Thus the rate constant k 2 , initial sorption rate h , and predicted q e can be calculated from the slope and respectively the intercept of plot t / q t versus t [38–40] by using Eq. (9). The values of kinetic parameters for pseudo-first and pseudo- second order equations together with correlation coefficients and values of experimental data obtained ( q e exp) are given in Tables 5–8. It was observed that the r 2 values were in the range 2 of 0.967. From Tables 5–8, it was also observed that the initial sorption rate h and the equilibrium sorption capacity increased with the increase of the initial concentration of dye, whereas pseudo- second-order-rate constant k 2 decreased. The decrease of k 2 values shows that the amount of dye sorbed in cryogel increases with the increasing of the initial concentration of MB solution, which means that the weight ratio polymer: MB sorbed in the sample at equilibrium decreases. A similar observation was previously reported by Kavitha and Namasivayam for MB adsorption onto coir pith carbon [41] and Ofomaja for MB adsorption onto palm kermel fibre [42]. The parameters k 2 , have been plotted also against c 0 ( Fig. 9). It was observed in all cases that k 2 decreases faster in the range 2.5 × 10 - 5 –3 × 10 - 5 mol/L then it tends to become constant. The lowest values of k 2 were obtained for PVA/Scl gels followed by PVA, PVA/cel and PVA/zein gels. This suggests that prepared materials are efficient in removal of the MB dye from much diluted solutions. Also, the equations that correlate the parameters q e with the initial concentration ( c 0 ) of methylene blue in aqueous solution have been determined (Table 9). Thus pseudo-second-order kinetic expressions were tested for its consistency in predicting the amount of methylene blue adsorbed for the entire sorption period. The q values were predicted by applying the calculated kinetic constants in their corresponding kinetic expressions. Thus the pseudo-second-order kinetic expression can be obtained by substituting the k 2 and predicted q e values in Eq. (10) which is given by:Join ResearchGate to access over 30 million figures and 100+ million publications – all in one place.Copy referenceCopy captionEmbed figurePublished in
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Data & Dec 2013PMCID: PMC3253993A rejoinder on energy versus impact indicators1 and
2,32Experimental Cardiology Group, Heart Failure Research Center, Academic Medical Center AMC, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands 3Department of Medical Physiology, University Medical Center, Utrecht, The Netherlands Loet Leydesdorff, Email: ..Corresponding author.
Citation distributions are so skewed that using the mean or any other central tendency measure is ill-advised. Unlike G. Prathap’s scalar measures (Energy, Exergy, and Entropy or EEE), the Integrated Impact Indicator (I3) is based on non-parametric statistics using the (100) percentiles of the distribution. Observed values can be tested a impact can be qualified at the article level and then aggregated.Keywords: Citation, Scalar, Integration, EEE, I3, Quality1Citations are discrete events and therefore the integral is in this case a step function: using Eq. , the frequency of papers in each percentile (xi) is multiplied by the percentile of each paper (f(xi)). The resulting scalar (Σ) of the total impact can then be scaled (i) in terms of various evaluation schemes (e.g., quartiles, or the six evaluation categories used in the U.S. Science and Engineering Indicators NSB () and by Bornmann and Mutz ()); (ii) tested for their significance against a theoretically s (iii) expressed as a single number, namely a percentage of total impact contained
and (iv) used to compare among and between various units of analysis such as journals, countries, institutes, by aggregating cases in a statistically controllable way (Theil ).In summary, the discussion over Rates of Averages versus Averages of Rates (Gingras and Larivière ) has taught us that a rate of averages is merely a quotient number that does not allow for testing, and is mathematically inconsistent (Waltman et al. ). The mean observed citation ratio (MOCR) should not be divided by the mean expected citation ratio (RCR = MOCR/MECR; Schubert and B cf. Glänzel et al. , p. 182), but observed values can be tested against expected values by using appropriate statistics.Secondly, citation indicators based on averaging skewed distributions—such as Prathap’s EEE and the new “crown indicator” MNCS—are unreliable. For example, Leydesdorff et al. () have shown that in the case of seven Principal Investigators