The anti-cancer effect of octagon and spherical silver nanoparticles on MCF-7 breast cancer cell line

Directory of Open Access Journals (Sweden)

Mehrdad Khatami

2017-04-01

Full Text Available Background: The modern science of nanotechnology is an interdisciplinary science that has contributed to advances in cancer treatment. This study was performed to evaluate the therapeutic effects of biosynthesized silver nanoparticles on breast cancer cell of line MCF-7 in vitro. Methods: This analytical study was performed in Kerman and Bam University of Medical Sciences, Bam City, Kerman Province, Iran from March 2015 to March 2016. Silver nanoparticles suspension was synthesized using palm kernel extract. The resulting silver nanoparticles were studied and characterized. The ultraviolet-visible spectroscopy and transmission electron microscopy used for screening of physicochemical properties. The average particle size of the biosynthesized silver nanoparticles was determined by transmission electron microscopy. The properties of different concentrations of synthesized silver nanoparticles (1 to 3 μg/ml and palm kernel extract (containing the same concentration of the extract was used for the synthesis of silver nanoparticles against MCF-7 human breast cancer cells were determined by MTT assay. MTT is used to assess cell viability as a function of redox potential. Actively respiring cells convert the water-soluble MTT to an insoluble purple formazan. Results: The ultraviolet-visible spectroscopy showed strong absorption peak at 429 nm. The X-ray diffraction (XRD and transmission electron microscopy (TEM images revealed the formation of silver nanoparticles with spherical and octagon shape and sizes in the range between 1-40 nm, with an average size approximately 17 nm. The anti-cancer effect of silver nanoparticles on cell viability was strongly depends on the concentration of silver nanoparticles and greatly decrease with increasing the concentration of silver nanoparticles. The IC50 amount of silver nanoparticle was 2 μg/ml. Conclusion: The biosynthesized silver nanoparticles showed a dose-dependent toxicity against MCF-7 human breast

Timescale of silver nanoparticle transformation in neural cell cultures impacts measured cell response

International Nuclear Information System (INIS)

Hume, Stephanie L.; Chiaramonti, Ann N.; Rice, Katherine P.; Schwindt, Rani K.; MacCuspie, Robert I.; Jeerage, Kavita M.

2015-01-01

Both serum protein concentration and ionic strength are important factors in nanoparticle transformation within cell culture environments. However, silver nanoparticles are not routinely tracked at their working concentration in the specific medium used for in vitro toxicology studies. Here we evaluated the transformation of electrostatically stabilized citrate nanoparticles (C-AgNPs) and sterically stabilized polyvinylpyrrolidone nanoparticles (PVP-AgNPs) in a low-serum (∼ 0.2 mg/mL bovine serum albumin) culture medium, while measuring the response of rat cortex neural progenitor cells, which differentiate in this culture environment. After 24 h, silver nanoparticles at concentrations up to 10 µg/mL did not affect adenosine triphosphate levels, whereas silver ions decreased adenosine triphosphate levels at concentrations of 1.1 µg/mL or higher. After 240 h, both silver nanoparticles, as well as silver ion, unambiguously decreased adenosine triphosphate levels at concentrations of 1 and 1.1 µg/mL, respectively, suggesting particle dissolution. Particle transformation was investigated in 1:10 diluted, 1:2 diluted, or undiluted differentiation medium, all having an identical protein concentration, to separate the effect of serum protein stabilization from ionic strength destabilization. Transmission electron microscopy images indicated that particles in 1:10 medium were not surrounded by proteins, whereas particles became clustered within a non-crystalline protein matrix after 24 h in 1:2 medium and at 0 h in undiluted medium. Despite evidence for a protein corona, particles were rapidly destabilized by high ionic strength media. Polyvinylpyrrolidone increased the stability of singly dispersed particles compared to citrate ligands; however, differences were negligible after 4 h in 1:2 medium or after 1 h in undiluted medium. Thus low-serum culture environments do not provide sufficient colloidal stability for long-term toxicology studies with citrate

Timescale of silver nanoparticle transformation in neural cell cultures impacts measured cell response

Energy Technology Data Exchange (ETDEWEB)

Hume, Stephanie L.; Chiaramonti, Ann N.; Rice, Katherine P.; Schwindt, Rani K. [National Institute of Standards and Technology (NIST), Applied Chemicals and Materials Division (United States); MacCuspie, Robert I. [National Institute of Standards and Technology (NIST), Materials Measurement Science Division (United States); Jeerage, Kavita M., E-mail: jeerage@boulder.nist.gov [National Institute of Standards and Technology (NIST), Applied Chemicals and Materials Division (United States)

2015-07-15

Both serum protein concentration and ionic strength are important factors in nanoparticle transformation within cell culture environments. However, silver nanoparticles are not routinely tracked at their working concentration in the specific medium used for in vitro toxicology studies. Here we evaluated the transformation of electrostatically stabilized citrate nanoparticles (C-AgNPs) and sterically stabilized polyvinylpyrrolidone nanoparticles (PVP-AgNPs) in a low-serum (∼ 0.2 mg/mL bovine serum albumin) culture medium, while measuring the response of rat cortex neural progenitor cells, which differentiate in this culture environment. After 24 h, silver nanoparticles at concentrations up to 10 µg/mL did not affect adenosine triphosphate levels, whereas silver ions decreased adenosine triphosphate levels at concentrations of 1.1 µg/mL or higher. After 240 h, both silver nanoparticles, as well as silver ion, unambiguously decreased adenosine triphosphate levels at concentrations of 1 and 1.1 µg/mL, respectively, suggesting particle dissolution. Particle transformation was investigated in 1:10 diluted, 1:2 diluted, or undiluted differentiation medium, all having an identical protein concentration, to separate the effect of serum protein stabilization from ionic strength destabilization. Transmission electron microscopy images indicated that particles in 1:10 medium were not surrounded by proteins, whereas particles became clustered within a non-crystalline protein matrix after 24 h in 1:2 medium and at 0 h in undiluted medium. Despite evidence for a protein corona, particles were rapidly destabilized by high ionic strength media. Polyvinylpyrrolidone increased the stability of singly dispersed particles compared to citrate ligands; however, differences were negligible after 4 h in 1:2 medium or after 1 h in undiluted medium. Thus low-serum culture environments do not provide sufficient colloidal stability for long-term toxicology studies with citrate

Preparation of spherical silver particles for solar cell electronic paste with gelatin protection

International Nuclear Information System (INIS)

Ao Yiwei; Yang Yunxia; Yuan Shuanglong; Ding Lihua; Chen Guorong

2007-01-01

Spherical silver particles used in electronic paste for solar cell were prepared using the chemical reduction method with ammonia as a complex agent, hydrazine hydrate as a reducing agent, and gelatin as a protective agent. The gelatin protective mechanism in the preparing process of spherical silver particles was studied. Observations of SEM and results of laser particle size analysis and ultraviolet absorption spectra demonstrate the formation of the coordinative complex of silver ions with gelatin in aqueous solution which accelerated the reduction of silver ions. Moreover, gelatin can promote the nucleation of the metallic silver particles, thus beneficiating availability of the monodisperse spherical silver particles

Detection and characterization of silver nanoparticles and dissolved species of silver in culture medium and cells by AsFlFFF-UV-Vis-ICPMS: application to nanotoxicity tests.

Science.gov (United States)

Bolea, E; Jiménez-Lamana, J; Laborda, F; Abad-Álvaro, I; Bladé, C; Arola, L; Castillo, J R

2014-03-07

A methodology based on Asymmetric Flow Field-Flow Fractionation (AsFlFFF) coupled with UV-Vis absorption spectrometry and ICP mass spectrometry (ICPMS) has been developed and applied to the study of silver nanoparticles (AgNPs) and dissolved species of silver in culture media and cells used in cytotoxicity tests. The effect of a nano-silver based product (protein stabilized silver nanoparticles ca. 15 nm average diameter) on human hepatoma (HepG2) cell viability has been studied. UV-Vis absorption spectrometry provided information about the nature (organic vs. nanoparticle) of the eluted species, whereas the silver was monitored by ICPMS. A shift towards larger hydrodynamic diameters was observed in the AgNPs after a 24 hour incubation period in the culture medium, which suggests a "protein corona" effect. Silver(I) associated with proteins present in the culture medium has also been detected, as a consequence of the oxidation process experimented by the AgNPs. However, the Ag(I) released into the culture medium did not justify the toxicity levels observed. AgNPs associated with the cultured HepG2 cells were also identified by AsFlFFF, after applying a solubilisation process based on the use of tetramethylammonium hydroxide (TMAH) and Triton X-100. These results have been confirmed by transmission electronic microscopy (TEM) analysis of the fractions collected from the AsFlFFF. The effect of AgNPs on HepG2 cells has been compared to that caused by silver(I) as AgNO3 under the same conditions. The determination of the total content of silver in the cells confirms that a much larger mass of silver as AgNPs with respect to AgNO3 (16 to 1) is needed to observe a similar toxicity.

Use of a silver ion selective electrode to assess mechanisms responsible for biological effects of silver nanoparticles

International Nuclear Information System (INIS)

Koch, Marcus; Kiefer, Silke; Cavelius, Christian; Kraegeloh, Annette

2012-01-01

For a detailed analysis of the biological effects of silver nanoparticles, discrimination between effects related to the nano-scale size of the particles and effects of released silver ions is required. Silver ions are either present in the initial particle dispersion or released by the nanoparticles over time. The aim of this study is to monitor the free silver ion activity {Ag + } in the presence of silver nanoparticles using a silver ion selective electrode. Therefore, silver in the form of silver nanoparticles, 4.2 ± 1.4 nm and 2–30 nm in size, or silver nitrate was added to cell culture media in the absence or presence of A549 cells as a model for human type II alveolar epithelial cells. The free silver ion activity measured after the addition of silver nanoparticles was determined by the initial ionic silver content. The p {Ag + } values indicated that the cell culture media decrease the free silver ion activity due to binding of silver ions by constituents of the media. In the presence of A549 cells, the free silver ion activity was further reduced. The morphology of A549 cells, cultivated in DME medium containing 9.1% (v/v) FBS, was affected by adding AgNO 3 at concentrations of ≥30 μM after 24 h. In comparison, silver nanoparticles up to a concentration of 200 μM Ag did not affect cellular morphology. Our experiments indicate that the effect of silver nanoparticles is mainly mediated by silver ions. An effect of silver on cellular morphology was observed at p {Ag + } ≤ 9.2.

Electrical pulse – mediated enhanced delivery of silver nanoparticles into living suspension cells for surface enhanced Raman spectroscopy

International Nuclear Information System (INIS)

Lin, J; Li, B; Feng, S; Chen, G; Li, Y; Huang, Z; Chen, R; Yu, Y; Huang, H; Lin, S; Li, C; Su, Y; Zeng, H

2012-01-01

Electrical pulse-mediated enhanced silver nanoparticles delivery is a much better method for intracellular surface-enhanced Raman spectroscopy (SERS) measurements of suspension cells. Robust and high-quality SERS spectra of living suspension cells were obtained based on an electroporation-SERS method, which can overcomes the shortcoming of non-uniform distribution of silver nanoparticles localized in the cell cytoplasm after electroporation and reduces the amount variance of silver nanoparticles delivered into different cells. The electroporation parameters include three 150 V (375 V/cm) electric pulses of 1, 5, and 5 ms durations respectively. Our results indicate that considerable amount of silver nanoparticles can be rapidly delivered into the human promyelocytic leukemia HL60 cells, and the satisfied SERS spectra were obtained while the viability of the treated cells was highly maintained (91.7%). The electroporation-SERS method offers great potential approach in delivering silver nanoparticles into living suspension cells, which is useful for widely biomedical applications including the real-time intracellular SERS analysis of living cells

Glucose capped silver nanoparticles induce cell cycle arrest in HeLa cells.

Science.gov (United States)

Panzarini, Elisa; Mariano, Stefania; Vergallo, Cristian; Carata, Elisabetta; Fimia, Gian Maria; Mura, Francesco; Rossi, Marco; Vergaro, Viviana; Ciccarella, Giuseppe; Corazzari, Marco; Dini, Luciana

2017-06-01

This study aims to determine the interaction (uptake and biological effects on cell viability and cell cycle progression) of glucose capped silver nanoparticles (AgNPs-G) on human epithelioid cervix carcinoma (HeLa) cells, in relation to amount, 2×10 3 or 2×10 4 NPs/cell, and exposure time, up to 48h. The spherical and well dispersed AgNPs (30±5nm) were obtained by using glucose as reducing agent in a green synthesis method that ensures to stabilize AgNPs avoiding cytotoxic soluble silver ions Ag + release. HeLa cells take up abundantly and rapidly AgNPs-G resulting toxic to cells in amount and incubation time dependent manner. HeLa cells were arrested at S and G2/M phases of the cell cycle and subG1 population increased when incubated with 2×10 4 AgNPs-G/cell. Mitotic index decreased accordingly. The dissolution experiments demonstrated that the observed effects were due only to AgNPs-G since glucose capping prevents Ag + release. The AgNPs-G influence on HeLa cells viability and cell cycle progression suggest that AgNPs-G, alone or in combination with chemotherapeutics, may be exploited for the development of novel antiproliferative treatment in cancer therapy. However, the possible influence of the cell cycle on cellular uptake of AgNPs-G and the mechanism of AgNPs entry in cells need further investigation. Copyright © 2017 Elsevier B.V. All rights reserved.

Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

Science.gov (United States)

Gorzelanny, Christian; Kmeth, Ralf; Obermeier, Andreas; Bauer, Alexander T.; Halter, Natalia; Kümpel, Katharina; Schneider, Matthias F.; Wixforth, Achim; Gollwitzer, Hans; Burgkart, Rainer; Stritzker, Bernd; Schneider, Stefan W.

2016-01-01

The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently. PMID:26955791

Silver nanoparticle induced cytotoxicity, oxidative stress, and DNA damage in CHO cells

Energy Technology Data Exchange (ETDEWEB)

Awasthi, Kumud Kant [University of Rajasthan, Department of Zoology (India); Awasthi, Anjali; Kumar, Narender; Roy, Partha [Indian Institute of Technology Roorkee, Department of Biotechnology (India); Awasthi, Kamlendra, E-mail: kamlendra.awasthi@gmail.com [Malaviya National Institute of Technology, Department of Physics (India); John, P. J., E-mail: placheriljohn@yahoo.com [University of Rajasthan, Department of Zoology (India)

2013-09-15

Silver nanoparticles (Ag NPs) are being used increasingly in wound dressings, catheters, and in various household products due to their antimicrobial activity. The present study reports the toxicity evaluation of synthesized and well characterized Ag NPs using Chinese hamster ovary (CHO) cells. The UV-Vis spectroscopy reveals the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 408-410 nm. Transmission electron microscopy (TEM) reveals that the average diameter of silver nanoparticles is about 5.0 {+-} 1.0 nm and that they have spherical shape. Cell visibility and cell viability percentage show dose-dependent cellular toxicity of Ag NPs. The half maximal inhibitory concentration (IC{sub 50}) for CHO cells is 68.0 {+-} 2.65 {mu}g/ml after 24 h Ag NPs exposure. Toxicity evaluations, including cellular morphology, mitochondrial function (MTT assay), reactive oxygen species (ROS), and DNA fragmentation assay (Ladder pattern) were assessed in unexposed CHO cells (control) and the cells exposed to Ag NPs concentrations of 15, 30, and 60 {mu}g/ml for 24 h. The findings may assist in the designing of Ag NPs for various applications and provide insights into their toxicity.

Citation Success

DEFF Research Database (Denmark)

Vaio, Gianfranco Di; Waldenström, Daniel; Weisdorf, Jacob Louis

2012-01-01

This study examines the determinants of citation success among authors who have recently published their work in economic history journals. Besides offering clues about how to improve one's scientific impact, our citation analysis also sheds light on the state of the field of economic history...... find similar patterns when assessing the same authors' citation success in economics journals. As a novel feature, we demonstrate that the diffusion of research — publication of working papers, as well as conference and workshop presentations — has a first-order positive impact on the citation rate........ Consistent with our expectations, we find that full professors, authors appointed at economics and history departments, and authors working in Anglo-Saxon and German countries are more likely to receive citations than other scholars. Long and co-authored articles are also a factor for citation success. We...

Aberration of the Citation.

Science.gov (United States)

Moustafa, Khaled

2016-01-01

Multiple inherent biases related to different citation practices (for e.g., self-citations, negative citations, wrong citations, multi-authorship-biased citations, honorary citations, circumstantial citations, discriminatory citations, selective and arbitrary citations, etc.) make citation-based bibliometrics strongly flawed and defective measures. A paper can be highly cited for a while (for e.g., under circumstantial or transitional knowledge), but years later it may appear that its findings, paradigms, or theories were untrue or invalid anymore. By contrast, a paper may remain shelved or overlooked for years or decades, but new studies or discoveries may actualize its subject at any moment. As citation-based metrics are transformed into "commercial activities," the "citation credit" should be considered on a commercial basis too, in the sense that "citation credit" should be shared out as a "citation dividend" by shareholders (coauthors) averagely or proportionally to their contributions but not fully appropriated by each of them. At equal numbers of citations, the greater number of authors, the lower "citation credit" should be and vice versa. Overlooking the presence of distorted and subjective citation practices makes many people and administrators "obsessed" with the number of citations to such an extent to run after "highly cited" authors and to create specialized citation databases for commercial purposes. Citation-based bibliometrics, however, are unreliable and unscientific measures; citation counts do not mean that a more cited work is of a higher quality or accuracy than a less cited work because citations do not measure the quality or accuracy. Citations do not mean that a highly cited author or journal is more commendable than a less cited author or journal. Citations are not more than countable numbers: no more, no less.

Inkjet-Printed Porous Silver Thin Film as a Cathode for a Low-Temperature Solid Oxide Fuel Cell.

Science.gov (United States)

Yu, Chen-Chiang; Baek, Jong Dae; Su, Chun-Hao; Fan, Liangdong; Wei, Jun; Liao, Ying-Chih; Su, Pei-Chen

2016-04-27

In this work we report a porous silver thin film cathode that was fabricated by a simple inkjet printing process for low-temperature solid oxide fuel cell applications. The electrochemical performance of the inkjet-printed silver cathode was studied at 300-450 °C and was compared with that of silver cathodes that were fabricated by the typical sputtering method. Inkjet-printed silver cathodes showed lower electrochemical impedance due to their porous structure, which facilitated oxygen gaseous diffusion and oxygen surface adsorption-dissociation reactions. A typical sputtered nanoporous silver cathode became essentially dense after the operation and showed high impedance due to a lack of oxygen supply. The results of long-term fuel cell operation show that the cell with an inkjet-printed cathode had a more stable current output for more than 45 h at 400 °C. A porous silver cathode is required for high fuel cell performance, and the simple inkjet printing technique offers an alternative method of fabrication for such a desirable porous structure with the required thermal-morphological stability.

Cycle life test. Evaluation program for secondary spacecraft cells. [performance tests on silver zinc batteries, silver cadmium batteries, and nickel cadmium batteries

Science.gov (United States)

Harkness, J. D.

1976-01-01

Considerable research is being done to find more efficient and reliable means of starting electrical energy for orbiting satellites. Rechargeable cells offer one such means. A test program is described which has been established in order to further the evaluation of certain types of cells and to obtain performance and failure data as an aid to their continued improvement. The purpose of the program is to determine the cycling performance capabilities of packs of cells under different load and temperature conditions. The various kinds of cells tested were nickel-cadmium, silver-cadmium, and silver-zinc sealed cells. A summary of the results of the life cycling program is given in this report.

Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

Science.gov (United States)

Winans, Joshua David

As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

Fabrication and electromagnetic interference shielding effectiveness of polymeric composites filled with silver-coated microorganism cells

Energy Technology Data Exchange (ETDEWEB)

Lan, Mingming, E-mail: lan_mingming@163.com [College of Mechanical and Electrical Engineering, Henan Agricultural University, Zhengzhou 450002 (China); Zhang, Deyuan; Cai, Jun; Hu, Yanyan; Yuan, Liming [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

2014-07-01

In this paper, helical silver-coated Spirulina cells were used as conductive fillers for the fabrication of polymeric composites. The morphology and composition of the coated Spirulina cells were analyzed with scanning electron microscope and energy dispersive X-ray spectrometer. The densities of silver-coated Spirulina cells were measured using the standard Archimedes method with distilled water. The electrical resistivity was measured by four-probe technique using ammeter and voltmeter whereas electromagnetic interference shielding effectiveness was measured by four-port method using vector network analyzer and coaxial-airline sample holder. The results showed that the silver-coated Spirulina cells with different coating thickness were lightweight fillers compared to the other typical conductive particles. The polymeric composites could achieve good conductivity at the lower content of silver-coated Spirulina cells owing to their helical shape. The shielding effectiveness of polymeric composites had a strong dependence on their conductivity. At the coating thickness of 0.96 μm and the content of 40 vol%, the shielding effectiveness could reach above 74.3 dB in entire test wave band.

The disastrous boomerang effects of "citation mania".

Science.gov (United States)

Perbal, Annick

2017-09-01

The recent publication of a commentary article by Dadkhah et al. (J Cell Commun Signal 11:181-185, 2017) which addressed issues raised by the citation of questionable scientific papers in current databases and the recent retraction of manuscripts dealing with the biological properties of the CCN1 protein by Lin et al. (J Biol Chem 291(53):27433, 2016) prompted us to examine how this situation reflects an evolution of the original citation system, endangering scientific communication. We argue that the increasing number of publication retractions that have been witnessed over several years is a direct consequence of the bias created by the inconsistency of citation metrics.

Effect of media composition on bioavailability and toxicity of silver and silver nanoparticles in fish intestinal cells (RTgutGC).

Science.gov (United States)

Minghetti, Matteo; Schirmer, Kristin

2016-12-01

To understand conditions affecting bioavailability and toxicity of citrate-coated silver nanoparticles (cit-AgNP) and dissolved silver at the luminal enterocyte interface, we exposed rainbow trout (Oncorhynchus mykiss) gut cells (RTgutGC) in media of contrasting composition: two amino acid-containing media, one of which was supplemented with proteins, as can be expected during digestion; and two protein and amino acid-free media contrasting low and high chloride content, as can be expected in the lumen of fish adapting to freshwater or seawater, respectively. Dose-response curves were generated measuring cell metabolic activity, membrane and lysosome integrity over a period of 72 hours. Then, nontoxic doses were applied and total silver accumulation, metallothionein and glutathione reductase mRNA levels were determined. The presence of proteins stabilized cit-AgNP keeping them in suspension. Conversely, in protein-free media, cit-AgNP agglomerated and settled, resulting in higher cellular accumulation of silver and toxicity. Chloride concentrations in exposure media modulated the toxicity of AgNO 3 but not of cit-AgNP. Moreover, while amino acid-containing media are protective against AgNO 3 , likely due to the formation of thiolate complexes, they are only partially protective against cit-AgNP. Viability assays indicated that lysosomes are targets of cit-AgNP, supporting the hypothesis that cit-AgNP exert toxicity intracellularly. Metallothionein, a sensor of metal bioavailability, was induced by cit-AgNP in high chloride medium but not in low chloride medium, indicating that chloride might have a role in mobilizing silver from intercellular vesicles. Overall, this study shows that AgNP bioavailability and toxicity in the intestine is linked to its luminal content.

Bibliometrics and citation analysis from the science citation index to cybermetrics

CERN Document Server

De Bellis, Nicola

2009-01-01

Bibliometrics and Citation Analysis: From the Science Citation Index to Cybermetrics offers a comprehensive overview of theories, techniques, concepts, and applications in the interdisciplinary and steadily growing field of bibliometrics. This book looks at bibliographic citation and citation networks by discussing the past, present, and future of bibliometrics, from its foundations in the Science Citation Index to its expansion into the World Wide Web. It is useful to those in every area of scholarship involved in the quantitative analysis of information exchanges, but also to general readers

Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

International Nuclear Information System (INIS)

Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R; Kolar, M

2011-01-01

The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

Antibacterial activity and toxicity of silver - nanosilver versus ionic silver

Energy Technology Data Exchange (ETDEWEB)

Kvitek, L; Panacek, A; Prucek, R; Soukupova, J; Vanickova, M; Zboril, R [Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University, 17. Listopadu 12, 77146 Olomouc (Czech Republic); Kolar, M, E-mail: ales.panacek@upol.cz [Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University, Hnevotinska 3, 77520 Olomouc (Czech Republic)

2011-07-06

The in vitro study of antibacterial activity of silver nanoparticles (NPs), prepared via modified Tollens process, revealed high antibacterial activity even at very low concentrations around several units of mg/L. These concentrations are comparable with concentrations of ionic silver revealing same antibacterial effect. However, such low concentrations of silver NPs did not show acute cytotoxicity to mammalian cells - this occurs at concentrations higher than 60 mg/L of silver, while the cytotoxic level of ionic silver is much more lower (approx. 1 mg/L). Moreover, the silver NPs exhibit lower acute ecotoxicity against the eukaryotic organisms such as Paramecium caudatum, Monoraphidium sp. and D. melanogaster. The silver NPs are toxic to these organisms at the concentrations higher than 30 mg/L of silver. On contrary, ionic silver retains its cytoxicity and ecotoxicity even at the concentration equal to 1 mg/L. The performed experiments demonstrate significantly lower toxicity of silver NPs against the eukaryotic organisms than against the prokaryotic organisms.

Large silver-cadmium technology program

Science.gov (United States)

Charlip, S.; Lerner, S.

1971-01-01

The effects of varying cell design on operation factors on the electrochemical performance of sealed, silver-cadmium cells were determined. A factorial experiment was conducted for all test cells constructed with organic separators. Three operating factors were evaluated: temperature, depth of discharge, and charge rate. The six construction factors considered were separator, absorber, electrolyte quantity, cadmium electrode type, cadmium-to-silver ratio, and auxiliary electrode. Test cells of 4 ampere-hour capacity were fabricated and cycled. The best performing cells, on a 94 minute orbit, at 40% depth of discharge, were those containing silver-treated fibrous sausage casings as the separator, and Teflon-ated, pressed cadmium electrodes. Cycling data of cells with inorganic separators (Astroset) are given. Best performance was shown by cells with nonwoven nylon absorbers. Rigid inorganic separators provided the best barrier to silver migration.

CITOPP, CITMOD, CITWI, Processing codes for CITATION Code

International Nuclear Information System (INIS)

Albarhoum, M.

2008-01-01

Description of program or function: CITOPP processes the output file of the CITATION 3-D diffusion code. The program can plot axial, radial and circumferential flux distributions (in cylindrical geometry) in addition to the multiplication factor convergence. The flux distributions can be drawn for each group specified by the program and visualized on the screen. CITMOD processes both the output and the input files of the CITATION 3-D diffusion code. CITMOD can visualize both axial, and radial-angular models of the reactor described by CITATION input/output files. CITWI processes the input file (CIT.INP) of CITATION 3-D diffusion code. CIT.INP is processed to deduce the dimensions of the cell whose cross sections can be representative of the homonym reactor component in section 008 of CIT.INP

Collagen-based silver nanoparticles: Study on cell viability, skin permeation, and swelling inhibition

International Nuclear Information System (INIS)

Saura Cardoso, Vinicius; Carvalho Filgueiras, Marcelo de; Medeiros Dutra, Yago; Gomes Teles, Ramon Handerson; Rodrigues de Araújo, Alyne; Primo, Fernando Lucas; Mafud, Ana Carolina; Batista, Larissa Fernandes; Mascarenhas, Yvonne Primerano

2017-01-01

Collagen is considered the most abundant protein in the animal kingdom, comprising 30% of the total amount of proteins and 6% of the human body by weight. Studies that examine the interaction between silver nanoparticles and proteins have been highlighted in the literature in order to understand the stability of the nanoparticle system, the effects observed in biological systems, and the appearance of new chemical pharmaceutical products. The objective of this study was to analyze the behavior of silver nanoparticles stabilized with collagen (AgNPcol) and to check the skin permeation capacity and action in paw edema induced by carrageenan. AgNPcol synthesis was carried out using solutions of reducing agent sodium borohydride (NaBH 4 ), silver nitrate (AgNO 3 ) and collagen. Characterization was done by using dynamic light scattering (DLS) and X-ray diffraction (XRD) and AFM. Cellular viability testing was performed by using flow cytometry in human melanoma cancer (MV3) and murine fibroblast (L929) cells. The skin permeation study was conducted using a Franz diffusion cell, and the efficiency of AgNPcol against the formation of paw edema in mice was evaluated. The hydrodynamic diameter and zeta potential of AgNPcol were 140.7 ± 7.8 nm and 20.1 ± 0.7 mV, respectively. AgNPcol failed to induce early apoptosis, late apoptosis, and necrosis in L929 cells; however, it exhibited enhanced toxicity in cancer cells (MV3) compared to normal cells (L929). AgNPcol demonstrated increased toxicological effects in cancer MV3 cells, promoting skin permeation, and preventing paw edema. - Highlights: • Silver nanoparticles were synthesized with type I collagen (AgNPcol). • AgNPcol which was characterized by XRD and DLS. • AgNPcol exhibited enhanced toxicity in cancer cells. • The efficiency of the AgNPcol against the paw edema was evaluated.

Collagen-based silver nanoparticles: Study on cell viability, skin permeation, and swelling inhibition

Energy Technology Data Exchange (ETDEWEB)

Saura Cardoso, Vinicius, E-mail: vscfisio@ufpi.edu.br [Research Center in Biodiversity and Biotechnology, Biotec, Campus Ministro Reis Velloso, Federal University of Piauí, UFPI, 64202020 Parnaíba, Piauí (Brazil); Physiotherapy Department, Campus Ministro Reis Velloso, Federal University of Piauí, UFPI, 64202020 Parnaíba, Piauí (Brazil); Carvalho Filgueiras, Marcelo de; Medeiros Dutra, Yago; Gomes Teles, Ramon Handerson [Physiotherapy Department, Campus Ministro Reis Velloso, Federal University of Piauí, UFPI, 64202020 Parnaíba, Piauí (Brazil); Morphology and Muscle Physiology Laboratory, LAMFIM, Campus Ministro Reis Velloso, Federal University of Piauí, UFPI, 64202020 Parnaíba, Piauí (Brazil); Rodrigues de Araújo, Alyne [Research Center in Biodiversity and Biotechnology, Biotec, Campus Ministro Reis Velloso, Federal University of Piauí, UFPI, 64202020 Parnaíba, Piauí (Brazil); Primo, Fernando Lucas [Faculdade de Ciências Farmacêuticas, UNESP, Universidade Estadual Paulista, Campus de Araraquara, Departamento de Bioprocessos e Biotecnologia, 14800903 Araraquara, São Paulo (Brazil); Mafud, Ana Carolina; Batista, Larissa Fernandes; Mascarenhas, Yvonne Primerano [Institute of Physics of São Carlos, IFSC, University of São Paulo, USP, 13566590 São Carlos, SP (Brazil); and others

2017-05-01

Collagen is considered the most abundant protein in the animal kingdom, comprising 30% of the total amount of proteins and 6% of the human body by weight. Studies that examine the interaction between silver nanoparticles and proteins have been highlighted in the literature in order to understand the stability of the nanoparticle system, the effects observed in biological systems, and the appearance of new chemical pharmaceutical products. The objective of this study was to analyze the behavior of silver nanoparticles stabilized with collagen (AgNPcol) and to check the skin permeation capacity and action in paw edema induced by carrageenan. AgNPcol synthesis was carried out using solutions of reducing agent sodium borohydride (NaBH{sub 4}), silver nitrate (AgNO{sub 3}) and collagen. Characterization was done by using dynamic light scattering (DLS) and X-ray diffraction (XRD) and AFM. Cellular viability testing was performed by using flow cytometry in human melanoma cancer (MV3) and murine fibroblast (L929) cells. The skin permeation study was conducted using a Franz diffusion cell, and the efficiency of AgNPcol against the formation of paw edema in mice was evaluated. The hydrodynamic diameter and zeta potential of AgNPcol were 140.7 ± 7.8 nm and 20.1 ± 0.7 mV, respectively. AgNPcol failed to induce early apoptosis, late apoptosis, and necrosis in L929 cells; however, it exhibited enhanced toxicity in cancer cells (MV3) compared to normal cells (L929). AgNPcol demonstrated increased toxicological effects in cancer MV3 cells, promoting skin permeation, and preventing paw edema. - Highlights: • Silver nanoparticles were synthesized with type I collagen (AgNPcol). • AgNPcol which was characterized by XRD and DLS. • AgNPcol exhibited enhanced toxicity in cancer cells. • The efficiency of the AgNPcol against the paw edema was evaluated.

Citation networks of related trials are often disconnected: implications for bidirectional citation searches.

Science.gov (United States)

Robinson, Karen A; Dunn, Adam G; Tsafnat, Guy; Glasziou, Paul

2014-07-01

Reports of randomized controlled trials (RCTs) should set findings within the context of previous research. The resulting network of citations would also provide an alternative search method for clinicians, researchers, and systematic reviewers seeking to base decisions on all available evidence. We sought to determine the connectedness of citation networks of RCTs by examining direct (referenced trials) and indirect (through references of referenced trials, etc) citation of trials to one another. Meta-analyses were used to create citation networks of RCTs addressing the same clinical questions. The primary measure was the proportion of networks where following citation links between RCTs identifies the complete set of RCTs, forming a single connected citation group. Other measures included the number of disconnected groups (islands) within each network, the number of citations in the network relative to the maximum possible, and the maximum number of links in the path between two connected trials (a measure of indirectness of citations). We included 259 meta-analyses with a total of 2,413 and a median of seven RCTs each. For 46% (118 of 259) of networks, the RCTs formed a single connected citation group-one island. For the other 54% of networks, where at least one RCT group was not cited by others, 39% had two citation islands and 4% (10 of 257) had 10 or more islands. On average, the citation networks had 38% of the possible citations to other trials (if each trial had cited all earlier trials). The number of citation islands and the maximum number of citation links increased with increasing numbers of trials in the network. Available evidence to answer a clinical question may be identified by using network citations created with a small initial corpus of eligible trials. However, the number of islands means that citation networks cannot be relied on for evidence retrieval. Copyright © 2014 Elsevier Inc. All rights reserved.

Predicted energy densitites for nickel-hydrogen and silver-hydrogen cells embodying metallic hydrides for hydrogen storage

Science.gov (United States)

Easter, R. W.

1974-01-01

Simplified design concepts were used to estimate gravimetric and volumetric energy densities for metal hydrogen battery cells for assessing the characteristics of cells containing metal hydrides as compared to gaseous storage cells, and for comparing nickel cathode and silver cathode systems. The silver cathode was found to yield superior energy densities in all cases considered. The inclusion of hydride forming materials yields cells with very high volumetric energy densities that also retain gravimetric energy densities nearly as high as those of gaseous storage cells.

Citations Prize 2009 Citations Prize 2009

Science.gov (United States)

Webb, Steve; Harris, Simon

2009-12-01

Physics in Medicine & Biology (PMB) awards its 'Citations Prize' to the authors of the original research paper that has received the most citations in the preceding five years (according to the Institute for Scientific Information (ISI)). The lead author of the winning paper is presented with the Rotblat Medal (named in honour of Professor Sir Joseph Rotblat who was the second—and longest serving—Editor of PMB, from 1961-1972). The winning co-authors each receive a certificate. Photograph of the 2009 Citations Prize winners Some of the winning authors with their certificates, and Christian Morel with the Rotblat Medal, at the award ceremony in Orsay, near Paris. From left to right are Corinne Groiselle, Lydia Maigne, David Brasse, Irène Buvat, Dimitris Visvikis, Giovanni Santin, Uwe Pietrzyk, Pierre-François Honore, Christian Morel, Sébastien Jan and Arion Chatziioannou. The winner of the 2009 Citations Prize for the paper which has received the most citations in the previous 5 years (2004-2008) is GATE: a simulation toolkit for PET and SPECT Authors: S Jan, G Santin, D Strul, S Staelens, K Assié, D Autret, S Avner, R Barbier, M Bardiès, P M Bloomfield, D Brasse, V Breton, P Bruyndonckx, I Buvat, A F Chatziioannou, Y Choi, Y H Chung, C Comtat, D Donnarieix, L Ferrer, S J Glick, C J Groiselle, D Guez, P-F Honore, S Kerhoas-Cavata, A S Kirov, V Kohli, M Koole, M Krieguer, D J van der Laan, F Lamare, G Largeron, C Lartizien, D Lazaro, M C Maas, L Maigne, F Mayet, F Melot, C Merheb, E Pennacchio, J Perez, U Pietrzyk, F R Rannou, M Rey, D R Schaart, C R Schmidtlein, L~Simon, T Y Song, J-M Vieira, D Visvikis, R Van de Walle, E Wieörs and C Morel Reference: S Jan et al 2004 Phys. Med. Biol. 49 4543-61 Since its publication in 2004 this article has received over 200 citations. This extremely high figure is a testament to the great influence and usefulness of the work to the nuclear medicine community. More discussion of the winning paper can be found on

Encouraging data citation and discovery with the Data Citation Index.

Science.gov (United States)

Force, Megan M; Robinson, Nigel J

2014-10-01

An overview of the Data Citation Index is provided. Thomson Reuters developed this resource in response to a stated desire among members of the research community for increased attribution of non-traditional scholarly output. Launched in October of 2012 on the Web of science research platform, its aims include linking published research articles to their underlying data sets and tracking the citation of the data, as well as encouraging bibliographic citation of data. Cross-disciplinary search capabilities in the Index enable new possibilities for data discovery and synthesis. Data repositories are evaluated with respect to various selection criteria, with particular attention to their relevance to scientific and scholarly research. Index content reflects current data deposition practices. As data citation standards and practices continue to move toward widespread formalization and adoption, the initiative seeks to address issues of data citation, reuse, and author credit in a developing climate.

Enhancing Light-Trapping Properties of Amorphous Si Thin-Film Solar Cells Containing High-Reflective Silver Conductors Fabricated Using a Nonvacuum Process

Directory of Open Access Journals (Sweden)

Jun-Chin Liu

2014-01-01

Full Text Available We proposed a low-cost and highly reflective liquid organic sheet silver conductor using back contact reflectors in amorphous silicon (a-Si single junction superstrate configuration thin-film solar cells produced using a nonvacuum screen printing process. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (Jsc of sheet silver conductor cells was higher than 1.25 mA/cm2. Using external quantum efficiency measurements, the sheet silver conductor using back contact reflectors in cells was observed to effectively enhance the light-trapping ability in a long wavelength region (between 600 nm and 800 nm. Consequently, we achieved an optimal initial active area efficiency and module conversion efficiency of 9.02% and 6.55%, respectively, for the a-Si solar cells. The results indicated that the highly reflective sheet silver conductor back contact reflector layer prepared using a nonvacuum process is a suitable candidate for high-performance a-Si thin-film solar cells.

Silver Nanoparticles Induce HePG-2 Cells Apoptosis Through ROS-Mediated Signaling Pathways

Science.gov (United States)

Zhu, Bing; Li, Yinghua; Lin, Zhengfang; Zhao, Mingqi; Xu, Tiantian; Wang, Changbing; Deng, Ning

2016-04-01

Recently, silver nanoparticles (AgNPs) have been shown to provide a novel approach to overcome tumors, especially those of hepatocarcinoma. However, the anticancer mechanism of silver nanoparticles is unclear. Thus, the purpose of this study was to estimate the effect of AgNPs on proliferation and activation of ROS-mediated signaling pathway on human hepatocellular carcinoma HePG-2 cells. A simple chemical method for preparing AgNPs with superior anticancer activity has been showed in this study. AgNPs were detected by transmission electronic microscopy (TEM) and energy dispersive X-ray (EDX). The size distribution and zeta potential of silver nanoparticles were detected by Zetasizer Nano. The average size of AgNPs (2 nm) observably increased the cellular uptake by endocytosis. AgNPs markedly inhibited the proliferation of HePG-2 cells through induction of apoptosis with caspase-3 activation and PARP cleavage. AgNPs with dose-dependent manner significantly increased the apoptotic cell population (sub-G1). Furthermore, AgNP-induced apoptosis was found dependent on the overproduction of reactive oxygen species (ROS) and affecting of MAPKs and AKT signaling and DNA damage-mediated p53 phosphorylation to advance HePG-2 cells apoptosis. Therefore, our results show that the mechanism of ROS-mediated signaling pathways may provide useful information in AgNP-induced HePG-2 cell apoptosis.

Citation Success

DEFF Research Database (Denmark)

Di Vaio, Gianfranco; Waldenström, Daniel; Weisdorf, Jacob Louis

affects citations. In regard to author-specific characteristics, male authors, full professors and authors working economics or history departments, and authors employed in Anglo-Saxon countries, are more likely to get cited than others. As a ‘shortcut' to citation success, we find that research diffusion...

MOD silver metallization for photovoltaics

Science.gov (United States)

Vest, G. M.; Vest, R. W.

1984-01-01

The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

Biological synthesis of silver nanoparticles

International Nuclear Information System (INIS)

Maliszewska, I; Szewczyk, K; Waszak, K

2009-01-01

Fungus-mediated synthesis of silver nanoparticles is reported. The nanosilver was formed in contact with the cell-free filtrate of Penicillium strain studied. The nanoparticles were characterized by means of the UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized nanosilver showed a absorbed maximum at 425 nm in the visible region. The SEM characterization of the fungus cells treated with silver nitrite indicated that the protein might be responsible for the reduction of silver ions. Transmission electron microscopy (TEM) micrograph showed formation of silver nanoparticles in the range of 10-100 nm.

The measurement of the effect on citation inequality of differences in citation practices across scientific fields.

Science.gov (United States)

Crespo, Juan A; Li, Yunrong; Li, Yungrong; Ruiz-Castillo, Javier

2013-01-01

This paper has two aims: (i) to introduce a novel method for measuring which part of overall citation inequality can be attributed to differences in citation practices across scientific fields, and (ii) to implement an empirical strategy for making meaningful comparisons between the number of citations received by articles in 22 broad fields. The number of citations received by any article is seen as a function of the article's scientific influence, and the field to which it belongs. A key assumption is that articles in the same quantile of any field citation distribution have the same degree of citation impact in their respective field. Using a dataset of 4.4 million articles published in 1998-2003 with a five-year citation window, we estimate that differences in citation practices between the 22 fields account for 14% of overall citation inequality. Our empirical strategy is based on the strong similarities found in the behavior of citation distributions. We obtain three main results. Firstly, we estimate a set of average-based indicators, called exchange rates, to express the citations received by any article in a large interval in terms of the citations received in a reference situation. Secondly, using our exchange rates as normalization factors of the raw citation data reduces the effect of differences in citation practices to, approximately, 2% of overall citation inequality in the normalized citation distributions. Thirdly, we provide an empirical explanation of why the usual normalization procedure based on the fields' mean citation rates is found to be equally successful.

A generalized view of self-citation: direct, co-author, collaborative, and coercive induced self-citation.

Science.gov (United States)

Ioannidis, John P A

2015-01-01

The phenomenon of self-citation can present in many different forms, including direct, co-author, collaborative, and coercive induced self-citation. It can also pertain to the citation of single scientists, groups of scientists, journals, and institutions. This article presents some case studies of extreme self-citation practices. It also discusses the implications of different types of self-citation. Self-citation is not necessarily inappropriate by default. In fact, usually it is fully appropriate but often it is even necessary. Conversely, inappropriate self-citation practices may be highly misleading and may distort the scientific literature. Coercive induced self-citation is the most difficult to discover. Coercive Induced self-citation may happen directly from reviewers of articles, but also indirectly from reviewers of grants, scientific advisors who steer a research agenda, and leaders of funding agencies who may espouse spending disproportionately large funds in research domains that perpetuate their own self-legacy. Inappropriate self-citation can be only a surrogate marker of what might be much greater distortions of the scientific corpus towards conformity to specific opinions and biases. Inappropriate self-citations eventually affect also impact metrics. Different impact metrics vary in the extent to which they can be gamed through self-citation practices. Citation indices that are more gaming-proof are available and should be more widely used. We need more empirical studies to dissect the impact of different types of inappropriate self-citation and to examine the effectiveness of interventions to limit them. Copyright © 2014. Published by Elsevier Inc.

[Reference citation].

Science.gov (United States)

Brkić, Silvija

2013-01-01

Scientific and professional papers represent the information basis for scientific research and professional work. References important for the paper should be cited within the text, and listed at the end of the paper. This paper deals with different styles of reference citation. Special emphasis was placed on the Vancouver Style for reference citation in biomedical journals established by the International Committee of Medical Journal Editors. It includes original samples for citing various types of articles, both printed and electronic, as well as recommendations related to reference citation in accordance with the methodology and ethics of scientific research and guidelines for preparing manuscripts for publication.

The influence of lysosomal stability of silver nanomaterials on their toxicity to human cells.

Science.gov (United States)

Setyawati, Magdiel Inggrid; Yuan, Xun; Xie, Jianping; Leong, David Tai

2014-08-01

How silver nanomaterials (Ag NMs) could induce toxicity has been debated heatedly by many researchers. We utilized Ag nanoclusters (Ag NCs) with the same size and ligand protection but different core surface speciation. Ag(+)-rich NCs (Ag(+)-R NCs) and their counterpart, the reduced Ag(0)-rich NCs (Ag(0)-R NCs) are synthesized to represent possible dichotomous stages in silver nanomaterial degradation process. Here we show Ag(0)-R NCs induce higher cellular toxicity when compared to Ag(+)-R NCs. This cellular toxicity is brought about via the modulation of reactive oxygen species (ROS) in cells as a result of the more rapid release of Ag species from Ag(0)-R NCs and subsequent oxidation into Ag(+) in the lysosomal compartment. The weaker Ag(0)-R bond greatly potentiated the release of Ag species in the acidic and enzymatic processes within the lysosomes. Since lysosomes are absent in bacteria, increasing silver nanomaterials stability may lower toxicity in mammalian cells whilst not reducing their efficacy to fight bacteria; this redesign can result in a safer silver nanomaterial. Copyright © 2014 Elsevier Ltd. All rights reserved.

Silver, gold, and alloyed silver–gold nanoparticles: characterization and comparative cell-biologic action

International Nuclear Information System (INIS)

Mahl, Dirk; Diendorf, Jörg; Ristig, Simon; Greulich, Christina; Li Zian; Farle, Michael; Köller, Manfred; Epple, Matthias

2012-01-01

Silver, gold, and silver–gold-alloy nanoparticles were prepared by citrate reduction modified by the addition of tannin during the synthesis, leading to a reduction in particle size by a factor of three. Nanoparticles can be prepared by this easy water-based synthesis and subsequently functionalized by the addition of either tris(3-sulfonatophenyl)phosphine or poly(N-vinylpyrrolidone). The resulting nanoparticles of silver (diameter 15–25 nm), gold (5–6 nm), and silver–gold (50:50; 10–12 nm) were easily dispersable in water and also in cell culture media (RPMI + 10 % fetal calf serum), as shown by nanoparticle tracking analysis and differential centrifugal sedimentation. High-resolution transmission electron microscopy showed a polycrystalline nature of all nanoparticles. EDX on single silver–gold nanoparticles indicated that the concentration of gold is higher inside a nanoparticle. The biologic action of the nanoparticles toward human mesenchymal stem cells (hMSC) was different: Silver nanoparticles showed a significant concentration-dependent influence on the viability of hMSC. Gold nanoparticles showed only a small effect on the viability of hMSC after 7 days. Surprisingly, silver–gold nanoparticles had no significant influence on the viability of hMSC despite the silver content. Silver nanoparticles and silver–gold nanoparticles in the concentration range of 5–20 μg mL −1 induced the activation of hMSC as indicated by the release of IL-8. In contrast, gold nanoparticles led to a reduction of the release of IL-6 and IL-8.

