerates cell cycle progression in ESCs it contributes to fate decisions and maintenance of pluripotent stem cell identity.

Adsorption kinetic investigations of low concentrated uranium in aqua media by polymeric adsorban

International Nuclear Information System (INIS)

Guerellier, R.

2004-02-01

In order to remove the uranium from aqueous media, the solution of polyethylene glycol in acrylonitrile was irradiated using ''6' degree Celsius Co γ-ray source and Interpenetrating Polymer Networks (IPNs) was formed. After IPNs were amidoximated at 65 0 for 3.5 hours, they were kept in 10''-''2 M of uranil nitrate solution at 17, 25, 35, 45 degree Celsius temperatures until to establish the adsorption equilibrium. Adsorption analyses were measured by gamma spectrometer, gravimetry and UV spectrofotometer. Structure analysis of IPN, before and after amidoximation and after the adsorption of uranium, was interpreted by FTIR spectrometer. It was found that as the temperature increased the amount of max adsorption also increased. The amount of max adsorption capacity at 45 degree Celsius was 602 mg U/g IPN. In addition to, it was determined that the uranium adsorption increased a little in shaking media. The reaction was determined as 'zeroth degree' until 240 minutes due to the changing of adsorption capacity by the time at different temperatures. It was observed that as the temperature increased, the adsorption rate also increased and the activation energy was calculated as 34.6 kJ/mol. By using the changing of adsorption equilibrium coefficient by the temperature, thermodynamic quantities of ΔH, ΔS and ΔG were calculated consecutively. Adsorption reaction was determined as endothermic and it was interpreted that the adsorption was controlled by particular diffusion, namely it was a physical adsorption. Adsorption isotherms were found by changing the solution concentrations from 5X10''4 to parallel x parallel O''- 2 M at 20, 25, 35, 45 degree Celsius temperatures. The obtained data from this study was applied to different adsorption isotherms. It was observed that at lower temperatures, the adsorption isotherms were fitted to Giles C type, at higher temperatures, they were fitted to Freundlich type

Robust gene network analysis reveals alteration of the STAT5a network as a hallmark of prostate cancer.

Science.gov (United States)

Reddy, Anupama; Huang, C Chris; Liu, Huiqing; Delisi, Charles; Nevalainen, Marja T; Szalma, Sandor; Bhanot, Gyan

2010-01-01

We develop a general method to identify gene networks from pair-wise correlations between genes in a microarray data set and apply it to a public prostate cancer gene expression data from 69 primary prostate tumors. We define the degree of a node as the number of genes significantly associated with the node and identify hub genes as those with the highest degree. The correlation network was pruned using transcription factor binding information in VisANT (http://visant.bu.edu/) as a biological filter. The reliability of hub genes was determined using a strict permutation test. Separate networks for normal prostate samples, and prostate cancer samples from African Americans (AA) and European Americans (EA) were generated and compared. We found that the same hubs control disease progression in AA and EA networks. Combining AA and EA samples, we generated networks for low low (cancer (e.g. possible turning on of oncogenes). (ii) Some hubs reduced their degree in the tumor network compared to their degree in the normal network, suggesting that these genes are associated with loss of regulatory control in cancer (e.g. possible loss of tumor suppressor genes). A striking result was that for both AA and EA tumor samples, STAT5a, CEBPB and EGR1 are major hubs that gain neighbors compared to the normal prostate network. Conversely, HIF-lα is a major hub that loses connections in the prostate cancer network compared to the normal prostate network. We also find that the degree of these hubs changes progressively from normal to low grade to high grade disease, suggesting that these hubs are master regulators of prostate cancer and marks disease progression. STAT5a was identified as a central hub, with ~120 neighbors in the prostate cancer network and only 81 neighbors in the normal prostate network. Of the 120 neighbors of STAT5a, 57 are known cancer related genes, known to be involved in functional pathways associated with tumorigenesis. Our method is general and can easily

Novel Hydrogels from Renewable Resources

Science.gov (United States)

Karaaslan, Muzafer Ahmet

2011-12-01

mechanical stability of semi-IPN hydrogels. In this last section of this study, the natural affinity of hemicellulose to cellulose was utilized to coat cellulose whiskers with chemically modified hemicellulose isolated from wood fiber. Surface modified cellulose nanowhiskers were used to prepare nanocomposite hydrogels using free radical polymerization of 2-hydroxyethyl methacrylate (HEMA), a biocompatible monomer. The effect of morphology and concentration of the incorporated nanocrystals on the hydrogel network was related to the mechanical properties, viscoelastic behavior and swelling of the hydrogels.

Networking Activities at the Library of Congress.

Science.gov (United States)

Maruyama, Lenore S.; Avram, Henriette D.

1979-01-01

Examines the background studies and high-priority projects which will lay the groundwork for the library bibliographic component of a National Library and Information Service Network and reviews the progress and problems of the national network as evidenced by current cooperative projects. (CWM)

Interpenetrating polymer network membranes for fuel cells: infrared vibrational spectroscopy; Membranes baseadas dm redes polimericas interpenetrantes para celulas a combustivel: estudo por espectroscopia vibracional no infravermelho

Energy Technology Data Exchange (ETDEWEB)

Loureiro, Felipe A.M.; Rocco, Ana Maria [Grupo de Materiais Condutores e Energia, Escola de Quimica, Universidade Federal do Rio de Janeiro, RJ (Brazil)], e-mail: amrocco@eq.ufrj.br; Pereira, Robson Pacheco [Instituto de Ciencias Exatas, Universidade Federal Fluminense (UFF), Volta Redonda, RJ (Brazil)

2011-07-01

In the present work, proton conductive membranes based on IPN matrices doped with H{sub 3}PO{sub 4} were developed. The characterization by infrared vibrational spectroscopy evidenced the polymerization of DGEBA and the immobilization of PEI chains, originating a structure containing basic sites suitable for proton coordination and conduction. The FTIR characterization evidenced the polymerization of DGEBA in the presence of PEI thus forming Semi-IPN membranes which, after doped with H{sub 3}PO{sub 4}, exhibited conductivity values of 10{sup -4} W{sup -1}cm{sup -1} at room temperature and 10{sup -3} {omega}{sup -1}cm{sup -1} at 80 degree C, as well as a dependency of conductivity with temperature following the Arrhenius model. The activation energy values (14,33 and 12,96 kJ.mol{sup -1}) indicated a proton conduction mechanism predominantly vehicular in the matrices studied under 100% relative humidity. (author)

Establishment of 2000 National Geodetic Control Network of China and It’s Technological Progress

Directory of Open Access Journals (Sweden)

CHEN Junyong

2007-02-01

Full Text Available Objectives: 2000’ National Geodetic Control Network of China is an important fundamental scientific engineering project in China. It consists of three parts which are establishment of 2000 National GPS Geodetic Network, its combination adjustment with national astro-geodetic network and 2000 National Gravity Fundamental network. It provides the high precise coordinate reference and gravity reference for three dimensional geo-center national coordinates system and gravity system, respectively. Additionally, it provides precise unified geometric and physical geodesy information for the economic construction, the national defense and the scientific research. Methods: 1. The larger number of data are processed in triple networks adjustment of 2000 National GPS Geodetic Network, which are chosen from the GPS monitoring stations, such as grade A, B of national GPS network , grade 1st and 2nd of national GPS network, crustal movement observation network of China, and others crustal deformation monitoring stations. Finally, the data of 2666 GPS stations are used in the data processing of 2000 National GPS Geodetic Network, including 124 external stations and 2542 internal stations. In order to the results of triple networks adjustment are corresponding to that of three dimensional geo-center coordinates system, ITRF 97 and epoch 2000.0 are chosen as the coordinate reference frame and epoch reference, respectively. The methods of “strong reference” and “weak reference” are combined used in the control data selection of triple networks adjustment. The scale and rotation scales are adopted for each sub network. The least square adjustment is firstly adopted in each sub network adjustment. The data of obvious abnormal baselines are found and rejected firstly. And the method of double factor robust estimation is adopted in the data processing. 2. The combined adjustment of 2000 National GPS Geodetic Network and national astro-geodetic network is

AmeriFlux Network Data Activities: updates, progress and plans

Science.gov (United States)

Yang, B.; Boden, T.; Krassovski, M.; Song, X.

2013-12-01

The Carbon Dioxide Information Analysis Center (CDIAC) at the Oak Ridge National Laboratory serves as the long-term data repository for the AmeriFlux network. Datasets currently available include hourly or half-hourly meteorological and flux observations, biological measurement records, and synthesis data products. In this presentation, we provide an update of this network database including a comprehensive review and evaluation of the biological data from about 70 sites, development of a new product for flux uncertainty estimates, and re-formatting of Level-2 standard files. In 2013, we also provided data support to two synthesis studies --- 2012 drought synthesis and FACE synthesis. Issues related to data quality and solutions in compiling datasets for these synthesis studies will be discussed. We will also present our work plans in developing and producing other high-level products, such as derivation of phenology from the available measurements at flux sites.

Progress in neuromorphic photonics

Science.gov (United States)

Ferreira de Lima, Thomas; Shastri, Bhavin J.; Tait, Alexander N.; Nahmias, Mitchell A.; Prucnal, Paul R.

2017-03-01

As society's appetite for information continues to grow, so does our need to process this information with increasing speed and versatility. Many believe that the one-size-fits-all solution of digital electronics is becoming a limiting factor in certain areas such as data links, cognitive radio, and ultrafast control. Analog photonic devices have found relatively simple signal processing niches where electronics can no longer provide sufficient speed and reconfigurability. Recently, the landscape for commercially manufacturable photonic chips has been changing rapidly and now promises to achieve economies of scale previously enjoyed solely by microelectronics. By bridging the mathematical prowess of artificial neural networks to the underlying physics of optoelectronic devices, neuromorphic photonics could breach new domains of information processing demanding significant complexity, low cost, and unmatched speed. In this article, we review the progress in neuromorphic photonics, focusing on photonic integrated devices. The challenges and design rules for optoelectronic instantiation of artificial neurons are presented. The proposed photonic architecture revolves around the processing network node composed of two parts: a nonlinear element and a network interface. We then survey excitable lasers in the recent literature as candidates for the nonlinear node and microring-resonator weight banks as the network interface. Finally, we compare metrics between neuromorphic electronics and neuromorphic photonics and discuss potential applications.

Eight challenges for network epidemic models

Directory of Open Access Journals (Sweden)

Lorenzo Pellis

2015-03-01

Full Text Available Networks offer a fertile framework for studying the spread of infection in human and animal populations. However, owing to the inherent high-dimensionality of networks themselves, modelling transmission through networks is mathematically and computationally challenging. Even the simplest network epidemic models present unanswered questions. Attempts to improve the practical usefulness of network models by including realistic features of contact networks and of host–pathogen biology (e.g. waning immunity have made some progress, but robust analytical results remain scarce. A more general theory is needed to understand the impact of network structure on the dynamics and control of infection. Here we identify a set of challenges that provide scope for active research in the field of network epidemic models.

Wireless local area network. A new technology of network

International Nuclear Information System (INIS)

Wu Yunjun; Zhao Zongtao

2003-01-01

This paper introduces Wireless Local Area Network (WLAN), including the concept, history, characters and the foreground of its development, it also narrates in detail the several key techniques used to implement IEEE802.11 WLAN, and ideas on key technology of future progress in wireless LAN field have also been presented. (authors)

Network-based Approaches in Pharmacology.

Science.gov (United States)

Boezio, Baptiste; Audouze, Karine; Ducrot, Pierre; Taboureau, Olivier

2017-10-01

In drug discovery, network-based approaches are expected to spotlight our understanding of drug action across multiple layers of information. On one hand, network pharmacology considers the drug response in the context of a cellular or phenotypic network. On the other hand, a chemical-based network is a promising alternative for characterizing the chemical space. Both can provide complementary support for the development of rational drug design and better knowledge of the mechanisms underlying the multiple actions of drugs. Recent progress in both concepts is discussed here. In addition, a network-based approach using drug-target-therapy data is introduced as an example. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The modularity of pollination networks

DEFF Research Database (Denmark)

Olesen, Jens Mogens; Bascompte, J.; Dupont, Yoko

2007-01-01

In natural communities, species and their interactions are often organized as nonrandom networks, showing distinct and repeated complex patterns. A prevalent, but poorly explored pattern is ecological modularity, with weakly interlinked subsets of species (modules), which, however, internally...... consist of strongly connected species. The importance of modularity has been discussed for a long time, but no consensus on its prevalence in ecological networks has yet been reached. Progress is hampered by inadequate methods and a lack of large datasets. We analyzed 51 pollination networks including...... almost 10,000 species and 20,000 links and tested for modularity by using a recently developed simulated annealing algorithm. All networks with >150 plant and pollinator species were modular, whereas networks with

VRML metabolic network visualizer.

Science.gov (United States)

Rojdestvenski, Igor

2003-03-01

A successful date collection visualization should satisfy a set of many requirements: unification of diverse data formats, support for serendipity research, support of hierarchical structures, algorithmizability, vast information density, Internet-readiness, and other. Recently, virtual reality has made significant progress in engineering, architectural design, entertainment and communication. We experiment with the possibility of using the immersive abstract three-dimensional visualizations of the metabolic networks. We present the trial Metabolic Network Visualizer software, which produces graphical representation of a metabolic network as a VRML world from a formal description written in a simple SGML-type scripting language.

Revealing networks from dynamics: an introduction

International Nuclear Information System (INIS)

Timme, Marc; Casadiego, Jose

2014-01-01

What can we learn from the collective dynamics of a complex network about its interaction topology? Taking the perspective from nonlinear dynamics, we briefly review recent progress on how to infer structural connectivity (direct interactions) from accessing the dynamics of the units. Potential applications range from interaction networks in physics, to chemical and metabolic reactions, protein and gene regulatory networks as well as neural circuits in biology and electric power grids or wireless sensor networks in engineering. Moreover, we briefly mention some standard ways of inferring effective or functional connectivity. (topical review)

Social network analysis community detection and evolution

CERN Document Server

Missaoui, Rokia

2015-01-01

This book is devoted to recent progress in social network analysis with a high focus on community detection and evolution. The eleven chapters cover the identification of cohesive groups, core components and key players either in static or dynamic networks of different kinds and levels of heterogeneity. Other important topics in social network analysis such as influential detection and maximization, information propagation, user behavior analysis, as well as network modeling and visualization are also presented. Many studies are validated through real social networks such as Twitter. This edit

Campus-Wide Networks: Three State-of-the-Art Demonstration Projects.

Science.gov (United States)

Chapman, Dale T.

1986-01-01

During the 1980's, the educational community has been keeping its eye hopefully on several campus-wide networking projects. Included are reports on progress in networks and networking at Carnegie Mellon University, the Massachussetts Institute of Technology (MIT), and at Brown University. (JN)

Reconfigurable optical implementation of quantum complex networks

Science.gov (United States)

Nokkala, J.; Arzani, F.; Galve, F.; Zambrini, R.; Maniscalco, S.; Piilo, J.; Treps, N.; Parigi, V.

2018-05-01

Network theory has played a dominant role in understanding the structure of complex systems and their dynamics. Recently, quantum complex networks, i.e. collections of quantum systems arranged in a non-regular topology, have been theoretically explored leading to significant progress in a multitude of diverse contexts including, e.g., quantum transport, open quantum systems, quantum communication, extreme violation of local realism, and quantum gravity theories. Despite important progress in several quantum platforms, the implementation of complex networks with arbitrary topology in quantum experiments is still a demanding task, especially if we require both a significant size of the network and the capability of generating arbitrary topology—from regular to any kind of non-trivial structure—in a single setup. Here we propose an all optical and reconfigurable implementation of quantum complex networks. The experimental proposal is based on optical frequency combs, parametric processes, pulse shaping and multimode measurements allowing the arbitrary control of the number of the nodes (optical modes) and topology of the links (interactions between the modes) within the network. Moreover, we also show how to simulate quantum dynamics within the network combined with the ability to address its individual nodes. To demonstrate the versatility of these features, we discuss the implementation of two recently proposed probing techniques for quantum complex networks and structured environments.

Competitive Liner Shipping Network Design

DEFF Research Database (Denmark)

Karsten, Christian Vad

.The contributions of this thesis cover modeling, methodology, and applications.The developed methods address operational (cargo routing), tactical (speed optimization and service selection), and strategic (network design) planning problems faced by liner shipping companies. Ultimately, the proposed methods help...... take the container transportation times that can be realized in the network nor the number of transshipments into consideration. This is mainly because the optimization problem is based on other transportation networks where these constraints are not decisive to the quality of the network. Furthermore......, the problem in itself is challenging to optimize due to its size and complexity. However, the field has seen crucial progress and is mature to include handling of competitiveness in the actual design of the network.As a liner shipping network is an organic entity, which is constantly changed to reflect...

Work in progress: a channel selection algorithm for a TVWS mesh network

CSIR Research Space (South Africa)

Zlobinsky, Natasha

2016-09-01

Full Text Available and routing for throughput optimization in multi-radio wireless mesh networks,” Proc. 11th Annu. Int. Conf. Mob. Comput. Netw. - MobiCom ’05, p. 58, 2005. [4] M. R. Rai, S. Vahid, and K. Moessner, “SINR based Topology Control for Multihop Wireless Networks...

The US Network of Pediatric Multiple Sclerosis Centers: Development, Progress, and Next Steps

Science.gov (United States)

Casper, T. Charles; Rose, John W.; Roalstad, Shelly; Waubant, Emmanuelle; Aaen, Gregory; Belman, Anita; Chitnis, Tanuja; Gorman, Mark; Krupp, Lauren; Lotze, Timothy E.; Ness, Jayne; Patterson, Marc; Rodriguez, Moses; Weinstock-Guttman, Bianca; Browning, Brittan; Graves, Jennifer; Tillema, Jan-Mendelt; Benson, Leslie; Harris, Yolanda

2014-01-01

Multiple sclerosis and other demyelinating diseases in the pediatric population have received an increasing level of attention by clinicians and researchers. The low incidence of these diseases in children creates a need for the involvement of multiple clinical centers in research efforts. The Network of Pediatric Multiple Sclerosis Centers was created initially in 2006 to improve the diagnosis and care of children with demyelinating diseases. In 2010, the Network shifted its focus to multicenter research while continuing to advance the care of patients. The Network has obtained support from the National Multiple Sclerosis Society, the Guthy-Jackson Charitable Foundation, and the National Institutes of Health. The Network will continue to serve as a platform for conducting impactful research in pediatric demyelinating diseases of the central nervous system. This article provides a description of the history and development, organization, mission, research priorities, current studies, and future plans of the Network. PMID:25270659

A new polymeric adsorbent developing for uranium recovering and richment from aqueous media

International Nuclear Information System (INIS)

Gueler, H.; Aycik, G. A.; Sahiner, N.; Gueven, O.

1997-01-01

Using adsorbents is thought to be the most effective method for recovering the low concentrations of uranium in the aqueous media because of their fast and selective uptake of uranium, a sufficient adsorption capacity and high physical and chemical stability against the media. In this study, a new polymeric adsorbent bearing both hydrophilic groups providing swelling in water and amidoxime groups for chelating with uranyl ions (UO 2 ''2+) has been developed and its adsorptive ability for uranium from aqueous media has been investigated. The polymers obtained by irradiating the solution of polyethylene glycol (PEG) in acrylonitrile (AN) are defined as Interpenetrating Polymer Networks (IPNs) and the adsorbent has been obtained by applying the amidoximation reaction to the IPNs with a conversion of % 60 approximately. Kinetics of the conversion reaction of nitrile (CN) group to amidoxime (HONCNH 2 ) group has been studied by reacting with hydroxylamine (NH 2 OH) solution at a molar ratio of NH 2 OH/CN=1.25 in aqueous media at different temperatures, 30,40,50''0C, for 3-4 days. The degree of amidoximation was determined by UO 2 ''2+ ion adsorption and FTIR spectrometer and the UO 2 ''2+ ion adsorption values were found by both UV and gamma spectrometry and also by gravimetry. It was found that the polymeric adsorbent has a very high adsorption ability for uranium (∼ 540 mg U/g IPN/day)

Mapping Neurodegenerative Disease Onset and Progression.

Science.gov (United States)

Seeley, William W

2017-08-01

Brain networks have been of long-standing interest to neurodegeneration researchers, including but not limited to investigators focusing on conventional prion diseases, which are known to propagate along neural pathways. Tools for human network mapping, however, remained inadequate, limiting our understanding of human brain network architecture and preventing clinical research applications. Until recently, neuropathological studies were the only viable approach to mapping disease onset and progression in humans but required large autopsy cohorts and laborious methods for whole-brain sectioning and staining. Despite important advantages, postmortem studies cannot address in vivo, physiological, or longitudinal questions and have limited potential to explore early-stage disease except for the most common disorders. Emerging in vivo network-based neuroimaging strategies have begun to address these issues, providing data that complement the neuropathological tradition. Overall, findings to date highlight several fundamental principles of neurodegenerative disease anatomy and pathogenesis, as well as some enduring mysteries. These principles and mysteries provide a road map for future research. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

Networks and their use in high energy physics

International Nuclear Information System (INIS)

Poutissou, R.

1990-01-01

Networks of all kinds have taken an ever increasing importance in many facets of the work of high energy physicists. With the rapid progress experienced in bandwidth and connectivity, wide area and local area networking have vastly improved communications and made distributed processing a reality. In this paper, the characteristics and possible applications of various networks and protocols are reviewed

Preventing the progression to type 2 diabetes mellitus in adults at high risk: a systematic review and network meta-analysis of lifestyle, pharmacological and surgical interventions.

Science.gov (United States)

Stevens, John W; Khunti, Kamlesh; Harvey, Rebecca; Johnson, Maxine; Preston, Louise; Woods, Helen Buckley; Davies, Melanie; Goyder, Elizabeth

2015-03-01

Individuals with impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) have an increased risk of progression to Type 2 diabetes mellitus. The objective of this review was to quantify the effectiveness of lifestyle, pharmacological and surgical interventions in reducing the progression to Type 2 diabetes mellitus in people with IFG or IGT. A systematic review was carried out. A network meta-analysis (NMA) of log-hazard ratios was performed. Results are presented as hazard ratios and the probabilities of treatment rankings. 30 studies were included in the NMA. There was a reduced hazard of progression to Type 2 diabetes mellitus associated with all interventions versus standard lifestyle advice; glipizide, diet plus pioglitazone, diet plus exercise plus metformin plus rosiglitazone, diet plus exercise plus orlistat, diet plus exercise plus pedometer, rosiglitazone, orlistat and diet plus exercise plus voglibose produced the greatest effects. Lifestyle and some pharmacological interventions are beneficial in reducing the risk of progression to Type 2 diabetes mellitus. Lifestyle interventions require significant behaviour changes that may be achieved through incentives such as the use of pedometers. Adverse events and cost of pharmacological interventions should be taken into account when considering potential risks and benefits. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Feasibility study of networks. Progress report, July 15, 1975--July 14, 1976

International Nuclear Information System (INIS)

Campbell, E.J.; Kannel, M.; Saffran, K.

1976-01-01

The Laboratory for Nuclear Science has continued its study into the feasibility of networks, changing the focus of the investigation from the possible ways of collaborating with the MIT Information Processing Center in implementing a connection to the ARPA net to a wider consideration of the implications of computer resource sharing via networks. This report describes experiments performed on the ARPA net in collaboration with the Lawrence Berkeley Laboratory and experiments in more conventional forms of remote job entry to that site and others in ERDA. It discusses the use of the Multics mail as set up for ERDA, comparing it to other mail systems. Plans for future experiments in the ARPA net and for investigation of networks other than the ARPA net are proposed. The conclusion was reached that resource sharing via networks is both feasible and desirable provided certain interface problems are solved. Recommendations are made for more investigation into the human factors involved in network use, methods of providing consulting help to users, and determination of the most cost effective use of remote resource sharing. For the Laboratory for Nuclear Science, it is concluded that access to other ERDA computers via networks will meet some of our computing needs now and more in the future. However, remote resource sharing can be used only to supplement the on site computer, not replace it. At the present time, the best method of accessing the ARPA net for our users is via the MIT Multics System. However, as a permanent solution, a mini-host located in our computer center may provide more capability. In the next year, we plan to work out methods of attacking the problems of interfacing to the ARPA net and to use it in a limited manner for actual production work

Feasibility study of networks. Progress report, July 15, 1975--July 14, 1976

Energy Technology Data Exchange (ETDEWEB)

Campbell, E.J.; Kannel, M.; Saffran, K.

1976-04-30

The Laboratory for Nuclear Science has continued its study into the feasibility of networks, changing the focus of the investigation from the possible ways of collaborating with the MIT Information Processing Center in implementing a connection to the ARPA net to a wider consideration of the implications of computer resource sharing via networks. This report describes experiments performed on the ARPA net in collaboration with the Lawrence Berkeley Laboratory and experiments in more conventional forms of remote job entry to that site and others in ERDA. It discusses the use of the Multics mail as set up for ERDA, comparing it to other mail systems. Plans for future experiments in the ARPA net and for investigation of networks other than the ARPA net are proposed. The conclusion was reached that resource sharing via networks is both feasible and desirable provided certain interface problems are solved. Recommendations are made for more investigation into the human factors involved in network use, methods of providing consulting help to users, and determination of the most cost effective use of remote resource sharing. For the Laboratory for Nuclear Science, it is concluded that access to other ERDA computers via networks will meet some of our computing needs now and more in the future. However, remote resource sharing can be used only to supplement the on site computer, not replace it. At the present time, the best method of accessing the ARPA net for our users is via the MIT Multics System. However, as a permanent solution, a mini-host located in our computer center may provide more capability. In the next year, we plan to work out methods of attacking the problems of interfacing to the ARPA net and to use it in a limited manner for actual production work.