at the Academic Medical Center of the University of Amsterdam, the number one ranked PI would fall to fifth position, whereas the sixth-ranked PI would become the highest-ranked author if percentiles or percentile ranks are used.Thirdly, one should not test sets of documents as independent samples against each other, but as subsets of a reference set (Bornmann et al. ): each subset contributes a percentage impact to the set. The reference set allows for normalization and the specification of an expectation. (This specification can further be informed on theoretical grounds.) Using quantiles and percentile ranks, the observed values can be tested against the expected ones using non-parametric statistics.Furthermore, and not specific as criticism of EEE, field delineations do not have to be based on ex ante classification schemes such as the ISI Subject Categories. Hitherto, journal classifications have been unprecise and unreliable (Boyack and K L Pudovkin and G Rafols and Leydesdorff ). Fractional attribution of citations in the citing documents, however, can be used for normalization of differences in citation potentials (Garfield ) reflecting differences in citation behavior at the level of individual papers (Leydesdorff and B Leydesdorff and O Moed ).Given these recent improvements in citation normalization—such as the use of paper-based measures both cited and citing—the theoretical question remains whether citations can be used as indicators of scientific quality, and if so, when? (Amsterdamska and L Bornmann et al. ; G L Leydesdorff and Amsterdamska ). Opthof and Leydesdorff () opened this discussion by asking whether citation analysis enables us to legitimate the strategic selection of “excellent” as against merely “good” research?This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.1The software for measuring this indicator is available at .Amsterdamska O, Leydesdorff L. Citations: Indicators of significance? Scientometrics. 1989;15(5&#x9–471. doi: 10.1007/BF. []Bornmann L, Mutz R. Further steps towards an ideal method of measuring citation performance: The avoidance of citation (ratio) averages in field-normalization. Journal of Informetrics. 2011;5(1):228–230. doi: 10.1016/j.joi.. []Bornmann L, Mutz R, Neuhaus C, Daniel HD. Citation counts for research evaluation: Standards of good practice for analyzing bibliometric data and presenting and interpreting results. Ethics in Science and Environmental Politics. 2008;8(1):93–102. doi: 10.3354/esep00084. []Boyack, K. W., & Klavans, R. (2011). Multiple dimensions of journal specificity: Why journals can’t be assigned to disciplines. In E. Noyons, P. Ngulube & J. Leta (Eds.), The 13th Conference of the International Society for Scientometrics and Informetrics (Vol. I, pp. 123&#x). Durban, South Africa: ISSI, Leiden University and the University of Zululand.Garfield E. Is citation analysis a legitimate evaluation tool? Scientometrics. 1979;1(4):359–375. doi: 10.1007/BF. []Gingras, Y., & Larivière, V. (2011). There are neither “king” nor “crown” in scientometrics: Comments on a supposed “alternative” method of normalization. Journal of Informetrics, 5(1), 226&#x.Glänzel W. On reliability and robustness of scientometrics indicators based on stochastic models. An evidence-based opinion paper. Journal of Informetrics. 2010;4(3):313–319. doi: 10.1016/j.joi.. []Glänzel W, Thijs B, Schubert A, Debackere K. Subfield-specific normalized relative indicators and a new generation of relational charts: Methodological foundations illustrated on the assessment of institutional research performance. Scientometrics. 2009;78(1):165–188. doi: 10.-008-2109-5. []Leydesdorff, L. (1995). The challenge of scientometrics: The development, measurement, and self-organization of scientific communications. Leiden: DSWO Press, Leiden University. Retrieved from . Accessed 12 Sep 2011.Leydesdorff L. Theories of citation? Scientometrics. 1998;43(1):5–25. doi: 10.1007/BF. []Leydesdorff L. Can scientific journals be classified in terms of aggregated journal–journal citation relations using the journal citation reports? Journal of the American Society for Information Science and Technology. 2006;57(5):601–613. doi: 10.1002/asi.20322. []Leydesdorff L. Caveats for the use of citation indicators in research and journal evaluation. Journal of the American Society for Information Science and Technology. 2008;59(2):278–287. doi: 10.1002/asi.20743. []Leydesdorff L, Amsterdamska O. Dimensions of citation analysis. Science, Technology and Human Values. 