Sharing data increases citations

DEFF Research Database (Denmark)

Drachen, Thea Marie; Ellegaard, Ole; Larsen, Asger Væring

2016-01-01

This paper presents some indications to the existence of a citation advantage related to sharing data using astrophysics as a case. Through bibliometric analyses we find a citation advantage for astrophysical papers in core journals. The advantage arises as indexed papers are associated with data...... by bibliographical links, and consists of papers receiving on average significantly more citations per paper per year, than do papers not associated with links to data.......This paper presents some indications to the existence of a citation advantage related to sharing data using astrophysics as a case. Through bibliometric analyses we find a citation advantage for astrophysical papers in core journals. The advantage arises as indexed papers are associated with data...

High Photon-to-Current Conversion in Solar Cells Based on Light-Absorbing Silver Bismuth Iodide.

Science.gov (United States)

Zhu, Huimin; Pan, Mingao; Johansson, Malin B; Johansson, Erik M J

2017-06-22

Here, a lead-free silver bismuth iodide (AgI/BiI 3 ) with a crystal structure with space group R3‾ m is investigated for use in solar cells. Devices based on the silver bismuth iodide deposited from solution on top of TiO 2 and the conducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) as a hole-transport layer are prepared and the photovoltaic performance is very promising with a power conversion efficiency over 2 %, which is higher than the performance of previously reported bismuth-halide materials for solar cells. Photocurrent generation is observed between 350 and 700 nm, and the maximum external quantum efficiency is around 45 %. The results are compared to solar cells based on the previously reported material AgBi 2 I 7 , and we observe a clearly higher performance for the devices with the new silver and bismuth iodides composition and different crystal structure. The X-ray diffraction spectrum of the most efficient silver bismuth iodide material shows a hexagonal crystal structure with space group R3‾ m, and from the light absorption spectrum we obtain an indirect band gap energy of 1.62 eV and a direct band gap energy of 1.85 eV. This report shows the possibility for finding new structures of metal-halides efficient in solar cells and points out new directions for further exploration of lead-free metal-halide solar cells. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

A reverse engineering approach to the suppression of citation biases reveals universal properties of citation distributions.

Science.gov (United States)

Radicchi, Filippo; Castellano, Claudio

2012-01-01

The large amount of information contained in bibliographic databases has recently boosted the use of citations, and other indicators based on citation numbers, as tools for the quantitative assessment of scientific research. Citations counts are often interpreted as proxies for the scientific influence of papers, journals, scholars, and institutions. However, a rigorous and scientifically grounded methodology for a correct use of citation counts is still missing. In particular, cross-disciplinary comparisons in terms of raw citation counts systematically favors scientific disciplines with higher citation and publication rates. Here we perform an exhaustive study of the citation patterns of millions of papers, and derive a simple transformation of citation counts able to suppress the disproportionate citation counts among scientific domains. We find that the transformation is well described by a power-law function, and that the parameter values of the transformation are typical features of each scientific discipline. Universal properties of citation patterns descend therefore from the fact that citation distributions for papers in a specific field are all part of the same family of univariate distributions.

Silver manganese oxide electrodes for lithium batteries

Science.gov (United States)

Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

2006-05-09

This invention relates to electrodes for non-aqueous lithium cells and batteries with silver manganese oxide positive electrodes, denoted AgxMnOy, in which x and y are such that the manganese ions in the charged or partially charged electrodes cells have an average oxidation state greater than 3.5. The silver manganese oxide electrodes optionally contain silver powder and/or silver foil to assist in current collection at the electrodes and to improve the power capability of the cells or batteries. The invention relates also to a method for preparing AgxMnOy electrodes by decomposition of a permanganate salt, such as AgMnO4, or by the decomposition of KMnO4 or LiMnO4 in the presence of a silver salt.

Solution Processed Silver Nanoparticles in Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

Marko Berginc

2014-01-01

Full Text Available A plasmonic effect of silver nanoparticles (Ag NPs in dye-sensitized solar cells (DSSCs is studied. The solutions of silver nitrate in isopropanol, ethylene glycol, or in TiO2 sol were examined as possible precursors for Ag NPs formation. The solutions were dip-coated on the top of the porous TiO2 layer. The results of optical measurements confirmed the formation of Ag NPs throughout the porous TiO2 layer after the heat treatment of the layers above 100°C. Heat treatment at 220°C was found to be optimal regarding the formation of the Ag NPs. The porous TiO2 layers with Ag NPs have been evaluated also in DSSC by measuring current-voltage characteristics and the external quantum efficiency of the cells. In addition, the amount of adsorbed dye has been determined to prove the plasmonic effect in the cells. The I-V characterization of the DSSCs revealed an increase of the short circuit current in the presence of Ag NPs although the amount of the attached dye molecules decreased. These results confirm that the performance enhancement is related to the plasmonic effect. However, neither a thin sol-gel TiO2 layer nor poly(4-vinylpyridine shells provide effective protection for the long term stability of the Ag NPs against the corrosion of I3-/I- based electrolyte.

Transmission electron microscopy for elucidating the impact of silver-based treatments (ionic silver versus nanosilver-containing coating) on the model yeast Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Despax, B; Saulou, C; Raynaud, P [Universite de Toulouse, UPS, INPT, LAPLACE, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Datas, L [Universite de Toulouse, UPS, INPT, CIRIMAT, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Mercier-Bonin, M [Universite de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse (France)

2011-04-29

After exposure to ionic silver or nanosilver-containing plasma coating, the same visual aspect of scanning transmission electron microscopy (STEM) images was observed for the model yeast Saccharomyces cerevisiae. The main common feature was the presence of electron-dense nodules all over the cell. However, high resolution TEM (HRTEM), STEM, energy dispersive x-ray microanalysis spectroscopy (EDS) and electron microdiffraction revealed some striking differences. Regarding ionic silver exposure, the formation of electron-dense nodules was related to the Ag{sup +} reactivity towards sulfur-containing compounds to form clusters with Ag{sub 2}S-like structures, together with the production of a few silver nanocrystals, mainly at the cell wall periphery. For nanosilver-based treatment, some sulfur-containing silver clusters preferentially located at the cell wall periphery were detected, together with nodules composed of silver, sulfur and phosphorus all over the cell. In both silver-based treatments, nitrogen and silver signals overlapped, confirming the affinity of silver entities for proteinaceous compounds. Moreover, in the case of nanosilver, interactions of silver with phosphorus-containing subcellular structures were indicated.

Cytotoxic and genotoxic effects of silver nanoparticles in testicular cells

International Nuclear Information System (INIS)

Asare, Nana; Instanes, Christine; Sandberg, Wiggo J.; Refsnes, Magne; Schwarze, Per; Kruszewski, Marcin; Brunborg, Gunnar

2012-01-01

Serious concerns have been expressed about potential risks of engineered nanoparticles. Regulatory health risk assessment of such particles has become mandatory for the safe use of nanomaterials in consumer products and medicines; including the potential effects on reproduction and fertility, are relevant for this risk evaluation. In this study, we examined effects of silver particles of nano- (20 nm) and submicron- (200 nm) size, and titanium dioxide nanoparticles (TiO 2 -NPs; 21 nm), with emphasis on reproductive cellular- and genotoxicity. Ntera2 (NT2, human testicular embryonic carcinoma cell line), and primary testicular cells from C57BL6 mice of wild type (WT) and 8-oxoguanine DNA glycosylase knock-out (KO, mOgg1 −/− ) genotype were exposed to the particles. The latter mimics the repair status of human testicular cells vs oxidative damage and is thus a suitable model for human male reproductive toxicity studies. The results suggest that silver nano- and submicron-particles (AgNPs) are more cytotoxic and cytostatic compared to TiO 2 -NPs, causing apoptosis, necrosis and decreased proliferation in a concentration- and time-dependent manner. The 200 nm AgNPs in particular appeared to cause a concentration-dependent increase in DNA-strand breaks in NT2 cells, whereas the latter response did not seem to occur with respect to oxidative purine base damage analysed with any of the particles tested.

Visibility and Citation Impact

Science.gov (United States)

Ebrahim, Nader Ale; Salehi, Hadi; Embi, Mohamed Amin; Tanha, Farid Habibi; Gholizadeh, Hossein; Motahar, Seyed Mohammad

2014-01-01

The number of publications is the first criteria for assessing a researcher output. However, the main measurement for author productivity is the number of citations, and citations are typically related to the paper's visibility. In this paper, the relationship between article visibility and the number of citations is investigated. A case study of…

Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

Science.gov (United States)

Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

2015-07-21

Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

Characterizing and modeling citation dynamics.

Directory of Open Access Journals (Sweden)

Young-Ho Eom

Full Text Available Citation distributions are crucial for the analysis and modeling of the activity of scientists. We investigated bibliometric data of papers published in journals of the American Physical Society, searching for the type of function which best describes the observed citation distributions. We used the goodness of fit with Kolmogorov-Smirnov statistics for three classes of functions: log-normal, simple power law and shifted power law. The shifted power law turns out to be the most reliable hypothesis for all citation networks we derived, which correspond to different time spans. We find that citation dynamics is characterized by bursts, usually occurring within a few years since publication of a paper, and the burst size spans several orders of magnitude. We also investigated the microscopic mechanisms for the evolution of citation networks, by proposing a linear preferential attachment with time dependent initial attractiveness. The model successfully reproduces the empirical citation distributions and accounts for the presence of citation bursts as well.

Characterizing and Modeling Citation Dynamics

Science.gov (United States)

Eom, Young-Ho; Fortunato, Santo

2011-01-01

Citation distributions are crucial for the analysis and modeling of the activity of scientists. We investigated bibliometric data of papers published in journals of the American Physical Society, searching for the type of function which best describes the observed citation distributions. We used the goodness of fit with Kolmogorov-Smirnov statistics for three classes of functions: log-normal, simple power law and shifted power law. The shifted power law turns out to be the most reliable hypothesis for all citation networks we derived, which correspond to different time spans. We find that citation dynamics is characterized by bursts, usually occurring within a few years since publication of a paper, and the burst size spans several orders of magnitude. We also investigated the microscopic mechanisms for the evolution of citation networks, by proposing a linear preferential attachment with time dependent initial attractiveness. The model successfully reproduces the empirical citation distributions and accounts for the presence of citation bursts as well. PMID:21966387

Toxicity of silver nanoparticles in monocytes and keratinocytes

DEFF Research Database (Denmark)

Orłowski, Piotr; Krzyzowska, Malgorzata; Winnicka, Anna

2012-01-01

Silver nanoparticles are of interest to be used as antimicrobial agents in wound dressings and coatings in medical devices, but potential adverse effects have been reported in the literature. The possible local inflammatory response to silver nanoparticles and the role of cell death in determining...... these effects are largely unknown. Effects of the mixture of silver nanoparticles of different sizes were compared in in vitro assays for cytotoxicity, caspase-1 and caspase-9 activity and bax expression. In all tested concentrations, silver nanoparticles were more toxic for RAW 264.7 monocytes than for 291.03C...... keratinocytes and induced significant caspase-1 activity and necrotic cell death. In keratinocytes, more significantly than in macrophages, silver nanoparticles led to increase of caspase-9 activity and apoptosis. These results indicate that effects of silver nanoparticles depend on the type of exposed cells...

An analysis of citation analysis

International Nuclear Information System (INIS)

Nakamoto, Hideshiro

1982-01-01

This paper consists of a statistical processing of reader's opinions and correlation with citation data. Using the quantified journal ranking from questionnaires, which were programmed by pair comparison method, citation data was analyzed on chemical journals. Citation statistics had positive and strong correlation with quantified evaluation of questionnaire. Correlation factors of citation counts represented stable values and those of median age had higher values than other measures. (author)

引用文獻分析與引用動機研究 Citation Analysis and Citation Motivation

Directory of Open Access Journals (Sweden)

Ming-yueh Tsay

2001-06-01

Full Text Available 無Citation analysis has been an important area of informetrics (or bibliometrics for severai decades. It mainly deals with the study of the relationship between citing and cited documents. A number of studies have been done to explore citation analysis and its applications. These studies have different opinions about the nature and the complexities of the citing process. Theories of citation have been debated for decades and can never be complete. By reviewing many empirical studies, this article describes the development and critique of citation analysis. especially focuses on the citation classifications, citation functions, citation concepts and citation motivations.

Toxicity testing of four silver nanoparticle-coated dental castings in 3-D LO2 cell cultures.

Science.gov (United States)

Zhao, Yi-Ying; Chu, Qiang; Shi, Xu-Er; Zheng, Xiao-Dong; Shen, Xiao-Ting; Zhang, Yan-Zhen

To address the controversial issue of the toxicity of dental alloys and silver nanoparticles in medical applications, an in vivo-like LO2 3-D model was constructed within polyvinylidene fluoride hollow fiber materials to mimic the microenvironment of liver tissue. The use of microscopy methods and the measurement of liver-specific functions optimized the model for best cell performances and also proved the superiority of the 3-D LO2 model when compared with the traditional monolayer model. Toxicity tests were conducted using the newly constructed model, finding that four dental castings coated with silver nanoparticles were toxic to human hepatocytes after cell viability assays. In general, the toxicity of both the castings and the coated silver nanoparticles aggravated as time increased, yet the nanoparticles attenuated the general toxicity by preventing metal ion release, especially at high concentrations.

Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

International Nuclear Information System (INIS)

Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi

2015-01-01

The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO 3 aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20–30 nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50 wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. - Highlights: • Silver mirror reaction was used to prepare nanofibers loaded with silver nanoparticles. • The SAED patterns demonstrated the monocrystallinity of silver nanocrystals. • The XRD results showed nanoparticles tended to be face-centered cubic single silver. • The material showed excellent antimicrobial activities against bacteria and fungi

Can a novel silver nano coating reduce infections and maintain cell viability in vitro?

Science.gov (United States)

Qureshi, Ammar T; Landry, Jace P; Dasa, Vinod; Janes, Marlene; Hayes, Daniel J

2014-03-01

Herein we report a facile layer-by-layer method for creating an antimicrobial coating composed of silver nanoparticles on medical grade titanium test discs. Nanoscale silver nanoparticle layers are attached to the titanium orthopedic implant material via aminopropyltriethoxy silane crosslinker that reacts with neighboring silane moieties to create an interconnected network. A monolayer of silane, followed by a monolayer of silver nanoparticles would form one self-assembled layer and this process can be repeated serially, resulting in increased silver nanoparticles deposition. The release rate of silver ion increases predictably with increasing numbers of layers and at appropriate thicknesses these coatings demonstrate 3-4 log reduction of viable Escherichia coli and Staphylococcus aureus bacteria. Increasing the thickness of the coatings resulted in reduced bacterial colonization as determined by fluorescent staining and image analysis. Interestingly, the cytotoxicity of murine 3T3 cells as quantified by fluorescent staining and flow cytometry, was minimal and did not vary significantly with the coating thickness. Additionally, these coatings are mechanically stable and resist delamination by orthogonal stress test. This simple layer-by-layer coating technique may provide a cost-effective and biocompatible method for reducing microbial colonization of implantable orthopedic devices.

Citation graph based ranking in Invenio

CERN Document Server

Marian, Ludmila; Rajman, Martin; Vesely, Martin

2010-01-01

Invenio is the web-based integrated digital library system developed at CERN. Within this framework, we present four types of ranking models based on the citation graph that complement the simple approach based on citation counts: time-dependent citation counts, a relevancy ranking which extends the PageRank model, a time-dependent ranking which combines the freshness of citations with PageRank and a ranking that takes into consideration the external citations. We present our analysis and results obtained on two main data sets: Inspire and CERN Document Server. Our main contributions are: (i) a study of the currently available ranking methods based on the citation graph; (ii) the development of new ranking methods that correct some of the identified limitations of the current methods such as treating all citations of equal importance, not taking time into account or considering the citation graph complete; (iii) a detailed study of the key parameters for these ranking methods. (The original publication is ava...

Restrictive versus liberal transfusion strategy for red blood cell transfusion

DEFF Research Database (Denmark)

Holst, Lars B; Petersen, Marie W; Haase, Nicolai

2015-01-01

OBJECTIVE: To compare the benefit and harm of restrictive versus liberal transfusion strategies to guide red blood cell transfusions. DESIGN: Systematic review with meta-analyses and trial sequential analyses of randomised clinical trials. DATA SOURCES: Cochrane central register of controlled...... trials, SilverPlatter Medline (1950 to date), SilverPlatter Embase (1980 to date), and Science Citation Index Expanded (1900 to present). Reference lists of identified trials and other systematic reviews were assessed, and authors and experts in transfusion were contacted to identify additional trials....... TRIAL SELECTION: Published and unpublished randomised clinical trials that evaluated a restrictive compared with a liberal transfusion strategy in adults or children, irrespective of language, blinding procedure, publication status, or sample size. DATA EXTRACTION: Two authors independently screened...

The immunomodulatory effects of titanium dioxide and silver nanoparticles.

Science.gov (United States)

Lappas, Courtney M

2015-11-01

Due to their characteristic physical, chemical and optical properties, titanium dioxide and silver nanoparticles are attractive tools for use in a wide range of applications. The use of nanoparticles for biological applications is, however, dependent upon their biocompatibility with living cells. Because of the importance of inflammation as a modulator of human health, the safe and efficacious in vivo use of titanium dioxide and silver nanoparticles is inherently linked to a favorable interaction with immune system cells. However, both titanium dioxide and silver nanoparticles have demonstrated potential to exert immunomodulatory and immunotoxic effects. Titanium dioxide and silver nanoparticles are readily internalized by immune system cells, may accumulate in peripheral lymphoid organs, and can influence multiple manifestations of immune cell activity. Although the factors influencing the biocompatibility of titanium dioxide and silver nanoparticles with immune system cells have not been fully elucidated, nanoparticle core composition, size, concentration and the duration of cell exposure seem to be important. Because titanium dioxide and silver nanoparticles are widely utilized in pharmaceutical, commercial and industrial products, it is vital that their effects on human health and immune system function be more thoroughly evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.

High rate capability of lithium/silver vanadium oxide cells

International Nuclear Information System (INIS)

Takeuchi, E.S.; Zelinsky, M.A.; Keister, P.

1986-01-01

High rate characteristics of the lithium/silver vanadium oxide system were investigated in test cells providing four different limiting surface areas. The cells were tested by constant current and constant resistance discharge with current densities ranging from 0.04 to 6.4 mA/cm/sup 2/. The maximum current density under constant resistance and constant current discharges which would deliver 50% of theoretical capacity was determined. The ability of the cells to deliver high current pulses was evaluated by application of 10 second pulses with current densities ranging from 3 to 30 mA/cm/sup 2/. The voltage delay characteristics of the cells were determined after 1 to 3 months of storage at open circuit voltage or under low level background currents. The volumetric and gravimetric energy density of the SVO system is compared to other cathode materials

27 CFR 71.72 - Before citation.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Before citation. 71.72... Procedure Surrender of Permit § 71.72 Before citation. If a respondent surrenders the permit before citation... appropriate TTB officer, warrants citation for suspension, revocation or annulment, the surrender shall be...

Genotoxicity of Silver Nanoparticles in Lung Cells of Sprague Dawley Rats after 12 Weeks of Inhalation Exposure

Directory of Open Access Journals (Sweden)

Hyun Sun Cho

2013-11-01

Full Text Available Due to the widespread use of silver nanoparticles in consumer products, the toxicity of silver nanoparticles has also been studied in relation to their application. However, most genotoxicity studies of silver nanoparticles have been performed in vitro. Therefore, this study evaluated the DNA damage to lung cells caused by repeated inhalation of silver nanoparticles. Male Sprague Dawley rats were exposed to silver nanoparticles for 12 weeks in a whole-body inhalation chamber. The animals were divided into one control group and three dose groups that were exposed to silver nanoparticles (14–15 nm diameter at concentrations of 0.66 × 106 particles/cm3 (49 μg/m3, low dose, 1.41 × 106 particles/cm3 (117 μg/m3, middle dose, and 3.24 × 106 particles /cm3 (381 μg/m3, high dose, respectively, for six hours/day over 12 weeks. The rats were sacrificed after the 12-week exposure period and the DNA damage assessed using a Comet assay of cells obtained from the right lungs. The olive tail moment values were 2.93 ± 0.19, 3.81 ± 0.23, 3.40 ± 0.22, and 5.16 ± 0.32 for the control, low-, middle-, and high-dose groups, respectively. Although no dose-dependent results were observed, a significant increase in the level of DNA damage was noted for the high-dose group.

Does it matter where patent citations come from? : inventor versus examiner citations in European patents

NARCIS (Netherlands)

Verspagen, B.; Criscuolo, P.

2005-01-01

This paper investigates whether the distinction between patent citations added by the inventor or the examiner is relevant for the issue of geographical concentration of knowledge flows (as embodied in citations). The distinction between inventor and examiner citations enables us to work with a more

Electrospun polyacrylonitrile nanofibers loaded with silver nanoparticles by silver mirror reaction

Energy Technology Data Exchange (ETDEWEB)

Shi, Yongzheng; Li, Yajing; Zhang, Jianfeng; Yu, Zhongzhen; Yang, Dongzhi, E-mail: yangdz@mail.buct.edu.cn

2015-06-01

The silver mirror reaction (SMR) method was selected in this paper to modify electrospun polyacrylonitrile (PAN) nanofibers, and these nanofibers loaded with silver nanoparticles showed excellent antibacterial properties. PAN nanofibers were first pretreated in AgNO{sub 3} aqueous solution before the SMR process so that the silver nanoparticles were distributed evenly on the outer surface of the nanofibers. The final PAN nanofibers were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), TEM-selected area electron diffraction (SAED), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). SEM, TEM micrographs and SAED patterns confirmed homogeneous dispersion of the silver nanoparticles which were composed of monocrystals with diameters 20–30 nm. EDS and XRD results showed that these monocrystals tended to form face-centered cubic single silver. TGA test indicated that the nanoparticles loaded on the nanofibers reached above 50 wt.%. This material was also evaluated by the viable cell-counting method. The results indicated that PAN nanofibers loaded with silver nanoparticles exhibited excellent antimicrobial activities against gram-negative Escherichia coli (E. coli), gram-positive Staphylococcus aureus (S. aureus) and the fungus Monilia albicans. Thus, this material had many potential applications in biomedical fields. - Highlights: • Silver mirror reaction was used to prepare nanofibers loaded with silver nanoparticles. • The SAED patterns demonstrated the monocrystallinity of silver nanocrystals. • The XRD results showed nanoparticles tended to be face-centered cubic single silver. • The material showed excellent antimicrobial activities against bacteria and fungi.

Enhanced thermal property measurement of a silver zinc battery cell using isothermal calorimetry

Energy Technology Data Exchange (ETDEWEB)

Ubelhor, Ryan, E-mail: ryan.ubelhor@navy.mil [Naval Surface Warfare Center, Crane Division, 300 Highway 361, Crane, IN 47522 (United States); Ellison, Daniel [Science Applications International Corporation, 300 Highway 361, Crane, IN 47522 (United States); Pierce, Cecilia [Naval Surface Warfare Center, Crane Division, 300 Highway 361, Crane, IN 47522 (United States)

2015-04-20

Highlights: • Design and construction of novel heat flow calorimeter for large battery cell. • Heat flow characterization of silver zinc battery under load. • Thermal efficiency determination of silver zinc battery under load. • Surface map of heat flow of silver zinc battery under load. - Abstract: The push for increased energy density of electrochemical cells highlights the need for novel electrochemical techniques as well as additional characterization methods for these cells in order to meet user needs and safety requirements. To achieve ever increasing energy densities and faster controlled release of that energy, all materials of construction must be constantly evaluated from electrode to casing and everything in-between. Increasing the energy density of the cell improves its utility, but it also increases the waste heat and maximum potential uncontrolled energy release. Design agents and system developers need new ways to monitor and classify the probability and severity of the catastrophic failures as well as the system characteristics during intended operation. To support optimization of these battery cells it is necessary to understand their thermal characteristics at rest as well as under prescribed charge and discharge cycles. One of the many calorimetric tools available to observe and record these characteristics is heat flow calorimetry. Typically, a heat flow calorimeter is operated isothermally and measures the sum heat released or consumed by a sample material inside of a calorimetric measuring cell. For this study an improved calorimetric measuring cell for a modified Hart 6209 precision temperature bath was designed and constructed to measure the heat flow of larger electrochemical cells (18 × 8 × 16 cm). This new calorimetric measuring cell is constructed to allow independent measurements of heat flow among each of the sample’s six sides in contrast to the typical one measurement of the average heat flow. Heat flows from 0.01 to 7

Enhanced thermal property measurement of a silver zinc battery cell using isothermal calorimetry

International Nuclear Information System (INIS)

Ubelhor, Ryan; Ellison, Daniel; Pierce, Cecilia

2015-01-01

Highlights: • Design and construction of novel heat flow calorimeter for large battery cell. • Heat flow characterization of silver zinc battery under load. • Thermal efficiency determination of silver zinc battery under load. • Surface map of heat flow of silver zinc battery under load. - Abstract: The push for increased energy density of electrochemical cells highlights the need for novel electrochemical techniques as well as additional characterization methods for these cells in order to meet user needs and safety requirements. To achieve ever increasing energy densities and faster controlled release of that energy, all materials of construction must be constantly evaluated from electrode to casing and everything in-between. Increasing the energy density of the cell improves its utility, but it also increases the waste heat and maximum potential uncontrolled energy release. Design agents and system developers need new ways to monitor and classify the probability and severity of the catastrophic failures as well as the system characteristics during intended operation. To support optimization of these battery cells it is necessary to understand their thermal characteristics at rest as well as under prescribed charge and discharge cycles. One of the many calorimetric tools available to observe and record these characteristics is heat flow calorimetry. Typically, a heat flow calorimeter is operated isothermally and measures the sum heat released or consumed by a sample material inside of a calorimetric measuring cell. For this study an improved calorimetric measuring cell for a modified Hart 6209 precision temperature bath was designed and constructed to measure the heat flow of larger electrochemical cells (18 × 8 × 16 cm). This new calorimetric measuring cell is constructed to allow independent measurements of heat flow among each of the sample’s six sides in contrast to the typical one measurement of the average heat flow. Heat flows from 0.01 to 7

Modeling the citation network by network cosmology.

Science.gov (United States)

Xie, Zheng; Ouyang, Zhenzheng; Zhang, Pengyuan; Yi, Dongyun; Kong, Dexing

2015-01-01

Citation between papers can be treated as a causal relationship. In addition, some citation networks have a number of similarities to the causal networks in network cosmology, e.g., the similar in-and out-degree distributions. Hence, it is possible to model the citation network using network cosmology. The casual network models built on homogenous spacetimes have some restrictions when describing some phenomena in citation networks, e.g., the hot papers receive more citations than other simultaneously published papers. We propose an inhomogenous causal network model to model the citation network, the connection mechanism of which well expresses some features of citation. The node growth trend and degree distributions of the generated networks also fit those of some citation networks well.

Military Citation, Sixth Edition, July 1997

National Research Council Canada - National Science Library

1997-01-01

.... If the Military Citation and The Bluebook do not address a source of authority used in military practice, the author should attempt to maintain uniformity in citation style by adapting the most analogous and useful citation form that Military Citation and The Bluebook do address. Most importantly, the author should provide the reader with sufficient information to locate the referenced material swiftly.

silver nanoparticles on liver cancer cells (HepG2

Directory of Open Access Journals (Sweden)

Ahmed I. El-Batal

2018-01-01

Full Text Available This study demonstrates a novel approach for the synthesis of silver nanoparticles (AgNPs against human liver cancer cell line (HepG2 using prodigiosin pigment isolated from Serratia marcescens. It further investigates the influence of various parameters such as initial pH, temperature, silver nitrate (AgNO 3 concentration, and prodigiosin concentration on stability and optical properties of synthesized prodigiosin AgNPs. Highly stable, spherical prodigiosin-conjugated AgNPs were synthesized with a mean diameter of 9.98 nm using a rapid one-step method. The cytotoxic activity investigated in the present study indicated that prodigiosin and prodigiosin-conjugated AgNPs possessed a strong cytotoxic potency against human liver cancer. The In silico molecular docking results of prodigiosin and prodigiosin-conjugated AgNPs are congruent with the In vitro studies and these AgNPs can be considered as good inhibitors of mitogen-activated protein kinase 1 (MEK kinases. The study opened the possibility of using prodigiosin-conjugated AgNPs to increase the efficiency of liver cancer treatment.

Citations Prize 2013

Science.gov (United States)

Cherry, Simon; Ruffle, Jon

2014-06-01

Physics in Medicine and Biology (PMB) awards its 'Citations Prize' to the authors of the original research paper that has received the most citations in the preceding five years (according to the Institute for Scientific Information (ISI)). The lead author of the winning paper is presented with the Rotblat Medal (named in honour of Professor Sir Joseph Rotblat, a Nobel Prize winner who also was the second—and longest serving—Editor of PMB, from 1961-1972). The winner of the 2013 Citations Prize for the paper which has received the most citations in the previous five years (2008-2012) is Figure. Figure. Four of the prize winning authors. From left to right: Thomas Istel (Philips), Jens-Peter Schlomka (with medal, MorphoDetection), Ewald Roessl (Philips), and Gerhard Martens (Philips). Title: Experimental feasibility of multi-energy photon-counting K-edge imaging in pre-clinical computed tomography Authors: Jens Peter Schlomka1, Ewald Roessl1, Ralf Dorscheid2, Stefan Dill2, Gerhard Martens1, Thomas Istel1, Christian Bäumer3, Christoph Herrmann3, Roger Steadman3, Günter Zeitler3, Amir Livne4 and Roland Proksa1 Institutions: 1 Philips Research Europe, Sector Medical Imaging Systems, Hamburg, Germany 2 Philips Research Europe, Engineering & Technology, Aachen, Germany 3 Philips Research Europe, Sector Medical Imaging Systems, Aachen, Germany 4 Philips Healthcare, Global Research and Advanced Development, Haifa, Israel Reference: Schlomka et al 2008 Phys. Med. Biol. 53 4031-47 This paper becomes the first to win both this citations prize and also the PMB best paper prize (The Roberts Prize), which it won for the year 2008. Discussion of the significance of the winning paper can be found in this medicalphysicsweb article from the time of the Roberts Prize win (http://medicalphysicsweb.org/cws/article/research/39907). The author's enthusiasm for their prototype spectral CT system has certainly been reflected in the large number of citations the paper subsequently has

Citation analysis of the scientific publications of Britton Chance in ISI citation indexes

Directory of Open Access Journals (Sweden)

Lin Z. Li

2014-03-01

Full Text Available Britton Chance was a pioneer in many scientific fields such as enzymatic reaction kinetics, bioenergetics, metabolism, in vivo NMR, and biophotonics. As an engineer, physical chemist, physicist, physiologist, biophysicist, biochemist, innovator and educator, he had worked in diversified fields over extended periods between 1926 until his death in 2010, at the age of 97. In order to illustrate his scientific career and great impact on research from a new perspective, we employ scientometric analysis tools to analyze the publications of Britton Chance with data downloaded from the ISI Citation Indexes in April 2013. We included articles, reviews and proceeding papers but excluded meeting abstracts. In total, we obtained 1023 publication records with 1236 authors in 266 journals with 17,114 citations from 1945 to 2013. We show the annual publications and citations that Britton Chance received from 1945 to 2013, and generate HistCite maps on the basis of the global citations (GCS and local (self citations (LCS to show the citation relationships among the top-30 publications of Britton Chance. Metabolism and the development of physical methods to probe it appear to be the connecting thread of the lifelong research of Britton Chance. Furthermore, we generate the journal map and co-authorship map to show the broad scope of research topics and collaborators and the high impacts of the scientific oeuvre of Britton Chance ranging from physics, engineering, chemistry and biology to medicine.

In vitro cytotoxity of silver: implication for clinical wound care.

Science.gov (United States)

Poon, Vincent K M; Burd, Andrew

2004-03-01

In this study, we look at the cytotoxic effects of silver on keratinocytes and fibroblasts. We have assessed the viability of monolayer cultures using the MTT and BrdU assays. The composition of the culture medium and also the culture technique were modified to assess the effects of culture 'environment' on the susceptibility of the cells to the toxic action of silver. Further in vitro, experiments were performed using tissue culture models to allow cellular behavior in three dimensional planes which more closely simulated in vivo behavior. The silver source was both silver released from silver nitrate solution but also nanocrystalline silver released from a commercially available dressing. The results show that silver is highly toxic to both keratinocytes and fibroblasts in monolayer culture. When using optimized and individualized culture the fibroblasts appear to be more sensitive to silver than keratinocytes. However, when both cell types were grown in the same medium their viability was the same. Using tissue culture models again indicated an 'environmental effect' with decreased sensitivity of the cells to the cytotoxic effects of the silver. Nevertheless in these studies the toxic dose of skin cells ranging from 7 x 10(-4) to 55 x 10(-4)% was similar to that of bacteria. These results suggest that consideration of the cytotoxic effects of silver and silver-based products should be taken when deciding on dressings for specific wound care strategies. This is important when using keratinocyte culture, in situ, which is playing an increasing role in contemporary wound and burn care.

The toxicity of silver and silica nanoparticles in comparable human and mouse cell lines

DEFF Research Database (Denmark)

Foldbjerg, Rasmus; Beer, Christiane; Sutherland, Duncan S

The toxicity of silica (SiO2) and PVP-coated silver (Ag) nanoparticles (NPs) was investigated in two pairs of human or mouse cell lines originating from lung epithelium (A549 and ASB-XIV) and macrophages (THP-1 and J744A.1). Both NPs were characterized in H2O and cell media and demonstrated to be...

Researchers' perceptions of citations

NARCIS (Netherlands)

Aksnes, Dag W.; Rip, Arie

2009-01-01

This paper looks at how citations are perceived among scientists. Based on a questionnaire survey it traces the repertoire of views and experiences about citations that could be found among Norwegian scientists that had published highly cited papers. Their views circle around three issues: the

Large-size, high-uniformity, random silver nanowire networks as transparent electrodes for crystalline silicon wafer solar cells.

Science.gov (United States)

Xie, Shouyi; Ouyang, Zi; Jia, Baohua; Gu, Min

2013-05-06

Metal nanowire networks are emerging as next generation transparent electrodes for photovoltaic devices. We demonstrate the application of random silver nanowire networks as the top electrode on crystalline silicon wafer solar cells. The dependence of transmittance and sheet resistance on the surface coverage is measured. Superior optical and electrical properties are observed due to the large-size, highly-uniform nature of these networks. When applying the nanowire networks on the solar cells with an optimized two-step annealing process, we achieved as large as 19% enhancement on the energy conversion efficiency. The detailed analysis reveals that the enhancement is mainly caused by the improved electrical properties of the solar cells due to the silver nanowire networks. Our result reveals that this technology is a promising alternative transparent electrode technology for crystalline silicon wafer solar cells.

Gender Differences in Synchronous and Diachronous Self-citations

Energy Technology Data Exchange (ETDEWEB)

Ghiasi, G.; Lariviere, V.; Sugimoto, C.

2016-07-01

Citation rates are increasingly used as a currency of science, providing a basis to reward a scientist. Self-citations, an inevitable part of scholarly communication, may contribute to the inflation of citation counts and impose a considerable impact on research evaluation and academic career advancements. Self-citations are classified into two types in this study: synchronous self-citations (self-citations an author gives) and diachronous self-citations (selfcitations an author receives). The main objective of this paper is to provide a comprehensive gendered analysis of synchronous and diachronous self-citations across all scientific disciplines. For this purpose, citation data of 12,725,171 articles published in 2008-2014 are extracted from Web of Science and are further scrutinized for articles of each gender. The findings reveal that men receive citations from their own papers at a higher rate than their women counterparts. They also tend to give more citations to their own publications. Gender gap in citation impact decreases when first-author’s diachronous citations are eliminated in the impact analysis. However, the gap does not vary when all-authors’ diachronous citations are excluded. The results of this research is important for effective gender-related policy-making in the science and technology arena. (Author)

The potent antimicrobial properties of cell penetrating peptide-conjugated silver nanoparticles with excellent selectivity for gram-positive bacteria over erythrocytes.

Science.gov (United States)

Liu, Lihong; Yang, Jun; Xie, Jianping; Luo, Zhentao; Jiang, Jiang; Yang, Yi Yan; Liu, Shaomin

2013-05-07

Silver nanoparticles are of great interest for use as antimicrobial agents. Studies aimed at producing potent nano-silver biocides have focused on manipulation of particle size, shape, composition and surface charge. Here, we report the cell penetrating peptide catalyzed formation of antimicrobial silver nanoparticles in N,N-dimethylformamide. The novel nano-composite demonstrated a distinctly enhanced biocidal effect toward bacteria (gram-positive Bacillus subtilis, gram-negative Escherichia coli) and pathogenic yeast (Candida albicans), as compared to triangular and extremely small silver nanoparticles. In addition, a satisfactory biocompatibility was verified by a haemolysis test. Our results provide a paradigm in developing strategies that can maximize the silver nanoparticle application potentials while minimizing the toxic effects.

An analysis of the citation climate in neurosurgical literature and description of an interfield citation metric.

Science.gov (United States)

Madhugiri, Venkatesh S; Sasidharan, Gopalakrishnan M; Subeikshanan, Venkatesan; Dutt, Akshat; Ambekar, Sudheer; Strom, Shane F

2015-05-01

The citation climate in neurosurgical literature is largely undefined. To study the patterns of citation of articles in neurosurgery as a scientific field and to evaluate the performance of neurosurgery journals vis-à-vis journals in other fields. References cited in articles published in neurosurgery journals during a specified time period were analyzed to determine the age of articles cited in neurosurgical literature. In the next analysis, articles published in neurosurgical journals were followed up for 13 years after publication. The postpublication citation patterns were analyzed to determine the time taken to reach the maximally cited state and the time when articles stopped being cited. The final part of the study dealt with the evolution of a new interfield citation metric, which was then compared with other standardized citation indexes. The mean ± SD age of articles cited in neurosurgical literature was 11.6 ± 11.7 years (median, 8 years). Citations received by articles gradually increased to a peak (at 6.25 years after publication in neurosurgery) and then reached a steady state; articles were still cited well into the late postpublication period. Neurosurgical articles published in nonneurosurgical high-impact journals were cited more highly than those in neurosurgical journals, although they took approximately the same time to reach the maximally cited state (7.2 years). The most cited pure neurosurgery journal was Neurosurgery. The citation climate for neurosurgery was adequately described. The interfield citation metric was able to ensure cross-field comparability of journal performance. G1, group 1G2, group 2G3, group 3G4, group 4IFCM, interfield citation metric.

Patent citation network in nanotechnology (1976-2004)

International Nuclear Information System (INIS)

Li Xin; Chen Hsinchun; Huang Zan; Roco, Mihail C.

2007-01-01

The patent citation networks are described using critical node, core network, and network topological analysis. The main objective is understanding of the knowledge transfer processes between technical fields, institutions and countries. This includes identifying key influential players and subfields, the knowledge transfer patterns among them, and the overall knowledge transfer efficiency. The proposed framework is applied to the field of nanoscale science and engineering (NSE), including the citation networks of patent documents, submitting institutions, technology fields, and countries. The NSE patents were identified by keywords 'full-text' searching of patents at the United States Patent and Trademark Office (USPTO). The analysis shows that the United States is the most important citation center in NSE research. The institution citation network illustrates a more efficient knowledge transfer between institutions than a random network. The country citation network displays a knowledge transfer capability as efficient as a random network. The technology field citation network and the patent document citation network exhibit a less efficient knowledge diffusion capability than a random network. All four citation networks show a tendency to form local citation clusters

CMIP6 Data Citation of Evolving Data

Directory of Open Access Journals (Sweden)

Martina Stockhause

2017-06-01

Full Text Available Data citations have become widely accepted. Technical infrastructures as well as principles and recommendations for data citation are in place but best practices or guidelines for their implementation are not yet available. On the other hand, the scientific climate community requests early citations on evolving data for credit, e.g. for CMIP6 (Coupled Model Intercomparison Project Phase 6. The data citation concept for CMIP6 is presented. The main challenges lie in limited resources, a strict project timeline and the dependency on changes of the data dissemination infrastructure ESGF (Earth System Grid Federation to meet the data citation requirements. Therefore a pragmatic, flexible and extendible approach for the CMIP6 data citation service was developed, consisting of a citation for the full evolving data superset and a data cart approach for citing the concrete used data subset. This two citation approach can be implemented according to the RDA recommendations for evolving data. Because of resource constraints and missing project policies, the implementation of the second part of the citation concept is postponed to CMIP7.

Anticancer and enhanced antimicrobial activity of biosynthesizd silver nanoparticles against clinical pathogens

Science.gov (United States)

Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Vanaja, Mahendran; Annadurai, Gurusamy

2016-07-01

The present investigation shows the biosynthesis of eco-friendly silver nanoparticles using culture supernatant of Enterococcus sp. and study the effect of enhanced antimicrobial activity, anticancer activity against pathogenic bacteria, fungi and cancer cell lines. Silver nanoparticles was synthesized by adding 1 mM silver nitrate into the 100 ml of 24 h freshly prepared culture supernatant of Enterococcus sp. and were characterized by UV-vis spectroscopy, X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Selected Area Diffraction X-Ray (SAED), Energy Dispersive X Ray (EDX) and Fourier Transform Infra red Spectroscopy (FT-IR). The synthesized silver nanoparticles were impregnated with commercial antibiotics for evaluation of enhanced antimicrobial activity. Further these synthesized silver nanoparticles were assessed for its anticancer activity against cancer cell lines. In this study crystalline structured nanoparticles with spherical in the size ranges from 10 to 80 nm and it shows excellent enhanced antimicrobial activity than the commercial antibiotics. The in vitro assay of silver nanoparticles on anticancer have great potential to inhibit the cell viability. Amide linkages and carboxylate groups of proteins from Enterococcus sp. may bind with silver ions and convert into nanoparticles. The activities of commercial antibiotics were enhanced by coating silver nanoparticles shows significant improved antimicrobial activity. Silver nanoparticles have the great potential to inhibit the cell viability of liver cancer cells lines (HepG2) and lung cancer cell lines (A549).

78 FR 4766 - Authority Citation Correction

Science.gov (United States)

2013-01-23

...-19-11] Authority Citation Correction AGENCY: Securities and Exchange Commission. ACTION: Final rule..., respectively) that each included an inaccurate amendatory instruction pertaining to an authority citation. The Commission is publishing this technical amendment to accurately reflect the authority citation in the Code of...

Who actually receives cell phone use while driving citations and how much are these laws enforced among states? A descriptive, cross-sectional study.

Science.gov (United States)

Rudisill, Toni M; Zhu, Motao

2016-06-14

While numerous cell phone use while driving laws have been passed among states, little information exists regarding who gets cited for these traffic infractions and how much these laws are enforced at the state-level within the USA. Cross-sectional, descriptive study. 14 states and the District of Columbia. Those receiving cell phone use while driving citations within included states from 2007 to 2013. Demographic characteristics of cited drivers were assessed. Rates of infractions per 100 000 licensed in-state drivers per year for various cell phone use while driving violations were calculated. Drivers were cited for hand-held use violations (n=2.5 million) more than texting (n=14 682) or young driver all cell phone bans (n=342). Among states that provided data for all traffic violations, cell phone use while driving citations comprised 1% of all written citations. Regardless of ban type, males (68.2%) were cited more frequently than females. Drivers 25-64 years of age (90.8%) were more likely to be cited for hand-held phone use. The average yearly rate of infractions per 100 000 licensed in-state drivers from 2010-2013 was 5.8 for texting bans, 2607 for hand-held bans, and 9954 for any traffic violation. Among cited drivers, age and sex differences existed by the type of ban violated. State-level enforcement appeared sparse. Due to the potential serious consequences of cell phone use while driving in the USA, more enforcement and targeted public safety campaigns are likely needed. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Embedded vertical dual of silver nanoparticles for improved ZnO/Si heterojunction solar cells

Science.gov (United States)

Shokeen, Poonam; Jain, Amit; Kapoor, Avinashi

2017-10-01

A ZnO/Si heterojunction solar cell is studied with plasmonic nanoparticles embedded in the active layer. Two layers of silver nanoparticles are embedded in the ZnO layer. The effect of various parameters such as vertical-interparticle distance, horizontal-interparticle distance, relative dimensions of nanoparticles, and order of particle diameters are discussed in detail. Finite-difference time-domain studies suggest that particle dimensions of the top layer of silver nanoparticles should be less than the dimensions of the underneath layer of silver nanoparticles. The resulting structure acquires the benefits of each layer and improves the device performance over a broad spectrum. The dielectric separation of plasmonic layers is observed to be an important factor in favorable plasmonic response. Electric field diagrams are used to study the scattering of an incident field by proposed structure. Results are encouraging and suggest more concerted studies of multilayer plasmonic structures.

The antimicrobial activity of as-prepared silver-loaded phosphate glasses and zirconium phosphate

International Nuclear Information System (INIS)

Jing, Wang; Jiang, Ji Zhi; Yang, Yang; Yan, Zhao Chun; Yan, Wang Xiao; He, Shui Zhong

2016-01-01

The antimicrobial activities of silver-loaded zirconium phosphate (JDG) and silver-loaded phosphate glasses (ZZB) against Escherichia coli were studied. Although the silver content in JDG was higher than that in ZZB, ZZB suspensions showed better antimicrobial property than JDG suspensions, especially at low concentrations. The antimicrobial activity was analyzed using minimum inhibitory concentrations, bacterial inhibition ring tests, and detection of silver ions in the suspensions. Furthermore, the amounts of silver ions in suspensions with/without bacterial cells were analyzed. Results revealed that only a portion of released silver ions could be adsorbed by E. coli cells, which are critical to cell death. The damaged microstructures of E. coli cells observed by transmission electron microscopy may further prove that the adsorbed silver ions play an important role in the antimicrobial process.

Laminating solution-processed silver nanowire mesh electrodes onto solid-state dye-sensitized solar cells

KAUST Repository

Hardin, Brian E.; Gaynor, Whitney; Ding, I-Kang; Rim, Seung-Bum; Peumans, Peter; McGehee, Michael D.

2011-01-01

Solution processed silver nanowire meshes (Ag NWs) were laminated on top of solid-state dye-sensitized solar cells (ss-DSCs) as a reflective counter electrode. Ag NWs were deposited in <1 min and were less reflective compared to evaporated Ag

Cytotoxicity and antimicrobial activities of green synthesized silver nanoparticles.

Science.gov (United States)

Lokina, S; Stephen, A; Kaviyarasan, V; Arulvasu, C; Narayanan, V

2014-04-09

Bio-inspired silver nanoparticles are synthesized using Malus domestica (apple) extract. Polyphenols present in the apple extract act as a reducing and capping agent to produce the silver nanoparticles. UV-Visible analysis shows the surface plasmon resonance (SPR) absorption at 420 nm. The FTIR analysis was used to identify the functional groups responsible for the bio-reduction of silver ion. The XRD and HRTEM images confirm the formation of silver nanoparticles. The minimal inhibitory concentration (MIC) of silver nanoparticles was recorded against most of the bacteria and fungus. Further, MCF-7 human breast adenocarcinoma cancer cell line was employed to observe the efficacy of cancer cell killing. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Silver Nanoparticles Exhibit the Dose-Dependent Anti-Proliferative Effect against Human Squamous Carcinoma Cells Attenuated in the Presence of Berberine

Directory of Open Access Journals (Sweden)

Arkadiusz Dziedzic

2016-03-01

Full Text Available The biological activity of nanosize silver particles towards oral epithelium-derived carcinoma seems to be still underinvestigated. We evaluated the influence of low doses of nanosize scale silver particles on the proliferation and viability of malignant oral epithelial keratinocytes in vitro, alone and in conjunction with the plant alkaloid berberine. Cells of human tongue squamous carcinoma SCC-25 (ATCC CRL-1628, cultivated with the mixture of Dulbecco's modified Eagle’s medium, were exposed to silver nanoparticles alone (AgNPs, concentrations from 0.31 to 10 μg/mL and to a combination of AgNPs with berberine chloride (BER, 1/2 IC50 concentration during 24 h and 48 h. The cytotoxic activity of AgNPs with diameters of 10 nm ± 4 nm was measured by 3-(4,5-dimethyl-2-thiazyl-2,5-diphenyl-2H-tetrazolium bromide (MTT assay. Cell cycle analysis was performed by treating cells with propidium iodide followed by flow-activated cell sorting. RT-QPCR reaction was used to assess expression of anti-apoptotic proteins Bcl-2 and pro-apoptotic protein Bcl-2-associated X protein Bax genes expression. Monodisperse silver nanoparticles at a concentration of 10 μg/mL arrested SCC-25 cells cycle after 48 h at the G0/G1 phase in a dose- and time-dependent manner through disruption G0/G1 checkpoint, with increase of Bax/Bcl-2 ratio gene expression. AgNPs exhibit cytotoxic effects on SCC-25 malignant oral epithelial keratinocytes, which is diminished when combined with BER. The AgNPs concentration required to inhibit the growth of carcinoma cells by 50% (IC50 after 48 h was estimated at 5.19 μg/mL. AgNPs combined with BER increased the expression of Bcl-2 while decreasing the ratio of Bax/Bcl-2 in SCC-25 cells. Silver particles at low doses therefore reduce the proliferation and viability of oral squamous cell carcinoma cells. SCC-25 cells are susceptible to damage from AgNPs-induced stress, which can be regulated by the natural alkaloid berberine, suggesting

27 CFR 71.73 - After citation.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false After citation. 71.73 Section 71.73 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Procedure Surrender of Permit § 71.73 After citation. If a respondent surrenders the permit after citation...