Advances and Challenges in Convergent Communication Networks

DEFF Research Database (Denmark)

Toral-Cruz, Homero; Mihovska, Albena

2017-01-01

Welcome to this special issue of Wireless Personal Communications on Advances and Challenges in Convergent Communication Networks. The main purpose of this special issue is to present new progresses and challenges in convergent networks. Communication networks play an important role in our daily...... life because they allow communicating and sharing contents between heterogeneous nodes around the globe. The emergence of multiple network architectures and emerging technologies have resulted in new applications and services over a heterogeneous network. This heterogeneous network has undergone...... significant challenges in recent years, such as the evolution to a converged network with the capability to support multiple services, while maintaining a satisfactory level of QoE/QoS, security, efficiency and trust. The special issue on Advances and Challenges in Convergent Communication Networks...

Advancing Health Professions Education Research by Creating a Network of Networks.

Science.gov (United States)

Carney, Patricia A; Brandt, Barbara; Dekhtyar, Michael; Holmboe, Eric S

2018-02-27

Producing the best evidence to show educational outcomes, such as competency achievement and credentialing effectiveness, across the health professions education continuum will require large multisite research projects and longitudinal studies. Current limitations that must be overcome to reach this goal include the prevalence of single-institution study designs, assessments of a single curricular component, and cross-sectional study designs that provide only a snapshot in time of a program or initiative rather than a longitudinal perspective.One solution to overcoming these limitations is to develop a network of networks that collaborates, using longitudinal approaches, across health professions and regions of the United States. Currently, individual networks are advancing educational innovation toward understanding the effectiveness of educational and credentialing programs. Examples of such networks include: (1) the American Medical Association's Accelerating Change in Medical Education initiative, (2) the National Center for Interprofessional Practice and Education, and (3) the Accreditation Council for Graduate Medical Education's Accreditation System. In this Invited Commentary, the authors briefly profile these existing networks, identify their progress and the challenges they have encountered, and propose a vigorous way forward toward creating a national network of networks designed to determine the effectiveness of health professions education and credentialing.

Unveiling network-based functional features through integration of gene expression into protein networks.

Science.gov (United States)

Jalili, Mahdi; Gebhardt, Tom; Wolkenhauer, Olaf; Salehzadeh-Yazdi, Ali

2018-06-01

Decoding health and disease phenotypes is one of the fundamental objectives in biomedicine. Whereas high-throughput omics approaches are available, it is evident that any single omics approach might not be adequate to capture the complexity of phenotypes. Therefore, integrated multi-omics approaches have been used to unravel genotype-phenotype relationships such as global regulatory mechanisms and complex metabolic networks in different eukaryotic organisms. Some of the progress and challenges associated with integrated omics studies have been reviewed previously in comprehensive studies. In this work, we highlight and review the progress, challenges and advantages associated with emerging approaches, integrating gene expression and protein-protein interaction networks to unravel network-based functional features. This includes identifying disease related genes, gene prioritization, clustering protein interactions, developing the modules, extract active subnetworks and static protein complexes or dynamic/temporal protein complexes. We also discuss how these approaches contribute to our understanding of the biology of complex traits and diseases. This article is part of a Special Issue entitled: Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers. Copyright © 2018 Elsevier B.V. All rights reserved.

The occurrence and prevention of Infectious Pancreatic Necrosis Virus (IPNV) in rainbow trout fish farms: the importance of improved sanitary practices

OpenAIRE

AGIM REXHEPI; KURTESH SHERIFI; PETER SCHEINERT; LINDA GRAPCI-KOTORRI

2014-01-01

The viral diseases of rainbow trout are of worldwide concern including infectious pancreatic necrosis (IPN). On this study good sanitary practices are applied to prevent outbreaks and minimize losses caused from IPN disease. To highlight importance of improvements on sanitary practices in IPN prevention were compared results from two studies, first conducted in year 2006-2009 with results from one year later study conducted in 2010. In year 2010, samples of organs are collected from 260 fish ...

Real-Time Fault Tolerant Networking Protocols

National Research Council Canada - National Science Library

Henzinger, Thomas A

2004-01-01

We made significant progress in the areas of video streaming, wireless protocols, mobile ad-hoc and sensor networks, peer-to-peer systems, fault tolerant algorithms, dependability and timing analysis...

Standardised versus Individualised Parenteral Nutrition. Further Food for Thought.

Science.gov (United States)

McCarthy, R; Segurado, R; Crealey, M; Twomey, A

2016-04-11

Parenteral Nutrition may be prescribed as a standard PN (SPN) formulation or as an individualised PN (IPN) formulation. SPN may have advantages in terms of rapid availability, less prescription errors, decreased risk of infection and cost savings but IPN, specifically tailored to an infants needs, may achieve better outcomes in terms of nutrient intake and weight gain. The aim of our study was to determine if VLBW infants in our NICU benefited from receiving IPN over currently available SPN solutions. Our findings were that VLBW infants prescribed IPN received significantly more amino acid (28%), glucose (6%), energy (11%) and calcium (8%) from the aqueous phase of PN than had they received a similar volume of SPN. The benefits were seen over all the days for which PN was administered. In conclusion, IPN was found to offer significant benefits to our VLBW infants. Modifications to currently available SPN would result in better SPN formulations. Our study also supported the recent recommendation to reduce the calcium:phosphate ratio in PN solutions to avoid early hypophosphataemia.

Standardised versus Individualised Parenteral Nutrition. Further Food for Thought

LENUS (Irish Health Repository)

McCarthy, R

2016-04-01

Parenteral Nutrition may be prescribed as a standard PN (SPN) formulation or as an individualised PN (IPN) formulation. SPN may have advantages in terms of rapid availability, less prescription errors, decreased risk of infection and cost savings but IPN, specifically tailored to an infant’s needs, may achieve better outcomes in terms of nutrient intake and weight gain. The aim of our study was to determine if VLBW infants in our NICU benefited from receiving IPN over currently available SPN solutions. Our findings were that VLBW infants prescribed IPN received significantly more amino acid (28%), glucose (6%), energy (11%) and calcium (8%) from the aqueous phase of PN than had they received a similar volume of SPN. The benefits were seen over all the days for which PN was administered. In conclusion, IPN was found to offer significant benefits to our VLBW infants. Modifications to currently available SPN would result in better SPN formulations. Our study also supported the recent recommendation to reduce the calcium:phosphate ratio in PN solutions to avoid early hypophosphataemia

Regional connectivity in continental ASEAN

OpenAIRE

Taguchi, Hiroyuki; Nozaki, Kenji

2014-01-01

This chapter examines the issue on Mekong region’s connectivity on quantitative base through the analysis of the gravity trade model and its modified fragmentation model. The main findings are as follows: First, the evolution of international production networks (IPNs) between Thailand and Vietnam as well as the other advanced ASEAN could be identified in terms of their two-way trade integration of machinery parts and components beyond the gravity trade standard. Second, the trade intensity o...

Agent-based modeling and network dynamics

CERN Document Server

Namatame, Akira

2016-01-01

The book integrates agent-based modeling and network science. It is divided into three parts, namely, foundations, primary dynamics on and of social networks, and applications. The book begins with the network origin of agent-based models, known as cellular automata, and introduce a number of classic models, such as Schelling’s segregation model and Axelrod’s spatial game. The essence of the foundation part is the network-based agent-based models in which agents follow network-based decision rules. Under the influence of the substantial progress in network science in late 1990s, these models have been extended from using lattices into using small-world networks, scale-free networks, etc. The book also shows that the modern network science mainly driven by game-theorists and sociophysicists has inspired agent-based social scientists to develop alternative formation algorithms, known as agent-based social networks. The book reviews a number of pioneering and representative models in this family. Upon the gi...

Neutron production enhancements for the Intense Pulsed Neutron Source.

Energy Technology Data Exchange (ETDEWEB)

Iverson, E. B.

1999-01-04

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments.

Neutron production enhancements for the Intense Pulsed Neutron Source

International Nuclear Information System (INIS)

Iverson, E. B.

1999-01-01

The Intense Pulsed Neutron Source (IPNS) was the first high energy spallation neutron source in the US dedicated to materials research. It has operated for sixteen years, and in that time has had a very prolific record concerning the development of new target and moderator systems for pulsed spallation sources. IPNS supports a very productive user program on its thirteen instruments, which are oversubscribed by more than two times, meanwhile having an excellent overall reliability of 95%. Although the proton beam power is relatively low at 7 kW, the target and moderator systems are very efficient. The typical beam power which gives an equivalent flux for long-wavelength neutrons is about 60 kW, due to the use of a uranium target and liquid and solid methane moderators, precluded at some sources due to a higher accelerator power. The development of new target and moderator systems is by no means stagnant at IPNS. They are presently considering numerous enhancements to the target and moderators that offer prospects for increasing the useful neutron production by substantial factors. Many of these enhancements could be combined, although their combined benefit has not yet been well established. Meanwhile, IPNS is embarking on a coherent program of study concerning these improvements and their possible combination and implementation. Moreover, any improvements accomplished at IPNS would immediately increase the performance of IPNS instruments

OSD1 promotes meiotic progression via APC/C inhibition and forms a regulatory network with TDM and CYCA1;2/TAM.

Science.gov (United States)

Cromer, Laurence; Heyman, Jefri; Touati, Sandra; Harashima, Hirofumi; Araou, Emilie; Girard, Chloe; Horlow, Christine; Wassmann, Katja; Schnittger, Arp; De Veylder, Lieven; Mercier, Raphael

2012-01-01

Cell cycle control is modified at meiosis compared to mitosis, because two divisions follow a single DNA replication event. Cyclin-dependent kinases (CDKs) promote progression through both meiosis and mitosis, and a central regulator of their activity is the APC/C (Anaphase Promoting Complex/Cyclosome) that is especially required for exit from mitosis. We have shown previously that OSD1 is involved in entry into both meiosis I and meiosis II in Arabidopsis thaliana; however, the molecular mechanism by which OSD1 controls these transitions has remained unclear. Here we show that OSD1 promotes meiotic progression through APC/C inhibition. Next, we explored the functional relationships between OSD1 and the genes known to control meiotic cell cycle transitions in Arabidopsis. Like osd1, cyca1;2/tam mutation leads to a premature exit from meiosis after the first division, while tdm mutants perform an aberrant third meiotic division after normal meiosis I and II. Remarkably, while tdm is epistatic to tam, osd1 is epistatic to tdm. We further show that the expression of a non-destructible CYCA1;2/TAM provokes, like tdm, the entry into a third meiotic division. Finally, we show that CYCA1;2/TAM forms an active complex with CDKA;1 that can phosphorylate OSD1 in vitro. We thus propose that a functional network composed of OSD1, CYCA1;2/TAM, and TDM controls three key steps of meiotic progression, in which OSD1 is a meiotic APC/C inhibitor.

Progress made by the South African light metals development network

CSIR Research Space (South Africa)

Damm, O

2009-01-01

Full Text Available Through focused investment by the CSIR, the South African Innovation Fund, the Automotive Industry Development Centre and the Department of Science and Technology over the past eight years, the national Light Metals Development Network has been...

The US nuclear reaction data network. Summary of the first meeting, March 13 ampersand 14 1996

International Nuclear Information System (INIS)

1996-03-01

The first meeting of the US Nuclear Reaction Data Network (USNRDN) was held at the Colorado School of Mines, March 13-14, 1996 chaired by F. Edward Cecil. The Agenda of the meeting is attached. The Network, its mission, products and services; related nuclear data and data networks, members, and organization are described in Attachment 1. The following progress reports from the members of the USNRDN were distributed prior to the meeting and are given as Attachment 2. (1) Measurements and Development of Analytic Techniques for Basic Nuclear Physics and Nuclear Applications; (2) Nuclear Reaction Data Activities at the National Nuclear Data Center; (3) Studies of nuclear reactions at very low energies; (4) Nuclear Reaction Data Activities, Nuclear Data Group; (5) Progress in Neutron Physics at Los Alamos - Experiments; (6) Nuclear Reaction Data Activities in Group T2; (7) Progress Report for the US Nuclear Reaction Data Network Meeting; (8) Nuclear Astrophysics Research Group (ORNL); (9) Progress Report from Ohio University; (10) Exciton Model Phenomenology; and (11) Progress Report for Coordination Meeting USNRDN

Status of DOE information network modifications

International Nuclear Information System (INIS)

Fuchs, R.

1988-01-01

This paper provides an update on changes that have been made or are taking place to the Department of Energy's (DOE) National Information Network. Areas of focus are as follows: data acquisition from commercial disposal site operators, specifically, the information delivery system called Manifest Information Management System; improved access methods to DOE Information Network; progress on personal computer interfaces, and availability of end user support

The Reverse Thermal Effect in Epoxy Resins and Moisture Absorption in Semi-Interpenetrating Polymer Networks.

Science.gov (United States)

El-Sa'Ad, Leila

1989-12-01

Available from UMI in association with The British Library. Requires signed TDF. Epoxy resins exhibit many desirable properties which make them ideal subjects for use as matrices of composite materials in many commercial, military and space applications. However, due to their high cross-link density they are often brittle. Epoxy resin networks have been modified by incorporating tough, ductile thermoplastics. Such systems are referred to as Semi-Interpenetrating Polymer Networks (Semi-IPN). Systematic modification to the thermoplastics backbone allowed the morphology of the blend to be controlled from a homogeneous one-phase structure to fully separated structures. The moisture absorption by composites in humid environments has been found to lead to a deterioration in the physical and mechanical properties of the matrix. Therefore, in order to utilize composites to their full potential, their response to hot/wet environments must be known. The aims of this investigation were two-fold. Firstly, to study the effect of varying the temperature of exposure at different stages in the absorption process on the water absorption behaviour of a TGDDM/DDS epoxy resin system. Secondly, to study water absorption characteristics, under isothermal conditions, of Semi-Interpenetrating Polymer Networks possessing different morphologies, and develop a theoretical model to evaluate the diffusion coefficients of the two-phase structures. The mathematical treatment used in this analysis was based on Fick's second law of diffusion. Tests were performed on specimens immersed in water at 10 ^circ, 40^circ and 70^circC, their absorption behaviour and swelling behaviour, as a consequence of water absorption, were investigated. The absorption results of the variable temperature absorption tests indicated a saturation dependence on the absorption behaviour. Specimens saturated at a high temperature will undergo further absorption when transferred to a lower temperature. This behaviour was

Progress of studies on traditional chinese medicine based on complex network analysis

Directory of Open Access Journals (Sweden)

Qian-Ru Zhang

2017-01-01

Full Text Available Traditional Chinese medicine (TCM is a distinct medical system that deals with the life–health–disease–environment relationship using holistic, dynamic, and dialectical thinking. However, reductionism has often restricted the conventional studies on TCM, and these studies did not investigate the central concepts of TCM theory about the multiple relationships among life, health, disease, and environment. Complex network analysis describes a wide variety of complex systems in the real world, and it has the potential to bridge the gap between TCM and modern science owing to the holism of TCM theory. This article summarizes the current research involving TCM network analysis and highlights the computational tools and analysis methods involved in this research. Finally, to inspire a new approach, the article discussed the potential problems underlying the application of TCM network analysis.

Sync in Complex Dynamical Networks: Stability, Evolution, Control, and Application

OpenAIRE

Li, Xiang

2005-01-01

In the past few years, the discoveries of small-world and scale-free properties of many natural and artificial complex networks have stimulated significant advances in better understanding the relationship between the topology and the collective dynamics of complex networks. This paper reports recent progresses in the literature of synchronization of complex dynamical networks including stability criteria, network synchronizability and uniform synchronous criticality in different topologies, ...

Research in high speed fiber optics local area networks

Science.gov (United States)

Tobagi, F. A.

1986-01-01

The design of high speed local area networks (HSLAN) for communication among distributed devices requires solving problems in three areas: the network medium and its topology, the medium access control, and the network interface. Considerable progress was already made in the first two areas. Accomplishments are divided into two groups according to their theoretical or experimental nature. A brief summary is given.

Hierarchy in gene expression is predictive of risk, progression, and outcome in adult acute myeloid leukemia

Science.gov (United States)

Tripathi, Shubham; Deem, Michael W.

2015-02-01

Cancer progresses with a change in the structure of the gene network in normal cells. We define a measure of organizational hierarchy in gene networks of affected cells in adult acute myeloid leukemia (AML) patients. With a retrospective cohort analysis based on the gene expression profiles of 116 AML patients, we find that the likelihood of future cancer relapse and the level of clinical risk are directly correlated with the level of organization in the cancer related gene network. We also explore the variation of the level of organization in the gene network with cancer progression. We find that this variation is non-monotonic, which implies the fitness landscape in the evolution of AML cancer cells is non-trivial. We further find that the hierarchy in gene expression at the time of diagnosis may be a useful biomarker in AML prognosis.

Hierarchy in gene expression is predictive of risk, progression, and outcome in adult acute myeloid leukemia

International Nuclear Information System (INIS)

Tripathi, Shubham; Deem, Michael W

2015-01-01

Cancer progresses with a change in the structure of the gene network in normal cells. We define a measure of organizational hierarchy in gene networks of affected cells in adult acute myeloid leukemia (AML) patients. With a retrospective cohort analysis based on the gene expression profiles of 116 AML patients, we find that the likelihood of future cancer relapse and the level of clinical risk are directly correlated with the level of organization in the cancer related gene network. We also explore the variation of the level of organization in the gene network with cancer progression. We find that this variation is non-monotonic, which implies the fitness landscape in the evolution of AML cancer cells is non-trivial. We further find that the hierarchy in gene expression at the time of diagnosis may be a useful biomarker in AML prognosis. (paper)

Indeterminate Pulmonary Nodules in Colorectal-Cancer

DEFF Research Database (Denmark)

Nordholm-Carstensen, Andreas; Jorgensen, Lars N; Wille-Jørgensen, Peer A

2015-01-01

BACKGROUND: The clinical significance of indeterminate pulmonary nodules (IPN) at staging computed tomography (CT) for colorectal cancer (CRC), and the optimal diagnostic approach, are debated. This study aimed to analyse variability in radiologists' detection of IPN at staging CT for CRC. METHODS......: All patients with CRC referred to our center between 2006 and 2011 were included. Primary staging CT scans were re-evaluated by an experienced thoracic radiologist whose findings were entered into a dedicated database and merged with data from the Danish Colorectal Cancer Group database, the National...... investigated radiological characteristics or clinicopathological factors were significantly associated with malignancy of IPN. CONCLUSION: The characterization of pulmonary findings on staging CT for CRC varied greatly between the radiologists, and double-reading of scans with IPN is recommended prior...

Pneumonia's second wind? A case study of the global health network for childhood pneumonia.

Science.gov (United States)

Berlan, David

2016-04-01

Advocacy, policy, research and intervention efforts against childhood pneumonia have lagged behind other health issues, including malaria, measles and tuberculosis. Accelerating progress on the issue began in 2008, following decades of efforts by individuals and organizations to address the leading cause of childhood mortality and establish a global health network. This article traces the history of this network's formation and evolution to identify lessons for other global health issues. Through document review and interviews with current, former and potential network members, this case study identifies five distinct eras of activity against childhood pneumonia: a period of isolation (post WWII to 1984), the duration of WHO's Acute Respiratory Infections (ARI) Programme (1984-1995), Integrated Management of Childhood illness's (IMCI) early years (1995-2003), a brief period of network re-emergence (2003-2008) and recent accelerating progress (2008 on). Analysis of these eras reveals the critical importance of building a shared identity in order to form an effective network and take advantage of emerging opportunities. During the ARI era, an initial network formed around a relatively narrow shared identity focused on community-level care. The shift to IMCI led to the partial dissolution of this network, stalled progress on addressing pneumonia in communities and missed opportunities. Frustrated with lack of progress on the issue, actors began forming a network and shared identity that included a broad spectrum of those whose interests overlap with pneumonia. As the network coalesced and expanded, its members coordinated and collaborated on conducting and sharing research on severity and tractability, crafting comprehensive strategies and conducting advocacy. These network activities exerted indirect influence leading to increased attention, funding, policies and some implementation. Published by Oxford University Press in association with The London School of

Feasibility study of networks. Progress report, July 15, 1976--December 14, 1976. [ARPANET

Energy Technology Data Exchange (ETDEWEB)

Campbell, E.J.; Kannel, M.; Saffran, K.

1976-10-15

The Laboratory for Nuclear Science continued its study of the implications of computer resource sharing via networks. This report describes the current experiments being performed on the ARPANET in collaboration with the Lawrence Berkeley Laboratory. It discusses and compares the use of mail and teleconferencing systems such as TDA and PLANET. Plans for future experiments on the ARPANET, for expansion of computer-aided communication facilities, and for investigation of networks other than the ARPANET are proposed. The conclusion reached by the study is that resource sharing via networks is both feasible and desirable, provided certain interface problems are solved. Recommendations are made for more investigation into the human factors involved in network use, methods of providing consulting help to users, and determination of the most cost-effective use of remote resource sharing. For the Laboratory for Nuclear Science, it was concluded that access to other ERDA computers via networks will meet some of the computing needs now and more in the future. However, remote resource sharing can be used only to supplement the on-site computer, not replace it. At the present time, the best method of accessing the ARPANET for Laboratory users is via the MIT Multics system. However, immediate needs for remote computing are such that network access is a viable solution as an adjunct to conventional remote job entry but not as a substitute. Therefore, it is proposed to acquire conventional remote job entry equipment on a temporary basis for a year to be used in conjunction with access to the ARPANET.

Light fidelity (Li-Fi): towards all-optical networking

Science.gov (United States)

Tsonev, Dobroslav; Videv, Stefan; Haas, Harald

2013-12-01

Motivated by the looming radio frequency (RF) spectrum crisis, this paper aims at demonstrating that optical wireless communication (OWC) has now reached a state where it can demonstrate that it is a viable and matured solution to this fundamental problem. In particular, for indoor communications where most mobile data traffic is consumed, light fidelity (Li-Fi) which is related to visible light communication (VLC) offers many key advantages, and effective solutions to the issues that have been posed in the last decade. This paper discusses all key component technologies required to realize optical cellular communication systems referred to here as optical attocell networks. Optical attocells are the next step in the progression towards ever smaller cells, a progression which is known to be the most significant contributor to the improvements in network spectral efficiencies in RF wireless networks.

Synthesis of bioactive poly(ethylene glycol)/SiO2-CaO-P2O5 hybrids for bone regeneration

International Nuclear Information System (INIS)

Liu Wei; Wu Xiaohong; Zhan Hongbing; Yan Fuhua

2012-01-01

Poly(ethylene glycol) (PEG)/SiO 2 -CaO-P 2 O 5 hybrid xerogels were prepared using a room temperature sol-gel process. The advantage of this hybrid material over conventional composites is the molecular scale interactions between the bioactive inorganic components and the biodegradable organic components. Since PEG was added into the sol when the hydrolysis of tetraethoxysilane occurred, the molecular chain of PEG was penetrated into the SiO 2 networks to form a semi-IPN structure. Due to the excellent biocompatibility and aqueous solubility of PEG molecules, as well as the bioactivity of the inorganic components, the biological and mechanical properties of this hybrid xerogel exhibit great potential for bone regeneration applications. The formation of hydroxyapatite was observed when the xerogel was immersed into simulated body fluid, demonstrating good bioactivity of the hybrid. The cell toxicity test also demonstrated that the hybrid material is suitable for the proliferation of MC3T3-E1 cells. Thus, the PEG/SiO 2 -CaO-P 2 O 5 hybrid xerogel has great potential to meet the demands of bone regeneration materials. - Highlights: ► PEG was penetrated into the SiO 2 networks to form a semi-IPN structure. ► This hybrid xerogel exhibit great potential for bone regeneration applications. ► SEM micrographs confirm the bioactivity of the samples.

A high-damping magnetorheological elastomer with bi-directional magnetic-control modulus for potential application in seismology

Energy Technology Data Exchange (ETDEWEB)

Yu, Miao, E-mail: yumiao@cqu.edu.cn; Qi, Song; Fu, Jie; Zhu, Mi [Key Lab for Optoelectronic Technology and Systems, Ministry of Education, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

2015-09-14

A high-damping magnetorheological elastomer (MRE) with bi-directional magnetic-control modulus is developed. This MRE was synthesized by filling NdFeB particles into polyurethane (PU)/ epoxy (EP) interpenetrating network (IPN) structure. The anisotropic samples were prepared in a permanent magnetic field and magnetized in an electromagnetic field of 1 T. Dynamic mechanical responses of the MRE to applied magnetic fields are investigated through magneto-rheometer, and morphology of MREs is observed via scanning electron microscope (SEM). Test result indicates that when the test field orientation is parallel to that of the sample's magnetization, the shear modulus of sample increases. On the other hand, when the orientation is opposite to that of the sample's magnetization, shear modulus decreases. In addition, this PU/EP IPN matrix based MRE has a high-damping property, with high loss factor and can be controlled by applying magnetic field. It is expected that the high damping property and the ability of bi-directional magnetic-control modulus of this MRE offer promising advantages in seismologic application.