1990;15(3):305–335. doi: 10.. []Leydesdorff, L., & Bornmann, L. (2011a). Integrated Impact Indicators (I3) compared with Impact Factors (IFs): An alternative design with policy implications. Journal of the American Society for Information Science and Technology (in press).Leydesdorff L, Bornmann L. How fractional counting affects the Impact Factor: Normalization in terms of differences in citation potentials among fields of science. Journal of the American Society for Information Science and Technology. 2011;62(2):217–229. doi: 10.1002/asi.21450. []Leydesdorff L, Opthof T. Scopus’ Source Normalized Impact per Paper (SNIP) versus the Journal Impact Factor based on fractional counting of citations. Journal of the American Society for Information Science and Technology. 2010;61(11):. doi: 10.1002/asi.21371. []Leydesdorff L, Bornmann L, Mutz R, Opthof T. Turning the tables in citation analysis one more time: Principles for comparing sets of documents. Journal of the American Society for Information Science and Technology. 2011;62(7):. doi: 10.1002/asi.21534. []Moed HF. Measuring contextual citation impact of scientific journals. Journal of Informetrics. 2010;4(3):265–277. doi: 10.1016/j.joi.. []National Science Board. (2010). Science and engineering indicators. Washington, DC: National Science Foundation. Retrieved from . Accessed 12 Sep 2011.Opthof T, Leydesdorff L. Caveats for the journal and field normalizations in the CWTS (“Leiden”) evaluations of research performance. Journal of Informetrics. 2010;4(3):423–430. doi: 10.1016/j.joi.. []Opthof, T., & Leydesdorff, L. (2011). A comment to the paper by Waltman et al., Scientometrics, 87, 467&#x, 2011. Scientometrics, 88(3), 1011&#x. []
[]Prathap, G. (2011a). A comment to the papers by Opthof and Leydesdorff, Scientometrics, 88, 1011&#x, 2011 and Waltman et al., Scientometrics, 88, 1017&#x, 2011. Scientometrics. doi: 10.-011-0500-0.Prathap G. The Energy–Exergy–Entropy (or EEE) sequences in bibliometric assessment. Scientometrics. 2011;87(3):515–524. doi: 10.-011-0367-0. []Pudovkin AI, Garfield E. Algorithmic procedure for finding semantically related journals. Journal of the American Society for Information Science and Technology. 2002;53(13):. doi: 10.1002/asi.10153. []Rafols I, Leydesdorff L. Content-based and algorithmic classifications of journals: Perspectives on the dynamics of scientific communication and indexer effects. Journal of the American Society for Information Science and Technology. 2009;60(9):. doi: 10.1002/asi.21086. []Rousseau, R. (2011). Percentile rank scores are congruous indicators of relative performance, or aren’t they? Retrieved from . Accessed 12 Sep 2011.Schubert, A., & Braun, T. (1986). Relative indicators and relational charts for comparative assessment of publication output and citation impact. Scientometrics, 9(5), 281&#x.Seglen PO. The skewness of science. Journal of the American Society for Information Science. 1992;43(9):628–638. doi: 10.1002/(SICI)&#x::AID-ASI5&#x.CO;2-0. []Seglen PO. Why the impact factor of journals should not be used for evaluating research. British Medical Journal. 1997;314:498–502. doi: 10.1136/bmj.314.. []
[] []Theil H.
Statistical decomposition analysis. Amsterdam: North-H 1972. Raan AFJ. Comparison of the Hirsch-index with standard bibliometric indicators and with peer judgment for 147 chemistry research groups. Scientometrics. 2006;67(3):491–502.Raan AFJ, Leeuwen TN, Visser MS, Eck NJ, Waltman L. Rivals for the crown: Reply to Opthof and Leydesdorff. Journal of Informetrics. 2010;4(3):431–435. doi: 10.1016/j.joi.. []Waltman L, Eck NJ, Leeuwen TN, Visser MS, Raan AFJ. Towards a new crown indicator: Some theoretical considerations. Journal of Informetrics. 2011;5(1):37–47. doi: 10.1016/j.joi.. []Articles from Springer Open Choice are provided here courtesy of Springer
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Take part in our user survey.Eta photoproduction off the neutron at GRAAL Evidence for a resonant structure at W=1.67 Ge277_移动文库
&&Eta photoproduction off the neutron at GRAAL Evidence for a resonant structure at W=1.67 Ge
Eta photoproduction off the neutron at GRAAL Evidence for a resonant structure at W=1.67 Ge
New (preliminary) data on eta photoproduction off the neutron are presented. These data reveal a resonant structure at W=1.67 GeV.
002 ceD 42
4v2309040/ex-pe:hviXra1
ηphotoproductiono theneutronatGRAAL:
EvidenceforaresonantstructureatW=1.67GeV
V.Kuznetsov1a,O.Bartalini2,V.Bellini3,M.Castoldi4,A.D’Angelo2,J-P.Didelez5,R.DiSalvo2,A.Fantini2,D.Franco2,G.Gervino6,F.Ghio7,B.Girolami7,A.Giusa3,M.Guidal5,E.Hourany5,R.Kunne5,pik1,P.LeviSandri8,D.Moricciani2,L.Nicoletti3,C.Randieri3,N.Rudnev9,G.Russo3,C.Schaerf2,M.-L.Sperduto3,M.-C.Sutera3,A.
