Photoionization-ion mobility spectrometer for non-targeted screening analysis or for targeted analysis coupling a Tenax TA column

Photoionization-ion mobility spectrometer (UV-IMS) can be used as a screening instrument to distinguish gasoline vapors from other similar samples, obtaining characteristic fingerprints in a quick and simple analysis. A non-targeted approach can be used to resolve many problems, moreover, this device can also be used for targeted analysis. In this case a Tenax TA trap was connected to the UV-IMS as a pre-separation step in order to identify compounds present in the gasoline gaseous sample, such as benzene and toluene. Firstly, target analytes were trapped in a Tenax TA column at ambient temperature and then they were desorbed thermally in an oven and connected to the UV-IMS for their analysis. Instrumental parameters such as temperature ramp, sample gas flow rate, drift gas flow rate, adsorption time and adsorption flow rate were optimized to obtain high sensitivity, selectivity and precision to determine benzene and toluene in vapour gaseous samples. The UV-IMS was calibrated with standard gases generated in an exponential dilution flask, obtaining a limit of quantification of 1.8 and 1.9 mg m-3 for benzene and toluene, respectively. The method developed was successfully applied to identify these analytes in air samples close to a gasoline spillag

Thermal transport in glassy selenium: The role of low-frequency librations

7 págs.; 3 figs.The experimental curves giving the temperature dependence of the thermal conductivity of glassy selenium are considered in detail. The observed behavior can be taken into account quantitatively if the densities of states for short-wavelength phonons as well as for low-energy librations arising from computer simulations are used for the calculations. In particular, it is shown that the lowest frequency excitations of a chain of selenium atoms can give due account of the plateau observed at temperatures about 2-10 K. The implications of the present findings for the current debate regarding the mechanisms for thermal transport in glasses are finally discussed. © 1994 The American Physical Society.This work has been supported by DGICYT Grant No. PB92-0114-C03Peer Reviewe

Rapid and non-invasive method to determine toxic levels of alcohols and γ-hydroxylbutyric acid in saliva samples by gas chromatography-differential mobility spectrometry

A polydimethylsilicone oral sampler was used to extract methanol, ethanol, ethylene glycol, 1,3-propandiol and y-hydroxybutyric acid from samples of human saliva obtained using a passive-drool approach. The extracted compounds were recovered by thermal desorption, isolated by gas chromatography and detected with differential mobility spectrometry, operating with a programmed dispersion field. Complex signal behaviours were also observed that were consistent with hitherto unobserved fragmentation behaviours in differential mobility spectrometry. These yielded high-mobility fragments obscured within the envelope of the water-based reactant ion peak. Further, compensation field maxima shifts were also observed attributable to transport gas modification phenomena. Nevertheless, the responses obtained indicated that in-vivo saliva sampling with thermal desorption gas chromatography may be used to provide a semi-quantitative diagnostic screen over the toxicity threshold concentration ranges of 100 mg.dm-3 to 3 g.dm-3. A candidate method suitable for use in low resource settings for the non-invasive screening of patients intoxicated by alcohols and volatile sedatives has been demonstrated

Low-frequency excitations in glassy selenium: A comparison of neutron-scattering and molecular-dynamics results

12 págs.; 9 figs.; 1 tab.The microscopic low-frequency dynamics of glassy selenium is investigated by means of the concurrent use of neutron inelastic scattering and computer simulations. A separation of the dynamic response in terms of intra- and interchain processes is achieved from the analysis of the simulation results. The S(Q,E) dynamic structure factors are analyzed in terms of the frequency moments or from a model scattering law, and the wave-vector dependence of the relevant quantities is established. Finally, the anomalous behavior of the heat capacity at moderately low temperatures is shown to be originated by mostly interchain interactions. © 1993 The American Physical Society.This work has been supported in part by DGICYT Grant No. PB89-0037-C03.Peer Reviewe

A new method for comparing rankings through complex networks: Model and analysis of competitiveness of major European soccer leagues