Identification of genetic variants associated with Huntington's disease progression

DEFF Research Database (Denmark)

Hensman Moss, Davina J; Pardiñas, Antonio F; Langbehn, Douglas

2017-01-01

indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008-11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers...... in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression......BACKGROUND: Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate...

Neural network and its application to CT imaging

Energy Technology Data Exchange (ETDEWEB)

Nikravesh, M.; Kovscek, A.R.; Patzek, T.W. [Lawrence Berkeley National Lab., CA (United States)] [and others

1997-02-01

We present an integrated approach to imaging the progress of air displacement by spontaneous imbibition of oil into sandstone. We combine Computerized Tomography (CT) scanning and neural network image processing. The main aspects of our approach are (I) visualization of the distribution of oil and air saturation by CT, (II) interpretation of CT scans using neural networks, and (III) reconstruction of 3-D images of oil saturation from the CT scans with a neural network model. Excellent agreement between the actual images and the neural network predictions is found.

Efficacy of conservative treatment, without necrosectomy, for infected pancreatic necrosis: a systematic review and meta-analysis.

Science.gov (United States)

Mouli, Venigalla Pratap; Sreenivas, Vishnubhatla; Garg, Pramod Kumar

2013-02-01

Conservative treatment (intensive care, a combination of antimicrobial agents, and nutritional support, with or without drainage of the infected fluid) has recently been shown to be effective for patients with infected pancreatic necrosis (IPN), but the data from individual studies are not robust enough to recommend it as the standard of care. We performed a systematic review and meta-analysis of studies related to primary conservative management for IPN. We performed a literature search of MEDLINE/PubMed from January 1990 to March 2012 for studies of a priori protocols for primary conservative treatment, without necrosectomy, for consecutive patients with IPN. We analyzed data from 8 studies, comprising 324 patients with IPN who received primary conservative management. We then analyzed an additional 4 studies (comprising 157 patients) that reported the efficacy of percutaneous drainage in nonconsecutive patients with IPN. Outcome measures were the success of conservative management strategy, need for necrosectomy, and mortality. There was significant heterogeneity in results among the studies. Based on a random effects model, conservative management was successful for 64% of patients (95% confidence interval [CI], 51%-78%); mortality was 12% (95% CI, 6%-18%), and 26% of patients required necrosectomy or additional surgery for complications (95% CI, 15%-37%). A separate analysis of 4 studies that reported outcomes of nonconsecutive patients with IPN following percutaneous drainage had comparable results; 50% had successful outcomes (95% CI, 43%-58%), mortality was 18% (95% CI, 6%-30%), and 38% of patients required surgery (95% CI, 20%-56%). Conservative management without necrosectomy is a successful approach for 64% of patients with IPN. This approach has low mortality and prevents surgical necrosectomy. Copyright © 2013 AGA Institute. Published by Elsevier Inc. All rights reserved.

VTVH-MCD and DFT studies of thiolate bonding to [FeNO]7/[FeO2]8 complexes of isopenicillin N synthase: substrate determination of oxidase versus oxygenase activity in nonheme Fe enzymes.

Science.gov (United States)

Brown, Christina D; Neidig, Michael L; Neibergall, Matthew B; Lipscomb, John D; Solomon, Edward I

2007-06-13

Isopenicillin N synthase (IPNS) is a unique mononuclear nonheme Fe enzyme that catalyzes the four-electron oxidative double ring closure of its substrate ACV. A combination of spectroscopic techniques including EPR, absorbance, circular dichroism (CD), magnetic CD, and variable-temperature, variable-field MCD (VTVH-MCD) were used to evaluate the geometric and electronic structure of the [FeNO]7 complex of IPNS coordinated with the ACV thiolate ligand. Density Function Theory (DFT) calculations correlated to the spectroscopic data were used to generate an experimentally calibrated bonding description of the Fe-IPNS-ACV-NO complex. New spectroscopic features introduced by the binding of the ACV thiolate at 13 100 and 19 800 cm-1 are assigned as the NO pi*(ip) --> Fe dx2-y2 and S pi--> Fe dx2-y2 charge transfer (CT) transitions, respectively. Configuration interaction mixes S CT character into the NO pi*(ip) --> Fe dx2-y2 CT transition, which is observed experimentally from the VTVH-MCD data from this transition. Calculations on the hypothetical {FeO2}8 complex of Fe-IPNS-ACV reveal that the configuration interaction present in the [FeNO]7 complex results in an unoccupied frontier molecular orbital (FMO) with correct orientation and distal O character for H-atom abstraction from the ACV substrate. The energetics of NO/O2 binding to Fe-IPNS-ACV were evaluated and demonstrate that charge donation from the ACV thiolate ligand renders the formation of the FeIII-superoxide complex energetically favorable, driving the reaction at the Fe center. This single center reaction allows IPNS to avoid the O2 bridged binding generally invoked in other nonheme Fe enzymes that leads to oxygen insertion (i.e., oxygenase function) and determines the oxidase activity of IPNS.

Do FDI Inflows influence Merchandise Exports? Causality Analysis on India over 1991-2016

OpenAIRE

Chakraborty, Debashis; Mukherjee, Jaydeep; Lee, Jaewook

2016-01-01

The deepening waves of globalization since late eighties and the growth in the international integrated production networks (IPN) over the past decade have significantly increased both Foreign Direct Investment (FDI) and merchandise trade flows. India is no exception to this trend, whose share in global FDI inward stock and global merchandise exports have increased from 0.08 percent to 1.13 percent and 0.51 percent to 1.60 percent over 1989-2015 respectively. The current paper attempts to exp...

Progress on the NEPTUNE Canada Seismograph Network

Science.gov (United States)

Rogers, G. C.; Meldrum, R. D.; Heesemann, M.; Mulder, T. L.; Brillon, C. D.; Cassidy, J. F.

2012-12-01

NEPTUNE Canada is the world's first deep-sea regional multi-disciplinary scientific cabled ocean observatory. In the fall of 2007 an 800 kilometer ring of powered fiber optic cable was laid on the seafloor over the northern part of the Juan de Fuca plate and connected to a shore facility near Port Alberni on Vancouver Island. In September 2009, three broadband OBS packages were deployed in the form of a large triangle with apexes at mid plate near ODP 1027 (water depth of 2654m) and two sites on the continental slope, near ODP 889 (1256m) and Barkley Canyon (396m). The broadband systems comprise a broadband seismometer and strong motion accelerometer in a spherical titanium case surficially buried in a caisson backfilled with glass beads. Noise levels observed are as expected with the spectra being similar to, or quieter than, coastal seismograph stations in approximately the 10 to 20 second period range. The OBS's have higher noise levels at longer periods where ocean swells and the resultant infragravity waves dominate the noise spectra, and in the 1-10 Hz bandwidth typically used for locating local earthquakes. The shallowest site at Barkley Canyon has the highest noise levels. A small array, about 6 km in maximum dimension, is under construction on the Endeavour segment of the Juan de Fuca Ridge to record earthquake activity in the vicinity of the many NEPTUNE Canada multi-disciplinary ridge experiments. Two short period instruments were installed there in 2010. A broadband instrument and two additional short period instruments are planned to complete the initial ridge array. Even though the NEPTUNE Canada seismograph network is not yet complete, measured by the use of its data, it is a success already. The data are routinely used along with data from land seismographs of the Canadian National Seismograph Network for locating earthquakes in the region. However, the smallest seismic arrivals picked on the land stations cannot be routinely picked on the OBS

Nuclear reactor pump diagnostics via noise analysis/artificial neural networks

International Nuclear Information System (INIS)

Keyvan, S.; Rabelo, L.C.

1991-01-01

A feasibility study is performed on the utilization of artificial neural networks as a tool for reactor diagnostics. Reactor pump signals utilized in a wear-out monitoring system developed for early detection of degradation of pump shaft are analyzed as a semi-benchmark test to study the feasibility of neural networks for pattern recognition. The Adaptive Resonance Theory (ART 2) paradigm of artificial neural networks is applied in this study. The signals are collected signals as well as generated signals simulating the wear progress. The wear-out monitoring system applies noise analysis techniques, and is capable of distinguishing between these signals and providing a measure of the progress of the degradation. This paper presents the results of the analysis of these data via the ART 2 paradigm

Fundamental structures of dynamic social networks

DEFF Research Database (Denmark)

Sekara, Vedran; Stopczynski, Arkadiusz; Jørgensen, Sune Lehmann

2016-01-01

Social systems are in a constant state of flux, with dynamics spanning from minute-by-minute changes to patterns present on the timescale of years. Accurate models of social dynamics are important for understanding the spreading of influence or diseases, formation of friendships...... and their interactions in the network of real-world person-to-person proximity measured via Bluetooth, as well as their telecommunication networks, online social media contacts, geolocation, and demographic data. These high-resolution data allow us to observe social groups directly, rendering community detection......, and the productivity of teams. Although there has been much progress on understanding complex networks over the past decade, little is known about the regularities governing the microdynamics of social networks. Here, we explore the dynamic social network of a densely-connected population of ∼1,000 individuals...

Nanoporous ionic organic networks: from synthesis to materials applications

OpenAIRE

Sun, Jian-Ke; Antonietti, Markus; Yuan, Jiayin

2016-01-01

The past decade has witnessed rapid progress in the synthesis of nanoporous organic networks or polymer frameworks for various potential applications. Generally speaking, functionalization of porous networks to add extra properties and enhance materials performance could be achieved either during the pore formation (thus a concurrent approach) or by post-synthetic modification (a sequential approach). Nanoporous organic networks which include ion pairs bound in a covalent manner are of specia...

Proceedings of the symposium on networking

International Nuclear Information System (INIS)

Karita, Yukio; Abe, Fumio

1989-06-01

The first symposium on networking was held on February 6-7, 1989. Due to the increase of the needs of computer networks, several networks which connect among universities and laboratories are going to be constructed in Japan. However, the techniques in networking are not familiar to most people, and the information about these techniques is sometimes difficult to get, especially in multivendor connection. In such situation, an opportunity to hold a symposium on networking at the National Laboratory for High Energy Physics (KEK) was given. More than 200 people took part in this symposium, and the local area networks in institutions, the networks among institutions, the networks for high energy physics, the application of networks, the networks for academic research and so on are reported. The valuable discussion about networks was carried out, including the plans for near future. At the time of this symposium, the construction of the Gakujo-net and the Pacific network project of University of Hawaii were in progress, and many Japanese universities are going to construct their campus LANs, so the symposium seemed to be very timely. (K.I.)

Memristor-based neural networks

International Nuclear Information System (INIS)

Thomas, Andy

2013-01-01

The synapse is a crucial element in biological neural networks, but a simple electronic equivalent has been absent. This complicates the development of hardware that imitates biological architectures in the nervous system. Now, the recent progress in the experimental realization of memristive devices has renewed interest in artificial neural networks. The resistance of a memristive system depends on its past states and exactly this functionality can be used to mimic the synaptic connections in a (human) brain. After a short introduction to memristors, we present and explain the relevant mechanisms in a biological neural network, such as long-term potentiation and spike time-dependent plasticity, and determine the minimal requirements for an artificial neural network. We review the implementations of these processes using basic electric circuits and more complex mechanisms that either imitate biological systems or could act as a model system for them. (topical review)

Abnormal metabolic brain networks in Parkinson's disease from blackboard to bedside.

Science.gov (United States)

Tang, Chris C; Eidelberg, David

2010-01-01

Metabolic imaging in the rest state has provided valuable information concerning the abnormalities of regional brain function that underlie idiopathic Parkinson's disease (PD). Moreover, network modeling procedures, such as spatial covariance analysis, have further allowed for the quantification of these changes at the systems level. In recent years, we have utilized this strategy to identify and validate three discrete metabolic networks in PD associated with the motor and cognitive manifestations of the disease. In this chapter, we will review and compare the specific functional topographies underlying parkinsonian akinesia/rigidity, tremor, and cognitive disturbance. While network activity progressed over time, the rate of change for each pattern was distinctive and paralleled the development of the corresponding clinical symptoms in early-stage patients. This approach is already showing great promise in identifying individuals with prodromal manifestations of PD and in assessing the rate of progression before clinical onset. Network modulation was found to correlate with the clinical effects of dopaminergic treatment and surgical interventions, such as subthalamic nucleus (STN) deep brain stimulation (DBS) and gene therapy. Abnormal metabolic networks have also been identified for atypical parkinsonian syndromes, such as multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). Using multiple disease-related networks for PD, MSA, and PSP, we have developed a novel, fully automated algorithm for accurate classification at the single-patient level, even at early disease stages. Copyright © 2010 Elsevier B.V. All rights reserved.

Integrated control platform for converged optical and wireless networks

DEFF Research Database (Denmark)

Yan, Ying

The next generation of broadband access networks is expected to be heterogeneous. Multiple wired and wireless systems can be integrated, in order to simultaneously provide seamless access with an appropriate Quality of Service (QoS). Wireless networks support ubiquitous connectivity yet low data...... rates, whereas optical networks can offer much higher data rates but only provide fixed connection structures. Their complementary characteristics make the integration of the two networks a promising trend for next generation networks. With combined strengths, the converged network will provide both...... the complementary characteristics of the optical networks and the wireless networks, addresses motivations for their interworking, discusses the current progress in hybrid network architectures as well as the functionalities of a control system, and identifies the achieved research contributions in the integrated...

Effect drug loading process on dissolution mechanism of encapsulated amoxicillin trihydrate in hydrogel semi-IPN chitosan methyl cellulose with pore forming agent KHCO3 as a floating drug delivery system

Science.gov (United States)

Fithawati, Garnis; Budianto, Emil

2018-04-01

Common treatment for Helicobacter pylori by repeated oral consumption of amoxicillin trihydrate is not effective. Amoxicillin trihydrate has a very short residence time in stomach which leads into its ineffectiveness. Residence time of amoxicillin trihydrate can be improved by encapsulating amoxicillin trihydrate into a floating drug delivery system. In this study, amoxicillin trihydrate is encapsulated into hydrogel semi-IPN chitosan methyl cellulose matrix as a floating drug delivery system and then treated with 20% KHCO3 as pore forming agent. Drug loading process used are in-situ loading and post loading. In-situ loading process has higher efficiency percentage and dissolution percentage than post loading process. In-situ loading process resulted 100% efficiency with 92,70% dissolution percentage. Post loading process resulted 98,7% efficiency with 90,42% dissolution percentage. Mechanism of drug dissolution study by kinetics approach showed both in-situ loading process and post loading process are diffusion and degradation process (n=0,4913) and (n=0,4602) respectively. These results are supported by characterization data from optical microscope and scanning electron microscopy (SEM). Data from optical microscope showed both loading process resulted in coarser hydrogel surface. Characterization using SEM showed elongated pores in both loading process after dissolution test.

Estimating mental states of a depressed person with bayesian networks

NARCIS (Netherlands)

Klein, Michel C.A.; Modena, Gabriele

2013-01-01

In this work in progress paper we present an approach based on Bayesian Networks to model the relationship between mental states and empirical observations in a depressed person. We encode relationships and domain expertise as a Hierarchical Bayesian Network. Mental states are represented as latent

Age gene expression and coexpression progressive signatures in peripheral blood leukocytes.

Science.gov (United States)

Irizar, Haritz; Goñi, Joaquín; Alzualde, Ainhoa; Castillo-Triviño, Tamara; Olascoaga, Javier; Lopez de Munain, Adolfo; Otaegui, David

2015-12-01

Both cellular senescence and organismic aging are known to be dynamic processes that start early in life and progress constantly during the whole life of the individual. In this work, with the objective of identifying signatures of age-related progressive change at the transcriptomic level, we have performed a whole-genome gene expression analysis of peripheral blood leukocytes in a group of healthy individuals with ages ranging from 14 to 93 years. A set of genes with progressively changing gene expression (either increase or decrease with age) has been identified and contextualized in a coexpression network. A modularity analysis has been performed on this network and biological-term and pathway enrichment analyses have been used for biological interpretation of each module. In summary, the results of the present work reveal the existence of a transcriptomic component that shows progressive expression changes associated to age in peripheral blood leukocytes, highlighting both the dynamic nature of the process and the need to complement young vs. elder studies with longitudinal studies that include middle aged individuals. From the transcriptional point of view, immunosenescence seems to be occurring from a relatively early age, at least from the late 20s/early 30s, and the 49-56 year old age-range appears to be critical. In general, the genes that, according to our results, show progressive expression changes with aging are involved in pathogenic/cellular processes that have classically been linked to aging in humans: cancer, immune processes and cellular growth vs. maintenance. Copyright © 2015 Elsevier Inc. All rights reserved.

Algebraic connectivity of brain networks shows patterns of segregation leading to reduced network robustness in Alzheimer's disease

Science.gov (United States)

Daianu, Madelaine; Jahanshad, Neda; Nir, Talia M.; Leonardo, Cassandra D.; Jack, Clifford R.; Weiner, Michael W.; Bernstein, Matthew A.; Thompson, Paul M.

2015-01-01

Measures of network topology and connectivity aid the understanding of network breakdown as the brain degenerates in Alzheimer's disease (AD). We analyzed 3-Tesla diffusion-weighted images from 202 patients scanned by the Alzheimer's Disease Neuroimaging Initiative – 50 healthy controls, 72 with early- and 38 with late-stage mild cognitive impairment (eMCI/lMCI) and 42 with AD. Using whole-brain tractography, we reconstructed structural connectivity networks representing connections between pairs of cortical regions. We examined, for the first time in this context, the network's Laplacian matrix and its Fiedler value, describing the network's algebraic connectivity, and the Fiedler vector, used to partition a graph. We assessed algebraic connectivity and four additional supporting metrics, revealing a decrease in network robustness and increasing disarray among nodes as dementia progressed. Network components became more disconnected and segregated, and their modularity increased. These measures are sensitive to diagnostic group differences, and may help understand the complex changes in AD. PMID:26640830

Building AN International Polar Data Coordination Network

Science.gov (United States)

Pulsifer, P. L.; Yarmey, L.; Manley, W. F.; Gaylord, A. G.; Tweedie, C. E.

2013-12-01

In the spirit of the World Data Center system developed to manage data resulting from the International Geophysical Year of 1957-58, the International Polar Year 2007-2009 (IPY) resulted in significant progress towards establishing an international polar data management network. However, a sustained international network is still evolving. In this paper we argue that the fundamental building blocks for such a network exist and that the time is right to move forward. We focus on the Arctic component of such a network with linkages to Antarctic network building activities. A review of an important set of Network building blocks is presented: i) the legacy of the IPY data and information service; ii) global data management services with a polar component (e.g. World Data System); iii) regional systems (e.g. Arctic Observing Viewer; iv) nationally focused programs (e.g. Arctic Observing Viewer, Advanced Cooperative Arctic Data and Information Service, Polar Data Catalogue, Inuit Knowledge Centre); v) programs focused on the local (e.g. Exchange for Local Observations and Knowledge of the Arctic, Geomatics and Cartographic Research Centre). We discuss current activities and results with respect to three priority areas needed to establish a strong and effective Network. First, a summary of network building activities reports on a series of productive meetings, including the Arctic Observing Summit and the Polar Data Forum, that have resulted in a core set of Network nodes and participants and a refined vision for the Network. Second, we recognize that interoperability for information sharing fundamentally relies on the creation and adoption of community-based data description standards and data delivery mechanisms. There is a broad range of interoperability frameworks and specifications available; however, these need to be adapted for polar community needs. Progress towards Network interoperability is reviewed, and a prototype distributed data systems is demonstrated. We

Integration of Plant Metabolomics Data with Metabolic Networks: Progresses and Challenges.

Science.gov (United States)

Töpfer, Nadine; Seaver, Samuel M D; Aharoni, Asaph

2018-01-01

In the last decade, plant genome-scale modeling has developed rapidly and modeling efforts have advanced from representing metabolic behavior of plant heterotrophic cell suspensions to studying the complex interplay of cell types, tissues, and organs. A crucial driving force for such developments is the availability and integration of "omics" data (e.g., transcriptomics, proteomics, and metabolomics) which enable the reconstruction, extraction, and application of context-specific metabolic networks. In this chapter, we demonstrate a workflow to integrate gas chromatography coupled to mass spectrometry (GC-MS)-based metabolomics data of tomato fruit pericarp (flesh) tissue, at five developmental stages, with a genome-scale reconstruction of tomato metabolism. This method allows for the extraction of context-specific networks reflecting changing activities of metabolic pathways throughout fruit development and maturation.

Pneumonia’s second wind? A case study of the global health network for childhood pneumonia

Science.gov (United States)

Berlan, David

2016-01-01

Advocacy, policy, research and intervention efforts against childhood pneumonia have lagged behind other health issues, including malaria, measles and tuberculosis. Accelerating progress on the issue began in 2008, following decades of efforts by individuals and organizations to address the leading cause of childhood mortality and establish a global health network. This article traces the history of this network’s formation and evolution to identify lessons for other global health issues. Through document review and interviews with current, former and potential network members, this case study identifies five distinct eras of activity against childhood pneumonia: a period of isolation (post WWII to 1984), the duration of WHO’s Acute Respiratory Infections (ARI) Programme (1984–1995), Integrated Management of Childhood illness’s (IMCI) early years (1995–2003), a brief period of network re-emergence (2003–2008) and recent accelerating progress (2008 on). Analysis of these eras reveals the critical importance of building a shared identity in order to form an effective network and take advantage of emerging opportunities. During the ARI era, an initial network formed around a relatively narrow shared identity focused on community-level care. The shift to IMCI led to the partial dissolution of this network, stalled progress on addressing pneumonia in communities and missed opportunities. Frustrated with lack of progress on the issue, actors began forming a network and shared identity that included a broad spectrum of those whose interests overlap with pneumonia. As the network coalesced and expanded, its members coordinated and collaborated on conducting and sharing research on severity and tractability, crafting comprehensive strategies and conducting advocacy. These network activities exerted indirect influence leading to increased attention, funding, policies and some implementation. PMID:26438780

Scottish Stroke Research Network: the first three years.

Science.gov (United States)

McCormick, K; Langhorne, P; Graham, F E J; McFarlane, C

2010-08-01

Research networks were introduced in the UK to facilitate and improve clinical research and stroke was seen as a priority topic for local research network development. The Scottish Stroke Research Network (SSRN) is one of 11 stroke research networks in the UK. In this article we review the progress of the Scottish Stroke Research Network in the three years since inception. Between 2006-2009 the number of active hospital research sites has increased from 10 to 22 expanding to involve 20 stroke research nurses. There was a corresponding 58% increase in recruitment of participants into stroke studies, from 376 in 2006/07 to 594 in 2008/09. The majority (17/20) of our current studies are interventional. Data from one of these, the CLOTs trial (Clots in Legs Or sTocking after Stroke), demonstrates that the annual recruitment in Scotland increased from a median of 94 (range 6-122) patients per year in the six years before the SSRN, to 140 (135-158) patients per year after SSRN involvement. We currently screen about 50% of Scottish stroke patients and approximately 5% of Scottish stroke patients are participating in research studies that we support. The SSRN has made good progress in the first three years. Increasing the recruitment of screened patients remains a challenge.

Developing Strategies for Networked Education.

Science.gov (United States)

Peregoy, Richard; Kroder, Stanley

2000-01-01

Assesses the strengths, weaknesses, opportunities and threats (SWOT) of the distance learning approach to education, and discusses how one institution, the University of Dallas Graduate School of Management, has developed a progressively expanding networked distance education program. Includes quotes from three students that suggest the quality of…

Network-based identification of biomarkers coexpressed with multiple pathways.

Science.gov (United States)

Guo, Nancy Lan; Wan, Ying-Wooi

2014-01-01

Unraveling complex molecular interactions and networks and incorporating clinical information in modeling will present a paradigm shift in molecular medicine. Embedding biological relevance via modeling molecular networks and pathways has become increasingly important for biomarker identification in cancer susceptibility and metastasis studies. Here, we give a comprehensive overview of computational methods used for biomarker identification, and provide a performance comparison of several network models used in studies of cancer susceptibility, disease progression, and prognostication. Specifically, we evaluated implication networks, Boolean networks, Bayesian networks, and Pearson's correlation networks in constructing gene coexpression networks for identifying lung cancer diagnostic and prognostic biomarkers. The results show that implication networks, implemented in Genet package, identified sets of biomarkers that generated an accurate prediction of lung cancer risk and metastases; meanwhile, implication networks revealed more biologically relevant molecular interactions than Boolean networks, Bayesian networks, and Pearson's correlation networks when evaluated with MSigDB database.