Citation classics in epilepsy

Directory of Open Access Journals (Sweden)

Maryann Wilson

2013-01-01

Full Text Available BACKGROUND: The impact of a scientific article is proportional to the citations it has received. In this study, we set out to identify the most cited works in epileptology in order to evaluate research trends in this field. METHODS: According to the Web of Science database, articles with more than 400 citations qualify as "citation classics". We conducted a literature search on the ISI Web of Science bibliometric database for scientific articles relevant to epilepsy. RESULTS: We retrieved 67 highly cited articles (400 or more citations, which were published in 31 journals: 17 clinical studies, 42 laboratory studies, 5 reviews and 3 classification articles. Clinical studies consisted of epidemiological analyses (n=3, studies on the clinical phenomenology of epilepsy (n=5 – including behavioral and prognostic aspects – and articles focusing on pharmacological (n=6 and non-pharmacological (n=3 treatment. The laboratory studies dealt with genetics (n=6, animal models (n=27, and neurobiology (n=9 – including both neurophysiology and neuropathology studies. The majority (61% of citation classics on epilepsy were published after 1986, possibly reflecting the expansion of research interest in laboratory studies driven by the development of new methodologies, specifically in the fields of genetics and animal models. Consequently, clinical studies were highly cited both before and after the mid 80s, whilst laboratory researches became widely cited after 1990. CONCLUSIONS: Our study indicates that the main drivers of scientific impact in the field of epileptology have increasingly become genetic and neurobiological studies, along with research on animal models of epilepsy. These articles are able to gain the highest numbers of citations in the time span of a few years and suggest potential directions for future research.

Effective Strategies for Increasing Citation Frequency

Science.gov (United States)

Ebrahim, Nader Ale; Salehi, Hadi; Embi, Mohamed Amin; Tanha, Farid Habibi; Gholizadeh, Hossein; Motahar, Seyed Mohammad; Ordi, Ali

2013-01-01

Due to the effect of citation impact on The Higher Education (THE) world university ranking system, most of the researchers are looking for some helpful techniques to increase their citation record. This paper by reviewing the relevant articles extracts 33 different ways for increasing the citations possibilities. The results show that the article…

Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells.

Science.gov (United States)

Klíma, Petr; Laňková, Martina; Vandenbussche, Filip; Van Der Straeten, Dominique; Petrášek, Jan

2018-05-01

Silver ions increase plasma membrane permeability for water and small organic compounds through their stimulatory effect on plasma membrane calcium channels, with subsequent modulation of intracellular calcium levels and ion homeostasis. The action of silver ions at the plant plasma membrane is largely connected with the inhibition of ethylene signalling thanks to the ability of silver ion to replace the copper cofactor in the ethylene receptor. A link coupling the action of silver ions and cellular auxin efflux has been suggested earlier by their possible direct interaction with auxin efflux carriers or by influencing plasma membrane permeability. Using tobacco BY-2 cells, we demonstrate here that besides a dramatic increase of efflux of synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthalene acetic acid (NAA), treatment with AgNO 3 resulted in enhanced efflux of the cytokinin trans-zeatin (tZ) as well as the auxin structural analogues tryptophan (Trp) and benzoic acid (BA). The application of AgNO 3 was accompanied by gradual water loss and plasmolysis. The observed effects were dependent on the availability of extracellular calcium ions (Ca 2+ ) as shown by comparison of transport assays in Ca 2+ -rich and Ca 2+ -free buffers and upon treatment with inhibitors of plasma membrane Ca 2+ -permeable channels Al 3+ and ruthenium red, both abolishing the effect of AgNO 3 . Confocal microscopy of Ca 2+ -sensitive fluorescence indicator Fluo-4FF, acetoxymethyl (AM) ester suggested that the extracellular Ca 2+ availability is necessary to trigger the response to silver ions and that the intracellular Ca 2+ pool alone is not sufficient for this effect. Altogether, our data suggest that in plant cells the effects of silver ions originate from the primal modification of the internal calcium levels, possibly by their interaction with Ca 2+ -permeable channels at the plasma membrane.

Improving power conversion efficiency of perovskite solar cells by cooperative LSPR of gold-silver dual nanoparticles

Institute of Scientific and Technical Information of China (English)

Peng Liu; Cong-hua Zhou; Bing-chu Yang; Gang Liu; Run-sheng Wu; Chu-jun Zhang; Fang Wan; Shui-gen Li; Jun-liang Yang; Yong-li Gao

2017-01-01

Enhancing optical and electrical performances is effective in improving power conversion efficiency of photovoltaic devices.Here,gold and silver dual nanoparticles were imported and embedded in the hole transport layer of perovskite solar cells.Due to the cooperative localized surface plasmon resonance of these two kinds of metal nanostructures,light harvest of perovskite material layer and the electrical performance of device were improved,which finally upgraded short circuit current density by 10.0％,and helped to increase power conversion efficiency from 10.4％ to 11.6％ under AM 1.5G illumination with intensity of 100 mW/cm2.In addition,we explored the influence of silver and gold nanoparticles on charge carrier generation,dissociation,recombination,and transportation inside perovskite solar cells.

Characterization of Electrochemically Generated Silver

Science.gov (United States)

Adam, Niklas; Martinez, James; Carrier, Chris

2014-01-01

Silver biocide offers a potential advantage over iodine, the current state of the art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. Low concentrations of silver (Silver does not require hardware to remove it from a water system, and therefore can provide a simpler means for disinfecting water. The Russian segment of the International Space Station has utilized an electrochemically generated silver solution, which is colloidal in nature. To be able to reliably provide a silver biocide to drinking water by electrochemical means would reduce mass required for removing another biocide such as iodine from the water. This would also aid in crew time required to replace iodine removal cartridges. Future long term missions would benefit from electrochemically produced silver as the biocide could be produced on demand and requires only a small concentration to be effective. Since it can also be consumed safely, there is less mass in removal hardware and little consumables required for production. The goal of this project initially is to understand the nature of the electrochemically produced silver, the particle sizes produced by the electrochemical cell and the effect that voltage adjustment has on the particle size. In literature, it has been documented that dissolved oxygen and pH have an effect on the ionization of the electrochemical silver so those parameters would be measured and possibly adjusted to understand their effect on the silver.

Antibacterial properties and mechanisms of gold-silver nanocages

Science.gov (United States)

Wang, Yulan; Wan, Jiangshan; Miron, Richard J.; Zhao, Yanbin; Zhang, Yufeng

2016-05-01

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

Cytotoxicity and genotoxicity of biogenic silver nanoparticles

International Nuclear Information System (INIS)

Lima, R; Feitosa, L O; Ballottin, D; Tasic, L; Durán, N; Marcato, P D

2013-01-01

Biogenic silver nanoparticles with 40.3 ± 3.5 nm size and negative surface charge (− 40 mV) were prepared with Fusarium oxysporum. The cytotoxicity of 3T3 cell and human lymphocyte were studied by a TaliTM image-based cytometer and the genotoxicity through Allium cepa and comet assay. The results of BioAg-w (washed) and BioAg-nw (unwashed) biogenic silver nanoparticles showed cytotoxicity exceeding 50 μg/mL with no significant differences of response in 5 and 10 μg/mL regarding viability. Results of genotoxicity at concentrations 5.0 and 10.0 ug/mL show some response, but at concentrations 0.5 and 1.0 μg/mL the washed and unwashed silver nanoparticles did not present any effect. This in an important result since in tests with different bacteria species and strains, including resistant, MIC (minimal inhibitory concentration) had good answers at concentrations less than 1.9 μg/mL. This work concludes that biogenic silver nanoparticles may be a promising option for antimicrobial use in the range where no cyto or genotoxic effect were observed. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other cells.

Factors influencing the preparation of silver-coated glass frit with polyvinyl-pyrrolidone

Science.gov (United States)

Xiang, Feng; Gan, Weiping

2018-01-01

In this work, a new electroless silver plating method for the synthesis of silver-coated glass frit composite powders with good morphology has been proposed and the polyvinyl-pyrrolidone (PVP) was used the activating agent. It was found that the weight ratio of PVP to glass frit affected the distribution and number of silver nanoparticles. Moreover, the loading capacity of the glass frit, the pH value and reaction temperature could influence the size of the silver nanoparticles and morphology of silver on the surface of glass frit. The as-prepared silver-coated glass frit was used to prepare a silver paste using an optimized process to form silver nanoparticles with uniform size and high density. The silver paste with silver-coated glass frit increased the photovoltaic conversion efficiency of silicon solar cells by 0.271% compared with the silver paste prepared with pure glass frit. The silver nanoparticles can promoted the precipitation of Ag crystallites on the silicon wafer. Therefore, the silver-coated glass frit can further optimize and enhance the electrical performance of solar cells.

Texting and accessing the web while driving: traffic citations and crashes among young adult drivers.

Science.gov (United States)

Cook, Jerry L; Jones, Randall M

2011-12-01

We examined relations between young adult texting and accessing the web while driving with driving outcomes (viz. crashes and traffic citations). Our premise is that engaging in texting and accessing the web while driving is not only distracting but that these activities represent a pattern of behavior that leads to an increase in unwanted outcomes, such as crashes and citations. College students (N = 274) on 3 campuses (one in California and 2 in Utah) completed an electronic questionnaire regarding their driving experience and cell phone use. Our data indicate that 3 out of 4 (74.3%) young adults engage in texting while driving, over half on a weekly basis (51.8%), and some engage in accessing the web while driving (16.8%). Data analysis revealed a relationship between these cell phone behaviors and traffic citations and crashes. The findings support Jessor and Jessor's (1977) "problem behavior syndrome" by showing that traffic citations are related to texting and accessing the web while driving and that crashes are related to accessing the web while driving. Limitations and recommendations are discussed.

Incineration of organic solar cells: Efficient end of life management by quantitative silver recovery

DEFF Research Database (Denmark)

Søndergaard, Roar R.; Zimmermann, Yannick Serge; Espinosa Martinez, Nieves

2016-01-01

Recovery of silver from the electrodes of roll-to-roll processed organic solar cells after incineration has been performed quantitatively by extraction with nitric acid. This procedure is more than 10 times faster than previous reports and the amount of acid needed for the extraction is reduced...

Incites into Citation Linking using the OAI-PMH

CERN Multimedia

CERN. Geneva

2005-01-01

There are some 300 repositories of research material (Source: IAR), most of which have an OAI-PMH interface, but no current Institutional Repositories export reference data - nor do they provide their users with citation impact metrics. We propose a model for extending IR's to be citation aware and to expose that data to citation indices using the OAI-PMH and OpenURL. We present some techniques for the export of citation data using the OAI-PMH in Citebase Search. As part of a proposed Open Access Citation Information study we have developed a proposal for the integration of reference parsing and linking into the author- deposit process. This highly-distributed approach to citation linking utilises the OAI-PMH to transfer structured citation data between IRs and citation indexing services. OpenURL - a standard for contextual linking using bibliographic data - is now a NISO standard. As well as it's linking role, OpenURL is a useful standard for the transfer of bibliographic data for the purposes of citation in...

Using incomplete citation data for MEDLINE results ranking.

Science.gov (United States)

Herskovic, Jorge R; Bernstam, Elmer V

2005-01-01

Information overload is a significant problem for modern medicine. Searching MEDLINE for common topics often retrieves more relevant documents than users can review. Therefore, we must identify documents that are not only relevant, but also important. Our system ranks articles using citation counts and the PageRank algorithm, incorporating data from the Science Citation Index. However, citation data is usually incomplete. Therefore, we explore the relationship between the quantity of citation information available to the system and the quality of the result ranking. Specifically, we test the ability of citation count and PageRank to identify "important articles" as defined by experts from large result sets with decreasing citation information. We found that PageRank performs better than simple citation counts, but both algorithms are surprisingly robust to information loss. We conclude that even an incomplete citation database is likely to be effective for importance ranking.

Colouring of PK cells nucleoli with silver in case of hyperactivation and activation of RNA nucleoli synthesis under ultraviolet radiation

International Nuclear Information System (INIS)

Sacharov, V.N.; Voronkova, L.N.; Valova, T.M.

1988-01-01

Localization and redistribution of silver-coloured nucleolus proteins in pig embryo kidney cell nuclei under postmitotic formation and evolution of nucleoli in order and under UV-microirradiation stimulated degradation and neature nucleolus compensator hyperactivation in the interphase are studied. In the anaphase chromosome set only 4 silver granules colouring the nucleolus organizer proteins were usually detected. At the initial stages of nucleolus postmitotic formation the number of silver granules in nucleolus organizer increased rapidly up to 25-30 per a nucleus, and at subsequent cellular cycle stages it doubled gradually. Under the natural growth and stimulated modifications of nucleoli the change of silver granule number in nucleoli correlated with the changes of nucleolus sizes and with the change of nucleolus RNA synthesis level. A possible connection between the nucleolus functional activity and the presence of proteins coloured with silver is discussed

Silver-zinc: status of technology and applications

Energy Technology Data Exchange (ETDEWEB)

Karpinski, A.P.; Makovetski, B.; Russell, S.J.; Serenyi, J.R.; Williams, D.C. [Yardney Technical Products, Pawcatuck, CT (United States)

1999-07-01

available in small cylindrical cells) and lack of an established data base. In spite of the advantages noted for the popular secondary systems, the silver-zinc couple still is the system of choice where high specific energy/energy density, coupled with high specific power/power density are important for high-rate, weight or size-sensitive applications. In the 1950s, Yardney developed the first practical rechargeable silver-zinc cell for an underwater application. The U.S. Navy, recognizing the potential of this system for torpedo propulsion, soon adopted it to power the majority of its electric torpedoes - increasing their speed and range, and allowing more room for increasing the performance capability of the torpedo. One of the first programmes which adopted the silver-zinc technology was the MK58 or `Brush` torpedo which consisted of 44 A h cells. At that time, silver-zinc batteries became the preferred system for many other applications. Some of the unique systems include the largest silver-zinc battery ever made, a 256-ton battery for the Albacore G-5 submarine. This battery consisted of a two-section, two-hundred-and-eighty-cell battery, with each cell rated at 20,000 A h. Each cell was essentially the size of a standard four-drawer filing cabinet. Since that time, many of the silver-zinc applications have considerably scaled down their power requirements. Underwater applications are consistently using the larger sized batteries while the smallest are typically found in missile applications. This paper will describe some of the current activities in addressing the major components of the cell and a summary of the current applications of the silver-zinc system. (orig.)

Synthesis and Characterization of Silver Nanoparticles Using Cannonball Leaves and Their Cytotoxic Activity against MCF-7 Cell Line

International Nuclear Information System (INIS)

Devaraj, P.; Kumari, P.; Aarti, Ch.; Renganathan, A.

2013-01-01

Cannonball (Couroupita guianensis) is a tree belonging to the family Lecythidaceae. Various parts of the tree have been reported to contain oils, keto steroids, glycosides, couroupitine, indirubin, isatin, and phenolic substances. We report here the synthesis of silver nanoparticles (AgNPs) using cannonball leaves. Green synthesized nanoparticles have been characterized by UV-Vis spectroscopy, SEM, TEM, and FTIR. Cannonball leaf broth as a reducing agent converts silver ions to AgNPs in a rapid and eco friendly manner. The UV-Vis spectra gave surface plasmon resonance peak at 434 nm. TEM image shows well-dispersed silver nanoparticles with an average particle size of 28.4 nm. FTIR showed the structure and respective bands of the synthesized nanoparticles and the stretch of bonds. Green synthesized silver nanoparticles by cannonball leaf extract show cytotoxicity to human breast cancer cell line (MCF-7). Overall, this environmentally friendly method of biological silver nanoparticles production provides rates of synthesis faster than or comparable to those of chemical methods and can potentially be used in various human contacting areas such as cosmetics, foods, and medical applications.

Ranking national research systems by citation indicators

DEFF Research Database (Denmark)

Aksnes, Dag W.; Schneider, Jesper Wiborg; Gunnarsson, Magnus

2012-01-01

This paper presents an empirical analysis of two different methodologies for calculating national citation indicators: whole counts and fractionalised counts. The aim of our study is to investigate the effect on relative citation indicators when citations to documents are fractionalised among the...

Inspection Citations

Data.gov (United States)

U.S. Department of Health & Human Services — Disclosure of reporting citations provide the public with a rationale for the Agency’s enforcement actions and will also help to inform public and industry...

Silver as antibacterial towards Listeria monocytogenes

Directory of Open Access Journals (Sweden)

Simone eBelluco

2016-03-01

Full Text Available Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs or silver nitrate (AgNO3. Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action.

In vitro percutaneous penetration and characterization of silver from silver-containing textiles

Directory of Open Access Journals (Sweden)

Bianco C

2015-03-01

Full Text Available Carlotta Bianco,1 Sanja Kezic,2 Matteo Crosera,1 Vesna Svetličić,3 Suzana Šegota,3 Giovanni Maina,4 Canzio Romano,5 Francesca Larese,6,7 Gianpiero Adami11Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy; 2Academic Medical Center, Coronel Institute, University of Amsterdam, Amsterdam, the Netherlands; 3Laboratory for Bioelectrochemistry and Surface Imaging, Division for Marine and Environmental Research, Ruder Boškovic Institute, Zagreb, Croatia; 4Department of Clinical and Biological Sciences, University of Turin, Turin, Italy; 5Department of Public and Pediatric Health Sciences, University of Turin, Turin, Italy; 6Unit of Occupational Medicine, University of Trieste, Trieste, Italy; 7Department of Medical Sciences, University of Trieste, Trieste, ItalyAbstract: The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS and by inductively coupled plasma mass spectrometer (ICP-MS. The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX. Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM. On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration ranged from 0.7 to 4.7 µg/mL (0.6–4.0 µg/cm2, fitting the bactericidal range. Silver and silver

Mutagenicity of silver nanoparticles in CHO cells dependent on particle surface functionalization and metabolic activation

Science.gov (United States)

Guigas, Claudia; Walz, Elke; Gräf, Volker; Heller, Knut J.; Greiner, Ralf

2017-06-01

The potential of engineered nanomaterials to induce genotoxic effects is an important aspect of hazard identification. In this study, cytotoxicity and mutagenicity as a function of metabolic activation of three silver nanoparticle (AgNP) preparations differing in surface coating were determined in Chinese hamster ovary (CHO) subclone K1 cells. Three silver nanoparticle preparations ( x 90,0 culture medium containing 10% fetal calf serum (FCS) than in medium without FCS. The HPRT test without metabolic activation system S9 revealed that compared to the other AgNP formulations, citrate-coated Ag showed a lower genotoxic effect. However, addition of S9 increased the mutation frequency of all AgNPs and especially influenced the genotoxicity of Citrate-Ag. The results showed that exogenous metabolic activation of nanosilver is crucial even if interactions of the metabolic activation system, nanosilver, and cells are not really understood up to now.

Human skin penetration of silver nanoparticles through intact and damaged skin

International Nuclear Information System (INIS)

Larese, Francesca Filon; D'Agostin, Flavia; Crosera, Matteo; Adami, Gianpiero; Renzi, Nadia; Bovenzi, Massimo; Maina, Giovanni

2009-01-01

There is a growing interest on nanoparticle safety for topical use. The benefits of nanoparticles have been shown in several scientific fields, but little is known about their potential to penetrate the skin. This study aims at evaluating in vitro skin penetration of silver nanoparticles. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. Physiological solution was used as receiving phase and 70 μg/cm 2 of silver nanoparticles coated with polyvinylpirrolidone dispersed in synthetic sweat were applied as donor phase to the outer surface of the skin for 24 h. The receptor fluid measurements were performed by electro thermal atomic absorption spectroscopy (ETAAS). Human skin penetration was also determined by using transmission electron microscope (TEM) to verify the location of silver nanoparticles in exposed membranes. Median silver concentrations of 0.46 ng cm -2 (range -2 (range 0.43-11.6) were found in the receiving solutions of cells where the nanoparticles solution was applied on intact skin (eight cells) and on damaged skin (eight cells), respectively. Twenty-four hours silver flux permeation in damaged skin was 0.62 ± 0.2 ng cm -2 with a lag time <1 h. Our experimental data showed that silver nanoparticles absorption through intact and damaged skin was very low but detectable, and that in case of damaged skin it was possible an increasing permeation of silver applied as nanoparticles. Moreover, silver nanoparticles could be detected in the stratum corneum and the outermost surface of the epidermis by electron microscopy. We demonstrated for the first time that silver applied as nanoparticles coated with polyvinylpirrolidone is able to permeate the damaged skin in an in vitro diffusion cell system

Citation Sentiment Analysis in Clinical Trial Papers.

Science.gov (United States)

Xu, Jun; Zhang, Yaoyun; Wu, Yonghui; Wang, Jingqi; Dong, Xiao; Xu, Hua

2015-01-01

In scientific writing, positive credits and negative criticisms can often be seen in the text mentioning the cited papers, providing useful information about whether a study can be reproduced or not. In this study, we focus on citation sentiment analysis, which aims to determine the sentiment polarity that the citation context carries towards the cited paper. A citation sentiment corpus was annotated first on clinical trial papers. The effectiveness of n-gram and sentiment lexicon features, and problem-specified structure features for citation sentiment analysis were then examined using the annotated corpus. The combined features from the word n-grams, the sentiment lexicons and the structure information achieved the highest Micro F-score of 0.860 and Macro-F score of 0.719, indicating that it is feasible to use machine learning methods for citation sentiment analysis in biomedical publications. A comprehensive comparison between citation sentiment analysis of clinical trial papers and other general domains were conducted, which additionally highlights the unique challenges within this domain.

Models for mass transfer effects in semi-fuel cells and for a silver-zinc battery

Science.gov (United States)

Venkatraman, Murali Sankar

Semi-Fuel Cells (SFCs) and Silver-Zinc batteries have been recognized as batteries for high power applications. For channel flow between two parallel plates, featured in SFCs, obstacles may take the form of ordered asymmetrical porous nets. The net controls the spacing between the two electrode plates. The effect of the inert insulating net and its geometry on the heat and mass transfer characteristics in such a system is presented. The governing equations for momentum, continuity, and energy are solved in a three-dimensional domain using a commercial computational fluid dynamics software for fully developed flow with constant temperature boundary conditions. The local Nusselt number is calculated from the resulting temperature distribution. This net also affects the limiting current distribution in an SFC operating at limiting current because it disrupts the parabolic laminar flow velocity distribution. Hence, the current density distribution is obtained from the Nusselt number distribution through a heat and mass transfer analogy. The location, spacing, and number of the longitudinal and transverse ribs of the net are shown to affect the local and average current density distributions and Nusselt numbers on each of the two electrode plates. The results show that transverse ribs have a greater effect and that the enhancements of the average current density of 250% can be obtained for a spacing of 0.94 x 10-3 m with greater than 16 transverse ribs. A silver-zinc battery shows similar mass transfer limitations while discharged at moderate to high discharge rates. A one-dimensional mathematical model consisting of a negative (zinc) electrode, separator, and positive (silver) electrode, has been developed to study the performance and thermal behavior of the silver-zinc cell during discharge. The physical phenomena described here are reaction kinetics, mass transfer and heat generation. The analysis includes finite matrix conductivities (thermal and electrical

Citation Matching in Sanskrit Corpora Using Local Alignment

Science.gov (United States)

Prasad, Abhinandan S.; Rao, Shrisha

Citation matching is the problem of finding which citation occurs in a given textual corpus. Most existing citation matching work is done on scientific literature. The goal of this paper is to present methods for performing citation matching on Sanskrit texts. Exact matching and approximate matching are the two methods for performing citation matching. The exact matching method checks for exact occurrence of the citation with respect to the textual corpus. Approximate matching is a fuzzy string-matching method which computes a similarity score between an individual line of the textual corpus and the citation. The Smith-Waterman-Gotoh algorithm for local alignment, which is generally used in bioinformatics, is used here for calculating the similarity score. This similarity score is a measure of the closeness between the text and the citation. The exact- and approximate-matching methods are evaluated and compared. The methods presented can be easily applied to corpora in other Indic languages like Kannada, Tamil, etc. The approximate-matching method can in particular be used in the compilation of critical editions and plagiarism detection in a literary work.

Optimization of silver-dielectric-silver nanoshell for sensing applications

International Nuclear Information System (INIS)

Shirzaditabar, Farzad; Saliminasab, Maryam

2013-01-01

In this paper, resonance light scattering (RLS) properties of a silver-dielectric-silver nanoshell, based on quasi-static approach and plasmon hybridization theory, are investigated. Scattering spectrum of silver-dielectric-silver nanoshell has two intense and clearly separated RLS peaks and provides a potential for biosensing based on surface plasmon resonance and surface-enhanced Raman scattering. The two RLS peaks in silver-dielectric-silver nanoshell are optimized by tuning the geometrical dimensions. In addition, the optimal geometry is discussed to obtain the high sensitivity of silver-dielectric-silver nanoshell. As the silver core radius increases, the sensitivity of silver-dielectric-silver nanoshell decreases whereas increasing the middle dielectric thickness increases the sensitivity of silver-dielectric-silver nanoshell

In vitro studies of the toxic effects of silver nanoparticles on HeLa and U937 cells

Directory of Open Access Journals (Sweden)

Kaba SI

2015-03-01

Full Text Available Said I Kaba, Elena M Egorova Institute of General Pathology and Pathophysiology, Moscow, Russia Abstract: In the last decade, much attention has been paid to studies of the effect of silver nanoparticles (Ag NPs on tumor cells. Apart from elucidation of the mechanism of NPs’ interaction with mammalian cells, these studies are aimed at discovering new effective antitumor drugs. In this work, we report about the toxic effects of Ag NPs observed on two types of tumor cells: HeLa (adhesive cells and U937 (suspension cells. The Ag NPs were obtained by an original method of biochemical synthesis. Particle size was 13.2±4.72 nm, and zeta potential was -61.9±3.2 mV. The toxicity of Ag NPs in the concentration range 0.5–8.0 µg Ag/mL was determined by means of 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay and cytofluorometry after 4 and 24 hours' incubation. It was found that Ag NPs had high toxicity toward both cell types. The minimal concentrations where a toxicity effect was registered (toxicity thresholds lied in the range 0.5–2.0 µg Ag/mL. In parallel with the Ag NP solution, cells were incubated with water solutions of the NP stabilizer (aerosol-OT and Ag+ ions (as silver nitrate. It was shown that aerosol-OT had no effect on the viability on HeLa cells, but was moderately toxic toward U937, though less dangerous for these cells than Ag NPs. With Ag+ ions, for HeLa no toxic effect was observed, while for U937 they were as toxic as the Ag NPs. The data obtained indicate that Ag NPs as used in this study may prove to be useful for the creation of medicines for cancer therapy. Keywords: silver nanoparticles, cell viability, apoptosis, tumor cells

Automating data citation: the eagle-i experience.

Science.gov (United States)

Alawini, Abdussalam; Chen, Leshang; Davidson, Susan B; Da Silva, Natan Portilho; Silvello, Gianmaria

2017-06-01

Data citation is of growing concern for owners of curated databases, who wish to give credit to the contributors and curators responsible for portions of the dataset and enable the data retrieved by a query to be later examined. While several databases specify how data should be cited, they leave it to users to manually construct the citations and do not generate them automatically. We report our experiences in automating data citation for an RDF dataset called eagle-i, and discuss how to generalize this to a citation framework that can work across a variety of different types of databases (e.g. relational, XML, and RDF). We also describe how a database administrator would use this framework to automate citation for a particular dataset.

Silver nanoparticle protein corona composition in cell culture media.

Science.gov (United States)

Shannahan, Jonathan H; Lai, Xianyin; Ke, Pu Chun; Podila, Ramakrishna; Brown, Jared M; Witzmann, Frank A

2013-01-01

The potential applications of nanomaterials as drug delivery systems and in other products continue to expand. Upon introduction into physiological environments and driven by energetics, nanomaterials readily associate proteins forming a protein corona (PC) on their surface. This PC influences the nanomaterial's surface characteristics and may impact their interaction with cells. To determine the biological impact of nanomaterial exposure as well as nanotherapeutic applications, it is necessary to understand PC formation. Utilizing a label-free mass spectrometry-based proteomics approach, we examined the composition of the PC for a set of four silver nanoparticles (AgNPs) including citrate-stabilized and polyvinlypyrrolidone-stabilized (PVP) colloidal silver (20 or 110 nm diameter). To simulate cell culture conditions, AgNPs were incubated for 1 h in Dulbecco's Modified Eagle Medium supplemented with 10% fetal bovine serum, washed, coronal proteins solubilized, and proteins identified and quantified by label-free LC-MS/MS. To determine which attributes influence PC formation, the AgNPs were characterized in both water and cell culture media with 10% FBS. All AgNPs associated a common subset of 11 proteins including albumin, apolipoproteins, keratins, and other serum proteins. 110 nm citrate- and PVP-stabilized AgNPs were found to bind the greatest number of proteins (79 and 85 respectively) compared to 20 nm citrate- and PVP-stabilized AgNPs (45 and 48 respectively), suggesting a difference in PC formation based on surface curvature. While no relationships were found for other protein parameters (isoelectric point or aliphatic index), the PC on 20 nm AgNPs (PVP and citrate) consisted of more hydrophobic proteins compared to 110 nm AgNPs implying that this class of proteins are more receptive to curvature-induced folding and crowding in exchange for an increased hydration in the aqueous environment. These observations demonstrate the significance of electrostatic

Silver nanoparticle protein corona composition in cell culture media.

Directory of Open Access Journals (Sweden)

Jonathan H Shannahan

Full Text Available The potential applications of nanomaterials as drug delivery systems and in other products continue to expand. Upon introduction into physiological environments and driven by energetics, nanomaterials readily associate proteins forming a protein corona (PC on their surface. This PC influences the nanomaterial's surface characteristics and may impact their interaction with cells. To determine the biological impact of nanomaterial exposure as well as nanotherapeutic applications, it is necessary to understand PC formation. Utilizing a label-free mass spectrometry-based proteomics approach, we examined the composition of the PC for a set of four silver nanoparticles (AgNPs including citrate-stabilized and polyvinlypyrrolidone-stabilized (PVP colloidal silver (20 or 110 nm diameter. To simulate cell culture conditions, AgNPs were incubated for 1 h in Dulbecco's Modified Eagle Medium supplemented with 10% fetal bovine serum, washed, coronal proteins solubilized, and proteins identified and quantified by label-free LC-MS/MS. To determine which attributes influence PC formation, the AgNPs were characterized in both water and cell culture media with 10% FBS. All AgNPs associated a common subset of 11 proteins including albumin, apolipoproteins, keratins, and other serum proteins. 110 nm citrate- and PVP-stabilized AgNPs were found to bind the greatest number of proteins (79 and 85 respectively compared to 20 nm citrate- and PVP-stabilized AgNPs (45 and 48 respectively, suggesting a difference in PC formation based on surface curvature. While no relationships were found for other protein parameters (isoelectric point or aliphatic index, the PC on 20 nm AgNPs (PVP and citrate consisted of more hydrophobic proteins compared to 110 nm AgNPs implying that this class of proteins are more receptive to curvature-induced folding and crowding in exchange for an increased hydration in the aqueous environment. These observations demonstrate the significance of

Universality of Citation Distributions for Academic Institutions and Journals

Science.gov (United States)

Chatterjee, Arnab; Ghosh, Asim; Chakrabarti, Bikas K.

2016-01-01

Citations measure the importance of a publication, and may serve as a proxy for its popularity and quality of its contents. Here we study the distributions of citations to publications from individual academic institutions for a single year. The average number of citations have large variations between different institutions across the world, but the probability distributions of citations for individual institutions can be rescaled to a common form by scaling the citations by the average number of citations for that institution. We find this feature seems to be universal for a broad selection of institutions irrespective of the average number of citations per article. A similar analysis for citations to publications in a particular journal in a single year reveals similar results. We find high absolute inequality for both these sets, Gini coefficients being around 0.66 and 0.58 for institutions and journals respectively. We also find that the top 25% of the articles hold about 75% of the total citations for institutions and the top 29% of the articles hold about 71% of the total citations for journals. PMID:26751563

37 CFR 41.12 - Citation of authority.

Science.gov (United States)

2010-07-01

... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Citation of authority. 41.12... COMMERCE PRACTICE BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES General Provisions § 41.12 Citation.... (a) Citations to authority must include: (1) For any United States Supreme Court decision, a United...

Writing references and using citation management software.

Science.gov (United States)

Sungur, Mukadder Orhan; Seyhan, Tülay Özkan

2013-09-01

The correct citation of references is obligatory to gain scientific credibility, to honor the original ideas of previous authors and to avoid plagiarism. Currently, researchers can easily find, cite and store references using citation management software. In this review, two popular citation management software programs (EndNote and Mendeley) are summarized.

Citation Classics from Industrial Marketing Management

DEFF Research Database (Denmark)

Lindgreen, Adam; Di Benedetto, C. Anthony

2017-01-01

, system sellers and systems integrator, third-party logistics providers, and value). Finally, each of the 30 citation classics is introduced, and the classics' theoretical implications to business-to-business marketing management and fields related to (e.g., supply chain management, strategic management......This article proposes a categorization of what constitutes a citation classic. General observations reveal, with regard to the top 30 citation classics from Industrial Marketing Management, the number of authors per article, country of origin of the lead author, and type of article (literature...... review, qualitative methodology, or quantitative methodology). In addition, these citation classics can be classified by topic (firm performance, goods-dominant and service-dominant logics, Internet and high-technology markets, product innovation, relationships and business networks, supply chains...

Non-hazardous anticancerous and antibacterial colloidal 'green' silver nanoparticles.

Science.gov (United States)

Barua, Shaswat; Konwarh, Rocktotpal; Bhattacharya, Satya Sundar; Das, Pallabi; Devi, K Sanjana P; Maiti, Tapas K; Mandal, Manabendra; Karak, Niranjan

2013-05-01

Poly(ethylene glycol) stabilized colloidal silver nanoparticles were prepared using the reductive potency of the aqueous extract of Thuja occidentalis leaves under ambient conditions. The nanoparticles were well dispersed within a narrow size spectrum (7-14 nm) and displayed characteristic surface plasmon resonance peak at around 420 nm and Bragg's reflection planes of fcc structure. MTT assay revealed the dose-dependent cytocompatibility and toxicity of the nanoparticles with the L929 normal cell line. On the other hand, the antiproliferative action of the nanoparticles was evaluated on HeLa cell (cancerous cells) line. Fluorescence and phase contrast microscopic imaging indicated the appearance of multinucleate stages with aggregation and nuclear membrane disruption of the HeLa cells post treatment with the nanoparticles. The interaction at the prokaryotic level was also assessed via differential antibacterial efficacy against Staphylococcus aureus (MTCC 3160) and Escherichia coli (MTCC 40). Under these perspectives, it is also necessary to observe the environmental impact of the prepared silver nanoparticles. Hence, the dose dependent toxicity of silver nanoparticles was evaluated upon the earthworm species Eisenia fetida. Neither the survival nor the reproduction was affected by the addition of silver nanoparticles up to 1000 ppm. Thus these 'green' silver nanoparticles have promising potential as future materials. Copyright © 2012 Elsevier B.V. All rights reserved.

Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

International Nuclear Information System (INIS)

Liu Pengpeng; Guan Rongfa; Jiang Jiaxin; Liu Mingqi; Huang Guangrong; Chen Xiaoting; Ye Xingqian

2011-01-01

Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL -1 . LDH leakage significantly increased in cells exposed to Ag NPs (≥ 25 μg mL -1 ) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL -1 ). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

Science.gov (United States)

Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

2011-07-01

Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

Energy Technology Data Exchange (ETDEWEB)

Liu Pengpeng; Guan Rongfa; Jiang Jiaxin; Liu Mingqi; Huang Guangrong; Chen Xiaoting [Zhejiang Provincial Key Laboratory of Biometrology and Inspection and Quarantine, College of Life Sciences, China Jiliang University, Hangzhou 310018 (China); Ye Xingqian, E-mail: rfguan@163.com [Department of Food Science and Nutrition, School of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310029 (China)

2011-07-06

Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 {mu}g{center_dot}mL{sup -1}. LDH leakage significantly increased in cells exposed to Ag NPs ({>=} 25 {mu}g mL{sup -1}) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 {mu}g{center_dot}mL{sup -1}). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage

Citation Patterns of Engineering, Statistics, and Computer Science Researchers: An Internal and External Citation Analysis across Multiple Engineering Subfields

Science.gov (United States)

Kelly, Madeline

2015-01-01

This study takes a multidimensional approach to citation analysis, examining citations in multiple subfields of engineering, from both scholarly journals and doctoral dissertations. The three major goals of the study are to determine whether there are differences between citations drawn from dissertations and those drawn from journal articles; to…

1 CFR 5.8 - Form of citation.

Science.gov (United States)

2010-01-01

... 1 General Provisions 1 2010-01-01 2010-01-01 false Form of citation. 5.8 Section 5.8 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER GENERAL § 5.8 Form of citation. Without prejudice to any other form of citation, Federal Register material may be cited by volume...

Geographic trends of scientific output and citation practices in psychiatry.

Science.gov (United States)

Igoumenou, Artemis; Ebmeier, Klaus; Roberts, Nia; Fazel, Seena

2014-12-06

Measures of research productivity are increasingly used to determine how research should be evaluated and funding decisions made. In psychiatry, citation patterns within and between countries are not known, and whether these differ by choice of citation metric. In this study, we examined publication characteristics and citation practices in articles published in 50 Web of Science indexed psychiatric and relevant clinical neurosciences journals, between January 2004 and December 2009 comprising 51,072 records that produced 375,962 citations. We compared citation patterns, including self-citations, between countries using standard x(2) tests. We found that most publications came from the USA, with Germany being second and UK third in productivity. USA articles received most citations and the highest citation rate with an average 11.5 citations per article. The UK received the second highest absolute number of citations, but came fourth by citation rate (9.7 citations/article), after the Netherlands (11.4 citations/article) and Canada (9.8 citations/article). Within the USA, Harvard University published most articles and these articles were the most cited, on average 20.0 citations per paper. In Europe, UK institutions published and were cited most often. The Institute of Psychiatry/Kings College London was the leading institution in terms of number of published records and overall citations, while Oxford University had the highest citation rate (18.5 citations/record). There were no differences between the self-citation practices of American and European researchers. Articles that examined some aspect of treatment in psychiatry were the most published. In terms of diagnosis, papers about schizophrenia-spectrum disorders were the most published and the most cited. We found large differences between and within countries in terms of their research productivity in psychiatry and clinical neuroscience. In addition, the ranking of countries and institutions differed widely

Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

Energy Technology Data Exchange (ETDEWEB)

Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

2012-09-01

Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

DEFF Research Database (Denmark)

Palanco, Marta Espina; Mogensen, Klaus Bo; Guehlke, Marina

2016-01-01

We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial...... for one-and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic...... building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts....

Who actually receives cell phone use while driving citations and how much are these laws enforced among states? A descriptive, cross-sectional study

OpenAIRE

Rudisill, Toni M; Zhu, Motao

2016-01-01

Objectives While numerous cell phone use while driving laws have been passed among states, little information exists regarding who gets cited for these traffic infractions and how much these laws are enforced at the state-level within the USA. Design Cross-sectional, descriptive study. Setting 14 states and the District of Columbia. Participants Those receiving cell phone use while driving citations within included states from 2007 to 2013. Primary outcome Demographic characteristics of cited...

Synergistic antibacterial effects of β-lactam antibiotic combined with silver nanoparticles

Science.gov (United States)

Li, Ping; Li, Juan; Wu, Changzhu; Wu, Qingsheng; Li, Jian

2005-09-01

The bactericidal action of silver (0) nanoparticles and amoxicillin on Escherichia coli is studied, respectively. Increasing concentration of both amoxicillin (0-0.525 mg ml-1) and silver nanoparticles (0-40 µg ml-1) showed a higher antibacterial effect in Luria-Bertani (LB) medium. Escherichia coli cells have different bactericidal sensitivity to them. When amoxicillin and silver nanoparticles are combined, it results in greater bactericidal efficiency on Escherichia coli cells than when they were applied separately. Dynamic tests on bacterial growth indicated that exponential and stationary phases are greatly decreased and delayed in the synergistic effect of amoxicillin and silver nanoparticles. In addition, the effect induced by a preincubation with silver nanoparticles is examined. The results show that solutions with more silver nanoparticles have better antimicrobial effects. One hypothesized mechanism is proposed to explain this phenomenon.

Citation Analysis of Hepatitis Monthly by Journal Citation Report (ISI), Google Scholar, and Scopus.

Science.gov (United States)

Miri, Seyyed Mohammad; Raoofi, Azam; Heidari, Zahra

2012-09-01

Citation analysis as one of the most widely used methods of bibliometrics can be used for computing the various impact measures for scholars based on data from citation databases. Journal Citation Reports (JCR) from Thomson Reuters provides annual report in the form of impact factor (IF) for each journal. We aimed to evaluate the citation parameters of Hepatitis Monthly by JCR in 2010 and compare them with GS and Sc. All articles of Hepat Mon published in 2009 and 2008 which had been cited in 2010 in three databases including WoS, Sc and GS gathered in a spreadsheet. The IFs were manually calculated. Among the 104 total published articles the accuracy rates of GS and Sc in recording the total number of articles was 96% and 87.5%. There was a difference between IFs among the three databases (0.793 in ISI [Institute for Scientific Information], 0.945 in Sc and 0.85 GS). The missing rate of citations in ISI was 4% totally. Original articles were the main cited types, whereas, guidelines and clinical challenges were the least ones. None of the three databases succeed to record all articles published in the journal. Despite high sensitivity of GS comparing to Sc, it cannot be a reliable source for indexing since GS has lack of screening in the data collection and low specificity. Using an average of three IFs is suggested to find the correct IF. Editors should be more aware on the role of original articles in increasing IF and the potential efficacy of review articles in long term impact factor.

Interaction of multi-functional silver nanoparticles with living cells

International Nuclear Information System (INIS)

Sur, Ilknur; Cam, Dilek; Kahraman, Mehmet; Culha, Mustafa; Baysal, Asli

2010-01-01

Silver nanoparticles (AgNPs) are widely used in household products and in medicine due to their antibacterial and to wound healing properties. In recent years, there is also an effort for their use in biomedical imaging and photothermal therapy. The primary reason behind the effort for their utility in biomedicine and therapy is their unique plasmonic properties and easy surface chemistry for a variety of functionalizations. In this study, AgNPs modified with glucose, lactose, oligonucleotides and combinations of these ligands are investigated for their cytotoxicity and cellular uptake in living non-cancer (L929) and cancer (A549) cells. It is found that the chemical nature of the ligand strongly influences the toxicity and cellular uptake into the model cells. While the lactose-and glucose-modified AgNPs enter the L929 cells at about the same rate, a significant increase in the rate of lactose-modified AgNPs into the A549 cells is observed. The binding of oligonucleotides along with the carbohydrate on the AgNP surfaces influences the differential uptake rate pattern into the cells. The cytotoxicity study with the modified AgNPs reveals that only naked AgNPs influence the viability of the A549 cells. The findings of this study may provide the key to developing effective applications in medicine such as cancer therapy.

Citation Semantic Based Approaches to Identify Article Quality

OpenAIRE

S. Sendhilkumar; E. Elakkiya; G.S. Mahalakshmi

2013-01-01

Analyzing the structure of research articles and th e relationship between the articles has always been important in bibliometrics research area. One of the methods for analyzing articles is by its citation. Normally researchers rank the article based on the citation count. But this quantity based evaluation is not sufficient due to various c itation types like Random citation, Guest citation. Our paper aims in providing a new me...

From Excessive Journal Self-Cites to Citation Stacking: Analysis of Journal Self-Citation Kinetics in Search for Journals, Which Boost Their Scientometric Indicators.

Science.gov (United States)

Heneberg, Petr

2016-01-01

Bibliometric indicators increasingly affect careers, funding, and reputation of individuals, their institutions and journals themselves. In contrast to author self-citations, little is known about kinetics of journal self-citations. Here we hypothesized that they may show a generalizable pattern within particular research fields or across multiple fields. We thus analyzed self-cites to 60 journals from three research fields (multidisciplinary sciences, parasitology, and information science). We also hypothesized that the kinetics of journal self-citations and citations received from other journals of the same publisher may differ from foreign citations. We analyzed the journals published the American Association for the Advancement of Science, Nature Publishing Group, and Editura Academiei Române. We found that although the kinetics of journal self-cites is generally faster compared to foreign cites, it shows some field-specific characteristics. Particularly in information science journals, the initial increase in a share of journal self-citations during post-publication year 0 was completely absent. Self-promoting journal self-citations of top-tier journals have rather indirect but negligible direct effects on bibliometric indicators, affecting just the immediacy index and marginally increasing the impact factor itself as long as the affected journals are well established in their fields. In contrast, other forms of journal self-citations and citation stacking may severely affect the impact factor, or other citation-based indices. We identified here a network consisting of three Romanian physics journals Proceedings of the Romanian Academy, Series A, Romanian Journal of Physics, and Romanian Reports in Physics, which displayed low to moderate ratio of journal self-citations, but which multiplied recently their impact factors, and were mutually responsible for 55.9%, 64.7% and 63.3% of citations within the impact factor calculation window to the three journals

Using citation data to improve retrieval from MEDLINE.

Science.gov (United States)

Bernstam, Elmer V; Herskovic, Jorge R; Aphinyanaphongs, Yindalon; Aliferis, Constantin F; Sriram, Madurai G; Hersh, William R

2006-01-01

To determine whether algorithms developed for the World Wide Web can be applied to the biomedical literature in order to identify articles that are important as well as relevant. DESIGN AND MEASUREMENTS A direct comparison of eight algorithms: simple PubMed queries, clinical queries (sensitive and specific versions), vector cosine comparison, citation count, journal impact factor, PageRank, and machine learning based on polynomial support vector machines. The objective was to prioritize important articles, defined as being included in a pre-existing bibliography of important literature in surgical oncology. RESULTS Citation-based algorithms were more effective than noncitation-based algorithms at identifying important articles. The most effective strategies were simple citation count and PageRank, which on average identified over six important articles in the first 100 results compared to 0.85 for the best noncitation-based algorithm (p PageRank more than simple citation count. However, in spite of citation lag, citation-based algorithms remain more effective than noncitation-based algorithms. CONCLUSION Algorithms that have proved successful on the World Wide Web can be applied to biomedical information retrieval. Citation-based algorithms can help identify important articles within large sets of relevant results. Further studies are needed to determine whether citation-based algorithms can effectively meet actual user information needs.

Power-law citation distributions are not scale-free.