In this paper, we show a new technique to analyze families of rankings. In particular, we focus on sports rankings and, more precisely, on soccer leagues. We consider that two teams compete when they change their relative positions in consecutive rankings. This allows to define a graph by linking teams that compete. We show how to use some structural properties of this competitivity graph to measure to what extend the teams in a league compete. These structural properties are the mean degree, the mean strength, and the clustering coefficient. We give a generalization of the Kendall's correlation coefficient to more than two rankings. We also show how to make a dynamic analysis of a league and how to compare different leagues. We apply this technique to analyze the four major European soccer leagues: Bundesliga, Italian Lega, Spanish Liga, and Premier League. We compare our results with the classical analysis of sport ranking based on measures of competitive balance.This paper was partially supported by Spanish MICINN Funds and FEDER Funds MTM2009-13848, MTM2010-16153 and MTM2010-18674, and Junta de Andalucia Funds FQM-264.Criado Herrero, R.; García González, E.; Pedroche Sánchez, F.; Romance, M. (2013). A new method for comparing rankings through complex networks: Model and analysis of competitiveness of major European soccer leagues. Chaos. 23(4):1-10. https://doi.org/10.1063/1.4826446S110234Dobson, S., & Goddard, J. (2009). The Economics of Football. doi:10.1017/cbo9780511973864Kendall, M. G., & Smith, B. B. (1939). The Problem of $m$ Rankings. The Annals of Mathematical Statistics, 10(3), 275-287. doi:10.1214/aoms/1177732186KENDALL, M. G. (1938). A NEW MEASURE OF RANK CORRELATION. Biometrika, 30(1-2), 81-93. doi:10.1093/biomet/30.1-2.81Fagin, R., Kumar, R., Mahdian, M., Sivakumar, D., & Vee, E. (2006). Comparing Partial Rankings. SIAM Journal on Discrete Mathematics, 20(3), 628-648. doi:10.1137/05063088xLegendre, P. (2005). Species associations: the Kendall coefficient of concordance revisited. Journal of Agricultural, Biological, and Environmental Statistics, 10(2), 226-245. doi:10.1198/108571105x46642Emond, E. J., & Mason, D. W. (2002). A new rank correlation coefficient with application to the consensus ranking problem. Journal of Multi-Criteria Decision Analysis, 11(1), 17-28. doi:10.1002/mcda.313Blumm, N., Ghoshal, G., Forró, Z., Schich, M., Bianconi, G., Bouchaud, J.-P., & Barabási, A.-L. (2012). Dynamics of Ranking Processes in Complex Systems. Physical Review Letters, 109(12). doi:10.1103/physrevlett.109.128701Radicchi, F. (2011). Who Is the Best Player Ever? A Complex Network Analysis of the History of Professional Tennis. PLoS ONE, 6(2), e17249. doi:10.1371/journal.pone.0017249Chartier, T. P., Kreutzer, E., Langville, A. N., & Pedings, K. E. (2011). Sensitivity and Stability of Ranking Vectors. SIAM Journal on Scientific Computing, 33(3), 1077-1102. doi:10.1137/090772745Park, J., & Newman, M. E. J. (2005). A network-based ranking system for US college football. Journal of Statistical Mechanics: Theory and Experiment, 2005(10), P10014-P10014. doi:10.1088/1742-5468/2005/10/p10014Callaghan, T., Mucha, P. J., & Porter, M. A. (2007). Random Walker Ranking for NCAA Division I-A Football. The American Mathematical Monthly, 114(9), 761-777. doi:10.1080/00029890.2007.11920469Motegi, S., & Masuda, N. (2012). A network-based dynamical ranking system for competitive sports. Scientific Reports, 2(1). doi:10.1038/srep00904Pawlowski, T., Breuer, C., & Hovemann, A. (2010). Top Clubs’ Performance and the Competitive Situation in European Domestic Football Competitions. Journal of Sports Economics, 11(2), 186-202. doi:10.1177/1527002510363100A. Feddersen and W. Maennig, “ Trends in competitive balance: Is there evidence for growing imbalance in professional sport leagues?” Hamburg contemporary economic discussions No. 01/2005, University of Hamburg, 2005.Pedroche Sánchez, F. (2010). Competitivity groups on social network sites. Mathematical and Computer Modelling, 52(7-8), 1052-1057. doi:10.1016/j.mcm.2010.02.031PEDROCHE, F. (2012). A MODEL TO CLASSIFY USERS OF SOCIAL NETWORKS BASED ON PAGERANK. International Journal of Bifurcation and Chaos, 22(07), 1250162. doi:10.1142/s0218127412501623Pedroche, F., Moreno, F., González, A., & Valencia, A. (2013). Leadership groups on Social Network Sites based on Personalized PageRank. Mathematical and Computer Modelling, 57(7-8), 1891-1896. doi:10.1016/j.mcm.2011.12.026García, E., Pedroche, F., & Romance, M. (2013). On the localization of the personalized PageRank of complex networks. Linear Algebra and its Applications, 439(3), 640-652. doi:10.1016/j.laa.2012.10.051BOCCALETTI, S., LATORA, V., MORENO, Y., CHAVEZ, M., & HWANG, D. (2006). Complex networks: Structure and dynamics. Physics Reports, 424(4-5), 175-308. doi:10.1016/j.physrep.2005.10.009Humphreys, B. R. (2002). Alternative Measures of Competitive Balance in Sports Leagues. Journal of Sports Economics, 3(2), 133-148. doi:10.1177/152700250200300203M. Kringstad, “ Competitive balance in complex professional sports leagues,” Doctoral thesis (The University of Leeds. Leeds University Business School, 2008).Owen, P. D., Ryan, M., & Weatherston, C. R. (2007). Measuring Competitive Balance in Professional Team Sports Using the Herfindahl-Hirschman Index. Review of Industrial Organization, 31(4), 289-302. doi:10.1007/s11151-008-9157-