Optical Network Testbeds Workshop

Energy Technology Data Exchange (ETDEWEB)

Joe Mambretti

2007-06-01

technologies. Several years ago, when many of these optical networking research topics were first being investigated, they were the subject of controversial debate. The new techniques challenged many long-held concepts related to architecture and technology. However, today all major networking organizations are transitioning toward infrastructure that incorporates these new concepts. This progress has been assisted through the series of Optical Networking Testbed Workshops (ONT). The first (ONT1) outlined a general framework of key issues and topics and developed a series of recommendations (www.nren.nasa.gov/workshop7). The second (ONT2) developed a common vision of optical network technologies, services, infrastructure, and organizations (www.nren.nasa.gov/workshop8). Processes that allow for a common vision encourage widespread deployment of these types of resources among advanced networking communities. Also, such a shared vision enables key concepts and technologies to migrate from basic research testbeds to wider networking communities. The ONT-3 workshop built on these earlier activities by expanding discussion to include additional considerations of the international interoperability and of greater impact of optical networking technology on networking in general. In accordance with this recognition, the workshop confirmed that future-oriented research and development is indispensable to fundamentally change the current Internet architecture to create a global network incorporating completely new concepts. The workshop also recognized that the first priority to allow for this progress is basic research and development, including international collaborative activities, which are important for the global realization of interoperability of a new generation architecture.

Transport link scanner: simulating geographic transport network expansion through individual investments

NARCIS (Netherlands)

Koopmans, C.C.; Jacobs, C.G.W.

2016-01-01

This paper introduces a GIS-based model that simulates the geographic expansion of transport networks by several decision-makers with varying objectives. The model progressively adds extensions to a growing network by choosing the most attractive investments from a limited choice set. Attractiveness

Entropy Learning in Neural Network

Directory of Open Access Journals (Sweden)

Geok See Ng

2017-12-01

Full Text Available In this paper, entropy term is used in the learning phase of a neural network.  As learning progresses, more hidden nodes get into saturation.  The early creation of such hidden nodes may impair generalisation.  Hence entropy approach is proposed to dampen the early creation of such nodes.  The entropy learning also helps to increase the importance of relevant nodes while dampening the less important nodes.  At the end of learning, the less important nodes can then be eliminated to reduce the memory requirements of the neural network.

Nanoporous ionic organic networks: from synthesis to materials applications.

Science.gov (United States)

Sun, Jian-Ke; Antonietti, Markus; Yuan, Jiayin

2016-11-21

The past decade has witnessed rapid progress in the synthesis of nanoporous organic networks or polymer frameworks for various potential applications. Generally speaking, functionalization of porous networks to add extra properties and enhance materials performance could be achieved either during the pore formation (thus a concurrent approach) or by post-synthetic modification (a sequential approach). Nanoporous organic networks which include ion pairs bound in a covalent manner are of special importance and possess extreme application profiles. Within these nanoporous ionic organic networks (NIONs), here with a pore size in the range from sub-1 nm to 100 nm, we observe a synergistic coupling of the electrostatic interaction of charges, the nanoconfinement within pores and the addressable functional units in soft matter resulting in a wide variety of functions and applications, above all catalysis, energy storage and conversion, as well as environment-related operations. This review aims to highlight the recent progress in this area, and seeks to raise original perspectives that will stimulate future advancements at both the fundamental and applied level.

Assessment of network perturbation amplitudes by applying high-throughput data to causal biological networks

Directory of Open Access Journals (Sweden)

Martin Florian

2012-05-01

Full Text Available Abstract Background High-throughput measurement technologies produce data sets that have the potential to elucidate the biological impact of disease, drug treatment, and environmental agents on humans. The scientific community faces an ongoing challenge in the analysis of these rich data sources to more accurately characterize biological processes that have been perturbed at the mechanistic level. Here, a new approach is built on previous methodologies in which high-throughput data was interpreted using prior biological knowledge of cause and effect relationships. These relationships are structured into network models that describe specific biological processes, such as inflammatory signaling or cell cycle progression. This enables quantitative assessment of network perturbation in response to a given stimulus. Results Four complementary methods were devised to quantify treatment-induced activity changes in processes described by network models. In addition, companion statistics were developed to qualify significance and specificity of the results. This approach is called Network Perturbation Amplitude (NPA scoring because the amplitudes of treatment-induced perturbations are computed for biological network models. The NPA methods were tested on two transcriptomic data sets: normal human bronchial epithelial (NHBE cells treated with the pro-inflammatory signaling mediator TNFα, and HCT116 colon cancer cells treated with the CDK cell cycle inhibitor R547. Each data set was scored against network models representing different aspects of inflammatory signaling and cell cycle progression, and these scores were compared with independent measures of pathway activity in NHBE cells to verify the approach. The NPA scoring method successfully quantified the amplitude of TNFα-induced perturbation for each network model when compared against NF-κB nuclear localization and cell number. In addition, the degree and specificity to which CDK

RXTE All-Sky Monitor Localization of SGR 1627-41

OpenAIRE

Smith, Donald A.; Bradt, Hale V.; Levine, Alan M.

1999-01-01

The fourth unambiguously identified Soft Gamma Repeater (SGR), SGR1627-41, was discovered with the BATSE instrument on 1998 June 15 (Kouveliotou et al. 1998). Interplanetary Network (IPN) measurements and BATSE data constrained the location of this new SGR to a 6 deg segment of a narrow (19") annulus (Hurley et al. 1999; Woods et al. 1998). We present two bursts from this source observed by the All-Sky Monitor (ASM) on RXTE. We use the ASM data to further constrain the source location to a 5'...

Nuclear data progress in China (1987 ∼ 1990)

International Nuclear Information System (INIS)

Cai Dunjiu; Yuan Hanrong

1991-01-01

The nuclear data progress from 1987 to 1990 in China were described. It includes nuclear data evaluations and nuclear data library development, development of theory method and code used for nuclear data calculation and evaluation, group constant generating and benchmark testing, nuclear data measurement; international activities and co-operations. These works were carried out by the Chinese Nuclear Data Center and the chinese Nuclear Data Coordination Network

NRC TLD direct radiation monitoring network: Progress report, April--June 1988

International Nuclear Information System (INIS)

Struckmeyer, R.; McNamara, N.

1988-09-01

This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facility sites throughout the country for the second quarter of 1988

Security of Mobile Devices and Wi-Fi Networks

OpenAIRE

Hong, Zimeng

2015-01-01

Along with the progress of times and the development of science and technology, mobile devices have become more and more popular. At the same time, an increasing number of Wi-Fi networks are being built for the demand of mobile devices. Therefore, the security between mobile devices and Wi-Fi networks became a main object in the IT area. The purpose of the thesis is to analyze security threats and give relative advises for all the mobile device and Wi-Fi network users. The thesis mainly ta...

Targeting molecular networks for drug research

Directory of Open Access Journals (Sweden)

José Pedro Pinto

2014-06-01

Full Text Available The study of molecular networks has recently moved into the limelight of biomedical research. While it has certainly provided us with plenty of new insights into cellular mechanisms, the challenge now is how to modify or even restructure these networks. This is especially true for human diseases, which can be regarded as manifestations of distorted states of molecular networks. Of the possible interventions for altering networks, the use of drugs is presently the most feasible. In this mini-review, we present and discuss some exemplary approaches of how analysis of molecular interaction networks can contribute to pharmacology (e.g., by identifying new drug targets or prediction of drug side effects, as well as listing pointers to relevant resources and software to guide future research. We also outline recent progress in the use of drugs for in vitro reprogramming of cells, which constitutes an example par excellence for altering molecular interaction networks with drugs.

Global Monitoring of the CTBT: Progress, Capabilities and Plans (Invited)

Science.gov (United States)

Zerbo, L.

2013-12-01

The Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), established in 1996, is tasked with building up the verification regime of the CTBT. The regime includes a global system for monitoring the earth, the oceans and the atmosphere for nuclear tests, and an on-site inspection (OSI) capability. More than 80% of the 337 facilities of the International Monitoring System (IMS) have been installed and are sending data to the International Data Centre (IDC) in Vienna, Austria for processing. These IMS data along with IDC processed and reviewed products are available to all States that have signed the Treaty. Concurrent with the build-up of the global monitoring networks, near-field geophysical methods are being developed and tested for OSIs. The monitoring system is currently operating in a provisional mode, as the Treaty has not yet entered into force. Progress in installing and operating the IMS and the IDC and in building up an OSI capability will be described. The capabilities of the monitoring networks have progressively improved as stations are added to the IMS and IDC processing techniques refined. Detection thresholds for seismic, hydroacoustic, infrasound and radionuclide events have been measured and in general are equal to or lower than the predictions used during the Treaty negotiations. The measurements have led to improved models and tools that allow more accurate predictions of future capabilities and network performance under any configuration. Unplanned tests of the monitoring network occurred when the DPRK announced nuclear tests in 2006, 2009, and 2013. All three tests were well above the detection threshold and easily detected and located by the seismic monitoring network. In addition, noble gas consistent with the nuclear tests in 2006 and 2013 (according to atmospheric transport models) was detected by stations in the network. On-site inspections of these tests were not conducted as the Treaty has not entered

Primary Progressive Aphasia in the Network of French Alzheimer Plan Memory Centers.

Science.gov (United States)

Magnin, Eloi; Démonet, Jean-François; Wallon, David; Dumurgier, Julien; Troussière, Anne-Cécile; Jager, Alain; Duron, Emmanuelle; Gabelle, Audrey; de la Sayette, Vincent; Volpe-Gillot, Lisette; Tio, Gregory; Evain, Sarah; Boutoleau-Bretonnière, Claire; Enderle, Adeline; Mouton-Liger, François; Robert, Philippe; Hannequin, Didier; Pasquier, Florence; Hugon, Jacques; Paquet, Claire

2016-10-18

Few demographical data about primary progressive aphasia (PPA) are available, and most knowledge regarding PPA is based on tertiary centers' results. Our aims were to describe demographical characteristics of the PPA population in a large sample of PPA patients from the network of French Alzheimer plan memory centers (Sample 1), and to describe the stratification of cerebrospinal fluid (CSF) biomarkers in two different samples of PPA patients (Samples 2 and 3). All registered PPA patients in the French Alzheimer's disease (AD) databank (Sample 1: n = 2,035) and a subsample (Sample 2: n = 65) derived from a multicentric prospective cohort with CSF biomarker analysis were analyzed. A multicentric retrospective cohort from language expert tertiary centers (Sample 3: n = 97) with CSF biomarker analysis was added. Sample 3 was added to replicate the CSF results of the Sample 2 and to evaluate repartition of AD pathology in the three variant of PPA according to the latest classification. Non-Fluent/Agrammatic, Logopenic, and Unclassifiable PPA patients (NF/A-Logo-Unclass PPA) were older and more frequent than Semantic PPA patients (2.2 versus 0.8/100,000 inhabitants; p < 0.00001). Male predominance occurred after the age of 80 (p < 0.00001). A higher level of education was observed in the PPA population compared to a typical amnesic AD group. No demographical significant difference between PPA due to AD and not due to AD was observed. The Logopenic variant was most frequent with 85% of AD CSF biomarker profiles (35% in NF/A PPA; 20% in Semantic PPA). PPA occurs also in an elderly population, especially in male patients over 80. CSF biomarkers are useful to stratify PPA. The epidemiology of PPA should be further investigated to confirm gender and cognitive reserve role in PPA to better understand the factors and mechanisms leading to this language-predominant deficit during neurodegenerative diseases.

Using Social Network Analysis to Assess Mentorship and Collaboration in a Public Health Network.

Science.gov (United States)

Petrescu-Prahova, Miruna; Belza, Basia; Leith, Katherine; Allen, Peg; Coe, Norma B; Anderson, Lynda A

2015-08-20

Addressing chronic disease burden requires the creation of collaborative networks to promote systemic changes and engage stakeholders. Although many such networks exist, they are rarely assessed with tools that account for their complexity. This study examined the structure of mentorship and collaboration relationships among members of the Healthy Aging Research Network (HAN) using social network analysis (SNA). We invited 97 HAN members and partners to complete an online social network survey that included closed-ended questions about HAN-specific mentorship and collaboration during the previous 12 months. Collaboration was measured by examining the activity of the network on 6 types of products: published articles, in-progress manuscripts, grant applications, tools, research projects, and presentations. We computed network-level measures such as density, number of components, and centralization to assess the cohesiveness of the network. Sixty-three respondents completed the survey (response rate, 65%). Responses, which included information about collaboration with nonrespondents, suggested that 74% of HAN members were connected through mentorship ties and that all 97 members were connected through at least one form of collaboration. Mentorship and collaboration ties were present both within and across boundaries of HAN member organizations. SNA of public health collaborative networks provides understanding about the structure of relationships that are formed as a result of participation in network activities. This approach may offer members and funders a way to assess the impact of such networks that goes beyond simply measuring products and participation at the individual level.

Progress and perspectives of ASTEC applications in the European Network SARNET

International Nuclear Information System (INIS)

Van Dorsselaere, J.P.; Allelein, H.J.; Neu, K.

2006-01-01

The ASTEC integral code is jointly developed by IRSN (France) and GRS (Germany) for LWR source term Severe Accident (SA) evaluation, PSA level 2 studies and SA management evaluation. ASTEC constitutes now the reference European integral code through its role in the Network SARNET (Severe Accident Network of Excellence) in the EC 6. Framework Program. The models of next version V1.3, released before end of 2006, represent the current State of the Art, its validation is very extensive (in particular on Phebus FP) and, after next implementation of a model for reflooding of degraded cores, it will cover all needs for SA evaluation in PWR and VVER. It will be the reference code for the IRSN PSA level 2 (Probabilistic Safety Analysis) on French PWR 1300 MWe that starts in 2006. In the frame of SARNET, IRSN coordinates the ASTEC Topic gathering 30 partners that assess the code through validation against experiments and benchmarks with reference codes like CATHARE or RELAP5 for the reactor coolant circuit and COCOSYS for the containment. Plant application calculations are compared with MELCOR and MAAP4 results for a series of different SA sequences. Besides, the knowledge generated by SARNET Topics (Corium, Source Term and Containment) will be progressively integrated into the code through improved or new models. The 2. Users' Club organized at Aix-en-Provence in June 06, with 45 participants from 27 organizations, allowed fruitful discussions with the Maintenance Team. After 2 years of work, code validation shows good overall results, often close to results of reference codes. Some results reach the limits of present knowledge, for instance on Molten-Corium-Concrete-Interaction (MCCI) and Direct Containment Heating (DCH). Benchmarks on plant applications have been performed on diverse reactor types: PWR 900, Konvoi 1300, Westinghouse 1000, VVER-1000 and VVER-440. The main trends of results are similar to MELCOR or MAAP4 results. The objective of the quantitative

Thermally activated delayed fluorescence organic dots for two-photon fluorescence lifetime imaging

Science.gov (United States)

He, Tingchao; Ren, Can; Li, Zhuohua; Xiao, Shuyu; Li, Junzi; Lin, Xiaodong; Ye, Chuanxiang; Zhang, Junmin; Guo, Lihong; Hu, Wenbo; Chen, Rui

2018-05-01

Autofluorescence is a major challenge in complex tissue imaging when molecules present in the biological tissue compete with the fluorophore. This issue may be resolved by designing organic molecules with long fluorescence lifetimes. The present work reports the two-photon absorption (TPA) properties of a thermally activated delayed fluorescence (TADF) molecule with carbazole as the electron donor and dicyanobenzene as the electron acceptor (i.e., 4CzIPN). The results indicate that 4CzIPN exhibits a moderate TPA cross-section (˜9 × 10-50 cm4 s photon-1), high fluorescence quantum yield, and a long fluorescence lifetime (˜1.47 μs). 4CzIPN was compactly encapsulated into an amphiphilic copolymer via nanoprecipitation to achieve water-soluble organic dots. Interestingly, 4CzIPN organic dots have been utilized in applications involving two-photon fluorescence lifetime imaging (FLIM). Our work aptly demonstrates that TADF molecules are promising candidates of nonlinear optical probes for developing next-generation multiphoton FLIM applications.

Analyzing complex networks evolution through Information Theory quantifiers

International Nuclear Information System (INIS)

Carpi, Laura C.; Rosso, Osvaldo A.; Saco, Patricia M.; Ravetti, Martin Gomez

2011-01-01

A methodology to analyze dynamical changes in complex networks based on Information Theory quantifiers is proposed. The square root of the Jensen-Shannon divergence, a measure of dissimilarity between two probability distributions, and the MPR Statistical Complexity are used to quantify states in the network evolution process. Three cases are analyzed, the Watts-Strogatz model, a gene network during the progression of Alzheimer's disease and a climate network for the Tropical Pacific region to study the El Nino/Southern Oscillation (ENSO) dynamic. We find that the proposed quantifiers are able not only to capture changes in the dynamics of the processes but also to quantify and compare states in their evolution.

Fabrication of tough epoxy with shape memory effects by UV-assisted direct-ink write printing.

Science.gov (United States)

Chen, Kaijuan; Kuang, Xiao; Li, Vincent; Kang, Guozheng; Qi, H Jerry

2018-03-07

3D printing of epoxy-based shape memory polymers with high mechanical strength, excellent thermal stability and chemical resistance is highly desirable for practical applications. However, thermally cured epoxy in general is difficult to print directly. There have been limited numbers of successes in printing epoxy but they suffer from relatively poor mechanical properties. Here, we present an ultraviolet (UV)-assisted 3D printing of thermally cured epoxy composites with high tensile toughness via a two-stage curing approach. The ink containing UV curable resin and epoxy oligomer is used for UV-assisted direct-ink write (DIW)-based 3D printing followed by thermal curing of the part containing the epoxy oligomer. The UV curable resin forms a network by photo polymerization after the 1st stage of UV curing, which can maintain the printed architecture at an elevated temperature. The 2nd stage thermal curing of the epoxy oligomer yields an interpenetrating polymer network (IPN) composite with highly enhanced mechanical properties. It is found that the printed IPN epoxy composites enabled by the two-stage curing show isotropic mechanical properties and high tensile toughness. We demonstrated that the 3D-printed high-toughness epoxy composites show good shape memory properties. This UV-assisted DIW 3D printing via a two-stage curing method can broaden the application of 3D printing to fabricate thermoset materials with enhanced tensile toughness and tunable properties for high-performance and functional applications.

A network view on psychiatric disorders: network clusters of symptoms as elementary syndromes of psychopathology.

Science.gov (United States)

Goekoop, Rutger; Goekoop, Jaap G

2014-01-01

The vast number of psychopathological syndromes that can be observed in clinical practice can be described in terms of a limited number of elementary syndromes that are differentially expressed. Previous attempts to identify elementary syndromes have shown limitations that have slowed progress in the taxonomy of psychiatric disorders. To examine the ability of network community detection (NCD) to identify elementary syndromes of psychopathology and move beyond the limitations of current classification methods in psychiatry. 192 patients with unselected mental disorders were tested on the Comprehensive Psychopathological Rating Scale (CPRS). Principal component analysis (PCA) was performed on the bootstrapped correlation matrix of symptom scores to extract the principal component structure (PCS). An undirected and weighted network graph was constructed from the same matrix. Network community structure (NCS) was optimized using a previously published technique. In the optimal network structure, network clusters showed a 89% match with principal components of psychopathology. Some 6 network clusters were found, including "Depression", "Mania", "Anxiety", "Psychosis", "Retardation", and "Behavioral Disorganization". Network metrics were used to quantify the continuities between the elementary syndromes. We present the first comprehensive network graph of psychopathology that is free from the biases of previous classifications: a 'Psychopathology Web'. Clusters within this network represent elementary syndromes that are connected via a limited number of bridge symptoms. Many problems of previous classifications can be overcome by using a network approach to psychopathology.

News from IPNS

International Nuclear Information System (INIS)

Brown, B.S.

1995-01-01

Niobium-base alloys are candidate materials for the dive structure in fusion reactors. For this application, the materials should exhibit resistance to aqueous corrosion, hydrogen embrittlement, and radiation damage and should have high thermal conductivity and low thermal expansion. Results of corrosion and embrittlement screening tests of several binary and ternary alloys in high-temperature water indicated that Nb-1Zr, Nb-5Mo-1Zr and Nb-5V-1Zr (wt.%) showed sufficient promise for further investigation. These alloys, together with pure Nb and Zircaloy-4, have been exposed to high-purity water containing a low concentration of dissolved oxygen (<12 ppb) at 170, 230, and 300C for up to ∼3200 h. Weight-change data, microstructural observations, and qualitative mechanical-property evaluations reveal that Nb-5V-1Zr is the most promising alloy at higher temperatures. Below ∼200C the alloys exhibit similar corrosion behavior

Telecommunications energy and greenhouse gas emissions management for future network growth

International Nuclear Information System (INIS)

Chan, Chien Aun; Gygax, André F.; Leckie, Christopher; Wong, Elaine; Nirmalathas, Ampalavanapillai; Hinton, Kerry

2016-01-01

Highlights: • Model to evaluate key interdependencies of a fast growing telecommunications network. • Network growth analysis using real data and Monte Carlo simulation. • Importance of both operational and embodied energy efficiency improvements. • Embodied energy expected to dominate in the future under current energy efficiency trends. • Carbon footprint and energy management through optimum network replacement cycle. - Abstract: A key aspect of greener network deployment is how to achieve sustainable growth of a telecommunications network, both in terms of operational and embodied energy. Hence, in this paper we investigate how the overall energy consumption and greenhouse gas emissions of a fast growing telecommunications network can be minimized. Due to the complexities in modeling the embodied energy of networks, this aspect of energy consumption has received limited attention by network operators. Here, we present the first model to evaluate the interdependencies of the four main contributing factors in managing the sustainable growth of a telecommunications network: (i) the network’s operational energy consumption; (ii) the embodied energy of network equipment; (iii) network traffic growth; and (iv) the expected energy efficiency improvements in both the operational and embodied phases. Using Monte Carlo techniques with real network data, our results demonstrate that under the current trends in overall energy efficiency improvements the network embodied energy will account for over 40% of the total network energy in 2025 compared to 20% in 2015. Further, we find that the optimum equipment replacement cycle, which will result in the lowest total network life cycle energy, is directly dependent on the technological progress in energy efficiency improvements of both operational and embodied phases. Our model and analysis highlight the need for a comprehensive approach to better understand the interactions between network growth, technological

Progress in the last decade in our understanding of primary progressive aphasia

Directory of Open Access Journals (Sweden)

Ratnavalli Ellajosyula

2010-10-01

Full Text Available Primary progressive aphasia (PPA is a focal neurodegeneration of the brain affecting the language network. Patients can have isolated language impairment for years without impairment in other areas. PPA is classified as primary progressive nonfluent aphasia (PNFA, semantic dementia (SD, and logopenic aphasia, which have distinct patterns of atrophy on neuroimaging. PNFA and SD are included under frontotemporal lobar degenerations. PNFA patients have effortful speech with agrammatism, which is frequently associated with apraxia of speech and demonstrate atrophy in the left Broca′s area and surrounding region on neuroimaging. Patients with SD have dysnomia with loss of word and object (or face meaning with asymmetric anterior temporal lobe atrophy. Logopenic aphasics have word finding difficulties with frequent pauses in conversation, intact grammar, and word comprehension but impaired repetition for sentences. The atrophy is predominantly in the left posterior temporal and inferior parietal regions. Recent studies have described several progranulin mutations on chromosome 17 in PNFA. The three clinical syndromes have a less robust relationship to the underlying pathology, which is heterogeneous and includes tauopathy, ubiquitinopathy, Pick′s disease, corticobasal degeneration, progressive supranuclear palsy, and Alzheimer′s disease. Recent studies, however, seem to indicate that a better characterization of the clinical phenotype (apraxic, agrammatic, semantic, logopenic, jargon increases the predictive value of the underlying pathology. Substantial advances have been made in our understanding of PPAs but developing new biomarkers is essential in making accurate causative diagnoses in individual patients. This is critically important in the development and evaluation of disease-modifying drugs.

New spallation neutron sources, their performance and applications

International Nuclear Information System (INIS)

1985-01-01

Pulsed spallation sources now operating in the world are at the KEK Laboratory in Japan (the KENS source), at Los Alamos National Laboratory (WNR) and at Argonne National Laboratory (IPNS), both the latter being in the US. The Intense Pulsed Neutron Source (IPNS) is currently the world's most intense source with a peak neutron flux of 4 x 10 14 n cm -2 s -1 at a repetition rate of 30 Hz, and globally producing approx. 1.5 x 10 15 n/sec. Present pulsed sources are still relatively weak compared to their potential. In 1985 the Rutherford Spallation Neutron Source will come on line, and eventually be approx. 30 more intense than the present IPNS. Later, in 1986 the WNR/PSR option at Los Alamos will make that facility of comparable intensity, while a subcritical fission booster at IPNS will keep IPNS competitive. These new sources will expand the applications of pulsed neutrons but are still based on accelerators built for other scientific purposes, usually nuclear or high-energy physics. Accelerator physicists are now designing machines expressly for spallation neutron research, and the proton currents attainable appear in the milliamps. (IPNS now runs at 0.5 GeV and 14 μA). Such design teams are at the KFA Laboratory Julich, Argonne National Laboratory and KEK. Characteristics, particularly the different time structure of the pulses, of these new sources will be discussed. Such machines will be expensive and require national, if not international, collaboration across a wide spectrum of scientific disciplines. The new opportunities for neutron research will, of course, be dramatic with these new sources

Open Source in Higher Education: Towards an Understanding of Networked Universities

Science.gov (United States)

Quint-Rapoport, Mia

2012-01-01

This article addresses the question of understanding more about networked universities by looking at open source software developers working in academic contexts. It sketches their identities and work as an emerging professional community that both relies upon and develops digitally mediated networks and contributes to the progress of academic…

Electroactive polymer gels based on epoxy resin

Science.gov (United States)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Isolan - A Fibre Optic Network Conforming To IEEE 802.3 Standards

Science.gov (United States)

Roworth, D. A. A.; Howe, N.