Science.gov (United States)

Golosovsky, Michael

2017-09-01

We analyze time evolution of statistical distributions of citations to scientific papers published in the same year. While these distributions seem to follow the power-law dependence we find that they are nonstationary and the exponent of the power-law fit decreases with time and does not come to saturation. We attribute the nonstationarity of citation distributions to different longevity of the low-cited and highly cited papers. By measuring citation trajectories of papers we found that citation careers of the low-cited papers come to saturation after 10-15 years while those of the highly cited papers continue to increase indefinitely: The papers that exceed some citation threshold become runaways. Thus, we show that although citation distribution can look as a power-law dependence, it is not scale free and there is a hidden dynamic scale associated with the onset of runaways. We compare our measurements to our recently developed model of citation dynamics based on copying-redirection-triadic closure and find explanations to our empirical observations.

Relative Citation Ratio (RCR): A New Metric That Uses Citation Rates to Measure Influence at the Article Level.

Science.gov (United States)

Hutchins, B Ian; Yuan, Xin; Anderson, James M; Santangelo, George M

2016-09-01

Despite their recognized limitations, bibliometric assessments of scientific productivity have been widely adopted. We describe here an improved method to quantify the influence of a research article by making novel use of its co-citation network to field-normalize the number of citations it has received. Article citation rates are divided by an expected citation rate that is derived from performance of articles in the same field and benchmarked to a peer comparison group. The resulting Relative Citation Ratio is article level and field independent and provides an alternative to the invalid practice of using journal impact factors to identify influential papers. To illustrate one application of our method, we analyzed 88,835 articles published between 2003 and 2010 and found that the National Institutes of Health awardees who authored those papers occupy relatively stable positions of influence across all disciplines. We demonstrate that the values generated by this method strongly correlate with the opinions of subject matter experts in biomedical research and suggest that the same approach should be generally applicable to articles published in all areas of science. A beta version of iCite, our web tool for calculating Relative Citation Ratios of articles listed in PubMed, is available at https://icite.od.nih.gov.

Relative Citation Ratio (RCR: A New Metric That Uses Citation Rates to Measure Influence at the Article Level.

Directory of Open Access Journals (Sweden)

B Ian Hutchins

2016-09-01

Full Text Available Despite their recognized limitations, bibliometric assessments of scientific productivity have been widely adopted. We describe here an improved method to quantify the influence of a research article by making novel use of its co-citation network to field-normalize the number of citations it has received. Article citation rates are divided by an expected citation rate that is derived from performance of articles in the same field and benchmarked to a peer comparison group. The resulting Relative Citation Ratio is article level and field independent and provides an alternative to the invalid practice of using journal impact factors to identify influential papers. To illustrate one application of our method, we analyzed 88,835 articles published between 2003 and 2010 and found that the National Institutes of Health awardees who authored those papers occupy relatively stable positions of influence across all disciplines. We demonstrate that the values generated by this method strongly correlate with the opinions of subject matter experts in biomedical research and suggest that the same approach should be generally applicable to articles published in all areas of science. A beta version of iCite, our web tool for calculating Relative Citation Ratios of articles listed in PubMed, is available at https://icite.od.nih.gov.

Towards a simple mathematical theory of citation distributions.

Science.gov (United States)

Katchanov, Yurij L

2015-01-01

The paper is written with the assumption that the purpose of a mathematical theory of citation is to explain bibliometric regularities at the level of mathematical formalism. A mathematical formalism is proposed for the appearance of power law distributions in social citation systems. The principal contributions of this paper are an axiomatic characterization of citation distributions in terms of the Ekeland variational principle and a mathematical exploration of the power law nature of citation distributions. Apart from its inherent value in providing a better understanding of the mathematical underpinnings of bibliometric models, such an approach can be used to derive a citation distribution from first principles.

Data Publications Correlate with Citation Impact.

Science.gov (United States)

Leitner, Florian; Bielza, Concha; Hill, Sean L; Larrañaga, Pedro

2016-01-01

Neuroscience and molecular biology have been generating large datasets over the past years that are reshaping how research is being conducted. In their wake, open data sharing has been singled out as a major challenge for the future of research. We conducted a comparative study of citations of data publications in both fields, showing that the average publication tagged with a data-related term by the NCBI MeSH (Medical Subject Headings) curators achieves a significantly larger citation impact than the average in either field. We introduce a new metric, the data article citation index (DAC-index), to identify the most prolific authors among those data-related publications. The study is fully reproducible from an executable Rmd (R Markdown) script together with all the citation datasets. We hope these results can encourage authors to more openly publish their data.

Citation distribution profile in Brazilian journals of general medicine.

Science.gov (United States)

Lustosa, Luiggi Araujo; Chalco, Mario Edmundo Pastrana; Borba, Cecília de Melo; Higa, André Eizo; Almeida, Renan Moritz Varnier Rodrigues

2012-01-01

Impact factors are currently the bibliometric index most used for evaluating scientific journals. However, the way in which they are used, for instance concerning the study or journal types analyzed, can markedly interfere with estimate reliability. This study aimed to analyze the citation distribution pattern in three Brazilian journals of general medicine. This was a descriptive study based on numbers of citations of scientific studies published by three Brazilian journals of general medicine. The journals analyzed were São Paulo Medical Journal, Clinics and Revista da Associação Médica Brasileira. This survey used data available from the Institute for Scientific Information (ISI) platform, from which the total number of papers published in each journal in 2007-2008 and the number of citations of these papers in 2009 were obtained. From these data, the citation distribution was derived and journal impact factors (average number of citations) were estimated. These factors were then compared with those directly available from the ISI Journal of Citation Reports (JCR). Respectively, 134, 203 and 192 papers were published by these journals during the period analyzed. The observed citation distributions were highly skewed, such that many papers had few citations and a small percentage had many citations. It was not possible to identify any specific pattern for the most cited papers or to exactly reproduce the JCR impact factors. Use of measures like "impact factors", which characterize citations through averages, does not adequately represent the citation distribution in the journals analyzed.

PEDOT:PSS incorporated silver nanoparticles prepared by gamma radiation for the application in organic solar cells

Directory of Open Access Journals (Sweden)

Omayma A. Ghazy

2015-04-01

Full Text Available Poly(3,4-ethylenedioxythiophene:Polystyrene sulfonate (PEDOT:PSS is a dispersion used as a buffer layer on the ITO electrode in the organic solar cells. Silver nanoparticles (Ag NPs are incorporated to the dispersion using two different strategies. The first is by reduction of silver ions in the PEDOT:PSS dispersion. Chemical reduction of silver ions using sodium borohydried is compared with reduction using gamma radiation. The TEM and UV-visible spectra indicates that smaller Ag NPs are obtained for the chemical reduction method than those obtained from the radiochemical. The second strategy, is by preparing Ag NPs in polyvinyl pyrolidone (PVP solution using gamma irradiation then adding them to the PEDOT:PSS dispersion. Layers of the PEDOT:PSS incorporated different concentrations of Ag NPs (1, 2, 4, 6, 8, 10% are formed. The SEM and AFM studies of the layers morphology reveal that smooth morphology on the obtained for layers containing Ag NPs up to concentrations of 4%.

Silica artificial opal incorporated with silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

2009-07-15

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

Silica artificial opal incorporated with silver nanoparticles

International Nuclear Information System (INIS)

Li Wenjiang; Sun Tan

2009-01-01

The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

In situ probing of cholesterol in astrocytes at the single-cell level using laser desorption ionization mass spectrometric imaging with colloidal silver.

Science.gov (United States)

Perdian, D C; Cha, Sangwon; Oh, Jisun; Sakaguchi, Donald S; Yeung, Edward S; Lee, Young Jin

2010-04-30

Mass spectrometric imaging has been utilized to localize individual astrocytes and to obtain cholesterol populations at the single-cell level in laser desorption ionization (LDI) with colloidal silver. The silver ion adduct of membrane-bound cholesterol was monitored to detect individual cells. Good correlation between mass spectrometric and optical images at different cell densities indicates the ability to perform single-cell studies of cholesterol abundance. The feasibility of quantification is confirmed by the agreement between the LDI-MS ion signals and the results from a traditional enzymatic fluorometric assay. We propose that this approach could be an effective tool to study chemical populations at the cellular level. Published in 2010 by John Wiley & Sons, Ltd.

Mandatory and Self-citation; Types, Reasons, Their Benefits and Disadvantages.

Science.gov (United States)

Hemmat Esfe, Mohammad; Wongwises, Somchai; Asadi, Amin; Karimipour, Arash; Akbari, Mohammad

2015-12-01

This paper defines and discusses two important types of citations, self-citation and mandatory citation, in engineering journals. Citation can be classified in three categories: optional; semi-mandatory; and mandatory. There are some negative and positive impacts for the authors' paper and journals' reputation if mandatory citation of a paper or set of papers is requested. These effects can be different based on the recommended papers for citing in the new research. Mandatory citation has various types discussed in this paper. Self-citation and its reasons and impacts are also discussed in the present study.

The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1), Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo.

Science.gov (United States)

Sankova, Tatiana P; Orlov, Iurii A; Saveliev, Andrey N; Kirilenko, Demid A; Babich, Polina S; Brunkov, Pavel N; Puchkova, Ludmila V

2017-11-03

There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST) and the N-terminal domain (ectodomain) of human high affinity copper transporter CTR1 (hNdCTR1), which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell's copper metabolism and its chelating properties are discussed.

Survey of formal and informal citation in Google search engine

Directory of Open Access Journals (Sweden)

Afsaneh Teymourikhani

2016-03-01

Full Text Available Aim: Informal citations is bibliographic information (title or Internet address, citing sources of information resources for informal scholarly communication and always neglected in traditional citation databases. This study is done, in order to answer the question of whether informal citations in the web environment are traceable. The present research aims to determine what proportion of web citations of Google search engine is related to formal and informal citation. Research method: Webometrics is the method used. The study is done on 1344 research articles of 98 open access journal, and the method that is used to extract the web citation from Google search engine is “Web / URL citation extraction". Findings: The findings showed that ten percent of the web citations of Google search engine are formal and informal citations. The highest formal citation in the Google search engine with 19/27% is in the field of library and information science and the lowest official citation by 1/54% is devoted to the field of civil engineering. The highest percentage of informal citations with 3/57% is devoted to sociology and the lowest percentage of informal citations by 0/39% is devoted to the field of civil engineering. Journal Citation is highest with 94/12% in the surgical field and lowest with 5/26 percent in the philosophy filed. Result: Due to formal and informal citations in the Google search engine which is about 10 percent and the reduction of this amount compared to previous research, it seems that track citations by this engine should be treated with more caution. We see that the amount of formal citation is variable in different disciplines. Cited journals in the field of surgery, is highest and in the filed of philosophy is lowest, this indicates that in the filed of philosophy, that is a subset of the social sciences, journals in scientific communication do not play a significant role. On the other hand, book has a key role in this filed

Citation distribution profile in Brazilian journals of general medicine

Directory of Open Access Journals (Sweden)

Luiggi Araujo Lustosa

Full Text Available CONTEXT AND OBJECTIVE: Impact factors are currently the bibliometric index most used for evaluating scientific journals. However, the way in which they are used, for instance concerning the study or journal types analyzed, can markedly interfere with estimate reliability. This study aimed to analyze the citation distribution pattern in three Brazilian journals of general medicine. DESIGN AND SETTING: This was a descriptive study based on numbers of citations of scientific studies published by three Brazilian journals of general medicine. METHODS: The journals analyzed were São Paulo Medical Journal, Clinics and Revista da Associação Médica Brasileira. This survey used data available from the Institute for Scientific Information (ISI platform, from which the total number of papers published in each journal in 2007-2008 and the number of citations of these papers in 2009 were obtained. From these data, the citation distribution was derived and journal impact factors (average number of citations were estimated. These factors were then compared with those directly available from the ISI Journal of Citation Reports (JCR. RESULTS: Respectively, 134, 203 and 192 papers were published by these journals during the period analyzed. The observed citation distributions were highly skewed, such that many papers had few citations and a small percentage had many citations. It was not possible to identify any specific pattern for the most cited papers or to exactly reproduce the JCR impact factors. CONCLUSION: Use of measures like "impact factors", which characterize citations through averages, does not adequately represent the citation distribution in the journals analyzed.

Citation analysis in JAERI

International Nuclear Information System (INIS)

Nakamoto, Hideshiro; Shimizu, Takehiro.

1982-01-01

For purposes of the acquisition strategy the citation statistics were investigated on the articles which were published by JAERI staff in 1976, '77 and '78. The citations of 14,769 listed in the off-prints of 1,300 were analized by types of Literature, publication year, scattering, and so on. The results show that the occupation of technical reports increased and the lifetime became longer compared with the results of fifteen years ago. The journal ranking list is the important material for the acquisition of journals in our library. (author)

Green synthesis of silver nanoparticles from aqueous leaf extract of Pomegranate (Punica granatum) and their anticancer activity on human cervical cancer cells

Science.gov (United States)

Sarkar, Sonia; Kotteeswaran, Venkatesan

2018-06-01

Plants contain different important phytochemicals that can be used as a potential treatment for various ailments including cancer. The green synthesis of silver nanoparticles from the extract of different plant parts has gained a wide range of engrossment among the researchers due to its unique optical and structural property. The aim of this study is green synthesis of silver nanoparticles from the aqueous leaf extract of pomegranate (Punica granatum) and to investigate its anticancer activity on human cervical cancer cells (HeLa). The synthesis of silver nanoparticle was depicted by the colour change from golden yellowish to dark brownish, UV-visible spectral analysis gave a characteristic surface plasmon absorption peak at . Further morphological characterization was done by Zeta potential where the size analysis was depicted to be 46.1 nm and zeta potential as . Fourier transform infrared spectroscopy (FTIR) inferred 3 intense sharp peaks at , , , confirmed the presence of flavonoids and polyphenols. The scanning electron microscopy (SEM) analysis with energy diffraction spectroscopy (EDS) confirmed the presence of silver nanoparticles with size ranged from to . X-ray diffraction (XRD) confirmed the crystallographic nature of silver. The cell proliferation activity of nanoparticles was tested by 3, ‑4, 5 dimethylthiazol-2,5 diphenyl tetrazolium bromide (MTT) assay where the inhibitory concentration () was found at inhibiting of HeLa cell line. The anticancer activity of nanoparticles was determined by lactate dehydrogenase (LDH) assay where showed of cytotoxicity. Furthermore, the anticancer property of nanoparticles was confirmed by the DNA fragmentation assay.

36 CFR 1150.48 - PER: Citation, answer, amendment.

Science.gov (United States)

2010-07-01

... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false PER: Citation, answer...; Pleadings and Motions § 1150.48 PER: Citation, answer, amendment. (a) Unless otherwise specified, other..., the citation shall request PER when it appears to the Executive Director that immediate and...

Hyaluronan/Tween 80-assisted synthesis of silver nanoparticles for biological application

Science.gov (United States)

Li, Hui-Jun; Zhang, An-Qi; Sui, Li; Qian, Dong-Jin; Chen, Meng

2015-02-01

Water-soluble and well-stabilized silver nanoparticles (NPs) of small size have been synthesized using hyaluronan (HA) and Tween 80 as reducing and stabilizing agents. The effect of reaction conditions on the formation process of silver NPs was studied, and an aggregative growth mechanism of the silver NPs dominated in HA/Tween 80 system at pH 12 has been proposed. The obtained Ag NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. Moreover, the stability of the HA-Tween 80-silver NPs in normal saline was also studied, and a flexible blend membrane containing chitosan, gelatin, and the HA-Tween 80-silver NPs was prepared for further biological applications. Due to the high specific surface area and improved stability of silver NPs, the chitosan-gelatin-silver membrane has shown high antibacterial activity for strains of Escherichia coli. The cell viability tests indicate that the polymer membrane is non-cytotoxic to HepG2 cells, which might be attributed to its good biocompatibility.

Hyaluronan/Tween 80-assisted synthesis of silver nanoparticles for biological application

International Nuclear Information System (INIS)

Li, Hui-Jun; Zhang, An-Qi; Sui, Li; Qian, Dong-Jin; Chen, Meng

2015-01-01

Water-soluble and well-stabilized silver nanoparticles (NPs) of small size have been synthesized using hyaluronan (HA) and Tween 80 as reducing and stabilizing agents. The effect of reaction conditions on the formation process of silver NPs was studied, and an aggregative growth mechanism of the silver NPs dominated in HA/Tween 80 system at pH 12 has been proposed. The obtained Ag NPs were characterized by UV–Vis spectroscopy, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy. Moreover, the stability of the HA–Tween 80-silver NPs in normal saline was also studied, and a flexible blend membrane containing chitosan, gelatin, and the HA–Tween 80-silver NPs was prepared for further biological applications. Due to the high specific surface area and improved stability of silver NPs, the chitosan–gelatin-silver membrane has shown high antibacterial activity for strains of Escherichia coli. The cell viability tests indicate that the polymer membrane is non-cytotoxic to HepG2 cells, which might be attributed to its good biocompatibility

Multiple Citation Indicators and Their Composite across Scientific Disciplines.

Science.gov (United States)

Ioannidis, John P A; Klavans, Richard; Boyack, Kevin W

2016-07-01

Many fields face an increasing prevalence of multi-authorship, and this poses challenges in assessing citation metrics. Here, we explore multiple citation indicators that address total impact (number of citations, Hirsch H index [H]), co-authorship adjustment (Schreiber Hm index [Hm]), and author order (total citations to papers as single; single or first; or single, first, or last author). We demonstrate the correlation patterns between these indicators across 84,116 scientists (those among the top 30,000 for impact in a single year [2013] in at least one of these indicators) and separately across 12 scientific fields. Correlation patterns vary across these 12 fields. In physics, total citations are highly negatively correlated with indicators of co-authorship adjustment and of author order, while in other sciences the negative correlation is seen only for total citation impact and citations to papers as single author. We propose a composite score that sums standardized values of these six log-transformed indicators. Of the 1,000 top-ranked scientists with the composite score, only 322 are in the top 1,000 based on total citations. Many Nobel laureates and other extremely influential scientists rank among the top-1,000 with the composite indicator, but would rank much lower based on total citations. Conversely, many of the top 1,000 authors on total citations have had no single/first/last-authored cited paper. More Nobel laureates of 2011-2015 are among the top authors when authors are ranked by the composite score than by total citations, H index, or Hm index; 40/47 of these laureates are among the top 30,000 by at least one of the six indicators. We also explore the sensitivity of indicators to self-citation and alphabetic ordering of authors in papers across different scientific fields. Multiple indicators and their composite may give a more comprehensive picture of impact, although no citation indicator, single or composite, can be expected to select all the

Multiple Citation Indicators and Their Composite across Scientific Disciplines.

Directory of Open Access Journals (Sweden)

John P A Ioannidis

2016-07-01

Full Text Available Many fields face an increasing prevalence of multi-authorship, and this poses challenges in assessing citation metrics. Here, we explore multiple citation indicators that address total impact (number of citations, Hirsch H index [H], co-authorship adjustment (Schreiber Hm index [Hm], and author order (total citations to papers as single; single or first; or single, first, or last author. We demonstrate the correlation patterns between these indicators across 84,116 scientists (those among the top 30,000 for impact in a single year [2013] in at least one of these indicators and separately across 12 scientific fields. Correlation patterns vary across these 12 fields. In physics, total citations are highly negatively correlated with indicators of co-authorship adjustment and of author order, while in other sciences the negative correlation is seen only for total citation impact and citations to papers as single author. We propose a composite score that sums standardized values of these six log-transformed indicators. Of the 1,000 top-ranked scientists with the composite score, only 322 are in the top 1,000 based on total citations. Many Nobel laureates and other extremely influential scientists rank among the top-1,000 with the composite indicator, but would rank much lower based on total citations. Conversely, many of the top 1,000 authors on total citations have had no single/first/last-authored cited paper. More Nobel laureates of 2011-2015 are among the top authors when authors are ranked by the composite score than by total citations, H index, or Hm index; 40/47 of these laureates are among the top 30,000 by at least one of the six indicators. We also explore the sensitivity of indicators to self-citation and alphabetic ordering of authors in papers across different scientific fields. Multiple indicators and their composite may give a more comprehensive picture of impact, although no citation indicator, single or composite, can be expected to

Author Self-Citation in the Otolaryngology Literature: A Pilot Study.

Science.gov (United States)

Tolisano, Anthony M; Song, Sungjin A; Cable, Benjamin B

2016-02-01

To determine the prevalence of author self-citation in the field of otolaryngology. A retrospective review of bibliographic references in 5 otolaryngology journals. Five high-impact otolaryngology journals were reviewed over a 3-month period between January and March 2014 to identify the pattern of author self-citations. Data included study type, otolaryngology topic, authorship, total citations, author self-citations, and country of origin. Nearly two-thirds of articles contained at least 1 self-citation, with an average of 2.6 self-citations per article. Self-citations represented nearly 10% of total citations. Articles with at least 1 self-citation had more authors (5.8 vs 4.9, P otolaryngology literature is common and compares similarly to other medical specialties previously studied. Self-citation should not be considered inappropriate, as it is often done to expand on earlier research. Nevertheless, editors, researchers, and readers should be aware of this increasingly recognized phenomenon and its associated potential implications to the process of scientific inquiry. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2015.

Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells

Czech Academy of Sciences Publication Activity Database

Klíma, Petr; Laňková, Martina; Vandenbussche, F.; Van Der Straeten, D.; Petrášek, Jan

2018-01-01

Roč. 37, č. 5 (2018), s. 809-818 ISSN 0721-7714 R&D Projects: GA ČR GA16-10948S Grant - others:OPPK(XE) CZ.2.16/3.1.00/21519 Institutional support: RVO:61389030 Keywords : Auxin * Calcium * Ethylene * Silver ions * Tobacco BY-2 cells * Transmembrane transport Subject RIV: ED - Physiology OBOR OECD: Cell biology Impact factor: 2.869, year: 2016

1 CFR 22.2 - Authority citation.

Science.gov (United States)

2010-01-01

... 1 General Provisions 1 2010-01-01 2010-01-01 false Authority citation. 22.2 Section 22.2 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER PREPARATION, TRANSMITTAL, AND PROCESSING OF DOCUMENTS PREPARATION OF NOTICES AND PROPOSED RULES Notices § 22.2 Authority citation. The authority under...

Biomechanics Scholar Citations across Academic Ranks

Directory of Open Access Journals (Sweden)

Knudson Duane

2015-11-01

Full Text Available Study aim: citations to the publications of a scholar have been used as a measure of the quality or influence of their research record. A world-wide descriptive study of the citations to the publications of biomechanics scholars of various academic ranks was conducted.

Cytoprotective effect of glutaraldehyde erythropoietin on HEK293 kidney cells after silver nanoparticle exposure

Directory of Open Access Journals (Sweden)

Sooklert K

2016-02-01

Full Text Available Kanidta Sooklert,1,2 Supreecha Chattong,3 Krissanapong Manotham,3 Chawikan Boonwong,1 I-yanut Klaharn,1 Depicha Jindatip,4 Amornpun Sereemaspun1,4 1Nanobiomedicine Laboratory, Department of Anatomy, Faculty of Medicine, 2Inter-Department Program of Biomedical Sciences, Faculty of Graduate School, Chulalongkorn University, 3Renal Unit, Department of Medicine, Lerdsin General Hospital, 4Department of Anatomy, Faculty of Medicine, Chulalongkorn University, Bangkok, ThailandAbstract: The toxic effects from exposure to silver nanoparticles (AgNPs, which are broadly present in many consumer products, have long raised concerns. Many studies have focused on the mechanisms of nanosilver, which cause toxicity in human cells, but little is known about prevention of this type of injury. This study investigated the in vitro effects of glutaraldehyde erythropoietin (GEPO, a cytoprotective compound derived from erythropoietin, in terms of cell protection against AgNP-induced injury. HEK293 cells were pretreated with or without GEPO before administration of AgNPs. The protective effects of GEPO in this cell line were assessed by the percentage of viable cells, alterations of cell morphology, and the proliferative capability of the cells. In addition, we assessed the role of GEPO in lowering cellular oxidative stress and regulating expression of the anti-apoptotic protein Bcl2. The results showed rescue effects on the percentage of viable and proliferative cells among GEPO pretreated cells. Pretreatment with GEPO maintained the normal cell shape and ultrastructural morphology. Moreover, GEPO reduced the generation of reactive oxygen species in cells and activated expression of Bcl2, which are the major mechanisms in protection against cellular toxicity induced by AgNPs. In conclusion, our study showed that the cytotoxic effects from exposure to AgNPs can be prevented by GEPO. Keywords: glutaraldehyde erythropoietin, silver nanoparticles, cytoprotection

All-solution processed semi-transparent perovskite solar cells with silver nanowires electrode

International Nuclear Information System (INIS)

Yang, Kaiyu; Li, Fushan; Zhang, Jianhua; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

2016-01-01

In this work, we report an all-solution route to produce semi-transparent high efficiency perovskite solar cells (PSCs). Instead of an energy-consuming vacuum process with metal deposition, the top electrode is simply deposited by spray-coating silver nanowires (AgNWs) under room temperature using fabrication conditions and solvents that do not damage or dissolve the underlying PSC. The as-fabricated semi-transparent perovskite solar cell shows a photovoltaic output with dual side illuminations due to the transparency of the AgNWs. With a back cover electrode, the open circuit voltage increases significantly from 1.01 to 1.16 V, yielding high power conversion efficiency from 7.98 to 10.64%. (paper)

Green synthesis of silver nanoparticles and silver colloidal solutions

International Nuclear Information System (INIS)

Nguyen Thi Phuong Phong; Ngo Hoang Minh; Ngo Vo Ke Thanh; Dang Mau Chien

2009-01-01

In this paper, silver colloidal solutions have been synthesized rapidly in green conditions by using microwave irradiation and non-toxic chemistry substances (acid oxalic, silver nitrate, polyvinyl pyrolidone (PVP; Mw = 55 000)). The particle size and morphology of these solutions can be controlled by altering several factors like the time, the power of microwave exposure, and the ratio of silver oxalate and PVP etc. The silver nanoparticles were fabricated by thermal decomposition of silver oxalate. The synthesized silver colloidal solutions and silver nanoparticles were characterized by several analytical techniques like UV- VIS, XRD, TEM, FESEM/EDS and ICP-AAS studies. Finally, we used the synthesized silver colloidal solutions for antibacterial purpose. The obtained results showed that the synthesized silver colloidal solutions, even at very low concentrations, have highly efficient anti-bacterial property.

Citation bias of hepato-biliary randomized clinical trials

DEFF Research Database (Denmark)

Kjaergard, Lise L; Gluud, Christian

2002-01-01

-1996. From each trial, we extracted the statistical significance of the primary study outcome (positive or negative), the disease area, and methodological quality (randomization and double blinding). The number of citations during two calendar years after publication was obtained from Science Citation Index....... There was a significant positive association between a statistically significant study outcome and the citation frequency (beta, 0.55, 95% confidence interval, 0.39-0.72). The disease area and adequate generation of the allocation sequence were also significant predictors of the citation frequency. We concluded...

41 CFR 105-1.150 - Citation.

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Citation. 105-1.150 Section 105-1.150 Public Contracts and Property Management Federal Property Management Regulations System (Continued) GENERAL SERVICES ADMINISTRATION 1-INTRODUCTION 1.1-Regulations System § 105-1.150 Citation. (a...

Citation patterns and trends of systematic reviews about mindfulness.

Science.gov (United States)

Chiesa, Alberto; Fazia, Teresa; Bernardinelli, Luisa; Morandi, Gabriella

2017-08-01

We performed a citation analysis of the literature about mindfulness aimed at describing the most significant topics and the impact of more relevant papers. We classified 128 systematic reviews about mindfulness-based intervention retrieved in Scopus according to their object, the population included and the type of mindfulness proposed. The citation counting was reported. The cumulative citation numbers per chronological years and article life were analyzed thorough a linear regression model. 1) We observed a general increase in the number of reviews published from 2003 to 2016; 2) two reviews collected the 33% of the overall citations; 3) citation counting for clinical and mixed population collected the 90% of total citations; 4) clinical reviews had higher cumulative citation per publication/year growth. As mindfulness research advances, higher attention should be given to the mechanisms by which mindfulness interventions work so as to provide fruitful insights for future research. Copyright © 2017 Elsevier Ltd. All rights reserved.

47 CFR 1.14 - Citation of Commission documents.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Citation of Commission documents. 1.14 Section... Rules of Practice and Procedure General § 1.14 Citation of Commission documents. The appropriate reference to the FCC Record shall be included as part of the citation to any document that has been printed...

Prevalence and Impact of Self-Citation in Academic Orthopedic Surgery.

Science.gov (United States)

Silvestre, Jason; Kamath, Atul F

2018-03-01

The h-index is a commonly utilized metric for academic productivity. Previous studies have proposed that self-citation may limit the utility of the h-index. The purpose of this study is to evaluate the impact of self-citation on the h-index among orthopedic investigators. The study cohort consisted of program directors, chairpersons, and faculty at orthopedic surgery residency programs in the United States. The Scopus database was used to determine the h-index and number of citations ± self-citations. The total number of publications was correlated with the change in the h-index via self-citation. A total of 463 researchers were included (198 National Institutes of Health-funded faculty, 147 chairpersons, 118 program directors). Of these researchers, 83.8% cited previous work at least once (mean, 123.9 ± 277.6). Self-citations accounted for 5.8% of all citations. Including these citations increased the author h-index from 18.5 ± 14.9 to 19.2 ± 15.6 (P < .001). A minority of researchers (36.3%, P < .001) had increased their h-index via self-citation (range, 0-11). The proportional increase in the h-index via self-citation was positively related to the number of publications (P < .001). While the practice of self-citation is prevalent in orthopedics, its impact on the h-index is minimal for most researchers. With more publications, researchers can increase their h-index to a greater degree via self-citation.

Antiproliferative effect of silver nanoparticles synthesized using amla on Hep2 cell line

Institute of Scientific and Technical Information of China (English)

Fathima Stanley Rosarin; Vadivel Arulmozhi; Samuthira Nagarajan; Sankaran Mirunalini

2013-01-01

Objective: To synthesize silver nanoparticles by amla extract, screen the cytotoxic, oxidative stress and apoptotic effect of silver nanoparticles (AgNPs) on Hep2 cell line (laryngeal carcinoma cells) in vitro, and to compare the effect of Phyllanthus emblica (P. emblica) (amla) with AgNPs synthesized by amla and 5-FU. Methods: AgNPs was synthesized by P. emblica (aqueous extract) and nanoparticles were characterized UV-Vis spec, the presence of biomoloecules of amla capped in AgNPs was found by FT-IR analysis, shape and size were examined by SEM and DLS. Cytotoxicity of experimental drugs was tested to find IC50 value. ROS generation in cells have been measured by DCFH-DA staining, AO-EtBr, Rhodamine-123 staining and DNA fragmentation were performed to assess apoptotic cell death, mitochondrial membrane potential and apoptotic DNA damage, respectively. Oxidative stress was analyzed by measuring lipid peroxides and antioxidants level to understand the cancer cell death by pro-oxidant mechanism.Results:PE-AgNPs was synthesized and confirmed through kinetic behavior of NPs. The shape of PE-AgNPs was spherical and cubic since it was agglomerated, and the nanoparticle surface was complicated. Average particle size distribution of PE-AgNPs was found to be 188 nm. Potent biomolecules of P. emblica such as polyphenols were capped with AgNPs and reduced its toxicity. In cytotoxicity assay the concentration in which the maximum number of cell death was 60 μg/mL and 50 μg/mL for P. emblica (alone) and AgNPs, respectively and IC50 values were fixed as 30 μg/mL and 20 μg/mL. ROS generation, apoptotic morphological changes, mitochondrial depolarization, DNA damage and oxidative stress was observed as more in AgNPs treated cells than in P. emblica (30 μg/mL) (alone) treated cells and 5-FU treated cells gave similar result.Conclusions:The results suggest that the AgNPs are capped with biomolecules of amla enhanced cytotoxicity in laryngeal cancer cells through oxidative

How accessibility influences citation counts: The case of citations to the full text articles available from ResearchGate

Directory of Open Access Journals (Sweden)

Mohammad Sababi

2017-08-01

Full Text Available It is generally believed that the number of citations to an article can positively be correlated to its free online availability. In the present study, we investigated the possible impact of academic social networks on the number of citations. We chose the social web service “ResearchGate” as a case. This website acts both as a social network to connect researchers, and at the same time, as an open access repository to publish post-print version of the accepted manuscripts and final versions of open access articles. We collected the data of 1823 articles published by the authors from four different universities. By analyzing these data, we showed that although different levels of full text availability are observed for the four universities, there is always a significant positive correlation between full text availability and the citation count. Moreover, we showed that both post-print version and publisher’s version (i.e., final published version of the archived manuscripts receive more citations than non-OA articles, and the difference in the citation counts of post-print manuscripts and publisher’s version articles is nonsignificant.

41 CFR 128-1.152 - Citation.

Science.gov (United States)

2010-07-01

... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Citation. 128-1.152 Section 128-1.152 Public Contracts and Property Management Federal Property Management Regulations System (Continued) DEPARTMENT OF JUSTICE 1-INTRODUCTION 1.1-Regulation System § 128-1.152 Citation. The JPMR will be...

Statistical modelling of citation exchange between statistics journals.

Science.gov (United States)

Varin, Cristiano; Cattelan, Manuela; Firth, David

2016-01-01

Rankings of scholarly journals based on citation data are often met with scepticism by the scientific community. Part of the scepticism is due to disparity between the common perception of journals' prestige and their ranking based on citation counts. A more serious concern is the inappropriate use of journal rankings to evaluate the scientific influence of researchers. The paper focuses on analysis of the table of cross-citations among a selection of statistics journals. Data are collected from the Web of Science database published by Thomson Reuters. Our results suggest that modelling the exchange of citations between journals is useful to highlight the most prestigious journals, but also that journal citation data are characterized by considerable heterogeneity, which needs to be properly summarized. Inferential conclusions require care to avoid potential overinterpretation of insignificant differences between journal ratings. Comparison with published ratings of institutions from the UK's research assessment exercise shows strong correlation at aggregate level between assessed research quality and journal citation 'export scores' within the discipline of statistics.

Causes of Low and High Citation Potentials in Science: Citation Analysis of Biochemistry and Plant Physiology Journals.

Science.gov (United States)

Marton, Janos

1983-01-01

Citation data of 16 biochemistry and plant physiology journals show that reasons for lower citation potentials of plant physiology articles are: (1) readership is narrower for plant physiology journals; (2) plant physiologists can cite fewer thematically relevant new articles; and (3) plant physiology research fields are more isolated. References…

Administration of silver sulfadiazine and radioactive derivatives thereof

International Nuclear Information System (INIS)

Wysor, M.S.

1977-01-01

Silver sulfadiazine has been found to be therapeutically useful when administered orally or subcutaneously in doses not exceeding 1,050 mg/kg. It also has been found that radioactive derivatives of silver sulfadiazine localize in tumors, the resultant radiation within the region of the tumor serving to eradicate malignant cells

Non-Traffic Citations

Data.gov (United States)

Allegheny County / City of Pittsburgh / Western PA Regional Data Center — Non-traffic citations (NTCs, also known as "summary offenses") document low-level criminal offenses where a law enforcement officer or other authorized official...

Biosynthesis and Characterization of Silver Nanoparticles by Aspergillus Species

Science.gov (United States)

Pourshahid, Seyedmohammad; Mehryar, Pouyan; Pakshir, Keyvan; Rahimi, Mohammad Javad; Arabi Monfared, Ali

2016-01-01

Currently, researchers turn to natural processes such as using biological microorganisms in order to develop reliable and ecofriendly methods for the synthesis of metallic nanoparticles. In this study, we have investigated extracellular biosynthesis of silver nanoparticles using four Aspergillus species including A. fumigatus, A. clavatus, A. niger, and A. flavus. We have also analyzed nitrate reductase activity in the studied species in order to determine the probable role of this enzyme in the biosynthesis of silver nanoparticles. The formation of silver nanoparticles in the cell filtrates was confirmed by the passage of laser light, change in the color of cell filtrates, absorption peak at 430 nm in UV-Vis spectra, and atomic force microscopy (AFM). There was a logical relationship between the efficiencies of studied Aspergillus species in the production of silver nanoparticles and their nitrate reductase activity. A. fumigatus as the most efficient species showed the highest nitrate reductase activity among the studied species while A. flavus exhibited the lowest capacity in the biosynthesis of silver nanoparticles which was in accord with its low nitrate reductase activity. The present study showed that Aspergillus species had potential for the biosynthesis of silver nanoparticles depending on their nitrate reductase activity. PMID:27652264

Do citation systems represent theories of truth?

Directory of Open Access Journals (Sweden)

Betsy Van der Veer Martens

2001-01-01

Full Text Available This article suggests that the citation can be viewed not only as a "concept symbol" but also as a "boundary object". The scientific, legal, and patent citation systems in America are examined at the micro, meso, and macro levels in order to understand how they function as commodified theories of truth in contemporary knowledge representation. This approach also offers a meta-theoretical overview of existing citation research efforts in science, law, and technology that may be of interdisciplinary interest.

Citation Searching: Search Smarter & Find More

Science.gov (United States)

Hammond, Chelsea C.; Brown, Stephanie Willen

2008-01-01

The staff at University of Connecticut are participating in Elsevier's Student Ambassador Program (SAmP) in which graduate students train their peers on "citation searching" research using Scopus and Web of Science, two tremendous citation databases. They are in the fourth semester of these training programs, and they are wildly successful: They…

Citation Styles For Internet Resources : A Webliography

Directory of Open Access Journals (Sweden)

2004-12-01

Full Text Available A Webliography collects resources about citation Styles For internet resources, it divided by the styles: Chicago University style, MLA style, APA style, ISO style, and some articles about internet resources citation.

Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers

International Nuclear Information System (INIS)

Quirós, Jennifer; Borges, João P.; Boltes, Karina; Rodea-Palomares, Ismael; Rosal, Roberto

2015-01-01

Highlights: • Electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc. • Antimicrobial effect for the bacteria Staphylococcus aureus and Escherichia coli. • Silver strongly reduced colony forming units and bacterial viability. • Silver, copper, and zinc led to a significant increase of non-viable cells on mats. - Abstract: The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals.

Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers

Energy Technology Data Exchange (ETDEWEB)

Quirós, Jennifer [Department of Chemical Engineering, University of Alcalá, 28871 Alcalá de Henares, Madrid (Spain); Borges, João P. [CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Boltes, Karina [Department of Chemical Engineering, University of Alcalá, 28871 Alcalá de Henares, Madrid (Spain); Madrid Institute for Advanced Studies of Water (IMDEA Agua), Parque Científico Tecnológico, E-28805, Alcalá de Henares, Madrid (Spain); Rodea-Palomares, Ismael [Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid (Spain); Rosal, Roberto [Department of Chemical Engineering, University of Alcalá, 28871 Alcalá de Henares, Madrid (Spain); Madrid Institute for Advanced Studies of Water (IMDEA Agua), Parque Científico Tecnológico, E-28805, Alcalá de Henares, Madrid (Spain)

2015-12-15

Highlights: • Electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc. • Antimicrobial effect for the bacteria Staphylococcus aureus and Escherichia coli. • Silver strongly reduced colony forming units and bacterial viability. • Silver, copper, and zinc led to a significant increase of non-viable cells on mats. - Abstract: The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals.

Potentially coercive self-citation by peer reviewers: a cross-sectional study.

Science.gov (United States)

Thombs, Brett D; Levis, Alexander W; Razykov, Ilya; Syamchandra, Achyuth; Leentjens, Albert F G; Levenson, James L; Lumley, Mark A

2015-01-01

Peer reviewers sometimes request that authors cite their work, either appropriately or via coercive self-citation to highlight the reviewers' work. The objective of this study was to determine in peer reviews submitted to one biomedical journal (1) the extent of peer reviewer self-citation; (2) the proportion of reviews recommending revision or acceptance versus rejection that included reviewer self-citations; and (3) the proportion of reviewer self-citations versus citations to others that included a rationale. Peer reviews for manuscripts submitted in 2012 to the Journal of Psychosomatic Research were evaluated. Data extraction was performed independently by two investigators. There were 616 peer reviews (526 reviewers; 276 manuscripts), of which 444 recommended revision or acceptance and 172 rejection. Of 428 total citations, there were 122 peer reviewer self-citations (29%) and 306 citations to others' work (71%). Self-citations were more common in reviews recommending revision or acceptance (105 of 316 citations; 33%) versus rejection (17/112; 15%; pcitations with no rationale (26 of 122; 21%) was higher than for citations to others' work (15 of 306; 5%; pcitation in peer reviews is common and may reflect a combination of appropriate citation to research that should be cited in published articles and inappropriate citation intended to highlight the work of the peer reviewer. Providing instructions to peer reviewers about self-citation and asking them to indicate when and why they have self-cited may help to limit self-citation to appropriate, constructive recommendations. Copyright © 2014 Elsevier Inc. All rights reserved.

Biosynthesis of silver nanoparticle and its application in cell wall disruption to release carbohydrate and lipid from C. vulgaris for biofuel production

Directory of Open Access Journals (Sweden)

Sirajunnisa Abdul Razack

2016-09-01

Full Text Available Microalgae are the fledging feedstocks yielding raw materials for the production of third generation biofuel. Assorted and conventional cell wall disruption techniques were helpful in extracting lipids and carbohydrates, nevertheless the disadvantages have led the biotechnologists to explore new process to lyse cell wall in a faster and an economical manner. Silver nanoparticles have the ability to break the cell wall of microalgae and release biomolecules effectively. Green synthesis of silver nanoparticles was performed using a novel bacterial isolate of Bacillus subtilis. Characterisation of nanosilver and its effect on cell wall lysis of microalgae were extensively analysed. Cell wall damage was confirmed by lactate dehydrogenase assay and visually by SEM analysis. This first piece of research work on direct use of nanoparticles for cell wall lysis would potentially be advantageous over its conventional approaches and a greener, cost effective and non laborious method for the production of biodiesel.

A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

Science.gov (United States)

Marambio-Jones, Catalina; Hoek, Eric M. V.

2010-06-01

Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules—all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

Energy Technology Data Exchange (ETDEWEB)

Marambio-Jones, Catalina; Hoek, Eric M. V., E-mail: emvhoek@ucla.ed [University of California, Los Angeles, Department of Civil and Environmental Engineering, California NanoSystems Institute (United States)

2010-06-15

Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

International Nuclear Information System (INIS)

Marambio-Jones, Catalina; Hoek, Eric M. V.

2010-01-01

Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver-dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules-all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

The Anatomy of a Data Citation: Discovery, Reuse, and Credit

Directory of Open Access Journals (Sweden)

Hailey Mooney

2012-05-01

Full Text Available INTRODUCTION Data citation should be a necessary corollary of data publication and reuse. Many researchers are reluctant to share their data, yet they are increasingly encouraged to do just that. Reward structures must be in place to encourage data publication, and citation is the appropriate tool for scholarly acknowledgment. Data citation also allows for the identification, retrieval, replication, and verification of data underlying published studies. METHODS This study examines author behavior and sources of instruction in disciplinary and cultural norms for writing style and citation via a content analysis of journal articles, author instructions, style manuals, and data publishers. Instances of data citation are benchmarked against a Data Citation Adequacy Index. RESULTS Roughly half of journals point toward a style manual that addresses data citation, but the majority of journal articles failed to include an adequate citation to data used in secondary analysis studies. DISCUSSION Full citation of data is not currently a normative behavior in scholarly writing. Multiplicity of data types and lack of awareness regarding existing standards contribute to the problem. CONCLUSION Citations for data must be promoted as an essential component of data publication, sharing, and reuse. Despite confounding factors, librarians and information professionals are well-positioned and should persist in advancing data citation as a normative practice across domains. Doing so promotes a value proposition for data sharing and secondary research broadly, thereby accelerating the pace of scientific research.

Incites into Citation Linking using the OAI-PMH

CERN Multimedia

CERN. Geneva

2005-01-01

deposit process. This highly-distributed approach to citation linking utilises the OAI-PMH to transfer structured citation data between IRs and citation indexing services. OpenURL - a standard for contextual linking using bibliographic data - is now a NISO standard. As well as it's linking role, OpenURL is a useful standard for the transfer of bibliographic data for the purposes of...

Citation Index: an indispensable information retrieval tool for research and evaluation

OpenAIRE

Kademani, B. S.; Vijai Kumar, *

2002-01-01

This paper highlights the information explosion, the need for bibliographic control, the need for information retrieval tools. Explains the emergence of Citation Index, concept of citation indexing, reasons for citing, its structure (print and electronic versions of Science citation Index and Social Science Citation Index ), and application of citation index. It also discusses the search effectiveness, factors taken into consideration for coverage of journals in citation indexes, Journal Cita...

Preconcentration of silver as silver xanthate on activated carbon

International Nuclear Information System (INIS)

Ramadevi, P.; Naidu, U.V.; Naidu, G.R.K.

1988-01-01

Silver from aqueous solution was preconcentrated by adsorption on activated carbon as silver xanthate. Factors influencing the adsorption of silver were studied. Optimum conditions for the preconcentration of silver were established. (author) 9 refs.; 3 tabs

Implications of silver nanoparticle induced cell apoptosis for in vitro gene therapy

International Nuclear Information System (INIS)

Gopinath, P; Ghosh, Siddhartha Sankar; Gogoi, Sonit Kumar; Chattopadhyay, Arun

2008-01-01

The impact of manufactured nanomaterials on human health and the environment is a major concern for commercial use of nanotechnology based products. A judicious choice of selective usage, lower nanomaterial concentration and use in combination with conventional therapeutic materials may provide the best solution. For example, silver nanoparticles (Ag NPs) are known to be bactericidal and also cytotoxic to mammalian cells. Herein, we investigate the molecular mechanism of Ag NP mediated cytotoxicity in both cancer and non-cancer cells and find that optimum particle concentration leads to programmed cell death in vitro. Also, the benefit of the cytotoxic effects of Ag NPs was tested for therapeutic use in conjunction with conventional gene therapy. The synergistic effect of Ag NPs on the uracil phosphoribosyltransferase expression system sensitized the cells more towards treatment with the drug 5-fluorouracil. Induction of the apoptotic pathway makes Ag NPs a representative of a new chemosensitization strategy for future application in gene therapy

Inactivation of the antibacterial and cytotoxic properties of silver ions by biologically relevant compounds.

Directory of Open Access Journals (Sweden)

Geraldine Mulley

Full Text Available There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells. Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC if Ag+ and thiols are added in a 1:1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec and Acticoat (Smith & Nephew to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants. We believe our findings are essential for the effective design and testing of antimicrobial silver coatings.

Nucleolar activity after 3-methylcholanthrene treatment of rat liver cells studied by silver staining procedure

Energy Technology Data Exchange (ETDEWEB)

Komaromy, L.; Tigyi, A.

1986-01-01

The influence of a single dose of 3-methylcholanthrene (3-MC) was studied in nucleoli of young rat liver cells by means of conventional and ultracytochemical methods. The nucleolar activity was stimulated in the authors experimental conditions: the appearance of the fibrillar centers in the liver cell nucleoli as well as the silver staining protein content of the fibrillar centers and the dense fibrillar component were increased by 3-MC. The results suggest that the activity of ribosomal genes was increased following 3-MC treatment.

Academic Citation Practice: A Sinking Sheep?

Science.gov (United States)

Rekdal, Ole Bjørn

2014-01-01

An explosion in access to electronic databases and digital information is changing the way we view source citation. While the original purpose of referencing--showing the reader exactly where the author got his or her input--is clearly more important than ever, citation is increasingly taking on other roles, ones that have little to do with good…

Citation classics in suicide and life threatening behavior: a research note.