Turinge10.1
InstituteforNuclearResearch,117312Moscow,Russia
INFNsezionediRomaIIandUniversit`adiRoma”TorVergata”,00133
Roma,Italy
INFNLaboratoriNazionalidelSudandUniversit`adiCatania,95123
Catania,Italy
INFNGenovaandUniversit`adiGenova,16146Genova,Italy5
IN2P3,InstitutdePhysiqueNucl´eaire,91406Orsay,France6
INFNsezionediTorinoandUniversit`adiTorino,10125Torino,Italy7
INFNsezioneSanit`aandIstitutoSuperiorediSanit`a,00161Roma,Italy
INFNLaboratoriNazionalidiFrascati,00044Frascati,Italy9
InstituteofTheoreticalandExperimentalPhysics,Moscow,Russia
RRC”KurchatovInstitute”,Moscow,Russia
New(preliminary)dataonηphotoproductionontheneutronarepresented.ThesedatarevealaresonantstructureatW=1.67GeV.
Mesonphotoproductionontheneutronmayprovideessentiallynewin-formationregardingthespectrumofbaryons.Anexampleisgivenbyamodel1whichexploitstheSU(6)symmetryandassumessingle-quarktran-sitionsfromgroundnucleonstothe[70,1 ]supermultiplet.ThemodelpredictsonlyweakphotoexcitationoftheD15(1675)resonancefromtheprotontarget.Conversely,photon-neutroncouplingsofD15(1675)calcu-latedintheframeworkofthisapproacharenotsmall.Measurementsoftherelativestrengthofphotoneutron/photoprotoninteractionarethereforeanimportanttestinggroundforthis(andothers)theoreticalapproaches.
Anotherexampleispossiblephotoexcitationofthenon-strangepen-taquarkstate,whichisassociatedwiththesecondmemberofanantide-cupletofexoticbaryons2,3.Evidenceforthelightestmemberofthean-
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1. Eta photoproduction off the neutron at GRAAL Evidence for a resonant structure at W=1.67 Ge_专业资料。New (preliminary) data on eta photoproduction off...2. Evidence for a missing n... 暂无评价 10页 ...eta photoproduction by the GRAAL, Tohoku LNS-...the neutron (upper row) and proton (lower row)...3. Photoproduction of the Eta Meson from the ...Since there is no strong experimental evidence [... is the momentum of the proton or neutron in ...4.$eta$-photoproduction on protons in the resonance...structure of the cross section without trying to ...nal experimental results obtained at GRAAL. Special...5. $eta -eta^prime$ Photoproduction and the Axial...ective theories on the nucleon structure all over... the strange content of the proton and neutron....
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where ω p and f p are the angular frequency and frequency corresponding to the peak in the Q -1 –f curve, respectively. For the relaxation before crystallization, it is related to a thermally activated process, and the relaxation time τ can be expressed by an Arrhenius equation [11]: ABSTRACT: The nature of internal friction (IF) peak in the internal friction versus temperature curve (Q- 1–T curve) remains a controversial problem in the field of bulk metallic glasses (BMGs). In order to study the mechanism of the internal friction peak, the evolutions of internal friction at fourteen frequencies and electrical resistivity with temperature were simultaneously measured in a Cu36Zr48Al8Ag8 BMG. The frequency dependence of internal friction (Q- 1–f curves) was acquired from the Q- 1–T curves by the linear interpolation method. The results show that there are two different mechanisms for the internal friction peaks in the Q- 1–T curves. The high-frequency internal friction peak is a first-order phase transformation peak and appears at the crystallization process. However, the low-frequency internal friction peak is a relaxation peak, which is also observed in the Q- 1–f curve at the corresponding temperature, and the relaxation process is controlled by a cooperative hopping movement of atoms. Full-text · Article · Dec 2014 +1 more author...Join ResearchGate to access over 30 million figures and 100+ million publications – all in one place.Copy referenceCopy captionEmbed figurePublished in
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ABSTRACT: Thin films based on silicon carbide and alumina were synthesized by means of rf-sputtering using a co-deposition process. Several nanostructures were created which consist of thin films (~200nm thick) with homogeneous distribution of SiC nanocrystals (~5nm mean diameter) in the host alumina matrices. Characterization methods including X-ray photoelectrons spectroscopy (XPS), UV–vis absorption and photoluminescence (PL) were used to identify the involved structures, compositions and optical features of these nanostructures. Thus, XPS investigations were relevant to point out the involved chemical bonding in the core SiC nanocrystals and in the host alumina environments. Additionally, mixed bonding such as Si–O–C was also shown and seems to correlate with the SiC–alumina interfaces. Optical properties of the nanostructures films such as UV–vis absorption and photoluminescence (PL) were measured in representative samples and compared to simulated PL responses obtained by a theoretical model. Full-text · Article · Dec 2011 +1 more author...}