1986-10-01

The progress of the IEEE 802.3 standard for fibre optic LANs is indicated with reference to both mixed media networks and full fibre networks. For a fibre optic network the most suitable layout is a "snowflake" topology composed of multiport repeaters and active fibre hubs. A range of components is described which enables the realisation of such a topology in conformance with the IEEE 802.3 standard.

Progressive multiple sequence alignments from triplets

Directory of Open Access Journals (Sweden)

Stadler Peter F

2007-07-01

Full Text Available Abstract Background The quality of progressive sequence alignments strongly depends on the accuracy of the individual pairwise alignment steps since gaps that are introduced at one step cannot be removed at later aggregation steps. Adjacent insertions and deletions necessarily appear in arbitrary order in pairwise alignments and hence form an unavoidable source of errors. Research Here we present a modified variant of progressive sequence alignments that addresses both issues. Instead of pairwise alignments we use exact dynamic programming to align sequence or profile triples. This avoids a large fractions of the ambiguities arising in pairwise alignments. In the subsequent aggregation steps we follow the logic of the Neighbor-Net algorithm, which constructs a phylogenetic network by step-wisely replacing triples by pairs instead of combining pairs to singletons. To this end the three-way alignments are subdivided into two partial alignments, at which stage all-gap columns are naturally removed. This alleviates the "once a gap, always a gap" problem of progressive alignment procedures. Conclusion The three-way Neighbor-Net based alignment program aln3nn is shown to compare favorably on both protein sequences and nucleic acids sequences to other progressive alignment tools. In the latter case one easily can include scoring terms that consider secondary structure features. Overall, the quality of resulting alignments in general exceeds that of clustalw or other multiple alignments tools even though our software does not included heuristics for context dependent (mismatch scores.

Fifty years of progress in speech coding standards

Science.gov (United States)

Cox, Richard

2004-10-01

Over the past 50 years, speech coding has taken root worldwide. Early applications were for the military and transmission for telephone networks. The military gave equal priority to intelligibility and low bit rate. The telephone network gave priority to high quality and low delay. These illustrate three of the four areas in which requirements must be set for any speech coder application: bit rate, quality, delay, and complexity. While the military could afford relatively expensive terminal equipment for secure communications, the telephone network needed low cost for massive deployment in switches and transmission equipment worldwide. Today speech coders are at the heart of the wireless phones and telephone answering systems we use every day. In addition to the technology and technical invention that has occurred, standards make it possible for all these different systems to interoperate. The primary areas of standardization are the public switched telephone network, wireless telephony, and secure telephony for government and military applications. With the advent of IP telephony there are additional standardization efforts and challenges. In this talk the progress in all areas is reviewed as well as a reflection on Jim Flanagan's impact on this field during the past half century.

Research in elementary particle physics: Technical progress report, June 1, 1987-May 31, 1988

International Nuclear Information System (INIS)

Kirsch, L.E.; Schnitzer, H.J.; Abbott, L.F.; Bensinger, J.R.; Blocker, C.A.

1988-01-01

The main topics discussed in the progress report: electron/photon algorithm groups; W and Z analysis; heavy quark analysis; gas gain monitoring; database upgrade; CDF test beam studies; string theory; cosmology; and neutral networks

Progress report of the IAEA Nuclear Data Section, 2000-2001

International Nuclear Information System (INIS)

2002-01-01

This paper is the progress report of the IAEA Nuclear Data Section for the years 2000-2001. The paper comprises the following topics: Budget and staff summary, nuclear data compilations, nuclear data services, development of new generation databases, the network co-ordination of the nuclear reaction data centres and of the nuclear structure and decay data evaluators. (a.n.)

Neuromorphic atomic switch networks.

Directory of Open Access Journals (Sweden)

Audrius V Avizienis

Full Text Available Efforts to emulate the formidable information processing capabilities of the brain through neuromorphic engineering have been bolstered by recent progress in the fabrication of nonlinear, nanoscale circuit elements that exhibit synapse-like operational characteristics. However, conventional fabrication techniques are unable to efficiently generate structures with the highly complex interconnectivity found in biological neuronal networks. Here we demonstrate the physical realization of a self-assembled neuromorphic device which implements basic concepts of systems neuroscience through a hardware-based platform comprised of over a billion interconnected atomic-switch inorganic synapses embedded in a complex network of silver nanowires. Observations of network activation and passive harmonic generation demonstrate a collective response to input stimulus in agreement with recent theoretical predictions. Further, emergent behaviors unique to the complex network of atomic switches and akin to brain function are observed, namely spatially distributed memory, recurrent dynamics and the activation of feedforward subnetworks. These devices display the functional characteristics required for implementing unconventional, biologically and neurally inspired computational methodologies in a synthetic experimental system.

NRC TLD Direct Radiation Monitoring Network. Volume 5, No. 2. Progress report, April-June 1985

International Nuclear Information System (INIS)

Jang, J.; Kramaric, M.; Cohen, L.

1985-09-01

The US Nuclear Regulatory Commission (NRC) Direct Radiation Monitoring Network provides continuous measurement of the ambient radiation levels around licensed NRC facilities, primarily power reactors. The Network is intended to measure radiation levels during routine facility operations and to establish background radiation levels used to assess the radiological impact of an unusual condition, such as an accident. This report presents the radiation levels measured around all facilities in the Network for the second quarter of 1985. A complete listing of the site facilities monitored is included

Analyzing complex networks evolution through Information Theory quantifiers

Energy Technology Data Exchange (ETDEWEB)

Carpi, Laura C., E-mail: Laura.Carpi@studentmail.newcastle.edu.a [Civil, Surveying and Environmental Engineering, University of Newcastle, University Drive, Callaghan NSW 2308 (Australia); Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte (31270-901), MG (Brazil); Rosso, Osvaldo A., E-mail: rosso@fisica.ufmg.b [Departamento de Fisica, Instituto de Ciencias Exatas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte (31270-901), MG (Brazil); Chaos and Biology Group, Instituto de Calculo, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellon II, Ciudad Universitaria, 1428 Ciudad de Buenos Aires (Argentina); Saco, Patricia M., E-mail: Patricia.Saco@newcastle.edu.a [Civil, Surveying and Environmental Engineering, University of Newcastle, University Drive, Callaghan NSW 2308 (Australia); Departamento de Hidraulica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avenida Pellegrini 250, Rosario (Argentina); Ravetti, Martin Gomez, E-mail: martin.ravetti@dep.ufmg.b [Departamento de Engenharia de Producao, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, Belo Horizonte (31270-901), MG (Brazil)

2011-01-24

A methodology to analyze dynamical changes in complex networks based on Information Theory quantifiers is proposed. The square root of the Jensen-Shannon divergence, a measure of dissimilarity between two probability distributions, and the MPR Statistical Complexity are used to quantify states in the network evolution process. Three cases are analyzed, the Watts-Strogatz model, a gene network during the progression of Alzheimer's disease and a climate network for the Tropical Pacific region to study the El Nino/Southern Oscillation (ENSO) dynamic. We find that the proposed quantifiers are able not only to capture changes in the dynamics of the processes but also to quantify and compare states in their evolution.

Enabling dynamic network analysis through visualization in TVNViewer

Directory of Open Access Journals (Sweden)

Curtis Ross E

2012-08-01

Full Text Available Abstract Background Many biological processes are context-dependent or temporally specific. As a result, relationships between molecular constituents evolve across time and environments. While cutting-edge machine learning techniques can recover these networks, exploring and interpreting the rewiring behavior is challenging. Information visualization shines in this type of exploratory analysis, motivating the development ofTVNViewer (http://sailing.cs.cmu.edu/tvnviewer, a visualization tool for dynamic network analysis. Results In this paper, we demonstrate visualization techniques for dynamic network analysis by using TVNViewer to analyze yeast cell cycle and breast cancer progression datasets. Conclusions TVNViewer is a powerful new visualization tool for the analysis of biological networks that change across time or space.

Enabling dynamic network analysis through visualization in TVNViewer

Science.gov (United States)

2012-01-01

Background Many biological processes are context-dependent or temporally specific. As a result, relationships between molecular constituents evolve across time and environments. While cutting-edge machine learning techniques can recover these networks, exploring and interpreting the rewiring behavior is challenging. Information visualization shines in this type of exploratory analysis, motivating the development ofTVNViewer (http://sailing.cs.cmu.edu/tvnviewer), a visualization tool for dynamic network analysis. Results In this paper, we demonstrate visualization techniques for dynamic network analysis by using TVNViewer to analyze yeast cell cycle and breast cancer progression datasets. Conclusions TVNViewer is a powerful new visualization tool for the analysis of biological networks that change across time or space. PMID:22897913

On Prolonging Network Lifetime through Load-Similar Node Deployment in Wireless Sensor Networks

Science.gov (United States)

Li, Qiao-Qin; Gong, Haigang; Liu, Ming; Yang, Mei; Zheng, Jun

2011-01-01

This paper is focused on the study of the energy hole problem in the Progressive Multi-hop Rotational Clustered (PMRC)-structure, a highly scalable wireless sensor network (WSN) architecture. Based on an analysis on the traffic load distribution in PMRC-based WSNs, we propose a novel load-similar node distribution strategy combined with the Minimum Overlapping Layers (MOL) scheme to address the energy hole problem in PMRC-based WSNs. In this strategy, sensor nodes are deployed in the network area according to the load distribution. That is, more nodes shall be deployed in the range where the average load is higher, and then the loads among different areas in the sensor network tend to be balanced. Simulation results demonstrate that the load-similar node distribution strategy prolongs network lifetime and reduces the average packet latency in comparison with existing nonuniform node distribution and uniform node distribution strategies. Note that, besides the PMRC structure, the analysis model and the proposed load-similar node distribution strategy are also applicable to other multi-hop WSN structures. PMID:22163809

A network view on psychiatric disorders: network clusters of symptoms as elementary syndromes of psychopathology.

Directory of Open Access Journals (Sweden)

Rutger Goekoop

Full Text Available INTRODUCTION: The vast number of psychopathological syndromes that can be observed in clinical practice can be described in terms of a limited number of elementary syndromes that are differentially expressed. Previous attempts to identify elementary syndromes have shown limitations that have slowed progress in the taxonomy of psychiatric disorders. AIM: To examine the ability of network community detection (NCD to identify elementary syndromes of psychopathology and move beyond the limitations of current classification methods in psychiatry. METHODS: 192 patients with unselected mental disorders were tested on the Comprehensive Psychopathological Rating Scale (CPRS. Principal component analysis (PCA was performed on the bootstrapped correlation matrix of symptom scores to extract the principal component structure (PCS. An undirected and weighted network graph was constructed from the same matrix. Network community structure (NCS was optimized using a previously published technique. RESULTS: In the optimal network structure, network clusters showed a 89% match with principal components of psychopathology. Some 6 network clusters were found, including "Depression", "Mania", "Anxiety", "Psychosis", "Retardation", and "Behavioral Disorganization". Network metrics were used to quantify the continuities between the elementary syndromes. CONCLUSION: We present the first comprehensive network graph of psychopathology that is free from the biases of previous classifications: a 'Psychopathology Web'. Clusters within this network represent elementary syndromes that are connected via a limited number of bridge symptoms. Many problems of previous classifications can be overcome by using a network approach to psychopathology.

The guitar chord-generating algorithm based on complex network

Science.gov (United States)

Ren, Tao; Wang, Yi-fan; Du, Dan; Liu, Miao-miao; Siddiqi, Awais

2016-02-01

This paper aims to generate chords for popular songs automatically based on complex network. Firstly, according to the characteristics of guitar tablature, six chord networks of popular songs by six pop singers are constructed and the properties of all networks are concluded. By analyzing the diverse chord networks, the accompaniment regulations and features are shown, with which the chords can be generated automatically. Secondly, in terms of the characteristics of popular songs, a two-tiered network containing a verse network and a chorus network is constructed. With this network, the verse and chorus can be composed respectively with the random walk algorithm. Thirdly, the musical motif is considered for generating chords, with which the bad chord progressions can be revised. This method can make the accompaniments sound more melodious. Finally, a popular song is chosen for generating chords and the new generated accompaniment sounds better than those done by the composers.

Fundamental studies of elastomers. Annual progress report, June 15, 1985-March 21, 1986

International Nuclear Information System (INIS)

Eichinger, B.E.

1986-01-01

The progress report for the first year of this grant described computer simulations on random networks, shape distributions, synthesis of chelation networks, and coordination polymers. Work has continued in all four of these areas in the past year. Highlighted here is the work that we have been doing on computer simulations of random cross-linking, wherein radiation damage is a very important feature of the chemical reactions that occur. Furthermore, we have made a coordination compound which looks quite encouraging at the present time. Our efforts on chelation networks are proceeding and we are developing very promising methods for creating the polymers that we need for these studies

ONU power saving modes in next generation optical access networks: progress, efficiency and challenges.

Science.gov (United States)

Dixit, Abhishek; Lannoo, Bart; Colle, Didier; Pickavet, Mario; Demeester, Piet

2012-12-10

The optical network unit (ONU), installed at a customer's premises, accounts for about 60% of power in current fiber-to-the-home (FTTH) networks. We propose a power consumption model for the ONU and evaluate the ONU power consumption in various next generation optical access (NGOA) architectures. Further, we study the impact of the power savings of the ONU in various low power modes such as power shedding, doze and sleep.

Node clustering for wireless sensor networks

International Nuclear Information System (INIS)

Bhatti, S.; Qureshi, I.A.; Memon, S.

2012-01-01

Recent years have witnessed considerable growth in the development and deployment of clustering methods which are not only used to maintain network resources but also increases the reliability of the WSNs (Wireless Sensor Network) and the facts manifest by the wide range of clustering solutions. Node clustering by selecting key parameters to tackle the dynamic behaviour of resource constraint WSN is a challenging issue. This paper highlights the recent progress which has been carried out pertaining to the development of clustering solutions for the WSNs. The paper presents classification of node clustering methods and their comparison based on the objectives, clustering criteria and methodology. In addition, the potential open issues which need to be considered for future work are high lighted. Keywords: Clustering, Sensor Network, Static, Dynamic

Beta 1- and beta 2-adrenergic 125I-pindolol binding sites in the interpeduncular nucleus of the rat: Normal distribution and the effects of deafferentation

International Nuclear Information System (INIS)

Battisti, W.P.; Artymyshyn, R.P.; Murray, M.

1989-01-01

The plasticity of the beta 1- and beta 2-adrenergic receptor subtypes was examined in the interpeduncular nucleus (IPN) of the adult rat. The beta-adrenergic receptor antagonist 125I-pindolol (125I-PIN) was used in conjunction with the selective subtype antagonists ICI 118,551 and ICI 89,406 to determine the subnuclear distribution of beta 1- and beta 2-adrenergic receptors in this nucleus and to correlate the receptor distribution with the distribution of both noradrenergic afferents from the locus coeruleus (LC) and non-noradrenergic afferents from the fasiculus retroflexus (FR). The density of these binding sites was examined following lesions that decreased (LC lesions) or increased (FR lesions) the density of the noradrenergic projection in the IPN. Quantitative radioautography indicated that beta 1-labeled binding sites account for the larger percentage of binding sites in the IPN. The beta 1-binding sites are densest in those subnuclei that receive a noradrenergic projection from the LC: the central, rostral, and intermediate subnuclei. beta 1-binding sites are algo homogeneously distributed throughout the lateral subnuclei, where there is no detectable noradrenergic innervation. beta 2-binding sites have a more restricted distribution. They are concentrated in the ventral half of the lateral subnuclei, where they account for 70% of total 125I-PIN binding sites. beta 2-binding sites are also present along the ventral border of the IPN. Some of this labeling extends into the central and intermediate subnuclei. Bilateral lesions of the LC, which selectively remove noradrenergic innervation to the IPN, result in an increase in the beta 1-binding sites. Bilateral lesions of the FR, which remove the major cholinergic and peptidergic input from the IPN, elicit an increase in noradrenergic projections and a decrease in beta 1-binding sites

NRC TLD Direct Radiation Monitoring Network. Progress report, January-June 1981

International Nuclear Information System (INIS)

1982-04-01

This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of 55 NRC-licensed facility sites throughout the country for the first half of 1981. The program objectives, scope, and methodology are given. The TLD system, dosimeter location, data processing scheme, and quality assurance program are outlined

Laterotopic representation of left-right information onto the dorso-ventral axis of a zebrafish midbrain target nucleus.

Science.gov (United States)

Aizawa, Hidenori; Bianco, Isaac H; Hamaoka, Takanori; Miyashita, Toshio; Uemura, Osamu; Concha, Miguel L; Russell, Claire; Wilson, Stephen W; Okamoto, Hitoshi

2005-02-08

The habenulae are part of an evolutionarily highly conserved limbic-system conduction pathway that connects telencephalic nuclei to the interpeduncular nucleus (IPN) of the midbrain . In zebrafish, unilateral activation of the Nodal signaling pathway in the left brain specifies the laterality of the asymmetry of habenular size . We show "laterotopy" in the habenulo-interpeduncular projection in zebrafish, i.e., the stereotypic, topographic projection of left-sided habenular axons to the dorsal region of the IPN and of right-sided habenular axons to the ventral IPN. This asymmetric projection is accounted for by a prominent left-right (LR) difference in the size ratio of the medial and lateral habenular sub-nuclei, each of which specifically projects either to ventral or dorsal IPN targets. Asymmetric Nodal signaling directs the orientation of laterotopy but is dispensable for the establishment of laterotopy itself. Our results reveal a mechanism by which information distributed between left and right sides of the brain can be transmitted bilaterally without loss of LR coding, which may play a crucial role in functional lateralization of the vertebrate brain .

Emergent intelligent properties of progressively structured pattern recognition nets

Energy Technology Data Exchange (ETDEWEB)

Aleksander, I

1983-07-01

The n-tuple recognition net is seen as a building brick of a progression of network structures. The emergent intelligent properties of such systems are discussed. They include the amplification of confidence for the recognition of images that differ in small detail, a short term memory of the last seen image, sequence sensitivity, sequence sensitivity, sequence acceptance and saccadic inspection as an aid in scene analysis. 12 references.

Networks dynamics in the case of emerging technologies

Energy Technology Data Exchange (ETDEWEB)

Rotolo, D

2016-07-01

This research in progress aims at increasing our understanding of how collaborative networks form, evolve and are configured in the case of emerging technologies. The architecture of the relationships among the variety of organisational actors involved in the emergence process exerts a significant influence in shaping technological change in certain directions rather than others, especially in the early stage of emergence. As a result, socially optimal or desirable technological trajectories may be ‘opportunistically’ rejected. Our empirical analysis is based on a case-study of an emerging medical technology, namely ‘microneedles’. On the basis of co-authorship data reported in 1,943 publications on the topic from 1990 to 2014, longitudinal collaboration (co-authorship) networks were built at two levels: affiliation and author. We examined the dynamics of co-authorship networks by building on recent methodological advancements in network analysis, i.e. Exponential Random Graph Models (ERGMs). These models enable us to make statistical inferences about on the extent to which a network configuration occurs more than could be expected by chance and to identify which social mechanisms may be shaping the network in certain configurations. The findings of the statistical analyses (currently in progress) combined with the qualitative understanding of the case will increase our understanding of which mechanisms are more likely to drive the network dynamics in the case of emerging technologies. These include evidence of the extent to which the likelihood of forming, maintaining, or terminating ties among actors (authors or affiliations) is affected by actors’ covariates such as types of organisations, diversity/specialisation of the research undertaken, and status. These findings have potential to provide important inputs for policymaking process in the case of emerging technologies. (Author)

Networks dynamics in the case of emerging technologies

International Nuclear Information System (INIS)

Rotolo, D

2016-01-01

This research in progress aims at increasing our understanding of how collaborative networks form, evolve and are configured in the case of emerging technologies. The architecture of the relationships among the variety of organisational actors involved in the emergence process exerts a significant influence in shaping technological change in certain directions rather than others, especially in the early stage of emergence. As a result, socially optimal or desirable technological trajectories may be ‘opportunistically’ rejected. Our empirical analysis is based on a case-study of an emerging medical technology, namely ‘microneedles’. On the basis of co-authorship data reported in 1,943 publications on the topic from 1990 to 2014, longitudinal collaboration (co-authorship) networks were built at two levels: affiliation and author. We examined the dynamics of co-authorship networks by building on recent methodological advancements in network analysis, i.e. Exponential Random Graph Models (ERGMs). These models enable us to make statistical inferences about on the extent to which a network configuration occurs more than could be expected by chance and to identify which social mechanisms may be shaping the network in certain configurations. The findings of the statistical analyses (currently in progress) combined with the qualitative understanding of the case will increase our understanding of which mechanisms are more likely to drive the network dynamics in the case of emerging technologies. These include evidence of the extent to which the likelihood of forming, maintaining, or terminating ties among actors (authors or affiliations) is affected by actors’ covariates such as types of organisations, diversity/specialisation of the research undertaken, and status. These findings have potential to provide important inputs for policymaking process in the case of emerging technologies. (Author)

Semi-interpenetrating network of acrylamide-grafted-sodium alginate microspheres for controlled release of diclofenac sodium, preparation and characterization.

Science.gov (United States)

Al-Kahtani, Ahmed A; Sherigara, B S

2014-03-01

The semi-interpenetrating networks (semi-IPNs) of acrylamide grafted sodium alginate (AAm-g-NaAlg) microspheres (MPs) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. The grafting of acrylamide onto sodium alginate was prepared by free-radical graft polymerization using ceric ammonium nitrate (CAN) as initiator at three acrylamide concentrations with monomer to polymer ratio of 1:1, 2:1 and 3:1, respectively. The grafting efficiency was found to be 91%. The produced MPs are almost spherical in nature with smooth surfaces. Diclofenac sodium (DS), an anti-inflammatory drug was successfully encapsulated into the MPs. The encapsulation efficiency was found to vary between 83% and 95%. The MPs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The diffusion coefficient (D) was dependent upon the amount of crosslinking agent (GA) and amount of grafting ratio in the matrix. The rate of release was found to be dependent on the amount of GA, AAm:NaAlg grafting ratio and % drug loading in the MPs. The release data have been fitted to an empirical equation to investigate the diffusional exponent (n), which indicated that the release mechanism from MPs follows the super Case II transport. Copyright © 2013 Elsevier B.V. All rights reserved.

Network-based stochastic competitive learning approach to disambiguation in collaborative networks

Science.gov (United States)

Christiano Silva, Thiago; Raphael Amancio, Diego

2013-03-01

Many patterns have been uncovered in complex systems through the application of concepts and methodologies of complex networks. Unfortunately, the validity and accuracy of the unveiled patterns are strongly dependent on the amount of unavoidable noise pervading the data, such as the presence of homonymous individuals in social networks. In the current paper, we investigate the problem of name disambiguation in collaborative networks, a task that plays a fundamental role on a myriad of scientific contexts. In special, we use an unsupervised technique which relies on a particle competition mechanism in a networked environment to detect the clusters. It has been shown that, in this kind of environment, the learning process can be improved because the network representation of data can capture topological features of the input data set. Specifically, in the proposed disambiguating model, a set of particles is randomly spawned into the nodes constituting the network. As time progresses, the particles employ a movement strategy composed of a probabilistic convex mixture of random and preferential walking policies. In the former, the walking rule exclusively depends on the topology of the network and is responsible for the exploratory behavior of the particles. In the latter, the walking rule depends both on the topology and the domination levels that the particles impose on the neighboring nodes. This type of behavior compels the particles to perform a defensive strategy, because it will force them to revisit nodes that are already dominated by them, rather than exploring rival territories. Computer simulations conducted on the networks extracted from the arXiv repository of preprint papers and also from other databases reveal the effectiveness of the model, which turned out to be more accurate than traditional clustering methods.

NRC TLD Direct Radiation Monitoring Network. Progress report, October--December 1996

International Nuclear Information System (INIS)

Struckmeyer, R.

1997-03-01

This report presents the results of the NRC Direct Radiation Monitoring Network for the fourth quarter of 1996. It provides the ambient radiation levels measured in the vicinity of 74 sites throughout the United States. In addition, it describes the equipment used, monitoring station selection criteria, characterization of the dosimeter response, calibration procedures, statistical methods, intercomparison, and quality assurance program. 3 figs., 4 tabs

NRC TLD Direct Radiation Monitoring Network. Progress report, October--December 1996

Energy Technology Data Exchange (ETDEWEB)

Struckmeyer, R.

1997-03-01

This report presents the results of the NRC Direct Radiation Monitoring Network for the fourth quarter of 1996. It provides the ambient radiation levels measured in the vicinity of 74 sites throughout the United States. In addition, it describes the equipment used, monitoring station selection criteria, characterization of the dosimeter response, calibration procedures, statistical methods, intercomparison, and quality assurance program. 3 figs., 4 tabs.