Science.gov (United States)

Stack, Steven

2012-12-01

The number of citations a scholarly work receives is a common measure of its impact on the scientific literature; "citation classics" are the most highly cited works. The content of Suicide and Life-Threatening Behavior (SLTB) citation classics is described here. The impact of SLTB citation classics is compared to their counterparts in journals having published the most suicide papers. All data are from the ISI electronic venue on the Web of Science and refer to the number of citations the top 1% of works received in each of ten journals from 1975 through August 10, 2011. Among all ten journals, SLTB ranked first in the number of works on suicide. The principle theme of half of SLTB suicide classics was literature review. The median number of citations for SLTB citation classics (top 1%) was 121.5, with a range between 96 and 279 citations, but classics from generalized psychiatric journals received more citations as anticipated. Journal impact factors explained 73% of the variance in classic's citation counts across journals. On average, suicide classics received 30% more citations than all classics. Among a second group of five specialized suicide journals, however, SLTB ranked first in average 5-year impact. Although SLTB produced the highest number of suicide articles of any journal, SLTB's citation classics received fewer citations than suicide classics in high-impact/prestige, general journals. Future work is needed to assess what predicts which SLTB articles ultimately become citation classics. © 2012 The American Association of Suicidology.

The Extracellular Domain of Human High Affinity Copper Transporter (hNdCTR1, Synthesized by E. coli Cells, Chelates Silver and Copper Ions In Vivo

Directory of Open Access Journals (Sweden)

Tatiana P. Sankova

2017-11-01

Full Text Available There is much interest in effective copper chelators to correct copper dyshomeostasis in neurodegenerative and oncological diseases. In this study, a recombinant fusion protein for expression in Escherichia coli cells was constructed from glutathione-S-transferase (GST and the N-terminal domain (ectodomain of human high affinity copper transporter CTR1 (hNdCTR1, which has three metal-bound motifs. Several biological properties of the GST-hNdCTR1 fusion protein were assessed. It was demonstrated that in cells, the protein was prone to oligomerization, formed inclusion bodies and displayed no toxicity. Treatment of E. coli cells with copper and silver ions reduced cell viability in a dose- and time-dependent manner. Cells expressing GST-hNdCTR1 protein demonstrated resistance to the metal treatments. These cells accumulated silver ions and formed nanoparticles that contained AgCl and metallic silver. In this bacterial population, filamentous bacteria with a length of about 10 µm were often observed. The possibility for the fusion protein carrying extracellular metal binding motifs to integrate into the cell’s copper metabolism and its chelating properties are discussed.

Citation analysis of Canadian psycho-oncology and supportive care researchers.

Science.gov (United States)

Hack, Thomas F; Crooks, Dauna; Plohman, James; Kepron, Emma

2014-02-01

The purpose of this study was to conduct a historical review of psycho-oncology and supportive care research in Canada using citation analysis and to review the clinical impact of the research conducted by the most highly cited researchers. The lifetime journal publication records of 109 psycho-oncology and supportive care researchers in Canada were subject to citation analysis using the Scopus database, based on citations since 1996 of articles deemed relevant to psychosocial oncology and supportive care, excluding self-citations. Three primary types of analysis were performed for each individual: the number of citations for each journal publication, a summative citation count of all published articles, and the Scopus h-index. The top 20 psycho-oncology/supportive care researchers for each of five citation categories are presented: the number of citations for all publications; the number of citations for first-authored publications; the most highly cited first-authored publications; the Scopus h-index for all publications; and the Scopus h-index for first-authored publications. The three most highly cited Canadian psycho-oncology researchers are Dr. Kerry Courneya (University of Alberta), Dr. Lesley Degner, (University of Manitoba), and Dr. Harvey Chochinov (University of Manitoba). Citation analysis is useful for examining the research performance of psycho-oncology and supportive care researchers and identifying leaders among them.

Assessing citation networks for dissemination and implementation research frameworks.

Science.gov (United States)

Skolarus, Ted A; Lehmann, Todd; Tabak, Rachel G; Harris, Jenine; Lecy, Jesse; Sales, Anne E

2017-07-28

A recent review of frameworks used in dissemination and implementation (D&I) science described 61 judged to be related either to dissemination, implementation, or both. The current use of these frameworks and their contributions to D&I science more broadly has yet to be reviewed. For these reasons, our objective was to determine the role of these frameworks in the development of D&I science. We used the Web of Science™ Core Collection and Google Scholar™ to conduct a citation network analysis for the key frameworks described in a recent systematic review of D&I frameworks (Am J Prev Med 43(3):337-350, 2012). From January to August 2016, we collected framework data including title, reference, publication year, and citations per year and conducted descriptive and main path network analyses to identify those most important in holding the current citation network for D&I frameworks together. The source article contained 119 cited references, with 50 published articles and 11 documents identified as a primary framework reference. The average citations per year for the 61 frameworks reviewed ranged from 0.7 to 103.3 among articles published from 1985 to 2012. Citation rates from all frameworks are reported with citation network analyses for the framework review article and ten highly cited framework seed articles. The main path for the D&I framework citation network is presented. We examined citation rates and the main paths through the citation network to delineate the current landscape of D&I framework research, and opportunities for advancing framework development and use. Dissemination and implementation researchers and practitioners may consider frequency of framework citation and our network findings when planning implementation efforts to build upon this foundation and promote systematic advances in D&I science.

Gender and citation impact in management research

DEFF Research Database (Denmark)

Nielsen, Mathias Wullum

2017-01-01

This study investigates the extent to which a gender gap exists in the citation rates of management researchers. Based on a cross-sectional sample of 26,783 publications and 65,436 authorships, we illuminate possible differences in women’s and men’s average citation impact per paper, adjusting......% most cited in their field. Yet given the sensitivity of our results to uncertainties in the data, these variations should not be overgeneralized. In the large picture, differences in citation rates appear to be a negligible factor in the reproduction of gender inequalities in management research....

Biosynthesis of Silver Nanoparticles Using Oscillatoria Extract and Evaluation the Anticancer and Antibacterial Activities

Directory of Open Access Journals (Sweden)

T Ghasemipour

2017-07-01

Full Text Available Abstract Background and aim: The emergence of nanotechnology is one of the most promising areas for medical research. Today, biological methods of synthesizing nanoparticles have been considered in the fight against many diseases. The purpose of this study was to evaluate the anti-cancer and anti-bacterial activity of silver nanoparticles, biosynthesized with cyanobacteria acetate extract. Methods: In the present experimental study, the silver nanoparticles biosynthesis was performed using silver ions regeneration with cyanobacteria acetate extracts. Techniques such as X-ray diffraction, scanning electron microscopy and transient evaluation of silver nanoparticles were evaluated. In order to investigate the antibacterial activity of synthesized nanosilver, serial dilution method was used for broth microdilution test to determine minimum inhibitory concentration (MIC. The effects of silver nanoparticle toxicity on T47D breast cancer cell line were evaluated using MTT colorimetric method. Also, the proximal anxine 0.5 propidoid yodide kit and flow cytometry system were evaluated to evaluate the percentage of apoptosis and necrosis in cancer cells treated with silver nanoparticles. Results: Characterization of biosynthetic silver nanoparticles indicated that these nanoparticles had a mean size of 30 nm with dominant spherical morphology. The evaluation of the antibacterial properties of biosynthetic nanoparticles showed that the minimum inhibitory concentration for Escherichia coli, Acinetobacter Bumanni and Staphylococcus aureus was 25, 50 and 12.5 μg / ml, respectively. The results of cell proliferation of nanoparticles showed that its effect depends on the concentration and time of treatment of silver nanoparticles on cancerous cells. In addition, flow cytometric results showed an apoptotic cell death rate of 35% in the T47D cell line. Conclusion: Biosynthesis nanoparticles have anticancer and antibacterial activity and can be studied further

In situ fluorescence activation of DNA-silver nanoclusters as a label-free and general strategy for cell nucleus imaging.

Science.gov (United States)

Li, Duo; Qiao, Zhenzhen; Yu, Yanru; Tang, Jinlu; He, Xiaoxiao; Shi, Hui; Ye, Xiaosheng; Lei, Yanli; Wang, Kemin

2018-01-25

A facile, general and turn-on nucleus imaging strategy was first developed based on in situ fluorescence activation of C-rich dark silver nanoclusters by G-rich telomeres. After a simple incubation without washing, nanoclusters could selectively stain the nucleus with intense red luminescence, which was confirmed using fixed/living cells and several cell lines.

A semi-supervised approach using label propagation to support citation screening.

Science.gov (United States)

Kontonatsios, Georgios; Brockmeier, Austin J; Przybyła, Piotr; McNaught, John; Mu, Tingting; Goulermas, John Y; Ananiadou, Sophia

2017-08-01

Citation screening, an integral process within systematic reviews that identifies citations relevant to the underlying research question, is a time-consuming and resource-intensive task. During the screening task, analysts manually assign a label to each citation, to designate whether a citation is eligible for inclusion in the review. Recently, several studies have explored the use of active learning in text classification to reduce the human workload involved in the screening task. However, existing approaches require a significant amount of manually labelled citations for the text classification to achieve a robust performance. In this paper, we propose a semi-supervised method that identifies relevant citations as early as possible in the screening process by exploiting the pairwise similarities between labelled and unlabelled citations to improve the classification performance without additional manual labelling effort. Our approach is based on the hypothesis that similar citations share the same label (e.g., if one citation should be included, then other similar citations should be included also). To calculate the similarity between labelled and unlabelled citations we investigate two different feature spaces, namely a bag-of-words and a spectral embedding based on the bag-of-words. The semi-supervised method propagates the classification codes of manually labelled citations to neighbouring unlabelled citations in the feature space. The automatically labelled citations are combined with the manually labelled citations to form an augmented training set. For evaluation purposes, we apply our method to reviews from clinical and public health. The results show that our semi-supervised method with label propagation achieves statistically significant improvements over two state-of-the-art active learning approaches across both clinical and public health reviews. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Citation Rate Predictors in the Plastic Surgery Literature.

Science.gov (United States)

Lopez, Joseph; Calotta, Nicholas; Doshi, Ankur; Soni, Ashwin; Milton, Jacqueline; May, James W; Tufaro, Anthony P

The purpose of this study is to determine and characterize the scientific and nonscientific factors that influence the rate of article citation in the field of plastic surgery. Cross-sectional study. We reviewed all entries in Annals of Plastic Surgery and Journal of Plastic, Reconstructive, and Aesthetic Surgery from January 1, 2007 to December 31, 2007; and Plastic and Reconstructive Surgery from January 1, 2007 to December 31, 2008. All scientific articles were analyzed and several article characteristics were extracted. The number of citations at 5 years was collected as the outcome variable. A multivariable analysis was performed to determine which variables were associated with higher citations rates. A total of 2456 articles were identified of which only 908 fulfilled the inclusion criteria. Most studies were publications in the fields of reconstructive (26.3%) or pediatric/craniofacial (17.6%) surgery. The median number of citations 5 years from publication was 8. In the multivariable analysis, factors associated with higher citations rates were subspecialty field (p = 0.0003), disclosed conflict of interest (p = 0.04), number of authors (p = 0.04), and journal (p = 0.02). We have found that higher level of evidence (or other study methodology factors) is not associated with higher citation rates. Instead, conflict of interest, subspecialty topic, journal, and number of authors are strong predictors of high citation rates in plastic surgery. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Data reuse and the open data citation advantage.

Science.gov (United States)

Piwowar, Heather A; Vision, Todd J

2013-01-01

Background. Attribution to the original contributor upon reuse of published data is important both as a reward for data creators and to document the provenance of research findings. Previous studies have found that papers with publicly available datasets receive a higher number of citations than similar studies without available data. However, few previous analyses have had the statistical power to control for the many variables known to predict citation rate, which has led to uncertain estimates of the "citation benefit". Furthermore, little is known about patterns in data reuse over time and across datasets. Method and Results. Here, we look at citation rates while controlling for many known citation predictors and investigate the variability of data reuse. In a multivariate regression on 10,555 studies that created gene expression microarray data, we found that studies that made data available in a public repository received 9% (95% confidence interval: 5% to 13%) more citations than similar studies for which the data was not made available. Date of publication, journal impact factor, open access status, number of authors, first and last author publication history, corresponding author country, institution citation history, and study topic were included as covariates. The citation benefit varied with date of dataset deposition: a citation benefit was most clear for papers published in 2004 and 2005, at about 30%. Authors published most papers using their own datasets within two years of their first publication on the dataset, whereas data reuse papers published by third-party investigators continued to accumulate for at least six years. To study patterns of data reuse directly, we compiled 9,724 instances of third party data reuse via mention of GEO or ArrayExpress accession numbers in the full text of papers. The level of third-party data use was high: for 100 datasets deposited in year 0, we estimated that 40 papers in PubMed reused a dataset by year 2, 100 by

Science Citation Index Expanded: The Effect of Journal Editorial Policies

Science.gov (United States)

Buchanan, Robert A.

2007-01-01

Citation attributes were found to be strongly associated with the omission of citations from the cited article lists in 603 "SCIE" records from six chemistry journals. By requiring well-documented citations and by making it easier to identify where one citation ends and the next one begins, journals can help minimize the number of omitted…

Real-time monitoring of the Trojan-horse effect of silver nanoparticles by using a genetically encoded fluorescent cell sensor.

Science.gov (United States)

You, Fang; Tang, Wenqin; Yung, Lin-Yue Lanry

2018-04-26

Silver nanoparticles (AgNPs) are widely incorporated into commercial products due to their antimicrobial properties. As a consequence, concerns about the adverse effects induced by AgNPs to humans and the environment need to be carefully examined. The existing literature reveals that AgNPs exhibit certain toxic effects, but it remains to be proved whether AgNPs or the ionic silver (Ag+) released from AgNPs are the main toxic species. Here, a genetically encoded fluorescent protein sensor with high affinity to Ag+ was developed. The resulting sensor, MT2a-FRET, was found to be ratiometric, sensitive and selective toward only Ag+ but inert against AgNPs. This makes this sensor a potential useful tool for monitoring the real-time intracellular dissolutions of AgNPs. Our data supported that AgNPs display the "Trojan-horse" mechanism, where AgNPs are internalized by cells and undergo dissolution intracellularly. We further found that cells exhibited a detoxification ability to remove active Ag+ from cells in 48 hours.

Silver-polypyrrole-silver structure fabrication and characterization over wide temperature

Science.gov (United States)

Taunk, Manish; Chand, Subhash

2012-10-01

Semiconducting polymers have applications in many electronic devices such as organic light emitting diodes, organic solar cells, field effect transistors, memory devices, and many flexible electronic devices. In the organic electronic devices, metal-organic semiconductor interface plays a major role in determining the electrical transport. Earlier most of the studies were performed on electrochemically polymerized polypyrrole. In this study polypyrrole-poly(vinylidene) fluoride composite films synthesized by chemical oxidation method were used for contact fabrication in sandwiched geometry. Electrical transport measurements have been carried out in silver-polypyrrole-silver sandwich structure to understand conduction mechanism in the temperature range of 10-300K. It has been observed that Ag forms Ohmic contact with PPy and bulk controlled space charge limited conduction was the dominant current transport process in these sandwiched structures.

Exploiting citation contexts for physics retrieval

DEFF Research Database (Denmark)

Dabrowska, Anna; Larsen, Birger

2015-01-01

The text surrounding citations within scientific papers may contain terms that usefully describe cited documents and can benefit retrieval. We present a preliminary study that investigates appending ci- tation contexts from citing documents to cited documents in the iSearch test collection. We ex...... in a large collection of physics papers, paving the way for future research that exploits citation contexts for retrieval....

Nickel-silver composition shows promise as catalyst for hydrogen-oxygen fuel cells

Science.gov (United States)

Magerl, J. A.; Murray, J. N.

1970-01-01

Carburized 3-1 nickel-silver preparation exhibits considerable catalytic activity, although not as high as platinum black. Cost and availability factors warrant further evaluation of nickel-silver materials.

Individual, country, and journal self-citation in soil science

NARCIS (Netherlands)

Minasny, B.; Hartemink, A.E.; McBratney, A.

2010-01-01

Self-citation is common practice in most sciences but it differs between disciplines, countries and journals. Here we report on self-citation in soil science. We investigated citations in the major soil science journals and conducted an analysis on a country basis and for the subdiscipline of

Ranking Scientific Publications Based on Their Citation Graph

CERN Document Server

Marian, L; Rajman, M

2009-01-01

CDS Invenio is the web-based integrated digital library system developed at CERN. It is a suite of applications which provides the framework and tools for building and managing an autonomous digital library server. Within this framework, the goal of this project is to implement new ranking methods based on the bibliographic citation graph extracted from the CDS Invenio database. As a first step, we implemented the Citation Count as a baseline ranking method. The major disadvantage of this method is that all citations are treated equally, disregarding their importance and their publication date. To overcome this drawback, we consider two different approaches: a link-based approach which extends the PageRank model to the bibliographic citation graph and a time-dependent approach which takes into account time in the citation counts. In addition, we also combined these two approaches in a hybrid model based on a time-dependent PageRank. In the present document, we describe the conceptual background behind our new...

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata.

Science.gov (United States)

Monteiro, D R; Gorup, L F; Silva, S; Negri, M; de Camargo, E R; Oliveira, R; Barbosa, D B; Henriques, M

2011-08-01

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4-3.3 μg ml(-1)). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ∼90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.

Rankings and Trends in Citation Patterns of Communication Journals

Science.gov (United States)

Levine, Timothy R.

2010-01-01

Journal citations are increasingly used as indicators of the impact of scholarly work. Because many communication journals are not included in the Social Science Citation Index (SSCI), SSCI impact factors are potentially misleading for communication journals. The current paper reports a citation analysis of 30 communication journals based on…

Predicting the long-term citation impact of recent publications

NARCIS (Netherlands)

Stegehuis, Clara; Litvak, Nelli; Waltman, Ludo

2015-01-01

A fundamental problem in citation analysis is the prediction of the long-term citation impact of recent publications. We propose a model to predict a probability distribution for the future number of citations of a publication. Two predictors are used: The impact factor of the journal in which a

Predicting the long-term citation impact of recent publications

NARCIS (Netherlands)

Stegehuis, Clara; Litvak, Nelli; Waltman, Ludo

A fundamental problem in citation analysis is the prediction of the long-term citation impact of recent publications. We propose a model to predict a probability distribution for the future number of citations of a publication. Two predictors are used: the impact factor of the journal in which a

Do usage and scientific collaboration associate with citation impact

Energy Technology Data Exchange (ETDEWEB)

Chi, P.S.; Glänzel, W.

2016-07-01

In this study usage counts and times cited from Web of Science Core Collection (WoS) were collected for each article published in 2013 with Belgian, Israeli and Iranian addresses. We investigate the relations among three indicators related to citation impact, usage counts coauthorship, respectively. In addition, we apply the method of Characteristic Scores and Scal (CSS) to analyse the distributions of citations and usage counts. The results show that citations and usage counts in WoS correlate to each other significantly, especially in the social sciences. However, the increase of the number of co-authors does not increase usage counts or citations significantly. Furthermore, the stability of CSS-class distributions proves the availability of CSS in characterising both usage and citation distributions. (Author)

Self-citations at the meso and individual levels: effects of different calculation methods.

Science.gov (United States)

Costas, Rodrigo; van Leeuwen, Thed N; Bordons, María

2010-03-01

This paper focuses on the study of self-citations at the meso and micro (individual) levels, on the basis of an analysis of the production (1994-2004) of individual researchers working at the Spanish CSIC in the areas of Biology and Biomedicine and Material Sciences. Two different types of self-citations are described: author self-citations (citations received from the author him/herself) and co-author self-citations (citations received from the researchers' co-authors but without his/her participation). Self-citations do not play a decisive role in the high citation scores of documents either at the individual or at the meso level, which are mainly due to external citations. At micro-level, the percentage of self-citations does not change by professional rank or age, but differences in the relative weight of author and co-author self-citations have been found. The percentage of co-author self-citations tends to decrease with age and professional rank while the percentage of author self-citations shows the opposite trend. Suppressing author self-citations from citation counts to prevent overblown self-citation practices may result in a higher reduction of citation numbers of old scientists and, particularly, of those in the highest categories. Author and co-author self-citations provide valuable information on the scientific communication process, but external citations are the most relevant for evaluative purposes. As a final recommendation, studies considering self-citations at the individual level should make clear whether author or total self-citations are used as these can affect researchers differently.

Graphene Oxide–Silver Nanoparticles Nanocomposite Stimulates Differentiation in Human Neuroblastoma Cancer Cells (SH-SY5Y

Directory of Open Access Journals (Sweden)

Sangiliyandi Gurunathan

2017-11-01

Full Text Available Recently, graphene and graphene related nanocomposite receive much attention due to high surface-to-volume ratio, and unique physiochemical and biological properties. The combination of metallic nanoparticles with graphene-based materials offers a promising method to fabricate novel graphene–silver hybrid nanomaterials with unique functions in biomedical nanotechnology, and nanomedicine. Therefore, this study was designed to prepare graphene oxide (GO silver nanoparticles (AgNPs nanocomposite (GO-AgNPs containing two different nanomaterials in single platform with distinctive properties using luciferin as reducing agents. In addition, we investigated the effect of GO-AgNPs on differentiation in SH-SY5Y cells. The synthesized GO-AgNPs were characterized by ultraviolet-visible absorption spectroscopy (UV-vis, X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM and Raman spectroscopy. The differentiation was confirmed by series of cellular and biochemical assays. The AgNPs were distributed uniformly on the surface of graphene oxide with an average size of 25 nm. As prepared GO-AgNPOs induces differentiation by increasing the expression of neuronal differentiation markers and decreasing the expression of stem cell markers. The results indicated that the redox biology involved the expression of various signaling molecules, which play an important role in differentiation. This study suggests that GO-AgNP nanocomposite could stimulate differentiation of SH-SY5Y cells. Furthermore, understanding the mechanisms of differentiation of neuroblastoma cells could provide new strategies for cancer and stem cell therapies. Therefore, these studies suggest that GO-AgNPs could target specific chemotherapy-resistant cells within a tumor.

Self-citation of Medical and Non-medical Universities in Northern Iran.

Science.gov (United States)

Jahani, Mohammad Ali; Yaminfirooz, Mousa

2016-12-01

Self-citation is one of the main challenges in the evaluation of researchers' scientific output. This study aimed at comparing the institutional self-citation among the universities located in Northern Iran. This study was conducted as a scientometric study. Research population included all scientific productions of 16 Northern Iran Universities with at least 100 indexed documents indexed in the Web of Science (WoS) by 2 June 2015. The citation analysis section of WoS was used for data collection. SPSS was applied for data analysis. Study hypotheses were tested with two independent sample t-test and paired sample t-test. Producing 16,399 papers, northern Iran universities had 5.33% of contribution in Iran's scientific production. They received 84,058 citations with 17% and 12% of self-citations belonged to the non-medical and medical universities, respectively. Testing hypotheses revealed that increase in received citations significantly increases the rate of self-citation and increase in scientific production does not necessarily increase the rate of self-citation. The rate of self-citation in the studied universities was not relatively high. However, investigating into the factors affecting the rate of and motives for self-citation needs further research.

Solution-processed parallel tandem polymer solar cells using silver nanowires as intermediate electrode.

Science.gov (United States)

Guo, Fei; Kubis, Peter; Li, Ning; Przybilla, Thomas; Matt, Gebhard; Stubhan, Tobias; Ameri, Tayebeh; Butz, Benjamin; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2014-12-23

Tandem architecture is the most relevant concept to overcome the efficiency limit of single-junction photovoltaic solar cells. Series-connected tandem polymer solar cells (PSCs) have advanced rapidly during the past decade. In contrast, the development of parallel-connected tandem cells is lagging far behind due to the big challenge in establishing an efficient interlayer with high transparency and high in-plane conductivity. Here, we report all-solution fabrication of parallel tandem PSCs using silver nanowires as intermediate charge collecting electrode. Through a rational interface design, a robust interlayer is established, enabling the efficient extraction and transport of electrons from subcells. The resulting parallel tandem cells exhibit high fill factors of ∼60% and enhanced current densities which are identical to the sum of the current densities of the subcells. These results suggest that solution-processed parallel tandem configuration provides an alternative avenue toward high performance photovoltaic devices.

Semi-automatic Citation Correction with Lemon8-XML

Directory of Open Access Journals (Sweden)

MJ Suhonos

2009-03-01

Full Text Available The Lemon8-XML software application, developed by the Public Knowledge Project (PKP, provides an open-source, computer-assisted interface for reliable citation structuring and validation. Lemon8-XML combines citation parsing algorithms with freely-available online indexes such as PubMed, WorldCat, and OAIster. Fully-automated markup of entire bibliographies may be a genuine possibility using this approach. Automated markup of citations would increase bibliographic accuracy while reducing copyediting demands.

Cytotoxicity of Silver Nanoparticles in Human Embryonic Stem Cell-Derived Fibroblasts and an L-929 Cell Line

Directory of Open Access Journals (Sweden)

Hui Peng

2012-01-01

Full Text Available Consensus about the toxicity of silver nanoparticles (Ag-NPs has not been reached, even though extensive attention has been paid to this issue. This confusion may be due to physicochemical factors of Ag-NPs and the cell model used for biological safety evaluation. In the present study, human embryonic stem cell-derived fibroblasts (EBFs, which have been considered a closer representative of the in vivo response, were used as a novel cell model to assess the cytotoxicity of Ag-NPs (~20 nm and ~100 nm in comparison with L-929 fibroblast cell line. Cell proliferation, cell cycle, apoptosis, p53 expression, and cellular uptake were examined. Results showed that Ag-NPs presented higher cytotoxicity to EBF than to L-929. EBF demonstrated a stronger capacity to ingest Ag-NPs, a higher G2/M arrest, and more upgraduated p53 expression after exposed to Ag-NPs for 48 h when compared with L-929. It could be concluded that EBF exhibited a more sensitive response to Ag-NPs compared with L-929 cells, indicating that EBF may be a valid candidate for cytotoxicity screening assays of nanoparticles.

Bibliometric Rankings of Journals Based on the Thomson Reuters Citations Database

NARCIS (Netherlands)

C-L. Chang (Chia-Lin); M.J. McAleer (Michael)

2015-01-01

markdownabstract__Abstract__ Virtually all rankings of journals are based on citations, including self citations by journals and individual academics. The gold standard for bibliometric rankings based on citations data is the widely-used Thomson Reuters Web of Science (2014) citations database,

Bibliometric Rankings of Journals based on the Thomson Reuters Citations Database

NARCIS (Netherlands)

C-L. Chang (Chia-Lin); M.J. McAleer (Michael)

2015-01-01

markdownabstract__Abstract__ Virtually all rankings of journals are based on citations, including self citations by journals and individual academics. The gold standard for bibliometric rankings based on citations data is the widely-used Thomson Reuters Web of Science (2014) citations database,

Application of CTLM method combining interfacial structure characterization to investigate contact formation of silver paste metallization on crystalline silicon solar cells

Science.gov (United States)

Xiong, Shenghu; Yuan, Xiao; Tong, Hua; Yang, Yunxia; Liu, Cui; Ye, Xiaojun; Li, Yongsheng; Wang, Xianhao; Luo, Lan

2018-04-01

Circular transmission line model (CTLM) measurements were applied to study the contact formation mechanism of the silver paste metallization on n-type emitter of crystalline silicon solar cells. The electrical performance parameters ρc,Rsk , and Lt , which are related to the physical and chemical states of the multiphase materials at the interface, were extracted from the CTLM measurements, and were found to be sensitive to sintering temperature. As the temperature increased from 585 °C to 780 °C, initially the ρc value decreased rapidly, then flattened out and increased slightly. The order of resistivity magnitude was restricted by the SiNx passivation layer in the early sintering stages, and relied on the carrier tunneling probability affected by the precipitated silver crystallites or colloids, emitter doping concentration and molten glass layer. Based on the calculations that the sheet resistance underneath the electrode was reduced form 110 Ω / □ to 0.186 Ω / □ , it could be inferred that there was formation of a highly conductive layer of silver crystallites and colloids contained glass on the emitter. The transfer length Lt exhibited a U-shaped variation along with the temperature, reflecting the variation of the interfacial electrical properties. Overall, this article shows that the CTLM method can become a new powerful tool for researchers to meet the challenges of silver paste metallization innovation for manufacturing high-efficiency silicon solar cells.

Data reuse and the open data citation advantage

Directory of Open Access Journals (Sweden)

Heather A. Piwowar

2013-10-01

Full Text Available Background. Attribution to the original contributor upon reuse of published data is important both as a reward for data creators and to document the provenance of research findings. Previous studies have found that papers with publicly available datasets receive a higher number of citations than similar studies without available data. However, few previous analyses have had the statistical power to control for the many variables known to predict citation rate, which has led to uncertain estimates of the “citation benefit”. Furthermore, little is known about patterns in data reuse over time and across datasets. Method and Results. Here, we look at citation rates while controlling for many known citation predictors and investigate the variability of data reuse. In a multivariate regression on 10,555 studies that created gene expression microarray data, we found that studies that made data available in a public repository received 9% (95% confidence interval: 5% to 13% more citations than similar studies for which the data was not made available. Date of publication, journal impact factor, open access status, number of authors, first and last author publication history, corresponding author country, institution citation history, and study topic were included as covariates. The citation benefit varied with date of dataset deposition: a citation benefit was most clear for papers published in 2004 and 2005, at about 30%. Authors published most papers using their own datasets within two years of their first publication on the dataset, whereas data reuse papers published by third-party investigators continued to accumulate for at least six years. To study patterns of data reuse directly, we compiled 9,724 instances of third party data reuse via mention of GEO or ArrayExpress accession numbers in the full text of papers. The level of third-party data use was high: for 100 datasets deposited in year 0, we estimated that 40 papers in PubMed reused a

Citation analysis in research evaluation

CERN Document Server

Moed, Henk F

2005-01-01

This book is written for members of the scholarly research community, and for persons involved in research evaluation and research policy. More specifically, it is directed towards the following four main groups of readers: - All scientists and scholars who have been or will be subjected to a quantitative assessment of research performance using citation analysis. - Research policy makers and managers who wish to become conversant with the basic features of citation analysis, and about its potentialities and limitations. - Members of peer review committees and other evaluators, who consider th

Fabrication and test of inorganic/organic separators. [for silver zinc batteries

Science.gov (United States)

Smatko, J. S.

1974-01-01

Completion of testing and failure analysis of MDC 40 Ahr silver zinc cells containing largely inorganic separators was accomplished. The results showed that the wet stand and cycle life objectives of the silver zinc cell development program were accomplished. Building, testing and failure analysis of two plate cells employing three optimum separators selected on the basis of extensive screening tests, was performed. The best separator material as a result of these tests was doped calcium zirconate.

Growing complex network of citations of scientific papers: Modeling and measurements.

Science.gov (United States)

Golosovsky, Michael; Solomon, Sorin

2017-01-01

We consider the network of citations of scientific papers and use a combination of the theoretical and experimental tools to uncover microscopic details of this network growth. Namely, we develop a stochastic model of citation dynamics based on the copying-redirection-triadic closure mechanism. In a complementary and coherent way, the model accounts both for statistics of references of scientific papers and for their citation dynamics. Originating in empirical measurements, the model is cast in such a way that it can be verified quantitatively in every aspect. Such validation is performed by measuring citation dynamics of physics papers. The measurements revealed nonlinear citation dynamics, the nonlinearity being intricately related to network topology. The nonlinearity has far-reaching consequences including nonstationary citation distributions, diverging citation trajectories of similar papers, runaways or "immortal papers" with infinite citation lifetime, etc. Thus nonlinearity in complex network growth is our most important finding. In a more specific context, our results can be a basis for quantitative probabilistic prediction of citation dynamics of individual papers and of the journal impact factor.

Journal rankings by citation analysis in health sciences librarianship.

Science.gov (United States)

Fang, M L

1989-01-01

The purpose of this study was to identify objectively a hierarchical ranking of journals for health sciences librarians with faculty status. Such a guideline can indicate a journal's value for promotion and tenure consideration. Lists of recent research articles (1982-1986) in health sciences librarianship, and articles written by health sciences librarians, were compiled by searching Social SCISEARCH and MEDLINE. The journals publishing those articles are presented. Results show BMLA as the most prominent journal in the field. Therefore, citations from articles in BMLA from 1982 to 1986 were chosen as a sample for citation analysis. Citation analysis was employed to identify the most frequently cited journals. Some characteristics of the citations in BMLA are also discussed. The ranking of journals based on citation frequency, as a result, was identified. PMID:2655785

[Antimicrobial activity of stable silver nanoparticles of a certain size].

Science.gov (United States)

Mukha, Iu P; Eremenko, A M; Smirnova, N P; Mikhienkova, A I; Korchak, G I; Gorchev, V F; Chunikhin, A Iu

2013-01-01

Conditions for obtaining stable silver nanoparticles smaller than 10 nm were developed using a binary stabilizer polyvinylpyrrolidone/sodium dodecylsulphate in optimal ratio. Optical spectra, morphology and dependence of size of the nanoparticles on the amount of reducing agent were studied. Colloidal solutions of nanosilver showed a high bactericidal activity against strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, and fungicidal activity against Candida albicans. The mechanism of action of nanosized silver on microbial cell was examined by laser scanning confocal microscope using fluorescent label. First step of antimicrobial effect on microorganisms was membrane damage and penetration of silver nanoparticles into the cell. Prolonged stability of nanoparticles and their antimicrobial activity over the past two years were showed.

Intravenous Exposure of Pregnant Mice to Silver Nanoparticles: Silver Tissue Distribution and Effects in Maternal and Extra-Embryonic Tissues and Embryos

Science.gov (United States)

Austin, Carlye Anne

This research explores the tissue distribution of silver, as well as adverse effects in pregnant mice and embryos, following prenatal silver nanoparticle (AgNP) exposure. Chapter one of this dissertation is a survey of the published literature on the reproductive and/or developmental toxicity of AgNPs. The available data indicate that AgNPs adversely affect sperm count, viability, and/or motility both in vivo and in vitro, and cause apoptosis and necrosis in spermatogonial stem cells and testicular cells. Additionally, AgNP exposure results in mortality and morphological deformities in fish embryos, but produces no adverse effects in chicken embryos. The current published research on in vivo AgNP exposure to mammals during gestation consists of only three studies, one of which is described in chapter two of this dissertation. These studies report results that may suggest a potential for adverse effects on fetal development (e.g. , decreased viability and fetal and placental weights, increased incidence of developmentally young embryos), but additional research is needed. Chapter two of this dissertation investigates the distribution of silver in tissues of pregnant mice and gestation day (GD) 10 embryos following intravenous maternal exposure to 50 nm AgNPs during early organogenesis (GDs 7-9). Examinations of embryo morphology and histology were also performed. Results demonstrated the presence of silver in all organs and tissues examined. Silver concentrations were highest in liver, spleen, and visceral yolk sac, and lowest in embryos. Groups of mice were also treated with soluble silver nitrate, and the pattern of silver tissue distribution following silver nitrate exposure was similar to that which followed AgNP treatment. Transmission electron microscopy-energy dispersive x-ray spectroscopy (TEM-EDS) confirmed the presence of vesicle-bound nanoparticulate silver in visceral yolk sac endoderm, but not mesoderm. This finding, along with the high silver

Citation ranking versus peer evaluation of senior faculty research performance

DEFF Research Database (Denmark)

Meho, Lokman I.; Sonnenwald, Diane H.

2000-01-01

The purpose of this study is to analyze the relationship between citation ranking and peer evaluation in assessing senior faculty research performance. Other studies typically derive their peer evaluation data directly from referees, often in the form of ranking. This study uses two additional...... indicator of research performance of senior faculty members? Citation data, book reviews, and peer ranking were compiled and examined for faculty members specializing in Kurdish studies. Analysis shows that normalized citation ranking and citation content analysis data yield identical ranking results....... Analysis also shows that normalized citation ranking and citation content analysis, book reviews, and peer ranking perform similarly (i.e., are highly correlated) for high-ranked and low-ranked senior scholars. Additional evaluation methods and measures that take into account the context and content...

Antibacterial potency of V.A.C. GranuFoam Silver(®) Dressing.

Science.gov (United States)

Sachsenmaier, Saskia; Peschel, Andreas; Ipach, Ingmar; Kluba, Torsten

2013-10-01

V.A.C.(®) GranuFoam™ therapy is regularly used in the surgical therapy of infected wounds and soft tissue injuries. Silver nanoparticles can destroy bacterial cell walls and inhibit enzymes for cell replication. Silver dressings are therefore successfully used for many indications in wound therapy. In this study, we investigated the antimicrobial potency of ionic silver released from the silver-coated V.A.C.(®) GranuFoam™ during vacuum therapy. Silver dressing was exposed to agar plates populated with bacteria to measure silver release. A total of 15 agar plates colonised with either Staphylococcus aureus populations or with Staphylococcus epidermidis, were loaded with V.A.C. GranuFoam Silver(®) Dressing polyurethane foam (KCI, San Antonio, Texas). Each of 13 pieces of silver-coated foam was applied to an agar plate. Two plates were loaded with conventional black foam without any coating. After connecting to a vacuum pump, the vacuum therapy of the 15 plates lasted 5 days. The zone of inhibition of bacterial growth around the foam was measured daily. Silver release was also determined as a function of time. At each time point, there was evidence of silver in the agar independent of bacterial colonisation. The S. aureus agar showed a consecutive increase in silver concentration from baseline upon 48 h after exposure to the negative pressure of V.A.C. therapy. An increasing mean silver level after 48, 72 and 96 h was measured under V.A.C. therapy with a peak value after 120 h. In contrast, the results from the S. epidermidis plates did not follow a linear pattern. At the beginning of vacuum therapy, we documented a rise in silver concentration. After 48-96h, the silver levels fluctuated. A maximum zone of inhibition in both bacterial colonised plates (S. aureus and S. epidermidis) was found 39 h after the start of the V.A.C. GranuFoam Silver(®) therapy. From our results, we confirmed the antimicrobial effect of the silver ions against S. aureus and S

Facile synthesis of mPEG-luteolin-capped silver nanoparticles with antimicrobial activity and cytotoxicity to neuroblastoma SK-N-SH cells.

Science.gov (United States)

Qing, Weixia; Wang, Yong; Li, Xiao; Lu, Minghua; Liu, Xiuhua

2017-12-01

We firstly report a facile route for the green synthesis of mPEG-luteolin-capped silver nanoparticles (mPEG-luteolin-AgNPs) using mPEG-luteolin as both the reducer and stabilizer. The reaction was carried out in a stirred aqueous solution at 50°C without additional poisonous reagents. The prepared mPEG-luteolin-AgNPs was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), zeta potential and UV-vis (UV-vis) spectrum, respectively. The proportions of mPEG-luteolin capped silver nanoparticles is about 89.9%, and the content of silver is 6.65%. The mPEG-luteolin-AgNPs was evaluated the antimicrobial effects on Staphlococcus aureus, Extended spectrum β-Lactamases Staphlococcus aureus, Escherichia Coli and Extended spectrum β-Lactamases Escherichia Coli using drilling hole method. The results showed that both gram-positive and gram-negative bacteria were killed by the mPEG-luteolin-AgNPs at low concentration. Meanwhile, the cell viability assay demonstrated that mPEG-luteolin-AgNPs had toxic effects on human neuroblastoma SK-N-SH cells. Copyright © 2017 Elsevier B.V. All rights reserved.

[Zero citation of Russian institute publications on the psychiatry and addiction].

Science.gov (United States)

Nemtsov, A V; Kuznetsova-Moreva, E A

To evaluate the zero-citation sizes. Based on the data of the Russian Science Citation Index the publication activity of four leading institutes in the field of Psychiatry and Addiction is analyzed. The same indices in the field of Neurology were used as a control. Number and percentage of publications with ≥1 citations and zero-citation were analyzed. It has been shown that in psychiatric science zero citation rate is quite high (from 32.8% to 47.2%, an average of 42.9%). It is higher compared to the control. Zero-citation indicator is essential to evaluate the effectiveness of scientific institutions.

Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review.

Science.gov (United States)

Hadrup, Niels; Lam, Henrik R

2014-02-01

Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached. Copyright © 2013 Elsevier Inc. All rights reserved.

A Citation Analysis of Who's Who in Introductory Textbooks

Science.gov (United States)

Griggs, Richard A.; Proctor, Derrick L.

2002-01-01

Given the many changes in the introductory psychology textbook market in the past 2 decades and the lack of a recent citation study of introductory texts, we conducted a citation analysis of a stratified random sample of current texts. To provide a more comprehensive picture of current citation emphases, we extended our analysis to the top 60…

32 CFR 935.125 - Citation in place of arrest.

Science.gov (United States)

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Citation in place of arrest. 935.125 Section 935... INSULAR REGULATIONS WAKE ISLAND CODE Peace Officers § 935.125 Citation in place of arrest. In any case in which a peace officer may make an arrest without a warrant, he may issue and serve a citation if he...

Lovely but dangerous: The impact of patent citations on patent duration

OpenAIRE

Maurseth, Per Botolf

2001-01-01

- What is the impact of patent citations on patent renewal behaviour? Patent citations are commonly used as an indicator of technology spillovers. For cited patents therefore, patent citations have a potentially ambiguous impact. On the one hand, patent citations may indicate a scientific breakthrough, a high value of the cited patent and therefore a long survival period. On the other hand, patent citations may indicate competing innovations that render the cited patent obsolete. By discri...

Oral toxicity of silver ions, silver nanoparticles and colloidal silver – a review

DEFF Research Database (Denmark)

Hadrup, Niels; Lam, Henrik Rye

2014-01-01

Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin......, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts...... and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least...

Electrodeposition of silver nanoparticle arrays on transparent conductive oxides

International Nuclear Information System (INIS)

Zhang, Dezhong; Tang, Yang; Jiang, Fuguo; Han, Zhihua; Chen, Jie

2016-01-01

Highlights: • The sliver nanoparticles' size and the distance between nanoparticles are tunable. - Abstract: In this paper, we present a facile method for the preparation of silver nanoparticles on aluminum-doped zinc oxide (AZO) via electrodeposition techniques at room temperature. The morphology and structure of silver nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. Due to localized surface plasmon resonances, as-prepared silver nanoparticles on AZO glass exhibited different reflectivity in contrast with bare AZO glass. The weighted reflection of AZO substrate increased from 10.2% to 12.8%. The high reflection property of silver nanoparticle arrays on AZO substrate might be applicable for thin film solar cells and other optoelectronics applications.

Electrodeposition of silver nanoparticle arrays on transparent conductive oxides

Energy Technology Data Exchange (ETDEWEB)

Zhang, Dezhong; Tang, Yang, E-mail: tangyang@nicenergy.com; Jiang, Fuguo; Han, Zhihua; Chen, Jie

2016-04-30

Highlights: • The sliver nanoparticles' size and the distance between nanoparticles are tunable. - Abstract: In this paper, we present a facile method for the preparation of silver nanoparticles on aluminum-doped zinc oxide (AZO) via electrodeposition techniques at room temperature. The morphology and structure of silver nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. Due to localized surface plasmon resonances, as-prepared silver nanoparticles on AZO glass exhibited different reflectivity in contrast with bare AZO glass. The weighted reflection of AZO substrate increased from 10.2% to 12.8%. The high reflection property of silver nanoparticle arrays on AZO substrate might be applicable for thin film solar cells and other optoelectronics applications.

Arginine-assisted immobilization of silver nanoparticles on ZnO nanorods: an enhanced and reusable antibacterial substrate without human cell cytotoxicity

Science.gov (United States)

Agnihotri, Shekhar; Bajaj, Geetika; Mukherji, Suparna; Mukherji, Soumyo

2015-04-01

Silver-based hybrid nanomaterials are gaining interest as potential alternatives for conventional antimicrobial agents. Herein, we present a simple, facile and eco-friendly approach for the deposition of silver nanoparticles (AgNPs) on ZnO nanorods, which act as a nanoreactor for in situ synthesis and as an immobilizing template in the presence of arginine. The presence of arginine enhanced the stability of ZnO deposition on the glass substrate by hindering the dissolution of zinc under alkaline conditions. Various Ag/ZnO hybrid nanorod (HNR) samples were screened to obtain a high amount of silver immobilization on the ZnO substrate. Ag/ZnO HNRs displayed potent antibacterial ability and could achieve 100% kill for both Escherichia coli and Bacillus subtilis strains under various test conditions. The hybrid material mediated its dual mode of antibacterial action through direct contact-killing and release of silver ions/nanoparticles and showed superior bactericidal performance compared to pure ZnO nanorods and colloidal AgNPs. No significant decline in antibacterial efficacy was observed even after the same substrate was repeatedly reused multiple times. Interestingly, the amount of Ag and Zn release was much below their maximal limit in drinking water, thus preventing potential health hazards. Immobilized AgNPs showed no cytotoxic effects on the human hepatocarcinoma cell line (HepG2). Moreover, treating cells with the antibacterial substrate for 24 hours did not lead to significant generation of reactive oxygen species (ROS). The good biocompatibility and bactericidal efficacy would thus make it feasible to utilize this immobilization strategy for preparing new-generation antibacterial coatings.Silver-based hybrid nanomaterials are gaining interest as potential alternatives for conventional antimicrobial agents. Herein, we present a simple, facile and eco-friendly approach for the deposition of silver nanoparticles (AgNPs) on ZnO nanorods, which act as a

Misuse of anecdotes in primatology: lessons from citation analysis.

Science.gov (United States)

Sarringhaus, Lauren A; McGrew, William C; Marchant, Linda F

2005-03-01

This study analyzes the accuracy of anecdotes cited in behavioral primatology publications. Anecdotes (n=1 cases) recounting tool use were sought in the four main primatological journals. Citations of anecdotes in the scientific literature that met three criteria were systematically coded for recognition and accuracy. The results showed that 60% of the time, authors who cited anecdotes did not explicitly acknowledge them as such. To a lesser extent, the citations exaggerated the frequency of anecdotal events or misrepresented their status. For tool use specifically, the actor was misreported more often than the tool or its target. Multiple citations were incorrect more often than single citations. Overall, it seems that citation of anecdotes is problematic and may have far-reaching implications in terms of misleading overgeneralizations. Primatologists should take care in citing singular or rare events. Copyright (c) 2005 Wiley-Liss, Inc.

[Scientific collaboration and article citations: practices in medical journals].

Science.gov (United States)

Bador, Pascal; Lafouge, Thierry

2012-01-01

In order to characterize scientific collaboration the best way is to study co-signature of articles. Two indicators are interesting: number of authors and international character. The objective is to study correlation between these two indicators and citation number. We selected two pharmacy and medicine journals in order to compare practices. We used a sample of about 800 articles published in 2002-2005 for which we collected citations up to 2010. We transformed numeric variables, authors number and citation number, into qualitative variables. "Authors" and "Citations" variables are not independent. Less cited articles are often published by one author or a very small team while international character of articles generally increases citation number. This micro-analysis also allowed us to better understand publication practices. © 2012 Société Française de Pharmacologie et de Thérapeutique.

Development of a Data Citations Database for an Interdisciplinary Data Center

Science.gov (United States)

Chen, R. S.; Downs, R. R.; Schumacher, J.; Gerard, A.

2017-12-01

The scientific community has long depended on consistent citation of the scientific literature to enable traceability, support replication, and facilitate analysis and debate about scientific hypotheses, theories, assumptions, and conclusions. However, only in the past few years has the community focused on consistent citation of scientific data, e.g., through the application of Digital Object Identifiers (DOIs) to data, the development of peer-reviewed data publications, community principles and guidelines, and other mechanisms. This means that, moving ahead, it should be easier to identify and track data citations and conduct systematic bibliometric studies. However, this still leaves the problem that many legacy datasets and past citations lack DOIs, making it difficult to develop a historical baseline or assess trends. With this in mind, the NASA Socioeconomic Data and Applications Center (SEDAC) has developed a searchable citations database, containing more than 3,400 citations of SEDAC data and information products over the past 20 years. These citations were collected through various indices and search tools and in some cases through direct contacts with authors. The citations come from a range of natural, social, health, and engineering science journals, books, reports, and other media. The database can be used to find and extract citations filtered by a range of criteria, enabling quantitative analysis of trends, intercomparisons between data collections, and categorization of citations by type. We present a preliminary analysis of citations for selected SEDAC data collections, in order to establish a baseline and assess options for ongoing metrics to track the impact of SEDAC data on interdisciplinary science. We also present an analysis of the uptake of DOIs within data citations reported in published studies that used SEDAC data.

Surface-enhanced Raman scattering from silver electrodes

International Nuclear Information System (INIS)

Trott, G.R.