Senescent synovial fibroblasts accumulate prematurely in rheumatoid arthritis tissues and display an enhanced inflammatory phenotype

[Abstract] Background Accumulation of senescent cells has been associated with pro-inflammatory effects with deleterious consequences in different human diseases. The purpose of this study was to analyze cell senescence in human synovial tissues (ST), and its impact on the pro-inflammatory function of synovial fibroblasts (SF). Results The expression of the senescence marker p16INK4a (p16) was analyzed by immunohistochemistry in rheumatoid arthritis (RA), osteoarthritis (OA), and normal ST from variably aged donors. The proportion of p16(+) senescent cells in normal ST from older donors was higher than from younger ones. Although older RA and OA ST showed proportions of senescent cells similar to older normal ST, senescence was increased in younger RA ST compared to age-matched normal ST. The percentage of senescent SA-β-gal(+) SF after 14 days in culture positively correlated with donor’s age. Initial exposure to H2O2 or TNFα enhanced SF senescence and increased mRNA expression of IL6, CXCL8, CCL2 and MMP3 and proteins secretion. Senescent SF show a heightened IL6, CXCL8 and MMP3 mRNA and IL-6 and IL-8 protein expression response upon further challenge with TNFα. Treatment of senescent SF with the senolytic drug fenofibrate normalized IL6, CXCL8 and CCL2 mRNA expression. Conclusions Accumulation of senescent cells in ST increases in normal aging and prematurely in RA patients. Senescence of cultured SF is accelerated upon exposure to TNFα or oxidative stress and may contribute to the pathogenesis of synovitis by increasing the production of pro-inflammatory mediators.Instituto de Salud Carlos III; FIS 16/00032Insituto de Salud Carlos III; RETICS RD16/0012 RIE

Hif-1α knockdown reduces glycolytic metabolism and induces cell death of human synovial fibroblasts under normoxic conditions

[Abstract] Increased glycolysis and HIF-1α activity are characteristics of cells under hypoxic or inflammatory conditions. Besides, in normal O2 environments, elevated rates of glycolysis support critical cellular mechanisms such as cell survival. The purpose of this study was to analyze the contribution of HIF-1α to the energy metabolism and survival of human synovial fibroblasts (SF) under normoxic conditions. HIF-1α was silenced using lentiviral vectors or small-interfering RNA (siRNA) duplexes. Expression analysis by qRT-PCR and western blot of known HIF-1α target genes in hypoxia demonstrated the presence of functional HIF-1α in normoxic SF and confirmed the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a HIF-1α target even in normoxia. HIF-1α silencing induced apoptotic cell death in cultured SF and, similarly, treatment with glycolytic, but not with OXPHOS inhibitors, induced SF death. Finally, in vivo HIF-1α targeting by siRNA showed a significant reduction in the viability of human SF engrafted into a murine air pouch. Our results demonstrate that SF are highly dependent on glycolytic metabolism and that HIF-1α plays a regulatory role in glycolysis even under aerobic conditions. Local targeting of HIF-1α provides a feasible strategy to reduce SF hyperplasia in chronic arthritic diseases.Instituto de Salud Carlos III; FIS 12/439Instituto de Salud Carlos III; RETICS RD12/009Instituto de Salud Carlos III; CP13/00014Comunidad de Madrid; RAPHYME-CM S2010/BMD235