On the Mathematical Structure of Balanced Chemical Reaction Networks Governed by Mass Action Kinetics

NARCIS (Netherlands)

Schaft, Arjan van der; Rao, Shodhan; Jayawardhana, Bayu

2013-01-01

Motivated by recent progress on the interplay between graph theory, dynamics, and systems theory, we revisit the analysis of chemical reaction networks described by mass action kinetics. For reaction networks possessing a thermodynamic equilibrium we derive a compact formulation exhibiting at the

Approximation Methods for Inference and Learning in Belief Networks: Progress and Future Directions

National Research Council Canada - National Science Library

Pazzan, Michael

1997-01-01

.... In this research project, we have investigated methods and implemented algorithms for efficiently making certain classes of inference in belief networks, and for automatically learning certain...

Libraries' Place in Virtual Social Networks

Science.gov (United States)

Mathews, Brian S.

2007-01-01

Do libraries belong in the virtual world of social networking? With more than 100 million users, this environment is impossible to ignore. A rising philosophy for libraries, particularly in blog-land, involves the concept of being where the users are. Simply using new media to deliver an old message is not progress. Instead, librarians should…

Optical Access Networks

Science.gov (United States)

Zheng, Jun; Ansari, Nirwan

2005-06-01

are now underway this hot area. The purpose of this feature issue is to expose the networking community to the latest research breakthroughs and progresses in the area of optical access networks. This feature issue aims to present a collection of papers that focus on the state-of-the-art research in various networking aspects of optical access networks. Original papers are solicited from all researchers involved in area of optical access networks. Topics of interest include but not limited to: Optical access network architectures and protocols Passive optical networks (BPON, EPON, GPON, etc.) Active optical networks Multiple access control Multiservices and QoS provisioning Network survivability Field trials and standards Performance modeling and analysis

Effect of drug loading method against the dissolution mechanism of encapsulated amoxicillin trihidrate drug in matrix of semi-IPN chitosan-poly (N-vinyl pyrrolidone) hydrogel with pore forming agent CaCO3

Science.gov (United States)

Nurjannah, Yanah; Budianto, Emil

2018-04-01

Heliobacter pylori (H.pylori) is a type of bacteria that causes inflammation in the lining of the stomach. The treatment of the bacterial infection by using conventional medicine which is amoxicillin trihidrate has a very short retention time in the stomach which is about 1-1,5 hours. Floating drug delivery system is expected to have a long retention time in the stomach so the efficiency of drug can be achieved. In this study, has been synthesized matrix of semi-IPN chitosan-Poly(N-vinil pyrrolidone) hydrogel with a pore-forming agent of CaCO3 under optimum conditions. Amoxicillin is encapsulated in a matrix hydrogel to be applied as a floating drug delivery system by in situ loading and post loading methods. The encapsulation efficiency and dissolution of in situ loading and post loading hydrogels are performed in vitro on gastric pH. In situ loading hydrogel shows higer percentage of encapsulation efficiency and dissolution compared to post loading hydrogel. The encapsulation efficiency of in situ and post loading hydrogels were 92,1% and 89,4%, respectively. The aim of drug dissolution by mathematical equation model is to know kinetics and the mecanism of dissolution. The kinetics release of in situ hydrogel tends to follow first order kinetics, while the post loading hydrogel follow the Higuchi model. The dissolution mecanism of hydrogels is erosion.

Endogenous molecular network reveals two mechanisms of heterogeneity within gastric cancer

Science.gov (United States)

Li, Site; Zhu, Xiaomei; Liu, Bingya; Wang, Gaowei; Ao, Ping

2015-01-01

Intratumor heterogeneity is a common phenomenon and impedes cancer therapy and research. Gastric cancer (GC) cells have generally been classified into two heterogeneous cellular phenotypes, the gastric and intestinal types, yet the mechanisms of maintaining two phenotypes and controlling phenotypic transition are largely unknown. A qualitative systematic framework, the endogenous molecular network hypothesis, has recently been proposed to understand cancer genesis and progression. Here, a minimal network corresponding to such framework was found for GC and was quantified via a stochastic nonlinear dynamical system. We then further extended the framework to address the important question of intratumor heterogeneity quantitatively. The working network characterized main known features of normal gastric epithelial and GC cell phenotypes. Our results demonstrated that four positive feedback loops in the network are critical for GC cell phenotypes. Moreover, two mechanisms that contribute to GC cell heterogeneity were identified: particular positive feedback loops are responsible for the maintenance of intestinal and gastric phenotypes; GC cell progression routes that were revealed by the dynamical behaviors of individual key components are heterogeneous. In this work, we constructed an endogenous molecular network of GC that can be expanded in the future and would broaden the known mechanisms of intratumor heterogeneity. PMID:25962957

How to secure a wireless sensor network

NARCIS (Netherlands)

Law, Y.W.; Havinga, Paul J.M.

2005-01-01

The security of wireless sensor networks (WSNs) is a complex issue. While security research of WSNs is progressing at a tremendous pace, and many security techniques have been proposed, no comprehensive framework has so far emerged that attempts to tie the bits and pieces together to ease the

High speed fiber optics local area networks: Design and implementation

Science.gov (United States)

Tobagi, Fouad A.

1988-01-01

The design of high speed local area networks (HSLAN) for communication among distributed devices requires solving problems in three areas: (1) the network medium and its topology; (2) the medium access control; and (3) the network interface. Considerable progress has been made in all areas. Accomplishments are divided into two groups according to their theoretical or experimental nature. A brief summary is given in Section 2, including references to papers which appeared in the literature, as well as to Ph.D. dissertations and technical reports published at Stanford University.

Region of interest and windowing-based progressive medical image delivery using JPEG2000

Science.gov (United States)

Nagaraj, Nithin; Mukhopadhyay, Sudipta; Wheeler, Frederick W.; Avila, Ricardo S.

2003-05-01

An important telemedicine application is the perusal of CT scans (digital format) from a central server housed in a healthcare enterprise across a bandwidth constrained network by radiologists situated at remote locations for medical diagnostic purposes. It is generally expected that a viewing station respond to an image request by displaying the image within 1-2 seconds. Owing to limited bandwidth, it may not be possible to deliver the complete image in such a short period of time with traditional techniques. In this paper, we investigate progressive image delivery solutions by using JPEG 2000. An estimate of the time taken in different network bandwidths is performed to compare their relative merits. We further make use of the fact that most medical images are 12-16 bits, but would ultimately be converted to an 8-bit image via windowing for display on the monitor. We propose a windowing progressive RoI technique to exploit this and investigate JPEG 2000 RoI based compression after applying a favorite or a default window setting on the original image. Subsequent requests for different RoIs and window settings would then be processed at the server. For the windowing progressive RoI mode, we report a 50% reduction in transmission time.

Cultured Neural Networks: Optimization of Patterned Network Adhesiveness and Characterization of their Neural Activity

Directory of Open Access Journals (Sweden)

W. L. C. Rutten

2006-01-01

Full Text Available One type of future, improved neural interface is the “cultured probe”. It is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity. It would consist of a microelectrode array (MEA on a planar substrate, each electrode being covered and surrounded by a local circularly confined network (“island” of cultured neurons. The main purpose of the local networks is that they act as biofriendly intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron–electrode interface. As a secondary purpose, one may envisage future information processing applications of these intermediary networks. In this paper, first, progress is shown on how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to “islands” surrounding an electrode site. Additional coating of neurophobic, polyimide-coated substrate by triblock-copolymer coating enhances neurophilic-neurophobic adhesion contrast. Secondly, results are given on neuronal activity in patterned, unconnected and connected, circular “island” networks. For connected islands, the larger the island diameter (50, 100 or 150 μm, the more spontaneous activity is seen. Also, activity may show a very high degree of synchronization between two islands. For unconnected islands, activity may start at 22 days in vitro (DIV, which is two weeks later than in unpatterned networks.

White matter disease correlates with lexical retrieval deficits in primary progressive aphasia

Directory of Open Access Journals (Sweden)

John P. Powers

2013-12-01

Full Text Available Objective: To relate fractional anisotropy changes associated with the semantic and logopenic variants of primary progressive aphasia to measures of lexical retrieval.Methods: We collected neuropsychological testing, volumetric MRI, and diffusion-weighted imaging on semantic variant primary progressive aphasia (n=11 and logopenic variant primary progressive aphasia (n=13 patients diagnosed using published criteria. We also acquired neuroimaging data on a group of demographically comparable healthy seniors (n=34. Fractional anisotropy was calculated and analyzed using a white matter tract-specific analysis approach. This approach utilizes anatomically guided data reduction to increase sensitivity and localizes results within canonically defined tracts. We used non-parametric, cluster-based statistical analysis to relate language performance to fractional anisotropy and determine regions of reduced fractional anisotropy in patients. Results: We found widespread fractional anisotropy reductions in white matter for both variants of primary progressive aphasia. Fractional anisotropy was related to both confrontation naming and category naming fluency performance in left uncinate fasciculus and corpus callosum in semantic variant primary progressive aphasia and left superior and inferior longitudinal fasciculi in logopenic variant primary progressive aphasia. Conclusions: Semantic variant primary progressive aphasia and logopenic variant primary progressive aphasia are associated with distinct disruptions of a large-scale network implicated in lexical retrieval, and the white matter disease in each phenotype may contribute to language impairments including lexical retrieval.

Markov Networks in Evolutionary Computation

CERN Document Server

Shakya, Siddhartha

2012-01-01

Markov networks and other probabilistic graphical modes have recently received an upsurge in attention from Evolutionary computation community, particularly in the area of Estimation of distribution algorithms (EDAs).  EDAs have arisen as one of the most successful experiences in the application of machine learning methods in optimization, mainly due to their efficiency to solve complex real-world optimization problems and their suitability for theoretical analysis. This book focuses on the different steps involved in the conception, implementation and application of EDAs that use Markov networks, and undirected models in general. It can serve as a general introduction to EDAs but covers also an important current void in the study of these algorithms by explaining the specificities and benefits of modeling optimization problems by means of undirected probabilistic models. All major developments to date in the progressive introduction of Markov networks based EDAs are reviewed in the book. Hot current researc...

Progress with the NESC spinning cylinder project and other NESC projects

International Nuclear Information System (INIS)

Wintle, J.B.; Hurst, R.C.; Hemsworth, B.

1995-01-01

The first international project (NESC I) of the Network of Evaluating Steel Components is a spinning cylinder, pressurized thermal shock (PTS) experiment. The main objective of the project is to validate the non-destructive evaluation and structural mechanics procedures for PWR reactor pressure vessels under PTS conditions. Contributing organizations world-wide will participate in this blind trial which embraces all aspects of structural integrity assessment. This paper describes the progress of the project to date, covering cylinder manufacture and inspection, materials evaluation, structural analysis and test instrumentation. It emphasizes the importance of networking global expertise in a managed framework and of the partnership, co-operation and teamwork developed by the contributing organizations through the five Task Groups constituting the NESC I. Finally, five new initiatives for projects managed by the Network are currently under review and described in this paper

Early depletion of proliferating B cells of germinal center in rapidly progressive simian immunodeficiency virus infection

International Nuclear Information System (INIS)

Zhang Zhiqiang; Casimiro, Danilo R.; Schleif, William A.; Chen, Minchun; Citron, Michael; Davies, Mary-Ellen; Burns, Janine; Liang, Xiaoping; Fu, Tong-Ming; Handt, Larry; Emini, Emilio A.; Shiver, John W.

2007-01-01

Lack of virus specific antibody response is commonly observed in both HIV-1-infected humans and SIV-infected monkeys with rapid disease progression. However, the mechanisms underlying this important observation still remain unclear. In a titration study of a SIVmac239 viral stock, three out of six animals with viral inoculation rapidly progressed to AIDS within 5 months. Unexpectedly, there was no obvious depletion of CD4 + T cells in both peripheral and lymph node (LN) compartments in these animals. Instead, progressive depletion of proliferating B cells and disruption of the follicular dendritic cell (FDC) network in germinal centers (GC) was evident in the samples collected at as early as 20 days after viral challenge. This coincided with undetectable, or weak and transient, virus-specific antibody responses over the course of infection. In situ hybridization of SIV RNA in the LN samples revealed a high frequency of SIV productively infected cells and large amounts of accumulated viral RNA in the GCs in these animals. Early severe depletion of GC proliferating B cells and disruption of the FDC network may thus result in an inability to mount a virus-specific antibody response in rapid progressors, which has been shown to contribute to accelerated disease progression of SIV infection

Development of the OASIS acquisition system

International Nuclear Information System (INIS)

Douet, R.

1999-01-01

OASIS is a general purpose data acquisition system built at IPN Orsay, which has been developed around UNIX and VME real time processors. This system can be used to acquire, process, store and display physics data. New OASIS is also used to process event data tapes coming from experiments and has been connected to the analysis software at IPN. (author)

Structural principles in network glasses

International Nuclear Information System (INIS)

Boolchand, P.

1986-01-01

Substantial progress in decoding the structure of network glasses has taken place in the past few years. Crucial insights into the molecular structure of glasses have emerged by application of Raman bond and Moessbauer site spectroscopy. In this context, the complimentary role of each spectroscopy as a check on the interpretation of the other, is perhaps one of the more significant developments in the field. New advances in the theory of the subject have also taken place. It is thus appropriate to inquire what general principles if any, have emerged on the structure of real glasses. The author reviews some of the principal ideas on the structure of inorganic network glasses with the aid of specific examples. (Auth.)

[Strategic thinking of the construction of national schistosomiasis laboratory network in China].

Science.gov (United States)

Qin, Zhi-Qiang; Xu, Jing; Feng, Ting; Zhu, Hong-Qing; Li, Shi-Zhu; Xiao, Ning; Zhou, Xiao-Nong

2013-08-01

A schistosomiasis laboratory network and its quality assurance system have been built and will be more and more perfect in China. This paper introduces the present situation of schistosomiasis diagnosis in China and expounds the basic ideas and the progress in the construction of schistosomiasis network platform. Furthermore, the face of schistosomiasis diagnosis network platform construction and operation of the challenge and the future work will be put forward in the latter part of this paper.

Networking for High Energy and Nuclear Physics

Science.gov (United States)

Newman, Harvey B.

2007-07-01

This report gives an overview of the status and outlook for the world's research networks and major international links used by the high energy physics and other scientific communities, network technology advances on which our community depends and in which we have an increasingly important role, and the problem of the Digital Divide, which is a primary focus of ICFA's Standing Committee on Inter-regional Connectivity (SCIC). Wide area networks of sufficient, and rapidly increasing end-to-end capability are vital for every phase of high energy physicists' work. Our bandwidth usage, and the typical capacity of the major national backbones and intercontinental links used by our field have progressed by a factor of more than 1000 over the past decade, and the outlook is for a similar increase over the next decade. This striking exponential growth trend, outstripping the growth rates in other areas of information technology, has continued in the past year, with many of the major national, continental and transoceanic networks supporting research and education progressing from a 10 Gigabits/sec (Gbps) backbone to multiple 10 Gbps links in their core. This is complemented by the use of point-to-point "light paths" to support the most demanding applications, including high energy physics, in a growing list of cases. As we approach the era of LHC physics, the growing need to access and transport Terabyte-scale and later 10 to 100 Terabyte datasets among more than 100 "Tier1" and "Tier2" centers at universities and laboratories spread throughout the world has brought the key role of networks, and the ongoing need for their development, sharply into focus. Bandwidth itself on an increasing scale is not enough. Realizing the scientific wealth of the LHC and our other major scientific programs depends crucially on our ability to use the bandwidth efficiently and reliably, with reliable high rates of data throughput, and effectively, where many parallel large-scale data

How Argonne's Intense Pulsed Neutron Source came to life and gained its niche : the view from an ecosystem perspective.

Energy Technology Data Exchange (ETDEWEB)

Westfall, C.; Office of The Director

2008-02-25

At first glance the story of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory (ANL) appears to have followed a puzzling course. When researchers first proposed their ideas for an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, the project seemed so promising that both Argonne managers and officials at the laboratory's funding agency, the Department of Energy (DOE), suggested that it be made larger and more expensive. But then, even though prototype building, testing, and initial construction went well a group of prominent DOE reviewers recommended in fall 1980 that it be killed, just months before it had been slated to begin operation, and DOE promptly accepted the recommendation. In response, Argonne's leadership declared the project was the laboratory's top priority and rallied to save it. In late 1982, thanks to another review panel led by the same scientist who had chaired the panel that had delivered the death sentence, the project was granted a reprieve. However, by the late 1980s, the IPNS was no longer top priority within the international materials science community, at Argonne, or within the DOE budget because prospects for another, larger materials science accelerator emerged. At just this point, the facility started to produce exciting scientific results. For the next two decades, the IPNS, its research, and its experts became valued resources at Argonne, within the U.S. national laboratory system, and within the international materials science community. Why did this Argonne project prosper and then almost suffer premature death, even though it promised (and later delivered) good science? How was it saved and how did it go on to have a long, prosperous life for more than a quarter of a century? In particular, what did an expert assessment of the quality of IPNS science have to do with its fate? Getting answers to such questions is important. The U.S. government

How Argonne's Intense Pulsed Neutron Source came to life and gained its niche : the view from an ecosystem perspective

International Nuclear Information System (INIS)

Westfall, C.

2008-01-01

At first glance the story of the Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory (ANL) appears to have followed a puzzling course. When researchers first proposed their ideas for an accelerator-driven neutron source for exploring the structure of materials through neutron scattering, the project seemed so promising that both Argonne managers and officials at the laboratory's funding agency, the Department of Energy (DOE), suggested that it be made larger and more expensive. But then, even though prototype building, testing, and initial construction went well a group of prominent DOE reviewers recommended in fall 1980 that it be killed, just months before it had been slated to begin operation, and DOE promptly accepted the recommendation. In response, Argonne's leadership declared the project was the laboratory's top priority and rallied to save it. In late 1982, thanks to another review panel led by the same scientist who had chaired the panel that had delivered the death sentence, the project was granted a reprieve. However, by the late 1980s, the IPNS was no longer top priority within the international materials science community, at Argonne, or within the DOE budget because prospects for another, larger materials science accelerator emerged. At just this point, the facility started to produce exciting scientific results. For the next two decades, the IPNS, its research, and its experts became valued resources at Argonne, within the U.S. national laboratory system, and within the international materials science community. Why did this Argonne project prosper and then almost suffer premature death, even though it promised (and later delivered) good science? How was it saved and how did it go on to have a long, prosperous life for more than a quarter of a century? In particular, what did an expert assessment of the quality of IPNS science have to do with its fate? Getting answers to such questions is important. The U.S. government spends a lot

Brain viscoelasticity alteration in chronic-progressive multiple sclerosis.

Directory of Open Access Journals (Sweden)

Kaspar-Josche Streitberger

Full Text Available INTRODUCTION: Viscoelastic properties indicate structural alterations in biological tissues at multiple scales with high sensitivity. Magnetic Resonance Elastography (MRE is a novel technique that directly visualizes and quantitatively measures biomechanical tissue properties in vivo. MRE recently revealed that early relapsing-remitting multiple sclerosis (MS is associated with a global decrease of the cerebral mechanical integrity. This study addresses MRE and MR volumetry in chronic-progressive disease courses of MS. METHODS: We determined viscoelastic parameters of the brain parenchyma in 23 MS patients with primary or secondary chronic progressive disease course in comparison to 38 age- and gender-matched healthy individuals by multifrequency MRE, and correlated the results with clinical data, T2 lesion load and brain volume. Two viscoelastic parameters, the shear elasticity μ and the powerlaw exponent α, were deduced according to the springpot model and compared to literature values of relapsing-remitting MS. RESULTS: In chronic-progressive MS patients, μ and α were reduced by 20.5% and 6.1%, respectively, compared to healthy controls. MR volumetry yielded a weaker correlation: Total brain volume loss in MS patients was in the range of 7.5% and 1.7% considering the brain parenchymal fraction. All findings were significant (P<0.001. CONCLUSIONS: Chronic-progressive MS disease courses show a pronounced reduction of the cerebral shear elasticity compared to early relapsing-remitting disease. The powerlaw exponent α decreased only in the chronic-progressive stage of MS, suggesting an alteration in the geometry of the cerebral mechanical network due to chronic neuroinflammation.

Net benefits: assessing the effectiveness of clinical networks in Australia through qualitative methods.

Science.gov (United States)

Cunningham, Frances C; Ranmuthugala, Geetha; Westbrook, Johanna I; Braithwaite, Jeffrey

2012-11-02

In the 21st century, government and industry are supplementing hierarchical, bureaucratic forms of organization with network forms, compatible with principles of devolved governance and decentralization of services. Clinical networks are employed as a key health policy approach to engage clinicians in improving patient care in Australia. With significant investment in such networks in Australia and internationally, it is important to assess their effectiveness and sustainability as implementation mechanisms. In two purposively selected, musculoskeletal clinical networks, members and stakeholders were interviewed to ascertain their perceptions regarding key factors relating to network effectiveness and sustainability. We adopted a three-level approach to evaluating network effectiveness: at the community, network, and member levels, across the network lifecycle. Both networks studied are advisory networks displaying characteristics of the 'enclave' type of non-hierarchical network. They are hybrids of the mandated and natural network forms. In the short term, at member level, both networks were striving to create connectivity and collaboration of members. Over the short to medium term, at network level, both networks applied multi-disciplinary engagement in successfully developing models of care as key outputs, and disseminating information to stakeholders. In the long term, at both community and network levels, stakeholders would measure effectiveness by the broader statewide influence of the network in changing and improving practice. At community level, in the long term, stakeholders acknowledged both networks had raised the profile, and provided a 'voice' for musculoskeletal conditions, evidencing some progress with implementation of the network mission while pursuing additional implementation strategies. This research sheds light on stakeholders' perceptions of assessing clinical network effectiveness at community, network, and member levels during the network

MET network in PubMed: a text-mined network visualization and curation system.

Science.gov (United States)

Dai, Hong-Jie; Su, Chu-Hsien; Lai, Po-Ting; Huang, Ming-Siang; Jonnagaddala, Jitendra; Rose Jue, Toni; Rao, Shruti; Chou, Hui-Jou; Milacic, Marija; Singh, Onkar; Syed-Abdul, Shabbir; Hsu, Wen-Lian

2016-01-01

Metastasis is the dissemination of a cancer/tumor from one organ to another, and it is the most dangerous stage during cancer progression, causing more than 90% of cancer deaths. Improving the understanding of the complicated cellular mechanisms underlying metastasis requires investigations of the signaling pathways. To this end, we developed a METastasis (MET) network visualization and curation tool to assist metastasis researchers retrieve network information of interest while browsing through the large volume of studies in PubMed. MET can recognize relations among genes, cancers, tissues and organs of metastasis mentioned in the literature through text-mining techniques, and then produce a visualization of all mined relations in a metastasis network. To facilitate the curation process, MET is developed as a browser extension that allows curators to review and edit concepts and relations related to metastasis directly in PubMed. PubMed users can also view the metastatic networks integrated from the large collection of research papers directly through MET. For the BioCreative 2015 interactive track (IAT), a curation task was proposed to curate metastatic networks among PubMed abstracts. Six curators participated in the proposed task and a post-IAT task, curating 963 unique metastatic relations from 174 PubMed abstracts using MET.Database URL: http://btm.tmu.edu.tw/metastasisway. © The Author(s) 2016. Published by Oxford University Press.

Institute of Nuclear Physics of Orsay - IPNO. Activity report 2008/2009

International Nuclear Information System (INIS)

2010-01-01

The Institute of Nuclear Physics of Orsay (IPN Orsay) is undertaking nuclear physics research that is centered on the nature of matter and its ultimate constituents. By the nature of its scientific activities, the IPN is at the heart of a wide range of international collaborations. IPN Orsay is a unit of both the CNRS (National Centre of Scientific Research) and of the Paris-Sud University. It plays a vital role in experiments being carried out by wide-ranging collaborations at major experimental facilities most notably in Europe, the United States and Japan. Its own facilities allows the IPN to carry out fundamental theoretical and experimental research studies in nuclear physics, astro-particle physics, radiochemistry but also in pluri-disciplinary activities. This document presents the activity of the Institute during the 2008-2009 years: 1 - Scientific activities: Nuclear structure; Hadronic physics and Astro-particles; Theoretical physics; Particle Matter Interactions; Nuclear dynamics and thermodynamics; Energy and Environment; 2 - Technical activities: Technical departments; Accelerators Division; Instrumentation division; 3 - Knowledge dissemination; 4 - General services; 5 - Appendixes: Publications, Proceedings, Conferences, workshops, collaboration meetings, Seminars, PhDs, accreditations to supervise research, Staff, Visitors, Work experiences

A Polyprotein-Expressing Salmonid Alphavirus Replicon Induces Modest Protection in Atlantic Salmon (Salmo Salar Against Infectious Pancreatic Necrosis

Directory of Open Access Journals (Sweden)

Azila Abdullah

2015-01-01

Full Text Available Vaccination is an important strategy for the control and prevention of infectious pancreatic necrosis (IPN in farmed Atlantic salmon (Salmo salar in the post-smolt stage in sea-water. In this study, a heterologous gene expression system, based on a replicon construct of salmonid alphavirus (SAV, was used for in vitro and in vivo expression of IPN virus proteins. The large open reading frame of segment A, encoding the polyprotein NH2-pVP2-VP4-VP3-COOH, as well as pVP2, were cloned and expressed by the SAV replicon in Chinook salmon embryo cells (CHSE-214 and epithelioma papulosum cyprini (EPC cells. The replicon constructs pSAV/polyprotein (pSAV/PP and pSAV/pVP2 were used to immunize Atlantic salmon (Salmo salar by a single intramuscular injection and tested in a subsequent IPN virus (IPNV challenge trial. A low to moderate protection against IPN was observed in fish immunized with the replicon vaccine that encoded the pSAV/PP, while the pSAV/pVP2 construct was not found to induce protection.