1982-01-01

The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process

Citation Analysis of the Korean Journal of Urology From Web of Science, Scopus, Korean Medical Citation Index, KoreaMed Synapse, and Google Scholar.

Science.gov (United States)

Huh, Sun

2013-04-01

The Korean Journal of Urology began to be published exclusively in English in 2010 and is indexed in PubMed Central/PubMed. This study analyzed a variety of citation indicators of the Korean Journal of Urology before and after 2010 to clarify the present position of the journal among the urology category journals. The impact factor, SCImago Journal Rank (SJR), impact index, Z-impact factor (ZIF, impact factor excluding self-citation), and Hirsch Index (H-index) were referenced or calculated from Web of Science, Scopus, SCImago Journal & Country Ranking, Korean Medical Citation Index (KoMCI), KoreaMed Synapse, and Google Scholar. Both the impact factor and the total citations rose rapidly beginning in 2011. The 2012 impact factor corresponded to the upper 84.9% in the nephrology-urology category, whereas the 2011 SJR was in the upper 58.5%. The ZIF in KoMCI was one fifth of the impact factor because there are only two other urology journals in KoMCI. Up to 2009, more than half of the citations in the Web of Science were from Korean researchers, but from 2010 to 2012, more than 85% of the citations were from international researchers. The H-indexes from Web of Science, Scopus, KoMCI, KoreaMed Synapse, and Google Scholar were 8, 10, 12, 9, and 18, respectively. The strategy of the language change in 2010 was successful from the perspective of citation indicators. The values of the citation indicators will continue to increase rapidly and consistently as the research achievement of authors of the Korean Journal of Urology increases.

Clustering of scientific citations in Wikipedia

DEFF Research Database (Denmark)

Nielsen, Finn Årup

The instances of templates in Wikipedia form an interesting data set of structured information. Here I focus on the cite journal template that is primarily used for citation to articles in scientific journals. These citations can be extracted and analyzed: Non-negative matrix factorization...... is performed on a (article x journal) matrix resulting in a soft clustering of Wikipedia articles and scientific journals, each cluster more or less representing a scientific topic....

Size- and coating-dependent cytotoxicity and genotoxicity of silver nanoparticles evaluated using in vitro standard assays.

Science.gov (United States)

Guo, Xiaoqing; Li, Yan; Yan, Jian; Ingle, Taylor; Jones, Margie Yvonne; Mei, Nan; Boudreau, Mary D; Cunningham, Candice K; Abbas, Mazhar; Paredes, Angel M; Zhou, Tong; Moore, Martha M; Howard, Paul C; Chen, Tao

2016-11-01

The physicochemical characteristics of silver nanoparticles (AgNPs) may greatly alter their toxicological potential. To explore the effects of size and coating on the cytotoxicity and genotoxicity of AgNPs, six different types of AgNPs, having three different sizes and two different coatings, were investigated using the Ames test, mouse lymphoma assay (MLA) and in vitro micronucleus assay. The genotoxicities of silver acetate and silver nitrate were evaluated to compare the genotoxicity of nanosilver to that of ionic silver. The Ames test produced inconclusive results for all types of the silver materials due to the high toxicity of silver to the test bacteria and the lack of entry of the nanoparticles into the cells. Treatment of L5718Y cells with AgNPs and ionic silver resulted in concentration-dependent cytotoxicity, mutagenicity in the Tk gene and the induction of micronuclei from exposure to nearly every type of the silver materials. Treatment of TK6 cells with these silver materials also resulted in concentration-dependent cytotoxicity and significantly increased micronucleus frequency. With both the MLA and micronucleus assays, the smaller the AgNPs, the greater the cytotoxicity and genotoxicity. The coatings had less effect on the relative genotoxicity of AgNPs than the particle size. Loss of heterozygosity analysis of the induced Tk mutants indicated that the types of mutations induced by AgNPs were different from those of ionic silver. These results suggest that AgNPs induce cytotoxicity and genotoxicity in a size- and coating-dependent manner. Furthermore, while the MLA and in vitro micronucleus assay (in both types of cells) are useful to quantitatively measure the genotoxic potencies of AgNPs, the Ames test cannot.

29 CFR 2700.23 - Review of a subsequent citation or order.

Science.gov (United States)

2010-07-01

... 29 Labor 9 2010-07-01 2010-07-01 false Review of a subsequent citation or order. 2700.23 Section... COMMISSION PROCEDURAL RULES Contests of Citations and Orders § 2700.23 Review of a subsequent citation or order. (a) The contesting party shall file any subsequent citation or order that modifies or terminates...

Citation Classics in "Suicide and Life Threatening Behavior": A Research Note

Science.gov (United States)

Stack, Steven

2012-01-01

The number of citations a scholarly work receives is a common measure of its impact on the scientific literature; "citation classics" are the most highly cited works. The content of "Suicide and Life-Threatening Behavior" ("SLTB") citation classics is described here. The impact of "SLTB" citation classics is compared to their counterparts in…

Improving MeSH classification of biomedical articles using citation contexts.

Science.gov (United States)

Aljaber, Bader; Martinez, David; Stokes, Nicola; Bailey, James

2011-10-01

Medical Subject Headings (MeSH) are used to index the majority of databases generated by the National Library of Medicine. Essentially, MeSH terms are designed to make information, such as scientific articles, more retrievable and assessable to users of systems such as PubMed. This paper proposes a novel method for automating the assignment of biomedical publications with MeSH terms that takes advantage of citation references to these publications. Our findings show that analysing the citation references that point to a document can provide a useful source of terms that are not present in the document. The use of these citation contexts, as they are known, can thus help to provide a richer document feature representation, which in turn can help improve text mining and information retrieval applications, in our case MeSH term classification. In this paper, we also explore new methods of selecting and utilising citation contexts. In particular, we assess the effect of weighting the importance of citation terms (found in the citation contexts) according to two aspects: (i) the section of the paper they appear in and (ii) their distance to the citation marker. We conduct intrinsic and extrinsic evaluations of citation term quality. For the intrinsic evaluation, we rely on the UMLS Metathesaurus conceptual database to explore the semantic characteristics of the mined citation terms. We also analyse the "informativeness" of these terms using a class-entropy measure. For the extrinsic evaluation, we run a series of automatic document classification experiments over MeSH terms. Our experimental evaluation shows that citation contexts contain terms that are related to the original document, and that the integration of this knowledge results in better classification performance compared to two state-of-the-art MeSH classification systems: MeSHUP and MTI. Our experiments also demonstrate that the consideration of Section and Distance factors can lead to statistically

Silver percutaneous absorption after exposure to silver nanoparticles: a comparison study of three human skin graft samples used for clinical applications.

Science.gov (United States)

Bianco, C; Adami, G; Crosera, M; Larese, F; Casarin, S; Castagnoli, C; Stella, M; Maina, G

2014-11-01

Silver nanoparticles (AgNPs) are increasingly applied to a wide range of materials for biomedical use. These enable a close contact with human skin, thanks to the large release of silver ions that is responsible for a broad spectrum of antimicrobial activity. Silver can permeate the skin; however, there are no data available on silver permeation through skin grafts commonly used in burns recovery. The aim of our study was to evaluate silver penetration using fresh, cryopreserved, and glycerolized human skin grafts after exposure to a suspension of AgNPs in synthetic sweat using a Franz diffusion cell apparatus for 24 h. Silver permeation profiles revealed a significantly higher permeation through glycerolized skin compared with both fresh and cryopreserved skin: 24-h silver flux penetration was 0.2 ng cm(-2) h(-1) (lag time: 8.2 h) for fresh skin, 0.3 ng cm(-2) h(-1) (lag time: 10.9 h) for cryopreserved skin, and 3.8 ng cm(-2) h(-1) (lag time: 6.3 h) for glycerolized skin. Permeation through glycerolized skin is significantly higher compared to both fresh and cryopreserved skin. This result can generate relevant clinical implications for burns treatment with products containing AgNPs. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Citation classics in pediatrics: a bibliometric analysis.

Science.gov (United States)

Chhapola, Viswas; Tiwari, Soumya; Deepthi, Bobbity; Kanwal, Sandeep Kumar

2018-03-06

Citation analysis provides insights into the history and developmental trajectory of scientific fields. Our objective was to perform an analysis of citation classics in the journals of pediatric specialty and to examine their characteristics. Initially, all the journals listed under the category of pediatrics (n = 120) were identified using Journal Citation Reports. Web of science database was then searched (1950-2016) to select the top-100 cited articles in the above identified pediatric journals. The top-100 cited article were categorized according the study design, sub-specialty, country, institutional affiliation, and language. The top-100 articles were published in 18 different journals, with Pediatrics having the highest numbers (n = 40), followed by The Journal of Pediatrics (n = 17). The majority (n = 62) of classics were published after 1990. The most cited article had citation count of 3516 and the least cited had a citation count of 593. The USA (n = 71) was the most commonly represented country, and 60 institutions contributed to 100 articles. Fifteen authors contributed to more than one classic as first or second author. Observational study (n = 55) was the commonest study design across all decades, followed by reviews (n = 12), scale development studies (n = 11), and guidelines (n = 11). Among the pediatric sub-specialties, growth and development articles were highly cited (n = 24), followed by pediatric psychiatry and behavior (n = 21), endocrinology (n = 15), and neonatology (n = 12). The top-100 cited articles in pediatrics identify the impactful authors, journals, institutes, and countries. Observational study design was predominant-implying that inclusion among citation classics is not related to soundness of study design.

1 CFR 8.9 - Form of citation.

Science.gov (United States)

2010-01-01

... 1 General Provisions 1 2010-01-01 2010-01-01 false Form of citation. 8.9 Section 8.9 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER SPECIAL EDITIONS OF THE FEDERAL REGISTER CODE OF FEDERAL REGULATIONS § 8.9 Form of citation. The Code of Federal Regulations may be cited by title and...

Biosynthesis of Silver Nanoparticles Using Taxus yunnanensis Callus and Their Antibacterial Activity and Cytotoxicity in Human Cancer Cells

Directory of Open Access Journals (Sweden)

Qian Hua Xia

2016-09-01

Full Text Available Plant constituents could act as chelating/reducing or capping agents for synthesis of silver nanoparticles (AgNPs. The green synthesis of AgNPs has been considered as an environmental friendly and cost-effective alternative to other fabrication methods. The present work described the biosynthesis of AgNPs using callus extracts from Taxus yunnanensis and evaluated their antibacterial activities in vitro and potential cytotoxicity in cancer cells. Callus extracts were able to reduce silver nitrate at 1 mM in 10 min. Transmission electron microscope (TEM indicated the synthesized AgNPs were spherical with the size range from 6.4 to 27.2 nm. X-ray diffraction (XRD confirmed the AgNPs were in the form of nanocrystals. Fourier transform infrared spectroscopy (FTIR suggested phytochemicals in callus extracts were possible reducing and capping agents. The AgNPs exhibited effective inhibitory activity against all tested human pathogen bacteria and the inhibition against Gram-positive bacteria was stronger than that of Gram-negative bacteria. Furthermore, they exhibited stronger cytotoxic activity against human hepatoma SMMC-7721 cells and induced noticeable apoptosis in SMMC-7721 cells, but showed lower cytotoxic against normal human liver cells (HL-7702. Our results suggested that biosynthesized AgNPs could be an alternative measure in the field of antibacterial and anticancer therapeutics.

The segregation of silver nanoparticles in low-cost ceramic water filters

International Nuclear Information System (INIS)

Larimer, Curtis; Ostrowski, Nicole; Speakman, Jacquelyn; Nettleship, Ian

2010-01-01

As an impregnated constituent in low-cost ceramic water filters, silver nanoparticles have a demonstrated antibacterial effect. The bactericidal mechanism is believed to be based on direct contact between silver and the cell wall of a contaminant organism. In this study microstructural analysis was used to examine the effect of the processing method on the distribution of silver nanoparticles in the filter material. Silver nanofluid was impregnated into fired clay ceramic samples by a low-cost soak-and-dry method. Analyses of filter samples by scanning electron microscopy, energy dispersive spectroscopy, and digital optical topological mapping showed that silver was concentrated in near surface pores, a condition that is not optimal for highest probability of silver contact. A simple experiment showed that segregation of silver occurs during the drying phase of impregnation. Drying curves showed that 90% of contained liquid evaporates from the external surface.

The influence of the surface chemistry of silver nanoparticles on cell death

International Nuclear Information System (INIS)

Sur, Ilknur; Altunbek, Mine; Kahraman, Mehmet; Culha, Mustafa

2012-01-01

The influence of the surface chemistry of silver nanoparticles (AgNPs) on p53 mediated cell death was evaluated using human dermal fibroblast (HDF) and lung cancer (A549) cells. The citrate reduced AgNPs (C-AgNPs) were modified with either lactose (L-AgNPs) or a 12-base long oligonucleotide (O-AgNPs). Both unmodified and modified AgNPs showed increased concentration and time dependent cytotoxicity and genotoxicity causing an increased p53 up-regulation within 6 h and led to apoptotic or necrotic cell deaths. The C-AgNPs induced more cytotoxicity and cellular DNA damage than the surface modified AgNPs. Modifying the C-AgNPs with lactose or the oligonucleotide reduced both necrotic and apoptotic cell deaths in the HDF cells. The C-AgNPs caused an insignificant necrosis in A549 cells whereas the modified AgNPs caused necrosis and apoptosis in both cell types. Compared to the O-AgNPs, the L-AgNPs triggered more cellular DNA damage, which led to up-regulation of p53 gene inducing apoptosis in A549 cells compared to HDF cells. This suggests that the different surface chemistries of the AgNPs cause different cellular responses that may be important not only for their use in medicine but also for reducing their toxicity. (paper)

Scientific citations favor positive results: a systematic review and meta-analysis.

Science.gov (United States)

Duyx, Bram; Urlings, Miriam J E; Swaen, Gerard M H; Bouter, Lex M; Zeegers, Maurice P

2017-08-01

Citation bias concerns the selective citation of scientific articles based on their results. We brought together all available evidence on citation bias across scientific disciplines and quantified its impact. An extensive search strategy was applied to the Web of Science Core Collection and Medline, yielding 52 studies in total. We classified these studies on scientific discipline, selection method, and other variables. We also performed random-effects meta-analyses to pool the effect of positive vs. negative results on subsequent citations. Finally, we checked for other determinants of citation as reported in the citation bias literature. Evidence for the occurrence of citation bias was most prominent in the biomedical sciences and least in the natural sciences. Articles with statistically significant results were cited 1.6 (95% confidence interval [CI] 1.3-1.8) times more often than articles with nonsignificant results. Articles in which the authors explicitly conclude to have found support for their hypothesis were cited 2.7 (CI 2.0-3.7) times as often. Article results and journal impact factor were associated with citation more often than any other reported determinant. Similar to what we already know on publication bias, also citation bias can lead to an overrepresentation of positive results and unfounded beliefs. Copyright © 2017 Elsevier Inc. All rights reserved.

Experimental study of mutagenous and mitosis modifying activity of silver nanoparticles

Directory of Open Access Journals (Sweden)

B. S. Kirbik

2015-01-01

Full Text Available Mutagenous and mitosis modifying impact of silver nanoparticles has been studied on outbred mice. Nanoparticles were of round shape with dimensions of 5-50 nm, size of generated organic shell of 2-5 nm, the quantity in 1 mcm3 makes 120-270. Metaphasic analysis of mice bone marrow cells was used as a testing technique. The frequency of chromosome aberrations and mitotic index of preparations were accounted. During single intraperitoneal administration of the agent in the dose of 250 mcg/kg the silver nanoparticles demonstrated mitosis stimulating activity. No mutagenous effect of silver nanoparticles by daily administration for 4 days of 25 mcg/kg and single administration in the dose of 250 mcg/kg has been registered, but there is statistically insignificant tendency of aberrant metaphases increase. Consequently silver nanoparticles in the investigated doses demonstrated no mutagenous activity and can be considered safe for mammalian cells.

Polyethylenimine-functionalized silver nanoparticle-based co-delivery of paclitaxel to induce HepG2 cell apoptosis

Directory of Open Access Journals (Sweden)

Li Y

2016-12-01

Full Text Available Yinghua Li,1,* Min Guo,1,* Zhengfang Lin,1 Mingqi Zhao,1 Misi Xiao,1 Changbing Wang,1 Tiantian Xu,1 Tianfeng Chen,2 Bing Zhu1 1Center Laboratory, Guangzhou Women and Children’s Medical Center, Guangzhou Medical University, 2Department of Chemistry, Jinan University, Guangzhou, People’s Republic of China *These authors contributed equally to this work Abstract: Hepatocarcinoma is the third leading cause of cancer-related deaths around the world. Recently, a novel emerging nanosystem as anticancer therapeutic agents with intrinsic therapeutic properties has been widely used in various medical applications. In this study, surface decoration of functionalized silver nanoparticles (AgNPs by polyethylenimine (PEI and paclitaxel (PTX was synthesized. The purpose of this study was to evaluate the effect of Ag@PEI@PTX on cytotoxic and anticancer mechanism on HepG2 cells. The transmission electron microscope image and 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay showed that Ag@PEI@PTX had satisfactory size distribution and high stability and selectivity between cancer and normal cells. Ag@PEI@PTX-induced HepG2 cell apoptosis was confirmed by accumulation of the sub-G1 cells population, translocation of phosphatidylserine, depletion of mitochondrial membrane potential, DNA fragmentation, caspase-3 activation, and poly(ADP-ribose polymerase cleavage. Furthermore, Ag@PEI@PTX enhanced cytotoxic effects on HepG2 cells and triggered intracellular reactive oxygen species; the signaling pathways of AKT, p53, and MAPK were activated to advance cell apoptosis. In conclusion, the results reveal that Ag@PEI@PTX may provide useful information on Ag@PEI@PTX-induced HepG2 cell apoptosis and as appropriate candidate for chemotherapy of cancer. Keywords: silver nanoparticles, polyethylenimine, paclitaxel, reactive oxygen species, apoptosis

Twitter Predicts Citation Rates of Ecological Research.

Science.gov (United States)

Peoples, Brandon K; Midway, Stephen R; Sackett, Dana; Lynch, Abigail; Cooney, Patrick B

2016-01-01

The relationship between traditional metrics of research impact (e.g., number of citations) and alternative metrics (altmetrics) such as Twitter activity are of great interest, but remain imprecisely quantified. We used generalized linear mixed modeling to estimate the relative effects of Twitter activity, journal impact factor, and time since publication on Web of Science citation rates of 1,599 primary research articles from 20 ecology journals published from 2012-2014. We found a strong positive relationship between Twitter activity (i.e., the number of unique tweets about an article) and number of citations. Twitter activity was a more important predictor of citation rates than 5-year journal impact factor. Moreover, Twitter activity was not driven by journal impact factor; the 'highest-impact' journals were not necessarily the most discussed online. The effect of Twitter activity was only about a fifth as strong as time since publication; accounting for this confounding factor was critical for estimating the true effects of Twitter use. Articles in impactful journals can become heavily cited, but articles in journals with lower impact factors can generate considerable Twitter activity and also become heavily cited. Authors may benefit from establishing a strong social media presence, but should not expect research to become highly cited solely through social media promotion. Our research demonstrates that altmetrics and traditional metrics can be closely related, but not identical. We suggest that both altmetrics and traditional citation rates can be useful metrics of research impact.

Twitter predicts citation rates of ecological research

Science.gov (United States)

Peoples, Brandon K.; Midway, Stephen R.; Sackett, Dana K.; Lynch, Abigail; Cooney, Patrick B.

2016-01-01

The relationship between traditional metrics of research impact (e.g., number of citations) and alternative metrics (altmetrics) such as Twitter activity are of great interest, but remain imprecisely quantified. We used generalized linear mixed modeling to estimate the relative effects of Twitter activity, journal impact factor, and time since publication on Web of Science citation rates of 1,599 primary research articles from 20 ecology journals published from 2012–2014. We found a strong positive relationship between Twitter activity (i.e., the number of unique tweets about an article) and number of citations. Twitter activity was a more important predictor of citation rates than 5-year journal impact factor. Moreover, Twitter activity was not driven by journal impact factor; the ‘highest-impact’ journals were not necessarily the most discussed online. The effect of Twitter activity was only about a fifth as strong as time since publication; accounting for this confounding factor was critical for estimating the true effects of Twitter use. Articles in impactful journals can become heavily cited, but articles in journals with lower impact factors can generate considerable Twitter activity and also become heavily cited. Authors may benefit from establishing a strong social media presence, but should not expect research to become highly cited solely through social media promotion. Our research demonstrates that altmetrics and traditional metrics can be closely related, but not identical. We suggest that both altmetrics and traditional citation rates can be useful metrics of research impact.

Biological Synthesis of Silver Nanoparticles by Cell-Free Extract of Spirulina platensis

Directory of Open Access Journals (Sweden)

Gaurav Sharma

2015-01-01

Full Text Available The present study explores biological synthesis of silver nanoparticles (AgNPs using the cell-free extract of Spirulina platensis. Biosynthesised AgNPs were characterised by UV-Vis spectroscopy, SEM, TEM, and FTIR analysis and finally evaluated for antibacterial activity. Extracellular synthesis using aqueous extract of S. platensis showed the formation of well scattered, highly stable, spherical AgNPs with an average size of 30–50 nm. The size and morphology of the nanoparticles were confirmed by SEM and TEM analysis. FTIR and UV-Vis spectra showed that biomolecules, proteins and peptides, are mainly responsible for the formation and stabilisation of AgNPs. Furthermore, the synthesised nanoparticles exhibited high antibacterial activity against pathogenic Gram-negative, that is, Escherichia coli, MTCC-9721; Proteus vulgaris, MTCC-7299; Klebsiella pneumoniae, MTCC-9751, and Gram-positive, that is, Staphylococcus aureus, MTCC-9542; S. epidermidis, MTCC-2639; Bacillus cereus, MTCC-9017, bacteria. The AgNPs had shown maximum zone of inhibition (ZOI that is 31.3±1.11 in P. vulgaris. Use of such a microalgal system provides a simple, cost-effective alternative template for the biosynthesis of nanomaterials of silver in a large scale that could be of great use in biomedical applications.

High temperature creep of single crystals of gold, silver and solid solution gold silver 50-50

International Nuclear Information System (INIS)

Dorizzi, Paul

1973-01-01

We have studied in compression creep along a direction, single crystals of gold, silver and a 50-50 gold-silver solid solution. The experiments were made at temperatures above 0.7 Tf. We have shown that under these conditions and for these three metals a new slip system is operating: the deformation is due to the slip of dislocations having a 1/2 burgers vector on the {110} planes. For gold the activation energy for creep is equal to the self-diffusion energy. We found the same result for silver when the contribution of divacancies to the self-diffusion energy is taken into account. For the alloy the activation energy for creep is very close to the self-diffusion energy of gold in a 50-50 gold-silver alloy, gold being the slower diffusing species in the alloy. The curves giving the creep rate versus the stress can be fitted with the following laws: ε 0 = σ 5 for gold; ε 0 = σ 2,2 for silver and ε 0 = σ 2,5 for the alloy. The dislocation substructure was studied using the crystalline contrast given by the electron microprobe. This new method gives images which are very sensitive to the sub-grains misorientation. The substructure is made of parallelepipedic cells divided by tilt boundaries that are perpendicular to the {110} slip planes. (author) [fr

Bibliometrics of systematic reviews: analysis of citation rates and journal impact factors

Science.gov (United States)

2013-01-01

Background Systematic reviews are important for informing clinical practice and health policy. The aim of this study was to examine the bibliometrics of systematic reviews and to determine the amount of variance in citations predicted by the journal impact factor (JIF) alone and combined with several other characteristics. Methods We conducted a bibliometric analysis of 1,261 systematic reviews published in 2008 and the citations to them in the Scopus database from 2008 to June 2012. Potential predictors of the citation impact of the reviews were examined using descriptive, univariate and multiple regression analysis. Results The mean number of citations per review over four years was 26.5 (SD ±29.9) or 6.6 citations per review per year. The mean JIF of the journals in which the reviews were published was 4.3 (SD ±4.2). We found that 17% of the reviews accounted for 50% of the total citations and 1.6% of the reviews were not cited. The number of authors was correlated with the number of citations (r = 0.215, P reviews published in the top quartile of JIFs (≥ 5.16) received citations in the bottom quartile (eight or fewer), whereas 9% of reviews published in the lowest JIF quartile (≤ 2.06) received citations in the top quartile (34 or more). Six percent of reviews in journals with no JIF were also in the first quartile of citations. Conclusions The JIF predicted over half of the variation in citations to the systematic reviews. However, the distribution of citations was markedly skewed. Some reviews in journals with low JIFs were well-cited and others in higher JIF journals received relatively few citations; hence the JIF did not accurately represent the number of citations to individual systematic reviews. PMID:24028376

Green Synthesis and Antimicrobial Activities of Silver Nanoparticles using Cell Free-Extracts of Enterococcus species

Directory of Open Access Journals (Sweden)

Iyabo C. OLADIPO

2017-06-01

Full Text Available Cell-free extracts of six strains of Enterococcus species obtained from fermented foods were used for the green synthesis of silver nanoparticles (AgNPs, which was characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR and transmission electron microscopy (TEM. The biosynthesized AgNPs were dark brown in colour having surface plasmon resonance in the range of 420-442 nm. The spherical shaped AgNPs had sizes of 4-55 nm, whose formations were facilitated by proteins as indicated by the presence of peaks 1,635-1,637 and 3,275-3,313 cm-1 in the FTIR spectra. The energy dispersive x-ray (EDX showed prominent presence of silver in the AgNPs colloidal solution, while the selected area electron diffraction was typified by the face-centred crystalline nature of silver. The particles inhibited the growth of multi-drug resistant clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris, and also potentiated the activities of ampicillin, ciprofloxacin and cefuroxime in the AgNPs-antibiotic synergy studies. In addition, the prospective relevance of the particles as nanopreservative in paints was demonstrated with the inhibition of growth of Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger and A. flavus in AgNPs-paint admixture. This report further demonstrates the green synthesis of AgNPs by strains of Enterococcus species.

Data Citation Services in the High-Energy Physics Community

CERN Document Server

Herterich, Patricia

2016-01-01

A paradigm change in scholarly communication is underway. Supporting Open Science, an effort to make scientific research data accessible to all interested parties by openly publishing research and encouraging others to do the same thereby making it easier to communicate scientific knowledge, is a part of the change that has become increasingly important for (digital) libraries. Digital libraries are able to play a significant role in enabling Open Science by facilitating data sharing, discovery and re-use. Because data citation is often mentioned as one incentive for data sharing, enabling data citation is a crucial feature of research data services. In this article we present a case study of data citation services for the High-Energy Physics (HEP) community using digital library technology. Our example shows how the concept of data citation is implemented for the complete research workflow, covering data production, publishing, citation and tracking of data reuse. We also describe challenges faced and distil...

Data Citation Index

Directory of Open Access Journals (Sweden)

Laura L. Pavlech

2016-01-01

Full Text Available Introduced by Thomson Reuters in 2012 as a, ‘‘Single point of access to quality research data from repositories across disciplines and around the world’’ [1], the Data Citation Index (DCI is a searchable collection of data sets and data studies from a select list of repositories.

Turkish Publications in Science Citation Index and Citation Index-Expanded Indexed Journals in the Field of Anaesthesiology: A Bibliographic Analysis.

Science.gov (United States)

Özbilgin, Şule; Hancı, Volkan

2017-02-01

Our study aimed to assess Turkish publications in Science Citation Index (SCI) and Science Citation Index Expanded (SCI-E) indexed journals in the field of 'anaesthesiology'. Journals related to 'anaesthesiology' in the Science Citation Index-Expanded database of 'Thomson Reuter Web of Science' were searched. The search engine of Institute for Scientific Information (ISI) Web of Science (WoS) was used in the advanced mode by typing 'IS=ISSN number' to identify publications in the journal. By typing 'IS=ISSN number AND CU=Turkey', Turkish papers on anaesthesiology were found. If Turkish and non-Turkish authors had collaborated, the article was included in the search when the corresponding author had provided a Turkey-based address. The catalogue information and statistics were used to determine Turkish publications as the percentage of total publications and the annual mean number of Turkish publications. In WoS, 'SU=anesthesiology' was used to determine the number, country, year and topic distributions of publications from 1975 to date and within the last 10 years. The citation numbers and h-indices were determined based on the country for publications within the last 10 years. From 1975 to the early 2000s Turkey was 20 th in the list of countries with highest number of publications on anaesthesiology, however in the last 10 years Turkey moved up to 18 th place. Its mean citation number has been 4.64, and it remains the 2 nd lowest country pertaining to citations among the 22 countries with the most number of publications. According to the percentage of publications in the field of anaesthesiology, the journals with highest rate of Turkish publications were Revista Brasileira de Anestesiologia, European Journal of Anaesthesiology and Journal of Anesthesia. In the field of anaesthesiology, the highest number of articles from Turkey was published in Revista Brasileira de Anestesiologia, European Journal of Anaesthesiology and Journal of Anesthesia. The mean citation

Radiation synthesis of silver nanostructures in cotton matrix

International Nuclear Information System (INIS)

Chmielewska, Dagmara; Sartowska, Bożena

2012-01-01

Cotton is one of the most popular natural fibres, composed mainly of cellulose, which finds a wide range of applications in paper, textile and health care products industry. Researchers have focused their interest on the synthesis of cotton nanocomposites, which enhances its mechanical, thermal and antimicrobial properties by the incorporation of various nanoparticles into the cotton matrix. Silver is one of the most popular antimicrobial agents with a wide spectrum of antibacterial and antifungal activity that results from a complex mechanism of its interactions with the cells of harmful microorganism. In this work, electron beam radiation was applied to synthesise silver nanostructures in cotton fibres. Investigations of the influence of the initial silver salt concentration on the size and distribution of the obtained silver nanostructures were carried out. A detailed characterisation of these nanocomposites with SEM-BSE and EDS methods was performed. TGA and DSC analyses were performed to assess the influence of different size silver nanoparticles and the effect of electron beam irradiation on the thermal properties of cotton fibres. A microbiological investigation to determine the antibacterial activity of Ag-cotton nanocomposites was carried out. - Highlights: ► Ag NPs embedded in cotton matrix were synthesised by electron beam irradiation. ► Concentration of silver salt solution influences on size of silver nanoparticles. ► Silver content as well as irradiation affect thermal properties of cotton fabrics. ► Ag-cotton nanocomposites exhibit antibacterial activity against bacteria and fungi.

A Ten Year Citation Analysis of Major Australian Research Institutions

Science.gov (United States)

Batterham, Robin J.

2011-01-01

The introduction of the Excellence in Research for Australia scheme has heightened debate amongst research institutions over the use of metrics such as citations, especially given the ready availability of citation data. An analysis is presented of the citation performance of nine Australian universities and the Commonwealth Scientific, Industrial…

Green synthesis of silver nanoparticles and their characterization by XRD

Science.gov (United States)

Mehta, B. K.; Chhajlani, Meenal; Shrivastava, B. D.

2017-05-01

A cost effective and environment friendly technique for green synthesis of silver nanoparticles has been reported. Silver nanoparticles have been synthesized using ethanol extract of fruits of Santalum album (Family Santalaceae), commonly known as East Indian sandalwood. Fruits of S.album were collected and crushed. Ethanol was added to the crushed fruits and mixture was exposed to microwave for few minutes. Extract was concentrated by Buchi rotavaporator. To this extract, 1mM aqueous solution of silver nitrate (AgNO3) was added. After about 24 hr incubation Ag+ ions in AgNO3 solution were reduced to Ag atoms by the extract. Silver nanoparticles were obtained in powder form. X-ray diffraction (XRD) pattern of the prepared sample of silver nanoparticles was recorded The diffractogram has been compared with the standard powder diffraction card of JCPDS silver file. Four peaks have been identified corresponding to (hkl) values of silver. The XRD study confirms that the resultant particles are silver nanoparticles having FCC structure. The average crystalline size D, the value of the interplanar spacing between the atoms, d, lattice constant and cell volume have been estimated. Thus, silver nanoparticles with well-defined dimensions could be synthesized by reduction of metal ions due to fruit extract of S.album.

Analysis and visualization of citation networks

CERN Document Server

Zhao, Dangzhi

2015-01-01

Citation analysis-the exploration of reference patterns in the scholarly and scientific literature-has long been applied in a number of social sciences to study research impact, knowledge flows, and knowledge networks. It has important information science applications as well, particularly in knowledge representation and in information retrieval.Recent years have seen a burgeoning interest in citation analysis to help address research, management, or information service issues such as university rankings, research evaluation, or knowledge domain visualization. This renewed and growing interest

Silver nanoparticle-E. coli colloidal interaction in water and effect on E. coli survival.

Science.gov (United States)

Dror-Ehre, A; Mamane, H; Belenkova, T; Markovich, G; Adin, A

2009-11-15

Silver nanoparticles exhibit antibacterial properties via bacterial inactivation and growth inhibition. The mechanism is not yet completely understood. This work was aimed at elucidating the effect of silver nanoparticles on inactivation of Escherichia coli, by studying particle-particle interactions in aqueous suspensions. Stable, molecularly capped, positively or negatively charged silver nanoparticles were mixed at 1 to 60microgmL(-1) with suspended E. coli cells to examine their effect on inactivation of the bacteria. Gold nanoparticles with the same surfactant were used as a control, being of similar size but made up of a presumably inert metal. Log reduction of 5log(10) and complete inactivation were obtained with the silver nanoparticles while the gold nanoparticles did not show any inactivation ability. The effect of molecularly capped nanoparticles on E. coli survival was dependent on particle number. Log reduction of E. coli was associated with the ratio between the number of nanoparticles and the initial bacterial cell count. Electrostatic attraction or repulsion mechanisms in silver nanoparticle-E. coli cell interactions did not contribute to the inactivation process.

Local Citation Analysis of Graduate Biology Theses: Collection Development Implications

Science.gov (United States)

Miller, Laura Newton

2011-01-01

This paper will focus on the citation analysis of graduate masters theses from Carleton University's Biology Department with implications for library collection management decisions. Twenty-five masters theses were studied to determine citation types and percentages, ranking of journals by frequency of citation and by number of authors citing, and…

Is There an Association between STARD Statement Adherence and Citation Rate?

Science.gov (United States)

Dilauro, Marc; McInnes, Matthew D F; Korevaar, Daniël A; van der Pol, Christian B; Petrcich, William; Walther, Stefan; Quon, Jeffrey; Kurowecki, Darya; Bossuyt, Patrick M M

2016-07-01

Purpose To determine if adherence to the Standards for Reporting of Diagnostic Accuracy (STARD) is associated with postpublication citation rates. Materials and Methods A comprehensive search of PubMed, EMBASE, and Cochrane Library databases was performed to identify published articles that have evaluated adherence of diagnostic accuracy studies to the STARD statement. These were included if the number of STARD items reported ("STARD result") could be obtained for each evaluated study. The date of publication, journal impact factor, and citation rate (citations per day) were extracted for the diagnostic accuracy studies. Univariate correlations were performed to identify any association between STARD result, impact factor, and citation rate. Multivariate regression analysis was performed to explore the effect of impact factor on postpublication citation rates. Results The authors were able to obtain the STARD results for 1002 "original" diagnostic accuracy studies from eight different "STARD evaluation" articles. The median impact factor was 3.97 (interquartile range [IQR]: 2.32-6.21), the median STARD result was 15 of 25 items (IQR: 12-18), and the median citation rate was 0.007 citations per day (IQR: 0.0032-0.017). The authors identified a weak positive correlation between STARD result and citation rate (r = 0.096; 95% confidence interval [CI]: 0.034, 0.157), a moderate positive correlation between impact factor and citation rate (r = 0.58; 95% CI: 0.535, 0.617), and a weak positive correlation between impact factor and STARD result (r = 0.13; 95% CI: 0.064, 0.186). Multivariate analysis accounting for journal clustering effects revealed that, when impact factor is partialed out, the positive correlation between citation rate and STARD result does not persist (r = 0.029; 95% CI: -0.033, 0.091). Conclusion There is a positive correlation between completeness of reporting, as evaluated with STARD, and citation rate as well as impact factor. When adjusted for

Antimicrobial effects of silver zeolite, silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

Institute of Scientific and Technical Information of China (English)

Sirikamon Saengmee-anupharb; Toemsak Srikhirin; Boonyanit Thaweboon; Sroisiri Thaweboon; Taweechai Amornsakchai; Surachai Dechkunakorn; Theeralaksna Suddhasthira

2013-01-01

Objective: To evaluate the antimicrobial activities of silver inorganic materials, including silver zeolite (AgZ), silver zirconium phosphate silicate (AgZrPSi) and silver zirconium phosphate (AgZrP), against oral microorganisms. In line with this objective, the morphology and structure of each type of silver based powders were also investigated. Methods: The antimicrobial activities of AgZ, AgZrPSi and AgZrP were tested against Streptococcus mutans, Lactobacillus casei, Candidaalbicans and Staphylococcus aureus using disk diffusion assay as a screening test. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were determined using the modified membrane method. Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials. Results: All forms of silver inorganic materials could inhibit the growth of all test microorganisms. The MIC of AgZ, AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L. In terms of morphology and structure, AgZrPSi and AgZrP had smaller sized particles (1.5-3.0 µm) and more uniformly shaped than AgZ. Conclusions: Silver inorganic materials in the form of AgZ, AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers. These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

Antimicrobial effects of silver zeolite,silver zirconium phosphate silicate and silver zirconium phosphate against oral microorganisms

Institute of Scientific and Technical Information of China (English)

Sirikamon; Saengmee-anupharb; Toemsak; Srikhirin; Boonyanit; Thaweboon; Sroisiri; Thaweboon; Taweechai; Amornsakchai; Surachai; Dechkunakorn; Theeralaksna; Suddhasthira

2013-01-01

Objective:To evaluate the antimicrobial activities of silver inorganic materials,including silver zeolite(AgZ),silver zirconium phosphate silicate(AgZrPSi)and silver zirconium phosphate(AgZrp),against oral microorganisms.In line with this objective,the morphology and structure of each type of silver based powders were also investigated.Methods:The antimicrobial activities of AgZ,AgZrPSi and AgZrP were tested against Streptococcus mutans,Lactobacillus casei,Candida albicans and Staphylococcus aureus using disk diffusion assay as a screening test.The minimum inhibitory concentration(MIC)and minimum lethal concentration(MLC)were determined using the modified membrane method.Scanning electron microscope and X-ray diffraction were used to investigate the morphology and structure of these silver materials.Results:All forms of silver inorganic materials could inhibit the growth of all test microorganisms.The MIC of AgZ,AgZrPSi and AgZrP was 10.0 g/L whereas MLC ranged between 10.0-60.0 g/L.In terms of morphology and structure.AgZrPSi and AgZrP had smaller sized particles(1.5-3.0μm)and more uniformly shaped than AgZ.Conclusions:Silver inorganic materials in the form of AgZ,AgZrPSi and AgZrP had antimicrobial effects against all test oral microorganisms and those activities may be influenced by the crystal structure of carriers.These results suggest that these silver materials may be useful metals applied to oral hygiene products to provide antimicrobial activity against oral infection.

Accumulation of silver nanoparticles by cultured primary brain astrocytes

Energy Technology Data Exchange (ETDEWEB)

Luther, Eva M; Koehler, Yvonne; Dringen, Ralf [Center for Biomolecular Interactions Bremen, University of Bremen, PO Box 330440, D-28334 Bremen (Germany); Diendorf, Joerg; Epple, Matthias, E-mail: ralf.dringen@uni-bremen.de [Inorganic Chemistry and Center for Nanointegration Duisburg-Essen, University of Duisburg-Essen, Universitaetsstrasse 5-7, D-45117 Essen (Germany)

2011-09-16

Silver nanoparticles (AgNP) are components of various food industry products and are frequently used for medical equipment and materials. Although such particles enter the vertebrate brain, little is known on their biocompatibility for brain cells. To study the consequences of an AgNP exposure of brain cells we have treated astrocyte-rich primary cultures with polyvinylpyrrolidone (PVP)-coated AgNP. The incubation of cultured astrocytes with micromolar concentrations of AgNP for up to 24 h resulted in a time- and concentration-dependent accumulation of silver, but did not compromise the cell viability nor lower the cellular glutathione content. In contrast, the incubation of astrocytes for 4 h with identical amounts of silver as AgNO{sub 3} already severely compromised the cell viability and completely deprived the cells of glutathione. The accumulation of AgNP by astrocytes was proportional to the concentration of AgNP applied and significantly lowered by about 30% in the presence of the endocytosis inhibitors chloroquine or amiloride. Incubation at 4 {sup 0}C reduced the accumulation of AgNP by 80% compared to the values obtained for cells that had been exposed to AgNP at 37 {sup 0}C. These data demonstrate that viable cultured brain astrocytes efficiently accumulate PVP-coated AgNP in a temperature-dependent process that most likely involves endocytotic pathways.

Citation metrics of excellence in sports biomechanics research.

Science.gov (United States)

Knudson, Duane

2017-11-13

This study extended research on key citation metrics of winners of two career scholar awards in sports biomechanics. Google Scholar (GS) was searched using Harzing's Publish or Perish software for the 13 most recent winners of the ISBS Geoffrey Dyson Award and the ASB Jim Hay Memorial Award. Returned records were corrected for author, and publications excluded for all but peer-reviewed journal articles, proceedings articles, chapters and books in English. These recent award winners had published about 150 publications that had been cited typically 4,082 and 6,648 times over a 26- and 28-year period before receiving these career awards for sports biomechanics research. Estimated median citations at time of their awards were 2,927 and 4,907 for the Dyson and Hay awards, respectively. Award winners had mean Hirsh indexes of 32-45 and mean h i of 19-28. Their mean g indexes (59-84) and their numerous citation classics (C > 100) indicated that they had many influential publications. The citation metrics of these scholars were outstanding and consistent with recent studies of top scholars in biomechanics and kinesiology/exercise science. Careful searching, cleaning and interpretation of several scholar-level citation metrics may provide useful confirmatory evidence for evaluations of awards committees.

The Ripple Effect: Citation Chain Reactions of a Nobel Prize

DEFF Research Database (Denmark)

Faber Frandsen, Tove; Nicolaisen, Jeppe

2013-01-01

This paper explores the possible citation chain reactions of a Nobel Prize using the mathematician Robert J. Aumann as a case example. The results show that the award of the Nobel Prize in 2005 affected not only the citations to his work, but also affected the citations to the references in his s...... citation network. The effect is discussed using innovation decision process theory as a point of departure to identify the factors that created a bandwagon effect leading to the reported observations....... scientific oeuvre. The results indicate that the spillover effect is almost as powerful as the effect itself. We are consequently able to document a ripple effect in which the awarding of the Nobel Prize ignites a citation chain reaction to Aumann's scientific ouvre and to the references in its nearest...

A Co-Citation Network of Young Children's Learning with Technology

Science.gov (United States)

Tang, Kai-Yu; Li, Ming-Chaun; Hsin, Ching-Ting; Tsai, Chin-Chung

2016-01-01

This paper used a novel literature review approach--co-citation network analysis--to illuminate the latent structure of 87 empirical papers in the field of young children's learning with technology (YCLT). Based on the document co-citation analysis, a total of 206 co-citation relationships among the 87 papers were identified and then graphically…

Observations on Citation Practices in Mathematics Education Research. Research Commentary

Science.gov (United States)

Leatham, Keith R.

2015-01-01

The author argues that the field of mathematics education as a whole can and should improve its citation practices. He discusses 4 forms of citation practice and considers how they vary with respect to transparency of voice. He also discusses several ways that citation practices may misrepresent cited authors' ideas. He concludes with suggestions…

Investigating the Link between self-citation and authors’ co-incidence with journal impact factors in Iran: Case study of Economic Journals indexed in Islamic Science Citation Database

Directory of Open Access Journals (Sweden)

Hashem Attapour

2010-03-01

Full Text Available   The present paper examines the links between self-citation and authors’ co-incidence with impact factors of economic journals indexed in ISC. It is essentially a scientometric research employing citation analysis and literature survey. Data was collected by querying ISC and leafing through the journals studied. Self-citation, authors’ co-incidence and impact factor of the journal studied formed the variables. Correlation analysis indicated that there is a significance between authors’ self-citations and co-incidence with impact factor of the journals studied. Significance was also found between authors’ co-incidence and self-citation of the journals studied.

The effect of silver nanoparticles (AgNPs) on proliferation and apoptosis of in ovo cultured glioblastoma multiforme (GBM) cells.

Science.gov (United States)

Urbańska, Kaja; Pająk, Beata; Orzechowski, Arkadiusz; Sokołowska, Justyna; Grodzik, Marta; Sawosz, Ewa; Szmidt, Maciej; Sysa, Paweł

2015-01-01

Recently, it has been shown that silver nanoparticles (AgNPs) provide a unique approach to the treatment of tumors, especially those of neuroepithelial origin. Thus, the aim of this study was to evaluate the impact of AgNPs on proliferation and activation of the intrinsic apoptotic pathway of glioblastoma multiforme (GBM) cells cultured in an in ovo model. Human GBM cells, line U-87, were placed on chicken embryo chorioallantoic membrane. After 8 days, the tumors were divided into three groups: control (non-treated), treated with colloidal AgNPs (40 μg/ml), and placebo (tumors supplemented with vehicle only). At the end of the experiment, all tumors were isolated. Assessment of cell proliferation and cell apoptosis was estimated by histological, immunohistochemical, and Western blot analyses. The results show that AgNPs can influence GBM growth. AgNPs inhibit proliferation of GBM cells and seem to have proapoptotic properties. Although there were statistically significant differences between control and AgNP groups in the AI and the levels of active caspase 9 and active caspase 3, the level of these proteins in GBM cells treated with AgNPs seems to be on the border between the spontaneous apoptosis and the induced. Our results indicate that the antiproliferative properties of silver nanoparticles overwhelm proapoptotic ones. Further research focused on the cytotoxic effect of AgNPs on tumor and normal cells should be conducted.

Power Reactor Docket Information. Annual cumulation (citations)

International Nuclear Information System (INIS)

1977-12-01

An annual cumulation of the citations to the documentation associated with civilian nuclear power plants is presented. This material is that which is submitted to the U.S. Nuclear Regulatory Commission in support of applications for construction and operating licenses. Citations are listed by Docket number in accession number sequence. The Table of Contents is arranged both by Docket number and by nuclear power plant name

Vectorization of three-dimensional neutron diffusion code CITATION

International Nuclear Information System (INIS)

Harada, Hiroo; Ishiguro, Misako

1985-01-01

Three-dimensional multi-group neutron diffusion code CITATION has been widely used for reactor criticality calculations. The code is expected to be run at a high speed by using recent vector supercomputers, when it is appropriately vectorized. In this paper, vectorization methods and their effects are described for the CITATION code. Especially, calculation algorithms suited for vectorization of the inner-outer iterative calculations which spend most of the computing time are discussed. The SLOR method, which is used in the original CITATION code, and the SOR method, which is adopted in the revised code, are vectorized by odd-even mesh ordering. The vectorized CITATION code is executed on the FACOM VP-100 and VP-200 computers, and is found to run over six times faster than the original code for a practical-scale problem. The initial value of the relaxation factor and the number of inner-iterations given as input data are also investigated since the computing time depends on these values. (author)

A Citation Tracking System to Facilitate Sponsoring Institution Oversight of ACGME-Accredited Programs.