Institute of Nuclear Physics of Orsay - IPNO. Activity report 2002-2003

International Nuclear Information System (INIS)

2004-01-01

The Institute of Nuclear Physics of Orsay (IPN Orsay) is undertaking nuclear physics research that is centered on the nature of matter and its ultimate constituents. By the nature of its scientific activities, the IPN is at the heart of a wide range of international collaborations. IPN Orsay is a unit of both the CNRS (National Centre of Scientific Research) and of the Paris-Sud University. It plays a vital role in experiments being carried out by wide-ranging collaborations at major experimental facilities most notably in Europe, the United States and Japan. Its own facilities allows the IPN to carry out fundamental theoretical and experimental research studies in nuclear physics, astro-particle physics, radiochemistry but also in pluri-disciplinary activities. This document presents the activity of the Institute during the 2002-2003 years: 1 - Scientific activities: Nuclear structure; Hadronic physics and matter; Astro-particles; Theoretical physics; Hot nuclei; Energy and Environment; Particle Matter Interactions; Physics-Biology-Medicine Interfaces in Neurobiology, Oncology and Genomic; Knowledge dissemination and communication; 2 - Technical activities: General and technical departments; Instrumentation/Detectors; Accelerators Division; 3 - Appendixes: Publications, meetings, seminars, workshops, PhDs, Staff

Institute of Nuclear Physics of Orsay - IPNO. Activity report 2006/2007

International Nuclear Information System (INIS)

2008-01-01

The Institute of Nuclear Physics of Orsay (IPN Orsay) is undertaking nuclear physics research that is centered on the nature of matter and its ultimate constituents. By the nature of its scientific activities, the IPN is at the heart of a wide range of international collaborations. IPN Orsay is a unit of both the CNRS (National Centre of Scientific Research) and of the Paris-Sud University. It plays a vital role in experiments being carried out by wide-ranging collaborations at major experimental facilities most notably in Europe, the United States and Japan. Its own facilities allows the IPN to carry out fundamental theoretical and experimental research studies in nuclear physics, astro-particle physics, radiochemistry but also in pluri-disciplinary activities. This document presents the activity of the Institute during the 2006-2007 years: 1 - Scientific activities: Nuclear structure; Hadronic physics and matter; Astro-particles; Theoretical physics; Hot nuclei; Energy and Environment; Particle Matter Interactions; Knowledge dissemination and communication; 2 - Administration; 3 - Technical activities: General and technical departments; Accelerators Division; 4 - Appendixes: Publications, Proceedings, Conferences, workshops, collaboration meetings, Seminars, Schools and lectures, PhDs, accreditations to supervise research, Books and works, Staff, Visitors

Epigenetics and Why Biological Networks are More Controllable than Expected

Science.gov (United States)

Motter, Adilson

2013-03-01

A fundamental property of networks is that perturbations to one node can affect other nodes, potentially causing the entire system to change behavior or fail. In this talk, I will show that it is possible to exploit this same principle to control network behavior. This approach takes advantage of the nonlinear dynamics inherent to real networks, and allows bringing the system to a desired target state even when this state is not directly accessible or the linear counterpart is not controllable. Applications show that this framework permits both reprogramming a network to a desired task as well as rescuing networks from the brink of failure, which I will illustrate through various biological problems. I will also briefly review the progress our group has made over the past 5 years on related control of complex networks in non-biological domains.

Selective verbal recognition memory impairments are associated with atrophy of the language network in non-semantic variants of primary progressive aphasia.

Science.gov (United States)

Nilakantan, Aneesha S; Voss, Joel L; Weintraub, Sandra; Mesulam, M-Marsel; Rogalski, Emily J

2017-06-01

Primary progressive aphasia (PPA) is clinically defined by an initial loss of language function and preservation of other cognitive abilities, including episodic memory. While PPA primarily affects the left-lateralized perisylvian language network, some clinical neuropsychological tests suggest concurrent initial memory loss. The goal of this study was to test recognition memory of objects and words in the visual and auditory modality to separate language-processing impairments from retentive memory in PPA. Individuals with non-semantic PPA had longer reaction times and higher false alarms for auditory word stimuli compared to visual object stimuli. Moreover, false alarms for auditory word recognition memory were related to cortical thickness within the left inferior frontal gyrus and left temporal pole, while false alarms for visual object recognition memory was related to cortical thickness within the right-temporal pole. This pattern of results suggests that specific vulnerability in processing verbal stimuli can hinder episodic memory in PPA, and provides evidence for differential contributions of the left and right temporal poles in word and object recognition memory. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Survey on Underwater Wireless Sensor Networks: Progresses, Applications, and Challenges

Directory of Open Access Journals (Sweden)

Premalatha J.

2016-01-01

Full Text Available The endangered underwater species always drew the attention of the scientific society since their disappearance would cause irreplaceable loss. Asia is home to some of the most diverse habitats in the earth, but it is estimated that more than one in four species are endangered. In Underwater, a lot of factors are putting marine life under immense pressure. Extreme population pressure is leading to pollution, over-fishing and the devastation of crucial habitats. Consequently, the numbers of almost all fish are declining and many are already endangered. To help these species to survive, their habitat should be strictly protected. This can be achieved by strictly monitoring them. During this course, several parameters, constraints about the species and its environments are focused. Now, advances in sensor technology facilitate the monitoring of species and their habitat with less expenditure. Indeed, the increasing sophistication of underwater wireless sensors offers chances that enable new challenges in a lot of areas, like surveillance one. This paper endorses the use of sensors for monitoring underwater species endangered in their habitat. This paper further examines the key approaches and challenges in the design and implementation of underwater wireless sensor networks. We summarize major applications and the main phenomena related to acoustic propagation, and discuss how they affect the design and operation of communication systems and networking protocols at various layers.

Net benefits: assessing the effectiveness of clinical networks in Australia through qualitative methods

Directory of Open Access Journals (Sweden)

Cunningham Frances C

2012-11-01

Full Text Available Abstract Background In the 21st century, government and industry are supplementing hierarchical, bureaucratic forms of organization with network forms, compatible with principles of devolved governance and decentralization of services. Clinical networks are employed as a key health policy approach to engage clinicians in improving patient care in Australia. With significant investment in such networks in Australia and internationally, it is important to assess their effectiveness and sustainability as implementation mechanisms. Methods In two purposively selected, musculoskeletal clinical networks, members and stakeholders were interviewed to ascertain their perceptions regarding key factors relating to network effectiveness and sustainability. We adopted a three-level approach to evaluating network effectiveness: at the community, network, and member levels, across the network lifecycle. Results Both networks studied are advisory networks displaying characteristics of the ‘enclave’ type of non-hierarchical network. They are hybrids of the mandated and natural network forms. In the short term, at member level, both networks were striving to create connectivity and collaboration of members. Over the short to medium term, at network level, both networks applied multi-disciplinary engagement in successfully developing models of care as key outputs, and disseminating information to stakeholders. In the long term, at both community and network levels, stakeholders would measure effectiveness by the broader statewide influence of the network in changing and improving practice. At community level, in the long term, stakeholders acknowledged both networks had raised the profile, and provided a ‘voice’ for musculoskeletal conditions, evidencing some progress with implementation of the network mission while pursuing additional implementation strategies. Conclusions This research sheds light on stakeholders’ perceptions of assessing clinical

Networks as systems.

Science.gov (United States)

Best, Allan; Berland, Alex; Greenhalgh, Trisha; Bourgeault, Ivy L; Saul, Jessie E; Barker, Brittany

2018-03-19

Purpose The purpose of this paper is to present a case study of the World Health Organization's Global Healthcare Workforce Alliance (GHWA). Based on a commissioned evaluation of GHWA, it applies network theory and key concepts from systems thinking to explore network emergence, effectiveness, and evolution to over a ten-year period. The research was designed to provide high-level strategic guidance for further evolution of global governance in human resources for health (HRH). Design/methodology/approach Methods included a review of published literature on HRH governance and current practice in the field and an in-depth case study whose main data sources were relevant GHWA background documents and key informant interviews with GHWA leaders, staff, and stakeholders. Sampling was purposive and at a senior level, focusing on board members, executive directors, funders, and academics. Data were analyzed thematically with reference to systems theory and Shiffman's theory of network development. Findings Five key lessons emerged: effective management and leadership are critical; networks need to balance "tight" and "loose" approaches to their structure and processes; an active communication strategy is key to create and maintain support; the goals, priorities, and membership must be carefully focused; and the network needs to support shared measurement of progress on agreed-upon goals. Shiffman's middle-range network theory is a useful tool when guided by the principles of complex systems that illuminate dynamic situations and shifting interests as global alliances evolve. Research limitations/implications This study was implemented at the end of the ten-year funding cycle. A more continuous evaluation throughout the term would have provided richer understanding of issues. Experience and perspectives at the country level were not assessed. Practical implications Design and management of large, complex networks requires ongoing attention to key issues like leadership

On the graph and systems analysis of reversible chemical reaction networks with mass action kinetics

NARCIS (Netherlands)

Rao, Shodhan; Jayawardhana, Bayu; Schaft, Arjan van der

2012-01-01

Motivated by the recent progresses on the interplay between the graph theory and systems theory, we revisit the analysis of reversible chemical reaction networks described by mass action kinetics by reformulating it using the graph knowledge of the underlying networks. Based on this formulation, we

Novel patternable and conducting metal-polymer nanocomposites: a step towards advanced mutlifunctional materials

Science.gov (United States)

Rodríguez-Cantó, Pedro J.; Martínez-Marco, Mariluz; Abargues, Rafael; Latorre-Garrido, Victor; Martínez-Pastor, Juan P.

2013-03-01

In this work, we present a novel patternable conducting nanocomposite containing gold nanoparticles. Here, the in-situ polymerization of 3T is carried out using HAuCl4 as oxidizing agent inside PMMA as host matrix. During the bake step, the gold salt is also reduced from Au(III) to Au(0) generating Au nanoparticles in the interpenetrating polymer network (IPN) system. We found that this novel multifunctional resist shows electrical conductivity and plasmonic properties as well as potential patterning capability provided by the host matrix. The resulting nanocomposite has been investigated by TEM and UV-Vis spectroscopy. Electrical characterization was also conducted for different concentration of 3T and Au(III) following a characteristic percolation behaviour. Conductivities values from 10-5 to 10 S/cm were successfully obtained depending on the IPN formulation. Moreover, The Au nanoparticles generated exhibited a localized surface plasmon resonance at around 520 nm. This synthetic approach is of potential application to modify the conductivity of numerous insulating polymers and synthesize Au nanoparticles preserving to some extent their physical and chemical properties. In addition, combination of optical properties (Plasmonics), electrical, and lithographic capability in the same material allows for the design of materials with novel functionalities and provides the basis for next generation devices.

Indonesia-DLN Is A Digital Library Network In Indonesia

International Nuclear Information System (INIS)

Fahmi, Ismail

2001-01-01

Within this paper, philosophy of the knowledge sharing, vision of the network, and how it can give benefits to Indonesia are described. The status of the network is described that show the successfulness of the architecture in tying together partner's knowledge from all big islands of Indonesia (Sumatera, Java, Kalimantan, Sulawesi, and Irian Jaya) whether they have dedicated internet connection or only a dial-up one. Currently 13 institutions have joined the network and 15+ in progress of developing their servers. Features of the software, Ganesha Digital Library (GDL version 3.1) are presented, that is now distributed as a Free-Software that is based on My SQL, PHP, and Apache

Cryogenic moderator simulations: confronting reality

International Nuclear Information System (INIS)

Iverson, E. B.

1999-01-01

The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source dedicated to materials research. Its three cryogenic methane moderators provide twelve neutron beams to fourteen instruments and test facilities. This report concerns ongoing activities for benchmarking our Monte Carlo model of the IPNS neutron generation system. This paper concentrates on the techniques (both experimental and calculational) used in such benchmarking activities

Chinese Herbal Medicine Meets Biological Networks of Complex Diseases: A Computational Perspective

Directory of Open Access Journals (Sweden)

Shuo Gu

2017-01-01

Full Text Available With the rapid development of cheminformatics, computational biology, and systems biology, great progress has been made recently in the computational research of Chinese herbal medicine with in-depth understanding towards pharmacognosy. This paper summarized these studies in the aspects of computational methods, traditional Chinese medicine (TCM compound databases, and TCM network pharmacology. Furthermore, we chose arachidonic acid metabolic network as a case study to demonstrate the regulatory function of herbal medicine in the treatment of inflammation at network level. Finally, a computational workflow for the network-based TCM study, derived from our previous successful applications, was proposed.

Chinese Herbal Medicine Meets Biological Networks of Complex Diseases: A Computational Perspective.

Science.gov (United States)

Gu, Shuo; Pei, Jianfeng

2017-01-01

With the rapid development of cheminformatics, computational biology, and systems biology, great progress has been made recently in the computational research of Chinese herbal medicine with in-depth understanding towards pharmacognosy. This paper summarized these studies in the aspects of computational methods, traditional Chinese medicine (TCM) compound databases, and TCM network pharmacology. Furthermore, we chose arachidonic acid metabolic network as a case study to demonstrate the regulatory function of herbal medicine in the treatment of inflammation at network level. Finally, a computational workflow for the network-based TCM study, derived from our previous successful applications, was proposed.

Progress with the NESC spinning cylinder project and other NESC projects

International Nuclear Information System (INIS)

Wintle, J.B.; Hurst, R.C.; Hemsworth, B.

1995-01-01

The first international project (NESC I) of the Network for Evaluating Steel Components is a spinning cylinder, pressurized thermal shock (PTS) experiment. The main objective of the project is to validate the non-destructive evaluation and structural mechanics procedures for PWR reactor pressure vessels under PTS conditions. Contributing organizations world-wide will participate in this blind trial which embraces all aspects of structural integrity assessment. This paper describes the progress of the project to date, covering cylinder manufacture and inspection, materials evaluation, structural analysis and test instrumentation. It emphasises the importance of networking global expertise in a managed framework and of the partnership, co-operation and teamwork developed by the contributing organizations through the five Task Groups constituting NESC I. Finally, five new initiatives for projects managed by the Network are currently under review and described in this paper. (author). 2 refs, 6 figs

The effect of network biology on drug toxicology

DEFF Research Database (Denmark)

Gautier, Laurent; Taboureau, Olivier; Audouze, Karine Marie Laure

2013-01-01

Introduction: The high failure rate of drug candidates due to toxicity, during clinical trials, is a critical issue in drug discovery. Network biology has become a promising approach, in this regard, using the increasingly large amount of biological and chemical data available and combining...... it with bioinformatics. With this approach, the assessment of chemical safety can be done across multiple scales of complexity from molecular to cellular and system levels in human health. Network biology can be used at several levels of complexity. Areas covered: This review describes the strengths and limitations...... of network biology. The authors specifically assess this approach across different biological scales when it is applied to toxicity. Expert opinion: There has been much progress made with the amount of data that is generated by various omics technologies. With this large amount of useful data, network...

Career Progression of Young Female Accountants: Evidence from the Accountancy Profession in Ireland.

Science.gov (United States)

Twomey, Ann Marie; Linehan, Margaret; Walsh, James S.

2002-01-01

A study of 12 male and 12 female accountants under age 30 in Ireland indicated that young women encountered gender-based obstacles in an industry still dominated by males. They had fewer opportunities for informal networking, and more women than men believed children would affect their career progress. (Contains 41 references.) (SK)

18F-FDG PET/CT and functional MRI in a case of crossed logopenic primary progressive aphasia.

Science.gov (United States)

Cabrera-Martín, M N; Matías-Guiu, J A; Yus-Fuertes, M; Valles-Salgado, M; Moreno-Ramos, T; Matías-Guiu, J; Carreras Delgado, J L

Primary progressive aphasia is a clinical syndrome caused by a neurodegeneration of areas and neural networks involved in language, usually in the left hemisphere. The term "crossed aphasia" denotes an acquired language dysfunction caused by a lesion in the hemisphere ipsilateral to the dominant hand. A case is presented on a 75-year-old right-handed woman with a logopenic variant of primary progressive aphasia with word-finding difficulties of 2 years onset. The 18 F-FDG PET/CT showed right temporoparietal hypometabolism. A functional MRI scan was performed during a verb naming task in order to characterise language lateralisation patterns. A similar activation pattern was observed in both hemispheres, with less activation than expected in bilateral inferior frontal gyrus. These findings support that logopenic variant of primary progressive aphasia should not be considered as a neurodegeneration starting in the left brain hemisphere, but as a syndrome characterised by asymmetric neurodegeneration of brain regions and neural networks involved in language. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

IPY Progress and Prospects

Science.gov (United States)

Carlson, D.

2008-12-01

We can summarize the IPY goals as: (a) make major advances in polar knowledge and understanding; (b) leave a legacy of new or enhanced observational systems, facilities and infrastructure; (c) excite a new generation of polar scientists and engineers, and (d) elicit exceptional interest and participation from polar residents, schoolchildren, the general public, and decision-makers, worldwide. This talk reports on the progress and prospects in each of those areas from an overall international view; separate talks will describe details of future researcher and the IPY outreach efforts. To achieve major advances in knowledge, IPY has entrained the intellectual resources of thousands of scientists, many more than expected, often from 'non- polar' nations, and representing an unprecedented breadth of scientific specialties; integration of those efforts across disciplines to achieve integrated system-level understanding remains a substantial challenge. Many national and international organizations prepare plans to sustain new and improved observational systems, but clear outcomes and the necessary resources remain elusive. International outreach networks gradually build breadth and strength, largely through IPY Polar Science Days and other internationally- coordinated IPY events. A new Association of Polar Early Career Scientists (APECS) devotes talent and energy to shaping the future of polar research. These activities and networks may, with time and with continued international coordination, achieve an exceptional level of interest and participation. In all areas, much work remains.

Human tracking over camera networks: a review

Science.gov (United States)

Hou, Li; Wan, Wanggen; Hwang, Jenq-Neng; Muhammad, Rizwan; Yang, Mingyang; Han, Kang

2017-12-01

In recent years, automated human tracking over camera networks is getting essential for video surveillance. The tasks of tracking human over camera networks are not only inherently challenging due to changing human appearance, but also have enormous potentials for a wide range of practical applications, ranging from security surveillance to retail and health care. This review paper surveys the most widely used techniques and recent advances for human tracking over camera networks. Two important functional modules for the human tracking over camera networks are addressed, including human tracking within a camera and human tracking across non-overlapping cameras. The core techniques of human tracking within a camera are discussed based on two aspects, i.e., generative trackers and discriminative trackers. The core techniques of human tracking across non-overlapping cameras are then discussed based on the aspects of human re-identification, camera-link model-based tracking and graph model-based tracking. Our survey aims to address existing problems, challenges, and future research directions based on the analyses of the current progress made toward human tracking techniques over camera networks.

Productive Tensions in a Cross-Cultural Peer Mentoring Women's Network: A Social Capital Perspective

Science.gov (United States)

Esnard, Talia; Cobb-Roberts, Deirdre; Agosto, Vonzell; Karanxha, Zorka; Beck, Makini; Wu, Ke; Unterreiner, Ann

2015-01-01

A growing body of researchers documents the unique barriers women face in their academic career progression and the significance of mentoring networks for advancement of their academic trajectories as faculty. However, few researchers explore the embedded tensions and conflicts in the social processes and relations of mentoring networks, and the…

Effects of Social Networking on Adolescent Education

Science.gov (United States)

Miah, Muhammed; Omar, Adnan; Allison-Golding, Monique

2013-01-01

In recent years, the use of social networking sites has grown tremendously especially among the teens and high school students. However, very little is known about the scale of use, the purpose, how students use these sites and, more specifically, whether these sites help or hurt their academic progress. This study investigates how high school…

On the development of online cities and neighborhoods: an exploration of cumulative and segmentive network effects in social media

NARCIS (Netherlands)

Maris, I.; Huizinga, A; Bouman, W.; Tuunainen, V.K.; Rossi, M.; Nandhakumar, J.

2011-01-01

This paper outlines a research in progress set to study network effects in social media. The focus is on outlining the theoretical framework in which this study is embedded. The concepts of cumulative network effects and segmentive network effects are introduced to explain the processes by which

NRC TLD [thermoluminescent dosimeter] Direct Radiation Monitoring Network: Progress report, January-March 1988

International Nuclear Information System (INIS)

Struckmeyer, R.; McNamara, N.

1988-06-01

This report provides the status and results of the NRC Thermoluminescent Dosimeter (TLD) Direct Radiation Monitoring Network. It presents the radiation levels measured in the vicinity of NRC licensed facility sites throughout the country for the first quarter of 1988

Recommender systems for location-based social networks

CERN Document Server

Symeonidis, Panagiotis; Manolopoulos, Yannis

2014-01-01

Online social networks collect information from users' social contacts and their daily interactions (co-tagging of photos, co-rating of products etc.) to provide them with recommendations of new products or friends. Lately, technological progressions in mobile devices (i.e. smart phones) enabled the incorporation of geo-location data in the traditional web-based online social networks, bringing the new era of Social and Mobile Web. The goal of this book is to bring together important research in a new family of recommender systems aimed at serving Location-based Social Networks (LBSNs). The chapters introduce a wide variety of recent approaches, from the most basic to the state-of-the-art, for providing recommendations in LBSNs. The book is organized into three parts. Part 1 provides introductory material on recommender systems, online social networks and LBSNs. Part 2 presents a wide variety of recommendation algorithms, ranging from basic to cutting edge, as well as a comparison of the characteristics of t...

Cumulative Significance of Hyporheic Exchange and Biogeochemical Processing in River Networks

Science.gov (United States)

Harvey, J. W.; Gomez-Velez, J. D.

2014-12-01

Biogeochemical reactions in rivers that decrease excessive loads of nutrients, metals, organic compounds, etc. are enhanced by hydrologic interactions with microbially and geochemically active sediments of the hyporheic zone. The significance of reactions in individual hyporheic flow paths has been shown to be controlled by the contact time between river water and sediment and the intrinsic reaction rate in the sediment. However, little is known about how the cumulative effects of hyporheic processing in large river basins. We used the river network model NEXSS (Gomez-Velez and Harvey, submitted) to simulate hyporheic exchange through synthetic river networks based on the best available models of network topology, hydraulic geometry and scaling of geomorphic features, grain size, hydraulic conductivity, and intrinsic reaction rates of nutrients and metals in river sediment. The dimensionless reaction significance factor, RSF (Harvey et al., 2013) was used to quantify the cumulative removal fraction of a reactive solute by hyporheic processing. SF scales reaction progress in a single pass through the hyporheic zone with the proportion of stream discharge passing through the hyporheic zone for a specified distance. Reaction progress is optimal where the intrinsic reaction timescale in sediment matches the residence time of hyporheic flow and is less efficient in longer residence time hyporheic flow as a result of the decreasing proportion of river flow that is processed by longer residence time hyporheic flow paths. In contrast, higher fluxes through short residence time hyporheic flow paths may be inefficient because of the repeated surface-subsurface exchanges required to complete the reaction. Using NEXSS we found that reaction efficiency may be high in both small streams and large rivers, although for different reasons. In small streams reaction progress generally is dominated by faster pathways of vertical exchange beneath submerged bedforms. Slower exchange

Systems pharmacology - Towards the modeling of network interactions.

Science.gov (United States)

Danhof, Meindert

2016-10-30

Mechanism-based pharmacokinetic and pharmacodynamics (PKPD) and disease system (DS) models have been introduced in drug discovery and development research, to predict in a quantitative manner the effect of drug treatment in vivo in health and disease. This requires consideration of several fundamental properties of biological systems behavior including: hysteresis, non-linearity, variability, interdependency, convergence, resilience, and multi-stationarity. Classical physiology-based PKPD models consider linear transduction pathways, connecting processes on the causal path between drug administration and effect, as the basis of drug action. Depending on the drug and its biological target, such models may contain expressions to characterize i) the disposition and the target site distribution kinetics of the drug under investigation, ii) the kinetics of target binding and activation and iii) the kinetics of transduction. When connected to physiology-based DS models, PKPD models can characterize the effect on disease progression in a mechanistic manner. These models have been found useful to characterize hysteresis and non-linearity, yet they fail to explain the effects of the other fundamental properties of biological systems behavior. Recently systems pharmacology has been introduced as novel approach to predict in vivo drug effects, in which biological networks rather than single transduction pathways are considered as the basis of drug action and disease progression. These models contain expressions to characterize the functional interactions within a biological network. Such interactions are relevant when drugs act at multiple targets in the network or when homeostatic feedback mechanisms are operative. As a result systems pharmacology models are particularly useful to describe complex patterns of drug action (i.e. synergy, oscillatory behavior) and disease progression (i.e. episodic disorders). In this contribution it is shown how physiology-based PKPD and

Computerized access to materials data. A progress report

International Nuclear Information System (INIS)

Rumble, J. Jr.

1985-01-01

As the effort to build a comprehensive computerized materials data system grows, it becomes more obvious that the benefits will be far-reaching. During this workshop, the enthusiasm of the participants grew steadily until the questions became not''What,'' but ''When?''. The engineering community within the United States has banded together many times to advance progress in engineering capability. The computerized materials data system requires such an effort, and the rewards will be substantial. Chapter 3 identifies changes in the use of materials data in the Nuclear Power Industry. Chapter 4 describes the EPRI experience in building computerized materials databases. In Chapter 5, the National Materials Property Data Network is discussed. The next four chapters present summaries of the workshop discussions and its conclusions. Chapter 6 discusses the content of the proposed system, Chapter 7 its size and the data sources, and Chapter 8 the user interfaces and system capabilities. In Chapter 9, ways of making further progress are outlined

Brookhaven Reactor Experiment Control Facility, a distributed function computer network

International Nuclear Information System (INIS)

Dimmler, D.G.; Greenlaw, N.; Kelley, M.A.; Potter, D.W.; Rankowitz, S.; Stubblefield, F.W.

1975-11-01

A computer network for real-time data acquisition, monitoring and control of a series of experiments at the Brookhaven High Flux Beam Reactor has been developed and has been set into routine operation. This reactor experiment control facility presently services nine neutron spectrometers and one x-ray diffractometer. Several additional experiment connections are in progress. The architecture of the facility is based on a distributed function network concept. A statement of implementation and results is presented

Discrete Fracture Network Modeling and Simulation of Subsurface Transport for the Topopah Springs and Lava Flow Aquifers at Pahute Mesa, FY 15 Progress Report

Energy Technology Data Exchange (ETDEWEB)

Makedonska, Nataliia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kwicklis, Edward Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Birdsell, Kay Hanson [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harrod, Jeremy Ashcraft [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karra, Satish [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-10-18

This progress report for fiscal year 2015 (FY15) describes the development of discrete fracture network (DFN) models for Pahute Mesa. DFN models will be used to upscale parameters for simulations of subsurface flow and transport in fractured media in Pahute Mesa. The research focuses on modeling of groundwater flow and contaminant transport using DFNs generated according to fracture characteristics observed in the Topopah Spring Aquifer (TSA) and the Lava Flow Aquifer (LFA). This work will improve the representation of radionuclide transport processes in large-scale, regulatory-focused models with a view to reduce pessimistic bounding approximations and provide more realistic contaminant boundary calculations that can be used to describe the future extent of contaminated groundwater. Our goal is to refine a modeling approach that can translate parameters to larger-scale models that account for local-scale flow and transport processes, which tend to attenuate migration.

Sensor signal analysis by neural networks for surveillance in nuclear reactors

International Nuclear Information System (INIS)

Keyvan, S.; Rabelo, L.C.

1992-01-01

The application of neural networks as a tool for reactor diagnostics is examined here. Reactor pump signals utilized in a wear-out monitoring system developed for early detection of the degradation of a pump shaft are analyzed as a semi-benchmark test to study the feasibility of neural networks for monitoring and surveillance in nuclear reactors. The Adaptive Resonance Theory (ART 2 and ART 2-A) paradigm of neural networks is applied in this study. The signals are collected signals as well as generated signals simulating the wear progress. The wear-out monitoring system applies noise analysis techniques, and is capable of distinguishing these signals apart and providing a measure of the progress of the degradation. This paper presents the results of the analysis of these data, and provides an evaluation on the performance of ART 2-A and ART 2 for reactor signal analysis. The selection of ART 2 is due to its desired design principles such as unsupervised learning, stability-plasticity, search-direct access, and the match-reset tradeoffs

The cancer cell map initiative: defining the hallmark networks of cancer.

Science.gov (United States)

Krogan, Nevan J; Lippman, Scott; Agard, David A; Ashworth, Alan; Ideker, Trey

2015-05-21

Progress in DNA sequencing has revealed the startling complexity of cancer genomes, which typically carry thousands of somatic mutations. However, it remains unclear which are the key driver mutations or dependencies in a given cancer and how these influence pathogenesis and response to therapy. Although tumors of similar types and clinical outcomes can have patterns of mutations that are strikingly different, it is becoming apparent that these mutations recurrently hijack the same hallmark molecular pathways and networks. For this reason, it is likely that successful interpretation of cancer genomes will require comprehensive knowledge of the molecular networks under selective pressure in oncogenesis. Here we announce the creation of a new effort, The Cancer Cell Map Initiative (CCMI), aimed at systematically detailing these complex interactions among cancer genes and how they differ between diseased and healthy states. We discuss recent progress that enables creation of these cancer cell maps across a range of tumor types and how they can be used to target networks disrupted in individual patients, significantly accelerating the development of precision medicine. Copyright © 2015 Elsevier Inc. All rights reserved.

Chinese Herbal Medicine Meets Biological Networks of Complex Diseases: A Computational Perspective

OpenAIRE

Shuo Gu; Jianfeng Pei

2017-01-01

With the rapid development of cheminformatics, computational biology, and systems biology, great progress has been made recently in the computational research of Chinese herbal medicine with in-depth understanding towards pharmacognosy. This paper summarized these studies in the aspects of computational methods, traditional Chinese medicine (TCM) compound databases, and TCM network pharmacology. Furthermore, we chose arachidonic acid metabolic network as a case study to demonstrate the regula...

Alignment of global supply networks based on strategic groups of supply chains

OpenAIRE

Nikos G. Moraitakis; Jiazhen Huo; Hans-Christian Pfohl

2017-01-01

Background: From a supply chain perspective, often big differences exist between global raw material suppliers’ approaches to supply their respective local markets. The progressing complexity of large centrally managed global supply networks and their often-unknown upstream ramifications increase the likelihood of undetected bottlenecks and inefficiencies. It is therefore necessary to develop an approach to strategically master the upstream complexity of such networks from a holistic su...

Efficient Mobility Management Signalling in Network Mobility Supported PMIPV6.

Science.gov (United States)

Samuelraj, Ananthi Jebaseeli; Jayapal, Sundararajan

2015-01-01

Proxy Mobile IPV6 (PMIPV6) is a network based mobility management protocol which supports node's mobility without the contribution from the respective mobile node. PMIPV6 is initially designed to support individual node mobility and it should be enhanced to support mobile network movement. NEMO-BSP is an existing protocol to support network mobility (NEMO) in PMIPV6 network. Due to the underlying differences in basic protocols, NEMO-BSP cannot be directly applied to PMIPV6 network. Mobility management signaling and data structures used for individual node's mobility should be modified to support group nodes' mobility management efficiently. Though a lot of research work is in progress to implement mobile network movement in PMIPV6, it is not yet standardized and each suffers with different shortcomings. This research work proposes modifications in NEMO-BSP and PMIPV6 to achieve NEMO support in PMIPV6. It mainly concentrates on optimizing the number and size of mobility signaling exchanged while mobile network or mobile network node changes its access point.

Efficient Mobility Management Signalling in Network Mobility Supported PMIPV6

Directory of Open Access Journals (Sweden)

Ananthi Jebaseeli Samuelraj

2015-01-01

Full Text Available Proxy Mobile IPV6 (PMIPV6 is a network based mobility management protocol which supports node’s mobility without the contribution from the respective mobile node. PMIPV6 is initially designed to support individual node mobility and it should be enhanced to support mobile network movement. NEMO-BSP is an existing protocol to support network mobility (NEMO in PMIPV6 network. Due to the underlying differences in basic protocols, NEMO-BSP cannot be directly applied to PMIPV6 network. Mobility management signaling and data structures used for individual node’s mobility should be modified to support group nodes’ mobility management efficiently. Though a lot of research work is in progress to implement mobile network movement in PMIPV6, it is not yet standardized and each suffers with different shortcomings. This research work proposes modifications in NEMO-BSP and PMIPV6 to achieve NEMO support in PMIPV6. It mainly concentrates on optimizing the number and size of mobility signaling exchanged while mobile network or mobile network node changes its access point.

Evaluation of knowledge management performances in NULIFE network

International Nuclear Information System (INIS)

Nitoi, Mirela; Cojan, Mihai; Pavelescu, Margarit

2009-01-01

One of the objectives of Nuclear Plant Life Prediction (NULIFE) network is the identification of experts and resources which can be used in the future. The major challenge is to use these competent personnel in an efficient manner, in the network. The paper presents the necessity of developing the knowledge management strategy for networks of excellence, as the specific issues of NULIFE network. In order to highlight the progress during the project operating, the developed indicators of performance are specified. The developed questionnaires evaluate the quality of knowledge management (development, use and distribution of knowledge), type of knowledge which is considered important for organization (at present and in future) and the benefits of knowledge transfer (immediate and in perspective). The developed questionnaires permit along with the evaluation of others groups activities, an auto-evaluation for the activity of the group where the subject is involved. (authors)

A SURVEY ON WAVELENGTH DIVISION MULTIPLEXING (WDM NETWORKS

Directory of Open Access Journals (Sweden)

G. Ramesh

2010-03-01

Full Text Available Communication networks have emerged as a source of empowerment in today’s society. At the global level, the Internet is becoming the backbone of the modern economy. The new generations in developed countries cannot even conceive of a world without broadband access to the Internet. The inability of the current Internet infrastructure to cope with the wide variety and ever growing number of users, emerging networked applications, usage patterns and business models is increasingly being recognized worldwide. The dynamic growth of Internet traffic and its bursty nature requires high transmission rate. With the advances and the progress in Wavelength Division Multiplexing (WDM technology, the amount of raw bandwidth available in fiber links has increased to high magnitude. This paper presents a survey on WDM networks from its development to the current status. Also an analysis on buffer size in optical networks for real time traffic was performed.

Cognitive Radio Wireless Sensor Networks: Applications, Challenges and Research Trends

Science.gov (United States)

Joshi, Gyanendra Prasad; Nam, Seung Yeob; Kim, Sung Won

2013-01-01

A cognitive radio wireless sensor network is one of the candidate areas where cognitive techniques can be used for opportunistic spectrum access. Research in this area is still in its infancy, but it is progressing rapidly. The aim of this study is to classify the existing literature of this fast emerging application area of cognitive radio wireless sensor networks, highlight the key research that has already been undertaken, and indicate open problems. This paper describes the advantages of cognitive radio wireless sensor networks, the difference between ad hoc cognitive radio networks, wireless sensor networks, and cognitive radio wireless sensor networks, potential application areas of cognitive radio wireless sensor networks, challenges and research trend in cognitive radio wireless sensor networks. The sensing schemes suited for cognitive radio wireless sensor networks scenarios are discussed with an emphasis on cooperation and spectrum access methods that ensure the availability of the required QoS. Finally, this paper lists several open research challenges aimed at drawing the attention of the readers toward the important issues that need to be addressed before the vision of completely autonomous cognitive radio wireless sensor networks can be realized. PMID:23974152

Cognitive Radio Wireless Sensor Networks: Applications, Challenges and Research Trends

Directory of Open Access Journals (Sweden)

Gyanendra Prasad Joshi

2013-08-01

Full Text Available A cognitive radio wireless sensor network is one of the candidate areas where cognitive techniques can be used for opportunistic spectrum access. Research in this area is still in its infancy, but it is progressing rapidly. The aim of this study is to classify the existing literature of this fast emerging application area of cognitive radio wireless sensor networks, highlight the key research that has already been undertaken, and indicate open problems. This paper describes the advantages of cognitive radio wireless sensor networks, the difference between ad hoc cognitive radio networks, wireless sensor networks, and cognitive radio wireless sensor networks, potential application areas of cognitive radio wireless sensor networks, challenges and research trend in cognitive radio wireless sensor networks. The sensing schemes suited for cognitive radio wireless sensor networks scenarios are discussed with an emphasis on cooperation and spectrum access methods that ensure the availability of the required QoS. Finally, this paper lists several open research challenges aimed at drawing the attention of the readers toward the important issues that need to be addressed before the vision of completely autonomous cognitive radio wireless sensor networks can be realized.

Cognitive radio wireless sensor networks: applications, challenges and research trends.

Science.gov (United States)

Joshi, Gyanendra Prasad; Nam, Seung Yeob; Kim, Sung Won

2013-08-22

A cognitive radio wireless sensor network is one of the candidate areas where cognitive techniques can be used for opportunistic spectrum access. Research in this area is still in its infancy, but it is progressing rapidly. The aim of this study is to classify the existing literature of this fast emerging application area of cognitive radio wireless sensor networks, highlight the key research that has already been undertaken, and indicate open problems. This paper describes the advantages of cognitive radio wireless sensor networks, the difference between ad hoc cognitive radio networks, wireless sensor networks, and cognitive radio wireless sensor networks, potential application areas of cognitive radio wireless sensor networks, challenges and research trend in cognitive radio wireless sensor networks. The sensing schemes suited for cognitive radio wireless sensor networks scenarios are discussed with an emphasis on cooperation and spectrum access methods that ensure the availability of the required QoS. Finally, this paper lists several open research challenges aimed at drawing the attention of the readers toward the important issues that need to be addressed before the vision of completely autonomous cognitive radio wireless sensor networks can be realized.

Informatics management at IPN

International Nuclear Information System (INIS)

Givaudan, V.

1999-01-01

This group manages and coordinates hardware and software equipment for the Institute. Migration towards UNIX system is now almost complete, as equipment and data have been secured.. Windows NT Operating system is used to cooperate the different environment of the Institute. (authors)

Characterization of subgraph relationships and distribution in complex networks

International Nuclear Information System (INIS)

Antiqueira, Lucas; Fontoura Costa, Luciano da

2009-01-01

A network can be analyzed at different topological scales, ranging from single nodes to motifs, communities, up to the complete structure. We propose a novel approach which extends from single nodes to the whole network level by considering non-overlapping subgraphs (i.e. connected components) and their interrelationships and distribution through the network. Though such subgraphs can be completely general, our methodology focuses on the cases in which the nodes of these subgraphs share some special feature, such as being critical for the proper operation of the network. The methodology of subgraph characterization involves two main aspects: (i) the generation of histograms of subgraph sizes and distances between subgraphs and (ii) a merging algorithm, developed to assess the relevance of nodes outside subgraphs by progressively merging subgraphs until the whole network is covered. The latter procedure complements the histograms by taking into account the nodes lying between subgraphs, as well as the relevance of these nodes to the overall subgraph interconnectivity. Experiments were carried out using four types of network models and five instances of real-world networks, in order to illustrate how subgraph characterization can help complementing complex network-based studies.

Heterogeneous Epidemic Model for Assessing Data Dissemination in Opportunistic Networks

DEFF Research Database (Denmark)

Rozanova, Liudmila; Alekseev, Vadim; Temerev, Alexander

2014-01-01

that amount of data transferred between network nodes possesses a Pareto distribution, implying scale-free properties. In this context, more heterogeneity in susceptibility means the less severe epidemic progression, and, on the contrary, more heterogeneity in infectivity leads to more severe epidemics...... — assuming that the other parameter (either heterogeneity or susceptibility) stays fixed. The results are general enough to be useful for estimating the epidemic progression with no significant acquired immunity — in the cases where Pareto distribution holds....

Progressive collapse susceptibility of a long span suspension bridge

DEFF Research Database (Denmark)

Olmati, Pierluigi; Giuliani, Luisa

2013-01-01

Long span bridges are complex structural systems, often having strategic roles in the network infrastructures; consequently their susceptibility to a disproportionate response in case of local failures needs to be assessed. In particular, current regulations prescribe that the structural robustness...... should be maintained in case of an accidental hanger detachment. Local damages in bridges, which are characterized by an horizontal load transfer system, may progress along the deck or along the suspension system, as the dynamic overloading of the structural elements immediately adjacent to the failed...

Scotland's knowledge network: a progress report on Knowledge into Action.

Science.gov (United States)

Wales, Ann; Boyle, Derek

2015-11-01

Launched in 2012, Knowledge into Action is the national knowledge management strategy for the health and social care workforce in Scotland. It is transforming the role of the national digital knowledge service--NHS Education for Scotlands' Knowledge Network--and the NHSS librarian role to offer more active, tailored support for translating knowledge into frontline clinical practice. This includes the development of a national evidence search and summary service, help with converting knowledge into practical and usable formats for easy use at point of care and with using digital tools to share clinicians' learning, experience and expertise. Through this practical support, Knowledge into Action is contributing to quality and safety outcomes across NHS Scotland, building clinicians' capacity and capability in applying knowledge in frontline practice and service improvement. © The Author(s) 2015.

Stochastic Boolean networks: An efficient approach to modeling gene regulatory networks

Directory of Open Access Journals (Sweden)

Liang Jinghang

2012-08-01

Full Text Available Abstract Background Various computational models have been of interest due to their use in the modelling of gene regulatory networks (GRNs. As a logical model, probabilistic Boolean networks (PBNs consider molecular and genetic noise, so the study of PBNs provides significant insights into the understanding of the dynamics of GRNs. This will ultimately lead to advances in developing therapeutic methods that intervene in the process of disease development and progression. The applications of PBNs, however, are hindered by the complexities involved in the computation of the state transition matrix and the steady-state distribution of a PBN. For a PBN with n genes and N Boolean networks, the complexity to compute the state transition matrix is O(nN22n or O(nN2n for a sparse matrix. Results This paper presents a novel implementation of PBNs based on the notions of stochastic logic and stochastic computation. This stochastic implementation of a PBN is referred to as a stochastic Boolean network (SBN. An SBN provides an accurate and efficient simulation of a PBN without and with random gene perturbation. The state transition matrix is computed in an SBN with a complexity of O(nL2n, where L is a factor related to the stochastic sequence length. Since the minimum sequence length required for obtaining an evaluation accuracy approximately increases in a polynomial order with the number of genes, n, and the number of Boolean networks, N, usually increases exponentially with n, L is typically smaller than N, especially in a network with a large number of genes. Hence, the computational efficiency of an SBN is primarily limited by the number of genes, but not directly by the total possible number of Boolean networks. Furthermore, a time-frame expanded SBN enables an efficient analysis of the steady-state distribution of a PBN. These findings are supported by the simulation results of a simplified p53 network, several randomly generated networks and a

Optical Access Networks

Science.gov (United States)

Zheng, Jun; Ansari, Nirwan

2005-01-01

have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or are now underway this hot area. The purpose of this feature issue is to expose the networking community to the latest research breakthroughs and progresses in the area of optical access networks. Scope of Contributions This feature issue aims to present a collection of papers that focus on the state-of-the-art research in various networking aspects of optical access networks. Original papers are solicited from all researchers involved in area of optical access networks. Topics of interest include but not limited to: Optical access network architectures and protocols Passive optical networks (BPON, EPON, GPON, etc.) Active optical networks Multiple access control Multiservices and QoS provisioning Network survivability Field trials and standards Performance modeling and analysis Manuscript Submission To submit to this special issue, follow the normal procedure for submission to JON, indicating ``Optical Access Networks feature' in the ``Comments' field of the online submission form. For all other questions relating to this feature issue, please send an e-mail to jon@osa.org, subject line ``Optical Access Networks' Additional information can be found on the JON website: http://www.osa-jon.org/submission/. Submission Deadline: 1 June 2005

Habenula and interpeduncular nucleus differentially modulate predator odor-induced innate fear behavior in rats.

Science.gov (United States)

Vincenz, Daniel; Wernecke, Kerstin E A; Fendt, Markus; Goldschmidt, Jürgen

2017-08-14

Fear is an important behavioral system helping humans and animals to survive potentially dangerous situations. Fear can be innate or learned. Whereas the neural circuits underlying learned fear are already well investigated, the knowledge about the circuits mediating innate fear is still limited. We here used a novel, unbiased approach to image in vivo the spatial patterns of neural activity in odor-induced innate fear behavior in rats. We intravenously injected awake unrestrained rats with a 99m-technetium labeled blood flow tracer (99mTc-HMPAO) during ongoing exposure to fox urine or water as control, and mapped the brain distribution of the trapped tracer using single-photon emission computed tomography (SPECT). Upon fox urine exposure blood flow increased in a number of brain regions previously associated with odor-induced innate fear such as the amygdala, ventromedial hypothalamus and dorsolateral periaqueductal grey, but, unexpectedly, decreased at higher significance levels in the interpeduncular nucleus (IPN). Significant flow changes were found in regions monosynaptically connected to the IPN. Flow decreased in the dorsal tegmentum and entorhinal cortex. Flow increased in the habenula (Hb) and correlated with odor effects on behavioral defensive strategy. Hb lesions reduced avoidance of but increased approach to the fox urine while IPN lesions only reduced avoidance behavior without approach behavior. Our study identifies a new component, the IPN, of the neural circuit mediating odor-induced innate fear behavior in mammals and suggests that the evolutionarily conserved Hb-IPN system, which has recently been implicated in cued fear, also forms an integral part of the innate fear circuitry. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Simulated, Emulated, and Physical Investigative Analysis (SEPIA) of networked systems.

Energy Technology Data Exchange (ETDEWEB)

Burton, David P.; Van Leeuwen, Brian P.; McDonald, Michael James; Onunkwo, Uzoma A.; Tarman, Thomas David; Urias, Vincent E.

2009-09-01

This report describes recent progress made in developing and utilizing hybrid Simulated, Emulated, and Physical Investigative Analysis (SEPIA) environments. Many organizations require advanced tools to analyze their information system's security, reliability, and resilience against cyber attack. Today's security analysis utilize real systems such as computers, network routers and other network equipment, computer emulations (e.g., virtual machines) and simulation models separately to analyze interplay between threats and safeguards. In contrast, this work developed new methods to combine these three approaches to provide integrated hybrid SEPIA environments. Our SEPIA environments enable an analyst to rapidly configure hybrid environments to pass network traffic and perform, from the outside, like real networks. This provides higher fidelity representations of key network nodes while still leveraging the scalability and cost advantages of simulation tools. The result is to rapidly produce large yet relatively low-cost multi-fidelity SEPIA networks of computers and routers that let analysts quickly investigate threats and test protection approaches.

Institute of Nuclear Physics of Orsay - IPNO. Activity report 2000-2001

International Nuclear Information System (INIS)

2002-01-01

The Institute of Nuclear Physics of Orsay (IPN Orsay) is undertaking nuclear physics research that is centered on the nature of matter and its ultimate constituents. By the nature of its scientific activities, the IPN is at the heart of a wide range of international collaborations. IPN Orsay is a unit of both the CNRS (National Centre of Scientific Research) and of the Paris-Sud University. It plays a vital role in experiments being carried out by wide-ranging collaborations at major experimental facilities most notably in Europe, the United States and Japan. Its own facilities allows the IPN to carry out fundamental theoretical and experimental research studies in nuclear physics, astro-particle physics, radiochemistry but also in pluri-disciplinary activities. This document presents the activity of the Institute during the 2000-2001 years: 1 - Scientific activities: exotic and hot nuclei; nucleon sub-structure; Mesons, Quarks and Gluons; Astro-particles; Theoretical physics (nuclear structure and reactions - N-body systems, fields theory applied to particle physics and to condensed matter physics); Radiochemistry; Physics of Downstream Cycle and Spallation Reactions; Particle Matter Interactions; Physics-Biology-Medicine Interfaces in Neurobiology, Oncology and Genomic; Science, Education, History and Society; 2 - Technical activities: General and technical departments; Detectors and associated instrumentation; Accelerators; Scientific and technical activities

Research on Influence of Cloud Environment on Traditional Network Security

Science.gov (United States)

Ming, Xiaobo; Guo, Jinhua

2018-02-01

Cloud computing is a symbol of the progress of modern information network, cloud computing provides a lot of convenience to the Internet users, but it also brings a lot of risk to the Internet users. Second, one of the main reasons for Internet users to choose cloud computing is that the network security performance is great, it also is the cornerstone of cloud computing applications. This paper briefly explores the impact on cloud environment on traditional cybersecurity, and puts forward corresponding solutions.

Developing a network: the PMM process.

Science.gov (United States)

Kamara, A

1997-11-01

Since 1988, the Prevention of Maternal Mortality (PMM) Network has developed, implemented and evaluated projects that focus directly on prevention of maternal deaths. The Network, which consists of 11 multidisciplinary teams in West Africa and one at Columbia University, grew from discussions between the Carnegie Corporation of New York and researchers at Columbia School of Public Health. Its goals are: to strengthen capacities in developing countries; to provide program models for preventing maternal deaths; and to inform policymakers about the importance of maternal mortality. This paper describes the development and functioning of the Network. The initial steps included identifying interested partners in Africa and encouraging them to form multidisciplinary teams. Each African team received two grants: one to perform a needs assessment and then another to develop and implement projects based on the results. The Columbia team provided technical assistance in a variety of ways, including site visits, workshops and correspondence. Teams tested program models and reported findings both to local policymakers and in international fora. Collaboration with government and community leaders helped facilitate progress at all stages. At the PMM Network Results Conference in 1996, the teams decided to continue their work by forming the Regional PMM (RPMM) Network, an entirely African entity.

Effect of drug loading method against drug dissolution mechanism of encapsulated amoxicillin trihydrate in matrix of semi-IPN chitosan-poly(N-vinylpyrrolidone) hydrogel with KHCO3 as pore forming agent in floating drug delivery system

Science.gov (United States)