Science.gov (United States)

Long, Timothy R; Poe, John D; Zimmerman, Richard S; Rose, Steven H

2012-12-01

The Accreditation Council for Graduate Medical Education (ACGME) requires the graduate medical education committee and the designated institutional official to ensure that citations for noncompliance with the accreditation standards and institutional trends in citations are reviewed and corrected. To describe a citation tracking system (CTS) that uses Microsoft Office Access to efficiently catalogue, monitor, and document resolution of citations. The CTS was implemented in a sponsoring institution with oversight of 133 ACGME-accredited programs. The designated institutional official and the graduate medical education committee review all program letters of notification and enter citations into the CTS. A program-correction plan is required for each citation and is entered into the database. Open citations and action plans are reviewed by the graduate medical education committee and the designated institutional official on a quarterly basis, with decisions ranging from "closing" the citation to approving the action plan in process to requiring a new or modified action plan. Citation categories and subcategories are accessed on the ACGME website and entered into the CTS to identify trends. All 236 citations received since the 2006 Mayo School of Graduate Medical Education institutional site visit were entered into the CTS. On November 22, 2011, 26 of 236 citations (11%) were in active status with ongoing action plans, and 210 (89%) citations had been resolved and were closed. The CTS uses commercially available software to ensure citations are monitored and addressed and to simplify analysis of citation trends. The approach requires minimal staff time for data input and updates and can be performed without institutional information technology assistance.

Low temperature processed planar heterojunction perovskite solar cells employing silver nanowires as top electrode

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jianhua; Li, Fushan, E-mail: fushanli@hotmail.com; Yang, Kaiyu; Veeramalai, Chandrasekar Perumal; Guo, Tailiang

2016-04-30

Graphical abstract: - Highlights: • All solution processed perovskite solar cells were realized with Ag nanowires. • ZnO nanoparticles were used as electron transport layer. • The solar cells showed a photovoltaic behavior with efficiency of 9.21%. • Device performance showed negligible difference between forward and reverse scan. - Abstract: In this paper, we reported a low temperature processed planar heterojunction perovskite solar cell employing silver nanowires as the top electrode and ZnO nanoparticles as the electron transport layer. The CH{sub 3}NH{sub 3}PbI{sub 3} perovskite was grown as the light absorber via two-step spin-coating technique. The as-fabricated perovskite solar cell exhibited the highest power conversion efficiency of 9.21% with short circuit current density of 19.75 mA cm{sup −2}, open circuit voltage of 1.02, and fill factor value of 0.457. The solar cell's performance showed negligible difference between the forward and reverse bias scan. This work paves a way for realizing low cost solution processable solar cells.

Application of progressive nucleation mechanism for the citation behavior of individual papers of different authors.

Science.gov (United States)

Sangwal, Keshra

2012-09-01

The basic concepts and equations of the progressive nucleation mechanism (PNM) are presented first for the growth and decay of items. The mechanism is then applied to describe the cumulative citations L and citations ΔL per year of the individual most-cited papers i of four selected Polish professors as a function of citation duration t. It was found that the PNM satisfactorily describes the time dependence of cumulative citations L of the papers published by different authors with sufficiently high citations ΔL, as represented by the highest yearly citations ΔL(max) during the entire citation period t (normal citation behavior). The citation period for these papers is less than 15 years and it is even 6-8 years in several cases. However, for papers with citation periods exceeding about 15 years, the growth behavior of citations does not follow the PNM in the entire citation period (anomalous citation behavior), and there are regions of citations in which the citation data may be described by the PNM. Normal and anomalous citation behaviors are attributed, respectively, to the occurrence and nonoccurrence of stationary nucleation of citations for the papers. The PNM also explains the growth and decay of citations ΔL per year of papers exhibiting normal citation behavior.

100 classic papers of interventional radiology: A citation analysis

Science.gov (United States)

Crockett, Matthew T; Browne, Ronan FJ; MacMahon, Peter J; Lawler, Leo

2015-01-01

AIM: To define the 100 citation classic papers of interventional radiology. METHODS: Using the database of Journal Citation Reports the 40 highest impact factor radiology journals were chosen. From these journals the 100 most cited interventional radiology papers were chosen and analysed. RESULTS: The top paper received 2497 citations and the 100th paper 200 citations. The average number of citations was 320. Dates of publication ranged from 1953 - 2005. Most papers originated in the United States (n = 67) followed by Italy (n = 20) and France (n = 10). Harvard University (n = 18) and Osped Civile (n = 11) were the most prolific institutions. Ten journals produced all of the top 100 papers with “Radiology” and “AJR” making up the majority. SN Goldberg and T Livraghi were the most prolific authors. Nearly two thirds of the papers (n = 61) were published after 1990. CONCLUSION: This analysis identifies many of the landmark interventional radiology papers and provides a fascinating insight into the changing discourse within the field. It also identifies topics, authors and institutions which have impacted greatly on the specialty. PMID:25918585

100 classic papers of interventional radiology: A citation analysis.

Science.gov (United States)

Crockett, Matthew T; Browne, Ronan Fj; MacMahon, Peter J; Lawler, Leo

2015-04-28

To define the 100 citation classic papers of interventional radiology. Using the database of Journal Citation Reports the 40 highest impact factor radiology journals were chosen. From these journals the 100 most cited interventional radiology papers were chosen and analysed. The top paper received 2497 citations and the 100(th) paper 200 citations. The average number of citations was 320. Dates of publication ranged from 1953 - 2005. Most papers originated in the United States (n = 67) followed by Italy (n = 20) and France (n = 10). Harvard University (n = 18) and Osped Civile (n = 11) were the most prolific institutions. Ten journals produced all of the top 100 papers with "Radiology" and "AJR" making up the majority. SN Goldberg and T Livraghi were the most prolific authors. Nearly two thirds of the papers (n = 61) were published after 1990. This analysis identifies many of the landmark interventional radiology papers and provides a fascinating insight into the changing discourse within the field. It also identifies topics, authors and institutions which have impacted greatly on the specialty.

Web-based Citation Management Systems: Which One Is Best?

Directory of Open Access Journals (Sweden)

Michael Steeleworthy

2013-04-01

Full Text Available Librarians and researchers have long used citation management systems as research tools to help scholars organize their work, improve workflows, and ultimately save time. For many years, RefWorks has been the dominant citation management tool in many parts of Canada: the maturity of the product and its integration with many scholarly databases reassures users that it works well with these resources. However, a number of competitors now offer citation management systems that are as strong as RefWorks but offer different features to the user, therefore warranting a comparison with this leading tool. This paper reviews RefWorks, Zotero, WizFolio, and Mendeley, which are all popular citation management systems that either have a long history of use or are now gaining traction in Canadian academic circles. To compare these tools, we examined their import capabilities as well as their organizing, searching, annotating, and sharing functions. This review will interest both librarians and researchers who are considering alternative citation management systems at either the personal or organizational level.

Comprehensive Investigation of Silver Nanoparticle/Aluminum Electrodes for Copper Indium Sulfide/Polymer Hybrid Solar Cells

DEFF Research Database (Denmark)

Arar, Mario; Pein, Andreas; Haas, Wernfried

2012-01-01

,1,3-benzothiadiazole)] (PSiF-DBT) nanocomposite solar cells, which improves the fill factor compared to pure aluminum electrodes. A comprehensive structural investigation was performed by means of transmission electron microscopy and time-of-flight secondary ion mass spectrometry revealing the presence of silver...... nanoparticles in an aluminum oxide matrix between the absorber layer and the aluminum cathode. In combination with complementary optical investigations, the origin of the improvement is ascribed to a facilitated charge extraction....

Green synthesis of silver nanoparticles and biopolymer ...

Indian Academy of Sciences (India)

2018-03-29

Mar 29, 2018 ... Keywords. Biogenic silver nanoparticles; biopolymer nanocomposites; nanoparticles stability; ... Production of nanomaterials by using living organisms of plant-based ... 2.1b Microorganisms and cell culture: The evaluation of.

What Effect Does Self-Citation Have on Bibliometric Measures in Academic Plastic Surgery?

Science.gov (United States)

Swanson, Edward W; Miller, Devin T; Susarla, Srinivas M; Lopez, Joseph; Lough, Denver M; May, James W; Redett, Richard J

2016-09-01

Research productivity plays a significant role in academic promotions. Currently, various bibliometric measures utilizing citation counts are used to judge an author's work. With increasing numbers of journals, numbers of open access publications, ease of online submission, and expedited indexing of accepted manuscripts, it is plausible that an author could influence his/her own bibliometric measures through self-citation. The purpose of this study was to determine the impact of self-citation in academic plastic surgery. A cohort of full-time academic plastic surgeons was identified from 9 U.S. plastic surgery training programs. For all included faculty, academic rank was retrieved from department/division websites, and bibliometric measures were assessed using a subscription bibliographic citation database (Scopus, Reed Elsevier, London, UK). Bibliometric measures included the Hirsch index (h-index, the number of publications h which are cited ≥ h times), total number of publications, and total number of citations. The h-index and total number of citations were collected with and without self-citations. Percent changes in the h-index and total citations were calculated after removal of self-citations and compared across academic ranks and levels of research productivity (total publications, h-index, and total citations). The study cohort consisted of 169 full-time academic plastic surgeons. The h-index and total citations experienced decreases of 2.8 ± 5.0% (P citation. More than half of the cohort (n = 113, 67%) did not experience a change in the h-index after removal of self-citations. These decreases did not vary across academic rank. Surgeons who self-cited at rates greater than 5% were 9.8 times more likely (95% confidence interval, 4.5-21.9; P citation (after adjusting for academic rank). There were weak correlations between percent decreases in the h-index and total citations and various biblimoteric measures (total publications, h-index, total citations

Template assisted solid state electrochemical growth of silver micro- and nanowires

International Nuclear Information System (INIS)

Peppler, Klaus; Janek, Juergen

2007-01-01

We report on a template based solid state electrochemical method for fabricating silver nanowires with predefined diameter, depending only on the pore diameter of the template. As templates we used porous silicon with pore diameters in the μm range and porous alumina with pore diameters in the nm range. The template pores were filled with silver sulfide (a mixed silver cation and electronic conductor) by direct chemical reaction of silver and sulfur. The filled template was then placed between a silver foil as anode (bottom side) and a microelectrode (top side) as cathode. An array of small cylindrical transference cells with diameters in the range of either micro- or nanometers was thus obtained. By applying a cathodic voltage to the microelectrode silver in the form of either micro- or nanowires was deposited at about 150 deg. C. The growth rate is controllable by the electric current

Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

International Nuclear Information System (INIS)

Venil, Chidambaram Kulandaisamy; Sathishkumar, Palanivel; Malathi, Mahalingam; Usha, Rajamanickam; Jayakumar, Rajarajeswaran; Yusoff, Abdull Rahim Mohd; Ahmad, Wan Azlina

2016-01-01

In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ("1H NMR and "1"3C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL"−"1. This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity

Synthesis of flexirubin-mediated silver nanoparticles using Chryseobacterium artocarpi CECT 8497 and investigation of its anticancer activity

Energy Technology Data Exchange (ETDEWEB)

Venil, Chidambaram Kulandaisamy, E-mail: ckvenil@gmail.com [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Sathishkumar, Palanivel [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Malathi, Mahalingam [Department of Chemistry, Bannari Amman Institute of Technology, Sathyamangalam 638 401, Tamil Nadu (India); Usha, Rajamanickam [Department of Microbiology, Karpagam University, Coimbatore 641 023, Tamil Nadu (India); Jayakumar, Rajarajeswaran [Department of Molecular Medicine, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur (Malaysia); Yusoff, Abdull Rahim Mohd [Centre for Environmental Sustainability and Water Security (IPASA), Research Institute for Sustainable Environment (RISE), Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Ahmad, Wan Azlina, E-mail: azlina@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia)

2016-02-01

In this work, the synthesis of silver nanoparticles from a pigment produced by a recently-discovered bacterium, Chryseobacterium artocarpi CECT 8497, was achieved, followed by an investigation of its anticancer properties. The bacterial pigment was identified as flexirubin following NMR ({sup 1}H NMR and {sup 13}C NMR), UV–Vis, and LC–MS analysis. An aqueous silver nitrate solution was treated with isolated flexirubin to produce silver nanoparticles. The synthesised silver nanoparticles were subsequently characterised by UV–Vis spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) Spectroscopy methodologies. Furthermore, the anticancer effects of synthesised silver nanoparticles in a human breast cancer cell line (MCF-7) were evaluated. The tests showed significant cytotoxicity activity of the silver nanoparticles in the cultured cells, with an IC50 value of 36 μg mL{sup −1}. This study demonstrates that silver nanoparticles, synthesised from flexirubin from C. artocarpi CECT 8497, may have potential as a novel chemotherapeutic agent. - Highlights: • First report on flexirubin mediated silver nanoparticles • Silver nanoparticles synthesised using flexirubin • Flexirubin mediated silver nanoparticles found to possess in vitro anti-cancer activity.

The e-index, complementing the h-index for excess citations.

Directory of Open Access Journals (Sweden)

Chun-Ting Zhang

Full Text Available BACKGROUND: The h-index has already been used by major citation databases to evaluate the academic performance of individual scientists. Although effective and simple, the h-index suffers from some drawbacks that limit its use in accurately and fairly comparing the scientific output of different researchers. These drawbacks include information loss and low resolution: the former refers to the fact that in addition to h(2 citations for papers in the h-core, excess citations are completely ignored, whereas the latter means that it is common for a group of researchers to have an identical h-index. METHODOLOGY/PRINCIPAL FINDINGS: To solve these problems, I here propose the e-index, where e(2 represents the ignored excess citations, in addition to the h(2 citations for h-core papers. Citation information can be completely depicted by using the h-index together with the e-index, which are independent of each other. Some other h-type indices, such as a and R, are h-dependent, have information redundancy with h, and therefore, when used together with h, mask the real differences in excess citations of different researchers. CONCLUSIONS/SIGNIFICANCE: Although simple, the e-index is a necessary h-index complement, especially for evaluating highly cited scientists or for precisely comparing the scientific output of a group of scientists having an identical h-index.

Biosynthesis of silver nanoparticles synthesized by Aspergillus ...

Indian Academy of Sciences (India)

Biotechnology Division, Applied Science Department, University of ... Abstract. In the present study, biosynthesis of silver nanoparticles and its antioxidant, antimicrobial and cytotoxic ... example of the biosynthesis using fungi was that the cell-.

Data Citation in Astronomy

Science.gov (United States)

Hourcle, Joseph

2014-06-01

Many observatories maintain bibliographies to document their impact and justify their continued funding[1], an effort that requires humans to discover and curate links between the scientific papers and the data that was used as evidence. The "Best Practices for Creating a Telescope Bibliography", endorsed by IAU C5 WG Libraries, recommends full text searching and human examination of each paper.[2] These efforts do not scale well.It is unlikely that articles published in journals from other disciples would be found. This is particularly a problem for solar physics, as solar data has applicability in astrophysics, space weather, and even the earth sciences.As our scientists are not on the editorial boards of the journals from other disciplines, we can't ensure proper attribution to allow these relationships to be discovered via full text searching.To better deal with tracking cross-discipline data usage, a number of groups have come up with guidelines and principles for data citation. In 2012, the National Academy's Board on Research Data and Information released the report "For Attribution-Developing Data Attribution and Citation Practices and Standards" [3] and it was followed last year by the CODATA-ICSTI report "Out of Cite, Out of Mind".[4]Participants from a number of groups synthesized a single set of principles for data citation that could be endorsed by all groups involved in research.[5] Implementing these principles can help to improve the scientific ecosystem by giving proper attribution to all contributors to data, improving transparency and reproducability, and making data more easily reusable to both astronomers and other researchers.We will present the Joint Declaration of Data Citation Principles, discuss the implications of them for astronomical data, and recommend steps towards implementation.References:[1] Accomazzi, et.al, 2012. http://adsabs.harvard.edu/abs/2012SPIE.8448E..0KA[2] Bishop, Grothkopf & Lagerstrom, 2012. http://iau-commission5

Electrically Conductive Silver Paste Obtained by Use of Silver Neodecanoate as Precursor

Science.gov (United States)

Shen, Longguang; Liu, Jianguo; Zeng, Xiaoyan; Ren, Zhao

2015-02-01

An electrically conductive silver paste has been prepared from an organometallic compound, silver neodecanoate, as silver precursor. The precursor was highly soluble in organic solvents and decomposed into metallic silver at low sintering temperatures (writing process, enabling production of silver lines on a substrate. The electrical resistivity of the silver lines was 9 × 10-6 Ω cm after sintering at 115°C for 60 min, 5.8 × 10-6 Ω cm when sintered at 150°C for 60 min, and 3 × 10-6 Ω cm when sintered above 300°C, values which are similar to those of bulk silver. Hence, the prepared paste can be successfully used on flexible substrates such as polymers.

A method for the automated, reliable retrieval of publication-citation records.

Directory of Open Access Journals (Sweden)

Derek Ruths

Full Text Available BACKGROUND: Publication records and citation indices often are used to evaluate academic performance. For this reason, obtaining or computing them accurately is important. This can be difficult, largely due to a lack of complete knowledge of an individual's publication list and/or lack of time available to manually obtain or construct the publication-citation record. While online publication search engines have somewhat addressed these problems, using raw search results can yield inaccurate estimates of publication-citation records and citation indices. METHODOLOGY: In this paper, we present a new, automated method that produces estimates of an individual's publication-citation record from an individual's name and a set of domain-specific vocabulary that may occur in the individual's publication titles. Because this vocabulary can be harvested directly from a research web page or online (partial publication list, our method delivers an easy way to obtain estimates of a publication-citation record and the relevant citation indices. Our method works by applying a series of stringent name and content filters to the raw publication search results returned by an online publication search engine. In this paper, our method is run using Google Scholar, but the underlying filters can be easily applied to any existing publication search engine. When compared against a manually constructed data set of individuals and their publication-citation records, our method provides significant improvements over raw search results. The estimated publication-citation records returned by our method have an average sensitivity of 98% and specificity of 72% (in contrast to raw search result specificity of less than 10%. When citation indices are computed using these records, the estimated indices are within of the true value 10%, compared to raw search results which have overestimates of, on average, 75%. CONCLUSIONS: These results confirm that our method provides

Implementation of Data Citations and Persistent Identifiers at the ORNL DAAC

Science.gov (United States)

Cook, R. B.; Santhana Vannan, S.; Devarakonda, Ranjeet; McMurry, B. F.; Kidder, J. H.; Shanafield, H. A.; Palanisamy, G.

2013-12-01

As research in Earth Science becomes more data intensive, a critical requirement of data archives is that data needs to be easily discovered, accessed, and used. One approach to improving data discovery and access is through data citations coupled with Digital Object Identifiers (DOI). Beginning in 1998, the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) has issued data product citations that have been accepted and used in AGU and other peer-reviewed journals. Citation elements established by the ORNL DAAC are similar to those used for journal articles (authors, titles, information to locate, and version), and beginning in 2007 included a DOI that is persistent, actionable, specific, and complete. The citation approach used at the DAAC also allows for referring to specific subsets of the data, by including within the citation the temporal and spatial portions of the data actually used. Citations allow others to find data and reproduce the results of the research article, and also use those data to test new hypotheses, design new sample collections, or construct or evaluate models. In addition to enhancing discovery and access of the data used in a research article, the citation gives credit to data generators, data centers and their funders, and, through citation indices, determine the scientific impact of a data set. The ORNL DAAC has developed a database that links research articles and their use of ORNL DAAC data products. The database allows determination of who, in which journal, and how the data have been used, in a manner analogous to author citation indices. The ORNL DAAC has been an initial contributor to the Thomson Reuters Data Citation Index. In addition, research data products deposited at the ORNL DAAC are linked using DOIs to relevant articles in Elsevier journals available on ScienceDirect. The ultimate goal of this implementation is that citations to data products become a routine part of the scientific process.

Leaching of Silver from Silver-Impregnated Food Storage Containers

Science.gov (United States)

Hauri, James F.; Niece, Brian K.

2011-01-01

The use of silver in commercial products has proliferated in recent years owing to its antibacterial properties. Food containers impregnated with micro-sized silver promise long food life, but there is some concern because silver can leach out of the plastic and into the stored food. This laboratory experiment gives students the opportunity to…

Silver niobates

International Nuclear Information System (INIS)

Tanirbergenov, B.; Rozhenko, S.P.

1979-01-01

By means of determination of residual concentrations and pH measurements investigated are the AgNO 3 -KNbO 3 -H 2 O, AgNO 3 -K 3 NbO 4 -H 2 O, AgNO 3 -K 8 Nb 16 O 19 -H 2 O systems and established is formation of meta-, ortho-and hexaniobates of silver. AgNbO 3 x H 2 O, Ag 8 Nb 6 O 19 x 6H 2 O and Ag 3 NbO 3 x 2.5H 2 O are separated from aqueous solution. Using the methods of differential-thermal, thermogravimetric and X-ray-phase analyses it is shown that silver metaniobate transforms into the crystal state at 530 deg C. Ortho- and hexaniobate of silver decompose at 500 deg C with formation of silver metaniobate and metal silver

Development of HSPA1A promoter-driven luciferase reporter gene assays in human cells for assessing the oxidative damage induced by silver nanoparticles

International Nuclear Information System (INIS)

Xin, Lili; Wang, Jianshu; Zhang, Leshuai W.; Che, Bizhong; Dong, Guangzhu; Fan, Guoqiang; Cheng, Kaiming

2016-01-01

The exponential increase in the total number of engineered nanoparticles in consumer products requires novel tools for rapid and cost-effective toxicology screening. In order to assess the oxidative damage induced by nanoparticles, toxicity test systems based on a human HSPA1A promoter-driven luciferase reporter in HepG2, LO2, A549, and HBE cells were established. After treated with heat shock and a group of silver nanoparticles (AgNPs) with different primary particle sizes, the cell viability, oxidative damage, and luciferase activity were determined. The time-dependent Ag + ions release from AgNPs in cell medium was also evaluated. Our results showed that heat shock produced a strong time-dependent induction of relative luciferase activity in the four luciferase reporter cells. Surprisingly, at 4 h of recovery, the relative luciferase activity was > 98 × the control level in HepG2-luciferase cells. Exposure to different sizes of AgNPs resulted in activation of the HSPA1A promoter in a dose-dependent manner, even at low cytotoxic or non-cytotoxic doses. The smaller (5 nm) AgNPs were more potent in luciferase induction than the larger (50 and 75 nm) AgNPs. These results were generally in accordance with the oxidative damage indicated by malondialdehyde concentration, reactive oxygen species induction and glutathione depletion, and Ag + ions release in cell medium. Compared with the other three luciferase reporter cells, the luciferase signal in HepG2-luciferase cells is obviously more sensitive and stable. We conclude that the luciferase reporter cells, especially the HepG2-luciferase cells, could provide a valuable tool for rapid screening of the oxidative damage induced by AgNPs. - Highlights: • We established the stable HSPA1A promoter-driven luciferase reporter cells. • Silver nanoparticles induced dose-dependent increases in luciferase activity. • HSPA1A promoter activity is a sensitive and responsive indicator of oxidative stress. • HepG2-luciferase

Development of HSPA1A promoter-driven luciferase reporter gene assays in human cells for assessing the oxidative damage induced by silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xin, Lili, E-mail: llxin@suda.edu.cn [School of Public Health, Medical College of Soochow University, 199 Renai Road, Suzhou 215123, Jiangsu (China); Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Diseases, School of Public Health, Soochow University, Suzhou 215123 (China); Wang, Jianshu [Suzhou Center for Disease Prevention and Control, 72 Sanxiang Road, Suzhou, Jiangsu (China); Zhang, Leshuai W. [School of Radiation Medicine and Protection & School for Radiological and Interdisciplinary Sciences (RAD-X), Soochow University, 215123 (China); Che, Bizhong; Dong, Guangzhu [School of Public Health, Medical College of Soochow University, 199 Renai Road, Suzhou 215123, Jiangsu (China); Fan, Guoqiang; Cheng, Kaiming [Suzhou Industrial Park Centers for Disease Control and Prevention, 58 Suqian Road, Suzhou, Jiangsu (China)

2016-08-01

The exponential increase in the total number of engineered nanoparticles in consumer products requires novel tools for rapid and cost-effective toxicology screening. In order to assess the oxidative damage induced by nanoparticles, toxicity test systems based on a human HSPA1A promoter-driven luciferase reporter in HepG2, LO2, A549, and HBE cells were established. After treated with heat shock and a group of silver nanoparticles (AgNPs) with different primary particle sizes, the cell viability, oxidative damage, and luciferase activity were determined. The time-dependent Ag{sup +} ions release from AgNPs in cell medium was also evaluated. Our results showed that heat shock produced a strong time-dependent induction of relative luciferase activity in the four luciferase reporter cells. Surprisingly, at 4 h of recovery, the relative luciferase activity was > 98 × the control level in HepG2-luciferase cells. Exposure to different sizes of AgNPs resulted in activation of the HSPA1A promoter in a dose-dependent manner, even at low cytotoxic or non-cytotoxic doses. The smaller (5 nm) AgNPs were more potent in luciferase induction than the larger (50 and 75 nm) AgNPs. These results were generally in accordance with the oxidative damage indicated by malondialdehyde concentration, reactive oxygen species induction and glutathione depletion, and Ag{sup +} ions release in cell medium. Compared with the other three luciferase reporter cells, the luciferase signal in HepG2-luciferase cells is obviously more sensitive and stable. We conclude that the luciferase reporter cells, especially the HepG2-luciferase cells, could provide a valuable tool for rapid screening of the oxidative damage induced by AgNPs. - Highlights: • We established the stable HSPA1A promoter-driven luciferase reporter cells. • Silver nanoparticles induced dose-dependent increases in luciferase activity. • HSPA1A promoter activity is a sensitive and responsive indicator of oxidative stress. • HepG2

Understanding long-term silver release from surface modified porous titanium implants.

Science.gov (United States)

Shivaram, Anish; Bose, Susmita; Bandyopadhyay, Amit

2017-08-01

Prevention of orthopedic device related infection (ODRI) using antibiotics has met with limited amount of success and is still a big concern during post-surgery. As an alternative, use of silver as an antibiotic treatment to prevent surgical infections is being used due to the well-established antimicrobial properties of silver. However, in most cases silver is used in particulate form with wound dressings or with short-term devices such as catheters but not with load-bearing implants. We hypothesize that strongly adherent silver to load-bearing implants can offer longer term solution to infection in vivo. Keeping that in mind, the focus of this study was to understand the long term release study of silver ions for a period of minimum 6months from silver coated surface modified porous titanium implants. Implants were fabricated using a LENS™ system, a powder based additive manufacturing technique, with at least 25% volume porosity, with and without TiO 2 nanotubes in phosphate buffer saline (pH 7.4) to see if the total release of silver ions is within the toxic limit for human cells. Considering the fact that infection sites may reduce the local pH, silver release was also studied in acetate buffer (pH 5.0) for a period of 4weeks. Along with that, the osseointegrative properties as well as cytotoxicity of porous titanium implants were assessed in vivo for a period of 12weeks using a rat distal femur model. In vivo results indicate that porous titanium implants with silver coating show comparable, if not better, biocompatibility and bonding at the bone-implant interface negating any concerns related to toxicity related to silver to normal cells. The current research is based on our recently patented technology, however focused on understanding longer-term silver release to mitigate infection related problems in load-bearing implants that can even arise several months after the surgery. Prevention of orthopedic device related infection using antibiotics has met

Silver enhances antibiotic activity against gram-negative bacteria.

Science.gov (United States)

Morones-Ramirez, J Ruben; Winkler, Jonathan A; Spina, Catherine S; Collins, James J

2013-06-19

A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive-specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.

The scientific impact of nations: journal placement and citation performance.

Directory of Open Access Journals (Sweden)

Matthew J Smith

Full Text Available International collaboration is becoming increasingly important for the advancement of science. To gain a more precise understanding of how factors such as international collaboration influence publication success, we divide publication success into two categories: journal placement and citation performance. Analyzing all papers published between 1996 and 2012 in eight disciplines, we find that those with more countries in their affiliations performed better in both categories. Furthermore, specific countries vary in their effects both individually and in combination. Finally, we look at the relationship between national output (in papers published and input (in citations received over the 17 years, expanding upon prior depictions by also plotting an expected proportion of citations based on Journal Placement. Discrepancies between this expectation and the realized proportion of citations illuminate trends in performance, such as the decline of the Global North in response to rapidly developing countries, especially China. Yet, most countries' show little to no discrepancy, meaning that, in most cases, citation proportion can be predicted by Journal Placement alone. This reveals an extreme asymmetry between the opinions of a few reviewers and the degree to which paper acceptance and citation rates influence career advancement.

Scientific citations favor positive results : a systematic review and meta-analysis

NARCIS (Netherlands)

Duyx, Bram; Urlings, Miriam J.E.; Swaen, Gerard M.H.; Bouter, Lex M.; Zeegers, Maurice P.

2017-01-01

Objectives Citation bias concerns the selective citation of scientific articles based on their results. We brought together all available evidence on citation bias across scientific disciplines and quantified its impact. Study Design and Setting An extensive search strategy was applied to the Web of

Edited volumes, monographs and book chapters in the Book Citation Index (BKCI) and Science Citation Index (SCI, SoSCI, A&HCI)

NARCIS (Netherlands)

Leydesdorff, L.; Felt, U.

2012-01-01

In 2011, Thomson-Reuters introduced the Book Citation Index (BKCI) as part of the Science Citation Index (SCI). The interface of the Web of Science version 5 enables users to search for both 'Books' and 'Book Chapters' as new categories. Books and book chapters, however, were always among the cited

Powerful colloidal silver nanoparticles for the prevention of gastrointestinal bacterial infections

International Nuclear Information System (INIS)

Le, Anh-Tuan; Le, Thi Tam; Nguyen, Van Quy; Tran, Huy Hoang; Dang, Duc Anh; Tran, Quang Huy; Vu, Dinh Lam

2012-01-01

In this work we have demonstrated a powerful disinfectant ability of colloidal silver nanoparticles (NPs) for the prevention of gastrointestinal bacterial infections. The silver NPs colloid was synthesized by a UV-enhanced chemical precipitation. Two gastrointestinal bacterial strains of Escherichia coli (ATCC 43888-O157:k-:H7) and Vibrio cholerae (O1) were used to verify the antibacterial activity of the as-prepared silver NPs colloid by means of surface disinfection assay in agar plates and turbidity assay in liquid media. Transmission electron microscopy was also employed to analyze the ultrastructural changes of bacterial cells caused by silver NPs. Noticeably, our silver NPs colloid displayed a highly effective bactericidal effect against two tested gastrointestinal bacterial strains at a silver concentration as low as ∼3 mg l −1 . More importantly, the silver NPs colloid showed an enhancement of antibacterial activity and long-lasting disinfectant effect as compared to conventional chloramin B (5%) disinfection agent. These advantages of the as-prepared colloidal silver NPs make them very promising for environmental treatments contaminated with gastrointestinal bacteria and other infectious pathogens. Moreover, the powerful disinfectant activity of silver-containing materials can also help in controlling and preventing further outbreak of diseases. (paper)

[MAXIMUM SINGLE DOSE OF COLLOIDAL SILVER NEGATIVELY AFFECTS ERYTHROPOIESIS IN VITRO].

Science.gov (United States)

Tishevskayal, N V; Zakharovl, Y M; Bolotovl, A A; Arkhipenko, Yu V; Sazontova, T G

2015-01-01

Erythroblastic islets (EI) of rat bone marrow were cultured for 24 h in the presence of silver nanoparticles (1.07 · 10(-4) mg/ml; 1.07 · 10(-3) mg/ml; and 1.07 · 10(-2) mg/mL). The colloidal silver at 1.07 · 10(-3) mg/ml concentration inhibited the formation of new Elby disrupting contacts of bone marrow macrophages with CFU-E (erythropoiesis de novo) by 65.3% (p Colloidal silver nanoparticles suppressed the reconstruction of erythropoiesis and inhibited the formation of new EI by disrupting contacts of CFU-E and central macrophages with matured erythroidal "crown" (erythropoiesis de repeto). The colloidal silver concentration of 1.07 · 10(-3) mg/ml in the culture medium also reduced the number of self-reconstructing EI by 67.5% (p colloidal silver reduced this value by 93.7% (p Silver nanoparticles retarded maturation of erythroid cells at the stage of oxiphylic normoblast denucleation: 1.07 · 10(-3) mg/ml colloidal silver increased the number of mature El by 53% (p colloidal silver in concentration equivalent to the maximum single dose is related to the effect of silver nanoparticles rather than glycerol present in the colloidal suspension.

Diet History Questionnaire: Suggested Citations

Science.gov (United States)

Use of the Diet History Questionnaire and Diet*Calc Analysis Software for publication purposes should contain a citation which includes version information for the software, questionnaire, and nutrient database.

Multi-functional bio-compatible luminescent apatite with fatty acid passivated nano silver covers and its theranostics potential

Science.gov (United States)

Asha, S.; Nimrodh Ananth, A.; Vanitha Kumari, G.; Prakash, B.; Jose, Sujin P.; Jothi Rajan, M. A.

2017-09-01

Europium doped hydroxyapatite (EDA) nanorods with linoleic acid passivated silver ions on their surfaces were synthesized using facile, one-step hydrothermal route. Annealing the samples at 250 °C resulted in formation of ultra-small silver (USS) nanoparticles on the surface by nucleation through diffusion process. EDA exhibited luminescence properties due to the presence of europium ions doped on the calcium sites of hydroxyapatite. These EDA nanorods exhibited a different luminescent behavior in the presence of silver ions and USS nanoparticles. This report also demonstrates excellent biocompatibility and cytotoxicity of EDA nanorods with silver ions towards fibroblast cell lines (F929) and breast cancer cells (MCF-7). Visible and near infra-red (NIR) emissions in EDA, induced by silver ions and USS nanoparticles makes it a potential system for deep tissue imaging applications. The arrangement of USS over the EDA was tunable and hence the selectivity and enhancement of the Eu3+ ions emission can also be tuned. The multifunctional properties of this system such as its active luminescence over a wide range, its cell proliferation towards normal cells and cytotoxicity towards cancer cells shows its potential for application in cancer theranostics.

Formation of carboxymethyl cellulose hydrogel containing silver nanoparticle

Energy Technology Data Exchange (ETDEWEB)

Park, Jong Seok; Kuang, Jia; Gwon, Hui Jeong; Lim, Youn Mook; Nho, Young Chang [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2010-12-15

Silver nanoparticles (AgNPs) can be used in the areas such as integrate circuit, cell electrode and antimicrobial deodorant. In this study, AgNPs have been prepared by using AgNO{sub 3} aqueous solution in the carboxymethyl cellulose (CMC) hydrogel. CMC powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make CMC hydrogel. CMC hydrogels were dipped into 1.0 x 10{sup -2} M AgNO{sub 3} solution for 1 hour. After that, the swollen hydrogels were irradiated by gamma-ray for the formation of AgNPs. The characteristics of silver nanoparticles in the CMC hydrogels were monitored by UV-Vis and the morphological study and dispersed coefficient of particles were investigated by FE-SEM/EDX. It was observed that the sodium salt in the CMC is crucial to the formation of silver nanoparticle. Finally, antibacterial tests indiacted that the hydrogel containing silver nanoparticle has antibacterial activity.

A Falsification of the Citation Impediment in the Taxonomic Literature.

Science.gov (United States)

Steiner, Florian M; Pautasso, Marco; Zettel, Herbert; Moder, Karl; Arthofer, Wolfgang; Schlick-Steiner, Birgit C

2015-09-01

Current science evaluation still relies on citation performance, despite criticisms of purely bibliometric research assessments. Biological taxonomy suffers from a drain of knowledge and manpower, with poor citation performance commonly held as one reason for this impediment. But is there really such a citation impediment in taxonomy? We compared the citation numbers of 306 taxonomic and 2291 non-taxonomic research articles (2009-2012) on mosses, orchids, ciliates, ants, and snakes, using Web of Science (WoS) and correcting for journal visibility. For three of the five taxa, significant differences were absent in citation numbers between taxonomic and non-taxonomic papers. This was also true for all taxa combined, although taxonomic papers received more citations than non-taxonomic ones. Our results show that, contrary to common belief, taxonomic contributions do not generally reduce a journal's citation performance and might even increase it. The scope of many journals rarely featuring taxonomy would allow editors to encourage a larger number of taxonomic submissions. Moreover, between 1993 and 2012, taxonomic publications accumulated faster than those from all biological fields. However, less than half of the taxonomic studies were published in journals in WoS. Thus, editors of highly visible journals inviting taxonomic contributions could benefit from taxonomy's strong momentum. The taxonomic output could increase even more than at its current growth rate if: (i) taxonomists currently publishing on other topics returned to taxonomy and (ii) non-taxonomists identifying the need for taxonomic acts started publishing these, possibly in collaboration with taxonomists. Finally, considering the high number of taxonomic papers attracted by the journal Zootaxa, we expect that the taxonomic community would indeed use increased chances of publishing in WoS indexed journals. We conclude that taxonomy's standing in the present citation-focused scientific landscape could

Citation analysis of meta-analysis articles on posttraumatic stress disorder.

Science.gov (United States)

Liao, Xi-Ming; Chen, Ping-Yan

2011-04-01

In the past two decades enormously scientific researches on posttraumatic stress disorder (PTSD) have been undertaken and many related meta-analyses have been published. Citation analysis was used to get comprehensive perspectives of meta-analysis articles (MA articles) on PTSD for the purpose of facilitating the researchers, physicians and policy-makers to understand the PTSD. MA articles on PTSD in any languages from January 1980 to March 2009 were included if they presented meta-analytical methods and received at least one citation recorded in the Web of Science (WoS). Whereas studies, in which any effect sizes of PTSD were not distinguished from other psychological disorders, were excluded. Citations to and by identified MA articles were documented basing on records in WoS. Citation analysis was used to examine distribution patterns of characteristics and citation impact of MA articles on PTSD. Canonical analysis was used to explore the relationship between the characteristics of MA articles and citation impact. Thirty-four MA articles published during 1998 and 2008 were identified and revealed multiple study topics on PTSD: 10 (29.4%) were about epidemiology, 13 (38.2%) about treatment or intervention, 6 (17.6%) about pathophysiology or neurophysiology or neuroendocrine, 3 (8.8%) about childhood and 2 (5.9%) about psychosocial adversity. Two articles cited most frequently with 456 and 145 counts were published in Journal of Consulting and Clinical Psychology by Brewin (2000) and Psychological Bulletin by Ozer (2003), respectively. Mean cited count was 7.48 ± 10.56 and mean age (year 2009 minus article publication year) was (4.24 ± 2.91) years. They had been cited approximately by 67 disciplines and by authors from 42 countries or territories. Characteristics of meta-analysis highly correlated with citation impact and reflected by canonical correlation of 0.899 (P < 0.000 01). The age of MA articles predicted their citation impact. Citation analysis would

Antibacterial and anticancerous biocompatible silver nanoparticles synthesised from the cold-tolerant strain of Spirulina platensis

Directory of Open Access Journals (Sweden)

Selvaraj Karthick Raja Namasivayam

2015-04-01

Full Text Available Objective: To synthesize silver nanoparticles from the biomass of cold tolerant strain of Spirulina platensis and evalute the synthesized nanoparticles against antibacterial and anticancer activity. Methods: Silver nanoparticles were synthesized by the algal culture and characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X ray diffraction studies. Antibacterial activity has been studied with free nanoparticles adopting agar diffusion assay, biofilm inhibition assay and nanoparticles fabricated wound dressing against representative Gram-negative organism Pseudomonas aeruginosa and Gram-positive organism Staphylococcus aureus respectively. The in vitro anticancer activity of silver nanoparticles were screened against human Hep2 cell lines by means of MTT assay. Results: Reduction of silver ions by the algal culture was observed during 72 h of incubation and the synthesized nanoparticles were further characterized. Antibacterial study reveals both the strains were susceptible to free nanoparticles and fabricated wound dressing treatment. The in vitro anticancer activity of silver nanoparticles were screened against human Hep 2 cell lines by means of MTT assay which reveals that cell viability has been reduced as dose dependent manner. Conclusions: The observed results imply that silver nanoparticles synthesized from Spirulina platensis cold tolerant strain can be used as potential antibacterial and anticancerous agent.

Antibacterial and anticancerous biocompatible silver nanoparticles synthesised from the cold-tolerant strain of Spirulina platensis

Institute of Scientific and Technical Information of China (English)

Duraisamy Jayakumar; Ramesh Kumar; Rajan SowriArvind Bharani

2015-01-01

Objective: To synthesize silver nanoparticles from the biomass of cold tolerant strain of Spirulina platensis and evalute the synthesized nanoparticles against antibacterial and anticancer activity. Methods: Silver nanoparticles were synthesized by the algal culture and characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X ray diffraction studies. Antibacterial activity has been studied with free nanoparticles adopting agar diffusion assay, biofilm inhibition assay and nanoparticles fabricated wound dressing against representative Gram-negative organism Pseudomonas aeruginosa and Gram-positive organism Staphylococcus aureus respectively. The in vitro anticancer activity of silver nanoparticles were screened against human Hep2 cell lines by means of MTT assay. Results: Reduction of silver ions by the algal culture was observed during 72 h of incubation and the synthesized nanoparticles were further characterized. Antibacterial study reveals both the strains were susceptible to free nanoparticles and fabricated wound dressing treatment. The in vitro anticancer activity of silver nanoparticles were screened against human Hep 2 cell lines by means of MTT assay which reveals that cell viability has been reduced as dose dependent manner. Conclusions: The observed results imply that silver nanoparticles synthesized from Spirulina platensis cold tolerant strain can be used as potential antibacterial and anticancerous agent.

Neuron cell positioning on polystyrene in culture by silver-negative ion implantation and region control of neural outgrowth

International Nuclear Information System (INIS)

Tsuji, Hiroshi; Sato, Hiroko; Baba, Takahiro; Ikemura, Shin'ichi; Gotoh, Yasuhito; Ishikawa, Junzo

2000-01-01

A new method to control the position of neuron cell attachment and extension region of neural outgrowth has been developed by using a pattering ion implantation with silver-negative ions into polystyrene dishes. This technique offers a promising method to form an artificially designed neural network in cell culture in vitro. Silver-negative ions were implanted into non-treated polystyrene dishes (NTPS) at conditions of 20 keV and 3x10 15 ions/cm 2 through a pattering mask, which had as many as 67 slits of 60 μm in width and 4 mm in length with a spacing of 60 μm. For cell culture in vitro, nerve cells of PC-12h (rat adrenal phechromocytoma) were used because they respond to a nerve growth factor (NGF). In the first 2 days in culture without NGF, we observed a selective cell attachment only to the ion-implanted region in patterning Ag - implanted polystyrene sample (p-Ag/NTPS). In another 2 days in culture with NGF, the nerve cells expanded neurites only over the ion-implanted region. For collagen-coated p-Ag/NTPS sample of which collagen was coated after the ion implantation (Collagen/p-Ag/NTPS), most nerve cells were also attached on the ion-implanted region. However, neurites expanded in both ion-implanted and unimplanted regions. The contact angle of NTPS decreased after the ion implantation from 86 deg. to 74 deg. . The region selectivity of neuron attachment and neurite extension is considered to be due to contact angle lowering by the ion implantation as radiation effect on the surface

ELECTRO-GRAVIMETRIC RECOVERY OF SILVER FROM ...

African Journals Online (AJOL)

2 M glacial acetic acid (CH3COOH) ... were escaped in the form of unstable volatile oxides using fire assay method as mentioned earlier. ... voltage 1.5 V was observed optimum cell voltage for maximum % recovery of silver [9-10]. Figure 1.

Silver-gold core-shell nanoparticles containing methylene blue as SERS labels for probing and imaging of live cells

International Nuclear Information System (INIS)

Guo, X.; Guo, Z.; Jin, Y.; Liu, Z.; Zhang, W.; Huang, D.

2012-01-01

We report on silver-gold core-shell nanostructures that contain Methylene Blue (MB) at the gold/x96silver interface. They can be used as reporter molecules in surface-enhanced Raman scattering (SERS) labels. The labels are stable and have strong SERS activity. TEM imaging revealed that these nanoparticles display bright and dark stripe structures. In addition, these labels can act as probes that can be detected and imaged through the specific Raman signatures of the reporters. We show that such SERS probes can identify cellular structures due to enhanced Raman spectra of intrinsic cellular molecules measured in the local optical fields of the core-shell nanostructures. They also provide structural information on the cellular environment as demonstrated for these nanoparticles as new SERS-active and biocompatible substrates for imaging of live cells. (author)

Multi-functional nano silver: A novel disruptive and theranostic agent for pathogenic organisms in real-time

Science.gov (United States)

Gopinath, Ponnusamy Manogaran; Ranjani, Anandan; Dhanasekaran, Dharumadurai; Thajuddin, Nooruddin; Archunan, Govindaraju; Akbarsha, Mohammad Abdulkader; Gulyás, Balázs; Padmanabhan, Parasuraman

2016-01-01

The present study was aimed at evaluating the fluorescence property, sporicidal potency against Bacillus and Clostridium endospores, and surface disinfecting ability of biogenic nano silver. The nano silver was synthesized using an actinobacterial cell-filtrate. The fluorescence property as well as imaging facilitator potency of this nano silver was verified adopting spectrofluorometer along with fluorescent and confocal laser scanning microscope wherein strong emission and bright green fluorescence, respectively, on the entire spore surface was observed. Subsequently, the endospores of B. subtilis, B. cereus, B. amyloliquefaciens, C. perfringens and C. difficile were treated with physical sporicides, chemical sporicides and nano silver, in which the nano silver brought about pronounced inhibition even at a very low concentration. Finally, the environmental surface-sanitizing potency of nano silver was investigated adopting cage co-contamination assay, wherein vital organs of mice exposed to the nano silver-treated cage did not show any signs of pathological lesions, thus signifying the ability of nano silver to completely disinfect the spore or reduce the count required for infection. Taken these observations together, we have shown the multi-functional biological properties of the nano silver, synthesized using an actinobacterial cell-filtrate, which could be of application in advanced diagnostics, biomedical engineering and therapeutics in the near future. PMID:27666290

Cryogenic refrigeration. (Latest citations from the NTIS Bibliographic database). Published Search

International Nuclear Information System (INIS)

1993-09-01

The bibliography contains citations concerning the development and applications of cryogenic refrigeration technology. Citations discuss performance evaluations of specific systems, equipment descriptions, the cooling of instrumentation, superconducting devices, reactor devices, and applications in satellites and spaceborne vehicles. (Contains 250 citations and includes a subject term index and title list.)

Cryogenic refrigeration. (Latest citations from the NTIS bibliographic database). Published Search

International Nuclear Information System (INIS)

1994-12-01

The bibliography contains citations concerning the development and applications of cryogenic refrigeration technology. Citations discuss performance evaluations of specific systems, equipment descriptions, the cooling of instrumentation, superconducting devices, reactor devices, and applications in satellites and spaceborne vehicles. (Contains 250 citations and includes a subject term index and title list.)

Citations and references as keys to relevance ranking in interactive IR

DEFF Research Database (Denmark)

Ingwersen, Peter

2012-01-01

According to the principle of Polyrepresentation (Ingwersen & Järvelin, 2005; Ingwersen, 2012) bibliographic references in scientific documents as well as citations to documents have the potential of serving as useful features for re-ranking of retrieved documents. References (and thus citations...... been demonstrated to improve retrieval performance (Skov et al. 2008), whereas the number of citations has not provided similar improvements. The presentation will discuss the following phenomena and characteristics of references and citations as means for relevance re-ranking: 1) Are academic...... references (and thus citations) associated with relevance? 2) What are their potentials for IR? 3) What are their limitations? The presentation will propose a range of potentials and provide an initial research design. Selected cases are exemplified from the Web of Science database....

A Study on Developing and Refining a Large Citation Service System

Directory of Open Access Journals (Sweden)

Kwang-Young Kim

2013-06-01

Full Text Available Today, citation index information is used as an outcome scale of spreading technology and encouraging research. Article citation information is an important factor to determine the authority of the relevant author. Google Scholar uses the article citation information to organize academic article search results with a rank algorithm. For an accurate analysis of such important citation index information, large amounts of bibliographic data are required. Therefore, this study aims to build a fast and efficient system for large amounts of bibliographic data, and to design and develop a system for quickly analyzing cited information for that data. This study also aims to use and analyze citation data to be a basic element for providing various advanced services to the academic article search system.

Exploring the effect of silver nanoparticle size and medium composition on uptake into pulmonary epithelial 16HBE14o-cells

NARCIS (Netherlands)

Kettler, K.; Krystek, P.W.; Giannakou, C.; Hendriks, A.J.; de Jong, W.H.

2016-01-01

The increasing number of nanotechnology products on the market poses increasing human health risks by particle exposures. Adverse effects of silver nanoparticles (AgNPs) in various cell lines have been measured based on exposure dose after a fixed time point, but NP uptake kinetics and the

Development kinetics of silver clusters on silver halides

International Nuclear Information System (INIS)

Grzesiak, S.; Belloni, J.; Marignier, J.-L.

2008-01-01

Silver nuclei are produced by pulse radiolysis at the surface of AgCl nanocrystallites in the presence of an electron donor, the methyl viologen, which induces the growth of silver nuclei. The experimental results observed on the increase of the silver atom concentration and on the decay of the donor concentration during this process, which is similar to the photographic development by an electron donor, are compared with the kinetics obtained from numerical simulation. The model assumes that the formation of silver clusters with a supercritical nuclearity is required before the start of an electron transfer reaction from the two reduced forms of the donor methyl viologen to the silver clusters. The reaction is controlled by the access of the donor to the surface sites of the AgCl crystallite. The rate constant values of the successive steps of the mechanism are derived from the adjustment of calculated kinetics to experimental signals under various conditions, using a single set of parameters which are fairly suitable under all conditions studied

The Anatomy of a Data Citation: Discovery, Reuse, and Credit

OpenAIRE

Mooney, Hailey; Newton, Mark P

2012-01-01

INTRODUCTION Data citation should be a necessary corollary of data publication and reuse. Many researchers are reluctant to share their data, yet they are increasingly encouraged to do just that. Reward structures must be in place to encourage data publication, and citation is the appropriate tool for scholarly acknowledgment. Data citation also allows for the identification, retrieval, replication, and verification of data underlying published studies. METHODS This study examines author beha...

Citation Rate of Highly-Cited Papers in 100 Kinesiology-Related Journals

Science.gov (United States)

Knudson, Duane

2015-01-01

This study extended previous research on several citation-based bibliometric variables for highly cited articles in a large (N = 100) number of journals related to Kinesiology. Total citations and citation rate of the 30 most highly cited articles in each journal were identified by searchers of "Google Scholar (GS)". Other major…

Biosorption of silver cations onto Lactococcus lactis and Lactobacillus casei isolated from dairy products.

Directory of Open Access Journals (Sweden)

Maciej Milanowski

Full Text Available The current work deals with the phenomenon of silver cations uptake by two kinds of bacteria isolated from dairy products. The mechanism of sorption of silver cations by Lactococcus lactis and Lactobacillus casei bacteria was investigated. Inductively coupled plasma-mass spectrometry (ICP-MS was used for determination of silver concentration sorbed by bacteria. Analysis of charge distribution was conducted by diffraction light scattering method. Changes in the ultrastructure of Lactococcus lactis and Lactobacillus casei cells after treatment with silver cations were investigated using transmission electron microscopy observation. Molecular spectroscopy methods, namely Fourier transform-infrared spectroscopy (FT-IR and matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS were employed for description of the sorption mechanism. Moreover, an analysis of volatile organic compounds (VOCs extracted from bacterial cells was performed.

Russell-Silver syndrome

Science.gov (United States)

Silver-Russell syndrome; Silver syndrome; RSS; Russell-Silver syndrome ... One in 10 children with this syndrome has a problem involving chromosome 7. In other people with the syndrome, it may affect chromosome 11. Most of the time, it ...

Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate

DEFF Research Database (Denmark)

Löschner, Katrin; Hadrup, Niels; Qvortrup, Klaus

2011-01-01

Background: The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food...... and food contact materials. Results: AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study...... in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of Ag...

Citation searching: a systematic review case study of multiple risk behaviour interventions.

Science.gov (United States)

Wright, Kath; Golder, Su; Rodriguez-Lopez, Rocio

2014-06-03

The value of citation searches as part of the systematic review process is currently unknown. While the major guides to conducting systematic reviews state that citation searching should be carried out in addition to searching bibliographic databases there are still few studies in the literature that support this view. Rather than using a predefined search strategy to retrieve studies, citation searching uses known relevant papers to identify further papers. We describe a case study about the effectiveness of using the citation sources Google Scholar, Scopus, Web of Science and OVIDSP MEDLINE to identify records for inclusion in a systematic review.We used the 40 included studies identified by traditional database searches from one systematic review of interventions for multiple risk behaviours. We searched for each of the included studies in the four citation sources to retrieve the details of all papers that have cited these studies.We carried out two analyses; the first was to examine the overlap between the four citation sources to identify which citation tool was the most useful; the second was to investigate whether the citation searches identified any relevant records in addition to those retrieved by the original database searches. The highest number of citations was retrieved from Google Scholar (1680), followed by Scopus (1173), then Web of Science (1095) and lastly OVIDSP (213). To retrieve all the records identified by the citation tracking searching all four resources was required. Google Scholar identified the highest number of unique citations.The citation tracking identified 9 studies that met the review's inclusion criteria. Eight of these had already been identified by the traditional databases searches and identified in the screening process while the ninth was not available in any of the databases when the original searches were carried out. It would, however, have been identified by two of the database search strategies if searches had been

In Vitro Evaluation of Colloidal Silver on Immune Function: Antilymphoproliferative Activity

Directory of Open Access Journals (Sweden)

M. A. Franco-Molina

2016-01-01

Full Text Available Colloidal silver (AgC is currently used by humans and it can be internalized through inhalation, injection, ingestion, and dermal contact. However, there is limited information about immunological activity; more investigations using colloidal silver are needed. In the present study, the effects of AgC (17.5 ng/mL on immunological parameters (proliferation and immunophenotyping using human peripheral blood mononuclear cells (PBMC and macrophages (phagocytosis and cytotoxicity on leukemia and lymphoma cancer cell lines (1.75 to 17.5 ng/mL were investigated. AgC was observed to significantly (p<0.05 decrease interleukin-2 (IL-2 production and proliferation induced by phytohemagglutinin or concanavalin A in PBMC without affecting its cell viability but with cytotoxic effect on cancer cells. IL-2, IL-4, IL-6, IL-10, INF-γ, and IL-17A cytokines production and CD3+, CD3−CD19+, CD3+CD4+, CD3+CD8+, and CD16+CD56+ PBMC phenotypes were not affected by AgC. The present study demonstrates that colloidal silver is harmless and nontoxic to the immune system cells and its ability to interfere with the immune response by decreasing cell proliferation when stimulated with mitogens demonstrated the antilymphoproliferative potential of AgC.

Which percentile-based approach should be preferred for calculating normalized citation impact values? An empirical comparison of five approaches including a newly developed citation-rank approach (P100)

NARCIS (Netherlands)

Bornmann, L.; Leydesdorff, L.; Wang, J.

2013-01-01

For comparisons of citation impacts across fields and over time, bibliometricians normalize the observed citation counts with reference to an expected citation value. Percentile-based approaches have been proposed as a non-parametric alternative to parametric central-tendency statistics. Percentiles

Silver matrix composites reinforced with galvanically silvered particles

OpenAIRE

J. Śleziona; J. Wieczorek,

2007-01-01

Purpose: The paper presents the possibility of the application of metalic layers drifted with the use of the galvanic methods on the ceramic particles surface. The application of the layers was aimed at obtaining the rewetting of the reinforcing particles with the liquid silver in the course of the producing of silver matrix composites with the use of mechanical stirring method. To enable introducing of the iron powder and glass carbon powder to liquid silver the solution of covering the powd...

Accuracy of citation and quotation in foot and ankle surgery journals.

Science.gov (United States)

Luo, Ma; Li, Charles Chuan; Molina, Domingo; Andersen, Clark R; Panchbhavi, Vinod K

2013-07-01

A recent review of technical editing of research suggests that over one third of references cited in articles in medical journals have some inaccuracies and one fifth of quotations to references in these articles are not accurate. Two hundred and forty-nine citation references and 408 quotes from 25 articles published in 5 orthopaedic journals were randomly selected to determine referencing accuracy. The presence of citation errors was examined by 1 of the authors while the presence of quotation errors was determined by 2 of the authors. Full copies of articles as well as the references were obtained to compare the accuracies. The total citation error rate was 41% (103 out of 249 references), and the total quotation error rate was 20% (80 out of 408 quotes) for the 5 orthopaedic journals. Citation and quotation errors were still relatively common in orthopaedic journals. While we did not identify any factors associated with citation and quotation errors, the use of technical editing may reduce the amount of citation errors. Readers and authors should be aware that many citations of studies are inaccurate and one should review the original source if it is to be used in another publication or to guide clinical treatment.

Definition and identification of journals as bibliographic and subject entities: Librarianship versus ISI Journal Citation Reports methods and their effect on citation measures

NARCIS (Netherlands)

Bensman, S.J.; Leydesdorff, L.

2009-01-01

This paper explores the ISI Journal Citation Reports (JCR) bibliographic and subject structures through Library of Congress (LC) and American research libraries cataloging and classification methodology. The 2006 Science Citation Index JCR Behavioral Sciences subject category journals are used as an

Comparison on Bactericidal and Cytotoxic Effect of Silver Nanoparticles Synthesized by Different Methods

Science.gov (United States)

Mala, R.; Celsia, A. S. Ruby; Malathi Devi, S.; Geerthika, S.

2017-08-01

Biologically synthesized silver nanoparticle are biocompatible for medical applications. The present work is aimed to synthesize silver nanoparticle using the fruit pulp of Tamarindusindica and to evaluate its antibacterial and anticancer activity against lung cancercell lines. Antibacterial activity was assessed by well diffusion method. Cytotoxicity was evaluated using MTT assay. GC-MS of fruit pulp extract showed the presence of levoglucosenone, n-hexadecanoic acid, 9,12-octadecadienoic acid etc. Antioxidant activity of the fruit pulp was determined by DPPH assay, hydrogen peroxide scavenging assay and lipid peroxidation. The size of biologically synthesized silver nanoparticle varied from 50 nm to 76 nm. It was 59 nm to 98 nm for chemically synthesized silver nanoparticle. Biologically synthesized silver nanoparticle showed 26 mm inhibition zone against E. coli and chemically synthesized silver nanoparticle showed 20 mm. Antioxidant activity of fruit extract by DPPH showed 84 % reduction. The IC 50 of biologically synthesized silver nanoparticle against lung cancer cell lines was 48 µg/ml. It was 95 µg/ml for chemically synthesized silver nanoparticle. The increased activity of biologically synthesized silver nanoparticle was due to its smaller size, stability and the bioactive compounds capping the silver nanoparticle extracted from the fruit extract.

Identifying Anomalous Citations for Objective Evaluation of Scholarly Article Impact.

Directory of Open Access Journals (Sweden)

Xiaomei Bai

Full Text Available Evaluating the impact of a scholarly article is of great significance and has attracted great attentions. Although citation-based evaluation approaches have been widely used, these approaches face limitations e.g. in identifying anomalous citations patterns. This negligence would inevitably cause unfairness and inaccuracy to the article impact evaluation. In this study, in order to discover the anomalous citations and ensure the fairness and accuracy of research outcome evaluation, we investigate the citation relationships between articles using the following factors: collaboration times, the time span of collaboration, citing times and the time span of citing to weaken the relationship of Conflict of Interest (COI in the citation network. Meanwhile, we study a special kind of COI, namely suspected COI relationship. Based on the COI relationship, we further bring forward the COIRank algorithm, an innovative scheme for accurately assessing the impact of an article. Our method distinguishes the citation strength, and utilizes PageRank and HITS algorithms to rank scholarly articles comprehensively. The experiments are conducted on the American Physical Society (APS dataset. We find that about 80.88% articles contain contributed citations by co-authors in 26,366 articles and 75.55% articles among these articles are cited by the authors belonging to the same affiliation, indicating COI and suspected COI should not be ignored for evaluating impact of scientific papers objectively. Moreover, our experimental results demonstrate COIRank algorithm significantly outperforms the state-of-art solutions. The validity of our approach is verified by using the probability of Recommendation Intensity.

Identifying Anomalous Citations for Objective Evaluation of Scholarly Article Impact.

Science.gov (United States)

Bai, Xiaomei; Xia, Feng; Lee, Ivan; Zhang, Jun; Ning, Zhaolong

2016-01-01

Evaluating the impact of a scholarly article is of great significance and has attracted great attentions. Although citation-based evaluation approaches have been widely used, these approaches face limitations e.g. in identifying anomalous citations patterns. This negligence would inevitably cause unfairness and inaccuracy to the article impact evaluation. In this study, in order to discover the anomalous citations and ensure the fairness and accuracy of research outcome evaluation, we investigate the citation relationships between articles using the following factors: collaboration times, the time span of collaboration, citing times and the time span of citing to weaken the relationship of Conflict of Interest (COI) in the citation network. Meanwhile, we study a special kind of COI, namely suspected COI relationship. Based on the COI relationship, we further bring forward the COIRank algorithm, an innovative scheme for accurately assessing the impact of an article. Our method distinguishes the citation strength, and utilizes PageRank and HITS algorithms to rank scholarly articles comprehensively. The experiments are conducted on the American Physical Society (APS) dataset. We find that about 80.88% articles contain contributed citations by co-authors in 26,366 articles and 75.55% articles among these articles are cited by the authors belonging to the same affiliation, indicating COI and suspected COI should not be ignored for evaluating impact of scientific papers objectively. Moreover, our experimental results demonstrate COIRank algorithm significantly outperforms the state-of-art solutions. The validity of our approach is verified by using the probability of Recommendation Intensity.

Photochemical Study of Silver Nanoparticles Formed from the Reduction of Silver Ions by Humic Acid

Science.gov (United States)

Leslie, Renee M.

This study focuses on the ability of silver ions and humic acid to form silver nanoparticles in the presence of UV and visible light. Silver nanoparticles have a number of industrial applications due primarily to their antimicrobial properties, but these properties pose an environmental threat. Silver nanoparticles can directly disrupt sensitive ecosystems by harming bacteria. Consumption of silver nanoparticles results in silver ions and silver nanoparticles entering waterways; the presence of silver ions raises the question of whether nanoparticles can reform in environmental waters. As our data show, silver nanoparticles can form from the reduction of silver ions by humic acid after irradiation with UV and visible light. In order to better understand the mechanism of these naturally synthesized silver nanoparticles, we investigated the effects of reactant concentration, experimental conditions and presence of ions/reactive species. We monitored silver nanoparticle growth with UV-visible spectroscopy. The evolution in time of nanoparticle size was monitored by dynamic light scattering (DLS).

Comparing Medline citations using modified N-grams

Science.gov (United States)

Nawab, Rao Muhammad Adeel; Stevenson, Mark; Clough, Paul

2014-01-01

Objective We aim to identify duplicate pairs of Medline citations, particularly when the documents are not identical but contain similar information. Materials and methods Duplicate pairs of citations are identified by comparing word n-grams in pairs of documents. N-grams are modified using two approaches which take account of the fact that the document may have been altered. These are: (1) deletion, an item in the n-gram is removed; and (2) substitution, an item in the n-gram is substituted with a similar term obtained from the Unified Medical Language System  Metathesaurus. N-grams are also weighted using a score derived from a language model. Evaluation is carried out using a set of 520 Medline citation pairs, including a set of 260 manually verified duplicate pairs obtained from the Deja Vu database. Results The approach accurately detects duplicate Medline document pairs with an F1 measure score of 0.99. Allowing for word deletions and substitution improves performance. The best results are obtained by combining scores for n-grams of length 1–5 words. Discussion Results show that the detection of duplicate Medline citations can be improved by modifying n-grams and that high performance can also be obtained using only unigrams (F1=0.959), particularly when allowing for substitutions of alternative phrases. PMID:23715801

Mentha arvensis (Linn.-mediated green silver nanoparticles trigger caspase 9-dependent cell death in MCF7 and MDA-MB-231 cells

Directory of Open Access Journals (Sweden)

Banerjee PP

2017-04-01

Full Text Available Prajna Paramita Banerjee,1 Arindam Bandyopadhyay,1 Singapura Nagesh Harsha,2 Rudragoud S Policegoudra,3 Shelley Bhattacharya,4 Niranjan Karak,2 Ansuman Chattopadhyay1 1Molecular Genetics Laboratory, Department of Zoology, Visva-Bharati, Santiniketan, West Bengal, 2Advanced Polymer and Nanomaterial Laboratory, Department of Chemical Sciences, Center for Polymer Science and Technology, Tezpur University, Napaam, 3Division of Pharmaceutical Technology, Defence Research Laboratory, Tezpur, Assam, 4Environmental Toxicology Laboratory, Department of Zoology, Visva-Bharati, Santiniketan, West Bengal, India Introduction: Leaf extract of Mentha arvensis or mint plant was used as reducing agent for the synthesis of green silver nanoparticles (GSNPs as a cost-effective, eco-friendly process compared to that of chemical synthesis. The existence of nanoparticles was characterized by ultraviolet–visible spectrophotometry, dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis, atomic-force microscopy and transmission electron microscopy analyses, which ascertained the formation of spherical GSNPs with a size range of 3–9 nm. Anticancer activities against breast cancer cell lines (MCF7 and MDA-MB-231 were studied and compared with those of chemically synthesized (sodium borohydride [NaBH4]-mediated silver nanoparticles (CSNPs. Materials and methods: Cell survival of nanoparticle-treated and untreated cells was studied by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT assay. Cell-cycle analyses were carried out using fluorescence-activated cell sorting. Cell morphology was observed by fluorescence microscopy. Expression patterns of PARP1, P53, P21, Bcl2, Bax and cleaved caspase 9 as well as caspase 3 proteins in treated and untreated MCF7 and MDA-MB-231 cells were studied by Western blot method. Results: MTT assay results showed that Mentha arvensis-mediated GSNPs

Methods for measuring the citations and productivity of scientists across time and discipline

Science.gov (United States)

Petersen, Alexander M.; Wang, Fengzhong; Stanley, H. Eugene

2010-03-01

Publication statistics are ubiquitous in the ratings of scientific achievement, with citation counts and paper tallies factoring into an individual’s consideration for postdoctoral positions, junior faculty, and tenure. Citation statistics are designed to quantify individual career achievement, both at the level of a single publication, and over an individual’s entire career. While some academic careers are defined by a few significant papers (possibly out of many), other academic careers are defined by the cumulative contribution made by the author’s publications to the body of science. Several metrics have been formulated to quantify an individual’s publication career, yet none of these metrics account for the collaboration group size, and the time dependence of citation counts. In this paper we normalize publication metrics in order to achieve a universal framework for analyzing and comparing scientific achievement across both time and discipline. We study the publication careers of individual authors over the 50-year period 1958-2008 within six high-impact journals: CELL, the New England Journal of Medicine (NEJM), Nature, the Proceedings of the National Academy of Science (PNAS), Physical Review Letters (PRL), and Science. Using the normalized metrics (i) “citation shares” to quantify scientific success, and (ii) “paper shares” to quantify scientific productivity, we compare the career achievement of individual authors within each journal, where each journal represents a local arena for competition. We uncover quantifiable statistical regularity in the probability density function of scientific achievement in all journals analyzed, which suggests that a fundamental driving force underlying scientific achievement is the competitive nature of scientific advancement.

Toxicity of silver nanoparticles in biological systems: Does the complexity of biological systems matter?

Science.gov (United States)

Vazquez-Muñoz, Roberto; Borrego, Belen; Juárez-Moreno, Karla; García-García, Maritza; Mota Morales, Josué D; Bogdanchikova, Nina; Huerta-Saquero, Alejandro

2017-07-05

Currently, nanomaterials are more frequently in our daily life, specifically in biomedicine, electronics, food, textiles and catalysis just to name a few. Although nanomaterials provide many benefits, recently their toxicity profiles have begun to be explored. In this work, the toxic effects of silver nanoparticles (35nm-average diameter and Polyvinyl-Pyrrolidone-coated) on biological systems of different levels of complexity was assessed in a comprehensive and comparatively way, through a variety of viability and toxicological assays. The studied organisms included viruses, bacteria, microalgae, fungi, animal and human cells (including cancer cell lines). It was found that biological systems of different taxonomical groups are inhibited at concentrations of silver nanoparticles within the same order of magnitude. Thus, the toxicity of nanomaterials on biological/living systems, constrained by their complexity, e.g. taxonomic groups, resulted contrary to the expected. The fact that cells and virus are inhibited with a concentration of silver nanoparticles within the same order of magnitude could be explained considering that silver nanoparticles affects very primitive cellular mechanisms by interacting with fundamental structures for cells and virus alike. Copyright © 2017 Elsevier B.V. All rights reserved.

Recent trends of citation status and suggestions for improved the academic authority of the journal of the Korean radiological society during 2000-2005: analysis of all citations using KoMCI

International Nuclear Information System (INIS)

Park, Soo Youn; Kim, Hyun Jin; Ihn, Yon Kwon; Cha, Eun Suk; Hwang, Seong Su

2006-01-01

We wanted to analyze the citation trend and to find a way to improve the impact factor (IF) of the Journal of the Korean Radiological Society (JKRS). The number of articles and references, the total citations and self-citations, the IF and the IF excluding self-citations (ZIF) were described by an analysis of Korean Medical Citation Index (KoMCI) during 2000-2005. The total and self citations of the JKRS were compared to that of the Top 5 journals. There was a 57% decrease of papers for 6 years. The Korean references/paper ranged from 0.98-0.85. The number of total citations received steadily decreased from 394 in 2000 to 180 in 2005. The IF (ZF) of the JKRS has been gradually lowered from 0.142 (0.049) in 2000 to 0.063 (0.059) in 2005. Although the total citations that cited all papers published/the annual number of papers was 55% of that of the top 5 journals, the total citations citing papers published within the recent two years was only 24% of that of the top 5 journals. The citation status of the JKRS has steadily decreased for the recent 6 years, and the IF of the JKRS was very low among all the Korean medical journals. To improve the IF, active advertising for the journal members of the importance of the IF is needed to encourage citing JKRS papers that have been published within the recent two years

Predicting long-term citation impact of articles in social and personality psychology.

Science.gov (United States)

Haslam, Nick; Koval, Peter

2010-06-01

The citation impact of a comprehensive sample of articles published in social and personality psychology journals in 1998 was evaluated. Potential predictors of the 10-yr. citation impact of 1580 articles from 37 journals were investigated, including number of authors, number of references, journal impact factor, author nationality, and article length, using linear regression. The impact factor of the journal in which articles appeared was the primary predictor of the citations that they accrued, accounting for 30% of the total variance. Articles with greater length, more references, and more authors were cited relatively often, although the citation advantage of longer articles was not proportionate to their length. A citation advantage was also enjoyed by authors from the United States of America, Canada, and the United Kingdom. 37% of the variance in the total number of citations was accounted for by the study variables.

Antimicrobial and cytotoxicity effect of silver nanoparticle synthesized by Croton bonplandianum Baill. leaves

Directory of Open Access Journals (Sweden)

K. Khanra

2016-01-01

Full Text Available Objective(s: For the development of reliable, ecofriendly, less expensive process for the synthesis of silver nanoparticles and to evaluate the bactericidal, and cytotoxicity properties of silver nanoparticles synthesized from root extract of Croton bonplandianum, Baill. Materials and Methods: The synthesis of silver nanoparticles by plant part of Croton bonplandianum was carried out.  The formation of nanoparticles was confirmed by Transmission Electron Microscopy (TEM, Scanning Electron Microscopy (SEM, XRD and UV-Vis spectrophotometric analysis.  The biochemical properties were assayed by antibacterial study, cytotoxicity assay using cancer cell line.  Results: The formation of silver nanoparticles was confirmed by UV-VIS spectroscopic analysis which showed absorbance peak at 425 nm.  X-ray diffraction photograph indicated the face centered cubic structure of the synthesized AgNPs.  TEM has displayed the different dimensional images of biogenic silver nanoparticles with particle size distribution ranging from 15-40 nm with an average size of 32 nm. Silver particles are spherical in shape, clustered.  The EDX analysis was used to identify the elemental composition of synthesized AgNPs. Antibacterial activity of the synthesized AgNPs against three Gram positive and Gram negative bacteria strains like Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa carried out showed significant zones of inhibition. The cytotoxicity study by AgNPS also showed cytotoxicity on ovarian cancer cell line PA-1 and lung epithelial cancer cell line A549.  Conclusion: The present study confirms that the AgNPs have great promise as antibacterial, and anticancer agent.

Mineral commodity profiles: Silver

Science.gov (United States)

Butterman, W.C.; Hilliard, Henry E.

2005-01-01

Overview -- Silver is one of the eight precious, or noble, metals; the others are gold and the six platinum-group metals (PGM). World mine production in 2001 was 18,700 metric tons (t) and came from mines in 60 countries; the 10 leading producing countries accounted for 86 percent of the total. The largest producer was Mexico, followed by Peru, Australia, and the United States. About 25 percent of the silver mined in the world in 2001 came from silver ores; 15 percent, from gold ores and the remaining 60 percent, from copper, lead, and zinc ores. In the United States, 14 percent of the silver mined in 2001 came from silver ores; 39 percent, from gold ores; 10 percent, from copper and copper-molybdenum ores; and 37 percent, from lead, zinc, and lead-zinc ores. The precious metal ores (gold and silver) came from 30 lode mines and 10 placer mines; the base-metal ores (copper, lead, molybdenum, and zinc) came from 24 lode mines. Placer mines yielded less than 1 percent of the national silver production. Silver was mined in 12 States, of which Nevada was by far the largest producer; it accounted for nearly one-third of the national total. The production of silver at domestic mines generated employment for about 1,100 mine and mill workers. The value of mined domestic silver was estimated to be $290 million. Of the nearly 27,000 t of world silver that was fabricated in 2001, about one-third went into jewelry and silverware, one-fourth into the light-sensitive compounds used in photography, and nearly all the remainder went for industrial uses, of which there were 7 substantial uses and many other small-volume uses. By comparison, 85 percent of the silver used in the United States went to photography and industrial uses, 8 percent to jewelry and silverware, and 7 percent to coins and medals. The United States was the largest consumer of silver followed by India, Japan, and Italy; the 13 largest consuming countries accounted for nearly 90 percent of the world total. In the

The Silver Oxide-Zinc Alkaline Primary Cell. Part 2. Effects of Various Types of Negative Electrodes on Cell Characteristics

National Research Council Canada - National Science Library

Shepherd, C. M

1951-01-01

... (generally a potassium hydroxide solution). During discharge, the silver peroxide in the positive electrode is reduced to metallic silver and the metallic zinc in the negative electrode is oxidized either to zinc oxide or to a complex zincate ion...

Green engineered biomolecule-capped silver and copper nanohybrids using Prosopis cineraria leaf extract: Enhanced antibacterial activity against microbial pathogens of public health relevance and cytotoxicity on human breast cancer cells (MCF-7).

Science.gov (United States)

Jinu, U; Gomathi, M; Saiqa, I; Geetha, N; Benelli, G; Venkatachalam, P

2017-04-01

This research focused on green engineering and characterization of silver (PcAgNPs) and copper nanoparticles (PcCuNPs) using Prosopis cineraria (Pc) leaf extract prepared by using microwave irradiation. We studied their enhanced antimicrobial activity on human pathogens as well as cytotoxicity on breast cancer cells (MCF-7). Biofabricated silver and copper nanoparticles exhibited UV-Visible absorbance peaks at 420 nm and 575 nm, confirming the bioreduction and stabilization of nanoparticles. Nanoparticles were characterized by FTIR, XRD, FESEM, and EDX analysis. FTIR results indicated the presence of alcohols, alkanes, aromatics, phenols, ethers, benzene, amines and amides that were possibly involved in the reduction and capping of silver and copper ions. XRD analysis was performed to confirm the crystalline nature of the silver and copper nanoparticles. FESEM analysis suggested that the nanoparticles were hexagonal or spherical in shape with size ranging from 20 to 44.49 nm and 18.9-32.09 nm for AgNPs and CuNPs, respectively. EDX analysis confirmed the presence of silver and copper elemental signals in the nanoparticles. The bioengineered silver and copper nanohybrids showed enhanced antimicrobial activity against Gram-positive and Gram-negative MDR human pathogens. MTT assay results indicated that CuNPs show potential cytotoxic effect followed by AgNPs against MCF-7 cancer cell line. IC 50 were 65.27 μg/ml, 37.02 μg/ml and 197.3 μg/ml for PcAgNPs, PcCuNPs and P. cineraria leaf extracts, respectively, treated MCF-7 cells. The present investigation highlighted an effective protocol for microwave-assisted synthesis of biomolecule-loaded silver and copper nanoparticles with enhanced antibacterial and anticancer activity. Results strongly suggested that bioengineered AgNPs and CuNPs could be used as potential tools against microbial pathogens and cancer cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biosynthesis, structural characterization and antimicrobial activity of gold and silver nanoparticles.

Science.gov (United States)

Ahmad, Tokeer; Wani, Irshad A; Manzoor, Nikhat; Ahmed, Jahangeer; Asiri, Abdullah M

2013-07-01

An eco friendly simple biosynthetic route was used for the preparation of monodisperse and highly crystalline gold and silver nanoparticles using cell free extract of fungus, Candida albicans. Transmission electron microscopic studies show the formation of gold and silver nanocrystals of average size of 5 nm and 30 nm with the specific surface areas of 18.9 m(2)/g and 184.4 m(2)/g respectively. The interaction of gold and silver nanoparticles with proteins has been formulated by FT-IR spectroscopy and thermal gravimetric analysis. The formation of gold and silver nanoparticles was also confirmed by the appearance of a surface plasmon band at 540 nm and 450 nm respectively. The antimicrobial activity of the synthesized gold and silver nanoparticles was investigated against both Staphylococcus aureus and Escherichia coli. The results suggest that these nanoparticles can be used as effective growth inhibitors against the test microorganisms. Greater bactericidal activity was observed for silver nanoparticles. The E. coli, a gram negative bacterium was found to be more susceptible to gold and silver nanoparticles than the S. aureus, a gram positive bacterium. Copyright © 2013 Elsevier B.V. All rights reserved.

Silver Flakes and Silver Dendrites for Hybrid Electrically Conductive Adhesives with Enhanced Conductivity

Science.gov (United States)

Ma, Hongru; Li, Zhuo; Tian, Xun; Yan, Shaocun; Li, Zhe; Guo, Xuhong; Ma, Yanqing; Ma, Lei

2018-03-01

Silver dendrites were prepared by a facile replacement reaction between silver nitrate and zinc microparticles of 20 μm in size. The influence of reactant molar ratio, reaction solution volume, silver nitrate concentration, and reaction time on the morphology of dendrites was investigated systematically. It was found that uniform tree-like silver structures are synthesized under the optimal conditions. Their structure can be described as a trunk, symmetrical branches, and leaves, which length scales of 5-10, 1-2 μm, and 100-300 nm, respectively. All features were systematically characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and x-ray powder diffraction. A hybrid fillers system using silver flakes and dendrites as electrically conductive adhesives (ECAs) exhibited excellent overall performance. This good conductivity can be attributed mainly to the synergy between the silver microflakes (5-20 μm sized irregular sheet structures) and dendrites, allowing more conductive pathways to be formed between the fillers. In order to further optimize the overall electrical conductivity, various mixtures of silver microflakes and silver dendrites were tested in ECAs, with results indicating that the highest conductivity was shown when the amounts of silver microflakes, silver dendrites and the polymer matrix were 69.4 wt.% (20.82 vol.%), 0.6 wt.% (0.18 vol.%), and 30.0 wt.% (79.00 vol.%), respectively. The corresponding mass ratio of silver flakes to silver dendrites was 347:3. The resistivity of ECAs reached as low as 1.7 × 10-4 Ω cm.

Croatian Medical Journal citation score in Web of Science, Scopus, and Google Scholar.

Science.gov (United States)

Sember, Marijan; Utrobicić, Ana; Petrak, Jelka

2010-04-01

To analyze the 2007 citation count of articles published by the Croatian Medical Journal in 2005-2006 based on data from the Web of Science, Scopus, and Google Scholar. Web of Science and Scopus were searched for the articles published in 2005-2006. As all articles returned by Scopus were included in Web of Science, the latter list was the sample for further analysis. Total citation counts for each article on the list were retrieved from Web of Science, Scopus, and Google Scholar. The overlap and unique citations were compared and analyzed. Proportions were compared using chi(2)-test. Google Scholar returned the greatest proportion of articles with citations (45%), followed by Scopus (42%), and Web of Science (38%). Almost a half (49%) of articles had no citations and 11% had an equal number of identical citations in all 3 databases. The greatest overlap was found between Web of Science and Scopus (54%), followed by Scopus and Google Scholar (51%), and Web of Science and Google Scholar (44%). The greatest number of unique citations was found by Google Scholar (n=86). The majority of these citations (64%) came from journals, followed by books and PhD theses. Approximately 55% of all citing documents were full-text resources in open access. The language of citing documents was mostly English, but as many as 25 citing documents (29%) were in Chinese. Google Scholar shares a total of 42% citations returned by two others, more influential, bibliographic resources. The list of unique citations in Google Scholar is predominantly journal based, but these journals are mainly of local character. Citations received by internationally recognized medical journals are crucial for increasing the visibility of small medical journals but Google Scholar may serve as an alternative bibliometric tool for an orientational citation insight.

Laminating solution-processed silver nanowire mesh electrodes onto solid-state dye-sensitized solar cells

KAUST Repository

Hardin, Brian E.

2011-06-01

Solution processed silver nanowire meshes (Ag NWs) were laminated on top of solid-state dye-sensitized solar cells (ss-DSCs) as a reflective counter electrode. Ag NWs were deposited in <1 min and were less reflective compared to evaporated Ag controls; however, AgNW ss-DSC devices consistently had higher fill factors (0.6 versus 0.69), resulting in comparable power conversion efficiencies (2.7%) compared to thermally evaporated Ag control (2.8%). Laminated Ag NW electrodes enable higher throughput manufacturing and near unity material usage, resulting in a cheaper alternative to thermally evaporated electrodes. © 2011 Elsevier B.V. All rights reserved.

Silver deposition in the central nervous system and the hematoencephalic barrier studied with the electron microscope.

Science.gov (United States)

VAN BREEMEN, V L; CLEMENTE, C D

1955-03-01

For the purpose of studying the hematoencephalic barrier as it is concerned with silver circulating in the blood stream, silver nitrate was vitally administered to rats in their drinking water over periods of 6 to 8 months. The cerebrum, cerebellum, medulla, area postrema, and choroid plexus were prepared for light and electron microscopy. Silver deposition was found in the perivascular spaces in the choroid plexus, area postrema, in the medulla surrounding the area postrema, and in minute quantities in the cerebrum, cerebellum, and most of the medulla. Two levels of the hematoencephalic barrier were apparently demonstrated in our investigations. The endothelial linings of the vessels in the cerebrum, cerebellum, and medulla constitute the first threshold of the hematoencephalic barrier (specifically here, blood-brain barrier). The cell membranes adjacent to the perivascular spaces form the second threshold, as follows:-the neuroglial cell membranes in the cerebrum, cerebellum, and medulla (blood-brain barrier); the membranes of the neuroglial cells in the area postrema (blood-brain barrier); and the membranes of the epithelial cells of the choroid plexus (blood-cerebrospinal fluid barrier). This study deals with silver deposition and does not infer that the penetration of ionic silver, if present in the blood stream, would necessarily be limited to the regions described. Bleb-like structures were observed to cover the epithelial cell surfaces in the choroid plexus. They may be cellular projections increasing the cell surface area or they may be secretory droplets.

Predictors of Citation Rate in Psychology: Inconclusive Influence of Effect and Sample Size.

Science.gov (United States)

Hanel, Paul H P; Haase, Jennifer

2017-01-01

In the present article, we investigate predictors of how often a scientific article is cited. Specifically, we focus on the influence of two often neglected predictors of citation rate: effect size and sample size, using samples from two psychological topical areas. Both can be considered as indicators of the importance of an article and post hoc (or observed) statistical power, and should, especially in applied fields, predict citation rates. In Study 1, effect size did not have an influence on citation rates across a topical area, both with and without controlling for numerous variables that have been previously linked to citation rates. In contrast, sample size predicted citation rates, but only while controlling for other variables. In Study 2, sample and partly effect sizes predicted citation rates, indicating that the relations vary even between scientific topical areas. Statistically significant results had more citations in Study 2 but not in Study 1. The results indicate that the importance (or power) of scientific findings may not be as strongly related to citation rate as is generally assumed.

Reduced graphene oxide–silver nanoparticle nanocomposite: a potential anticancer nanotherapy

Directory of Open Access Journals (Sweden)

Gurunathan S

2015-10-01

Full Text Available Sangiliyandi Gurunathan, Jae Woong Han, Jung Hyun Park, Eunsu Kim, Yun-Jung Choi, Deug-Nam Kwon, Jin-Hoi Kim Department of Animal Biotechnology, Konkuk University, Seoul, Republic of Korea Background: Graphene and graphene-based nanocomposites are used in various research areas including sensing, energy storage, and catalysis. The mechanical, thermal, electrical, and biological properties render graphene-based nanocomposites of metallic nanoparticles useful for several biomedical applications. Epithelial ovarian carcinoma is the fifth most deadly cancer in women; most tumors initially respond to chemotherapy, but eventually acquire chemoresistance. Consequently, the development of novel molecules for cancer therapy is essential. This study was designed to develop a simple, non-toxic, environmentally friendly method for the synthesis of reduced graphene oxide–silver (rGO–Ag nanoparticle nanocomposites using Tilia amurensis plant extracts as reducing and stabilizing agents. The anticancer properties of rGO–Ag were evaluated in ovarian cancer cells. Methods: The synthesized rGO–Ag nanocomposite was characterized using various analytical techniques. The anticancer properties of the rGO–Ag nanocomposite were evaluated using a series of assays such as cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, cellular levels of malonaldehyde and glutathione, caspase-3 activity, and DNA fragmentation in ovarian cancer cells (A2780. Results: AgNPs with an average size of 20 nm were uniformly dispersed on graphene sheets. The data obtained from the biochemical assays indicate that the rGO–Ag nanocomposite significantly inhibited cell viability in A2780 ovarian cancer cells and increased lactate dehydrogenase leakage, reactive oxygen species generation, caspase-3 activity, and DNA fragmentation compared with other tested nanomaterials such as graphene oxide, rGO, and AgNPs. Conclusion: T. amurensis plant extract

Analysis of self-citation and impact factor in dermatology journals.

Science.gov (United States)

Reiter, Ofer; Mimouni, Michael; Mimouni, Daniel

2016-09-01

Concerns have been raised regarding the impact factor's (IF) accuracy and credibility, which may be affected by different factors, including self-citations. To investigate the self-citation rate (SCR) of dermatology journals and its relationship to the IF. Data on all dermatology journals listed in the Journal Citation Reports (JCR) were retrieved, and the following parameters were analyzed: IF, total publications used to calculate the IF, total citations used to calculate the IF, self-citations used to calculate the IF, SCR, and IF without self-citations (corrected IF). The median SCR was 10.53% (0-50%), and the median IF and corrected IF, 1.54 (0.05-6.37) and 1.35 (0.03-5.84), respectively. There was an inverse correlation between the IF and the SCR. A statistically significant difference was noted in the SCR between general and subspecialty journals and between journals that offered a full English text and those that did not. In general, the IF of dermatology journals is not influenced by the SCR. However, journals with a lower IF tend to have a higher SCR. Subspecialty journals and foreign language journals have a higher SCR than general dermatology and English language journals, respectively, probably owing to their limited distribution and the difficulty experienced by international authors in accessing references in specific languages. © 2015 The International Society of Dermatology.

Book citations: influence of epidemiologic thought in the academic community

Directory of Open Access Journals (Sweden)

Porta Miquel

2006-01-01

Full Text Available Whilst their 'death' has often been certified, books remain highly important to most professions and academic disciplines. Analyses of citations received by epidemiologic texts may complement other views on epidemiology. The objective was to assess the number of citations received by some books of epidemiology and public health, as a first step towards studying the influence of epidemiological thought and thinking in academia. For this purpose, Institute for Scientific Information/ Thomson Scientific - Web of Science/ Web of Knowledgedatabase was consulted, in May 2006. The book by Rothman & Greenland appeared to have received the highest number of citations overall (over 8,000 and per year. The books by Kleinbaum et al, and by Breslow & Day received around 5,000 citations. In terms of citations per year the book by Sackett et al ranks 3rd, and the one by Rose, 4th of those included in this preliminary study. Other books which were influential in the classrooms collected comparatively less citations. Results offer a rich picture of the academic influences and trends of epidemiologic methods and reasoning on public health, clinical medicine and the other health, life and social sciences. They may contribute to assess epidemiologists' efforts to demarcate epidemiology and to assert epistemic authority, and to analyze some historical influences of economic, social and political forces on epidemiological research.

Developing Data Citations from Digital Object Identifier Metadata

Science.gov (United States)

Wanchoo, L.; James, N.

2015-12-01

NASA's Earth Science Data and Information System (ESDIS) Project has been processing information for the registration of Digital Object Identifiers (DOI) for the last five years of which an automated system has been in operation for the last two years. The ESDIS DOI registration system has registered over 2000 DOIs with over 1000 DOIs held in reserve until all required information has been collected. By working towards the goal of assigning DOIs to the 8000+ data collections under its management, ESDIS has taken the first step towards facilitating the use of data citations with those products. When registering DOIs, ESDIS requires certain DOI elements be collected for the DOI landing page as recommended by NASA's Earth Science Data System Working Group (ESDSWG). The landing page provides sufficient information to 1) identify NASA data as referenced in a science publication, 2) credit data creators and distributors, and 3) access the data itself enabling the trace-ability and reproducibility of the data. However, the required elements for this DOI landing page are also the core required elements for forming an Earth science data citation. Data citations are getting significant attention from the scientific community and data centers alike. So to encourage the citing of Earth science data products, each product DOI landing page displays a sample data citation and makes the required citation elements available to DataCite for use in its Data Citation generation tool. This paper will describe that process. ESDIS data centers are constantly developing technologies to better serve the Earth science user community such as Geospatial Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI), Land and Atmospheric Near Real-Time Capability for EOS (LANCE), and advanced tools that support virtual data collections, and virtual data products. These all provide easier access to data and make possible the creation of data products with user specified parameters

Borrowed Authority: The American Catholic Bishops' Argument by Citation

Science.gov (United States)

O'Keefe, Meaghan M.

2015-01-01

Rhetorical use of citation is a means of indirectly reaffirming authority while avoiding the appearance of argument. It is therefore an especially useful strategy for people and institutions with compromised public images. This article compares the American Catholic bishops' written citational patterns in the United States Conference of Catholic…

Robustness and discriminatory strength of citation-based journal indicators

DEFF Research Database (Denmark)

Andersen, Jens Peter; Christensen, Anette Luther

AIM: A plethora of journal indicators exists, and are used e.g. in national assessment exercises as part of the basis for university funding. Recent studies report as many as 39 indicators of which the major part are citation based. While studies have shown these citation-based journal indicators...

A comparative study of first and all-author co-citation counting, and two different matrix generation approaches applied for author co-citation analyses

DEFF Research Database (Denmark)

Schneider, Jesper Wiborg; Larsen, Birger; Ingwersen, Peter

2009-01-01

XML documents extracted from the IEEE collection. These data allow the construction of ad-hoc citation indexes, which enables us to carry out the hitherto largest all-author co-citation study. Four ACA are made, combining the different units of analyses with the different matrix generation approaches...

Association between success rate and citation count of studies of radiofrequency catheter ablation for atrial fibrillation: possible evidence of citation bias.

Science.gov (United States)

Perino, Alexander C; Hoang, Donald D; Holmes, Tyson H; Santangeli, Pasquale; Heidenreich, Paul A; Perez, Marco V; Wang, Paul J; Turakhia, Mintu P

2014-09-01

The preferential citation of studies with the highest success rates could exaggerate perceived effectiveness, particularly for treatments with widely varying published success rates such as radiofrequency catheter ablation for atrial fibrillation. We systematically identified observational studies and clinical trials of radiofrequency catheter ablation of atrial fibrillation between 1990 and 2012. Generalized Poisson regression was used to estimate association between study success rate and total citation count, adjusting for sample size, journal impact factor, time since publication, study design, and whether first or last author was a consensus-defined pre-eminent expert. We identified 174 articles meeting our inclusion criteria (36 289 subjects). After adjustment only for time since publication, a 10-point increase above the mean in pooled reported success rates was associated with a 17.8% increase in citation count at 5 years postpublication (95% confidence interval, 7.1-28.4%; Pcitation count; 95% confidence interval, 7.6-29.6%; Pcitation count, which may indicate citation bias. To readers of the literature, radiofrequency catheter ablation of atrial fibrillation could be perceived to be more effective than the data supports. These findings may have implications for a wide variety of novel cardiovascular therapies. © 2014 American Heart Association, Inc.

Differential Cytotoxic Potential of Silver Nanoparticles in Human Ovarian Cancer Cells and Ovarian Cancer Stem Cells

Directory of Open Access Journals (Sweden)

Yun-Jung Choi

2016-12-01

Full Text Available The cancer stem cell (CSC hypothesis postulates that cancer cells are composed of hierarchically-organized subpopulations of cells with distinct phenotypes and tumorigenic capacities. As a result, CSCs have been suggested as a source of disease recurrence. Recently, silver nanoparticles (AgNPs have been used as antimicrobial, disinfectant, and antitumor agents. However, there is no study reporting the effects of AgNPs on ovarian cancer stem cells (OvCSCs. In this study, we investigated the cytotoxic effects of AgNPs and their mechanism of causing cell death in A2780 (human ovarian cancer cells and OvCSCs derived from A2780. In order to examine these effects, OvCSCs were isolated and characterized using positive CSC markers including aldehyde dehydrogenase (ALDH and CD133 by fluorescence-activated cell sorting (FACS. The anticancer properties of the AgNPs were evaluated by assessing cell viability, leakage of lactate dehydrogenase (LDH, reactive oxygen species (ROS, and mitochondrial membrane potential (mt-MP. The inhibitory effect of AgNPs on the growth of ovarian cancer cells and OvCSCs was evaluated using a clonogenic assay. Following 1–2 weeks of incubation with the AgNPs, the numbers of A2780 (bulk cells and ALDH+/CD133+ colonies were significantly reduced. The expression of apoptotic and anti-apoptotic genes was measured by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR. Our observations showed that treatment with AgNPs resulted in severe cytotoxicity in both ovarian cancer cells and OvCSCs. In particular, AgNPs showed significant cytotoxic potential in ALDH+/CD133+ subpopulations of cells compared with other subpopulation of cells and also human ovarian cancer cells (bulk cells. These findings suggest that AgNPs can be utilized in the development of novel nanotherapeutic molecules for the treatment of ovarian cancers by specific targeting of the ALDH+/CD133+ subpopulation of cells.

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

Science.gov (United States)

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

2017-09-01

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

Citation Analysis for the Modern Instructor: An Integrated Review of Emerging Research

Directory of Open Access Journals (Sweden)

Chris Piotrowski

2013-07-01

Full Text Available While online instructors may be versed in conducting e-Research (Hung, 2012; Thelwall, 2009, today’s faculty are probably less familiarized with the rapidly advancing fields of bibliometrics and informetrics. One key feature of research in these areas is Citation Analysis, a rather intricate operational feature available in modern indexes such as Web of Science, Scopus, Google Scholar, and PsycINFO. This paper reviews the recent extant research on bibliometrics within the context of citation analysis. Particular focus is on empirical studies, review essays, and critical commentaries on citation-based metrics across interdisciplinary academic areas. Research that relates to the interface between citation analysis and applications in higher education is discussed. Some of the attributes and limitations of citation operations of contemporary databases that offer citation searching or cited reference data are presented. This review concludes that: a citation-based results can vary largely and contingent on academic discipline or specialty area, b databases, that offer citation options, rely on idiosyncratic methods, coverage, and transparency of functions, c despite initial concerns, research from open access journals is being cited in traditional periodicals, and d the field of bibliometrics is rather perplex with regard to functionality and research is advancing at an exponential pace. Based on these findings, online instructors would be well served to stay abreast of developments in the field.