Multivariate calibration applied to simultaneous chemiluminiscence determination of Cobalt and Chromium

The final publication is available at http://doi.org/ 10.1007/s00216-002-1637-8[EN] The simultaneous determination of chromium and cobalt in water samples has been studied. Chemiluminescence registers based on the luminol-hydrogen peroxide reaction have obtained by a batch procedure. PLS algorithms have employed to model the time-response (formation and destruction of emitter). The influence of the presence of two metals and the non-linearity relationship between response and concentration have been evaluated in the signal. Different experimental designs and the selection of variables have been tested. The calibration set has been selected based on two criteria: unicomponent and/or bicomponent standard solutions and the slope calculated from linear univariate calibration. The response has been modelled providing high percentages of explained variance, robust models and low prediction errors. The proposed methodology has been validated using test standard solutions and a standard reference material of fresh water. Accurate results have proved the advantages of this method for the simultaneous determination of chromium and cobalt in water samples.The authors are grateful to the DGICYT (Project no PB 97–1387) for financial support. S.M.Ll. and L.A.T.G. express their gratitude to Ministerio de Educación y Cultura (Spain) for the predoctoral grant.Campins-Falcó, P.; Tortajada-Genaro, LA.; Meseguer-Lloret, S.; Bosch-Reig, F. (2002). Multivariate calibration applied to simultaneous chemiluminiscence determination of Cobalt and Chromium. Analytical and Bioanalytical Chemistry. 374(7-8):1223-1229. https://doi.org/10.1007/s00216-002-1637-8S122312293747-

INTEGRAL serendipitous detection of the gamma-ray microquasar LS 5039

LS 5039 is the only X-ray binary persistently detected at TeV energies by the Cherenkov HESS telescope. It is moreover a gamma-ray emitter in the GeV and possibly MeV energy ranges. To understand important aspects of jet physics, like the magnetic field content or particle acceleration, and emission processes, such as synchrotron and inverse Compton (IC), a complete modeling of the multiwavelength data is necessary. LS 5039 has been detected along almost all the electromagnetic spectrum thanks to several radio, infrared, optical and soft X-ray detections. However, hard X-ray detections above 20 keV have been so far elusive and/or doubtful, partly due to source confusion for the poor spatial resolution of hard X-ray instruments. We report here on deep (300 ksec) serendipitous INTEGRAL hard X-ray observations of LS 5039, coupled with simultaneous VLA radio observations. We obtain a 20-40 keV flux of 1.1 +/- 0.3 mCrab (5.9 (+/-1.6) X 10^{-12} erg cm^{-2} s^{-1}), a 40-100 keV upper limit of 1.5 mCrab (9.5 x 10^{-12} erg cm^{-2}s^{-1}), and typical radio flux densities of about 25 mJy at 5GHz. These hard X-ray fluxes are significantly lower than previous estimates obtained with BATSE in the same energy range but, in the lower interval, agree with extrapolation of previous RXTE measurements. The INTEGRAL observations also hint to a break in the spectral behavior at hard X-rays. A more sensitive characterization of the hard X-ray spectrum of LS 5039 from 20 to 100 keV could therefore constrain key aspects of the jet physics, like the relativistic particle spectrum and the magnetic field strength. Future multiwavelength observations would allow to establish whether such hard X-ray synchrotron emission is produced by the same population of relativistic electrons as those presumably producing TeV emission through IC.Comment: 4 pages LaTeX, 1 postscript figure, to appear in Proceedings of the conference "The Multi-Messenger Approach to High-Energy Gamma-ray Sources" Barcelona/Spain (2006

Towards a population of HMXB/NS microquasars as counterparts of low-latitude unidentified EGRET sources

The discovery of the microquasar LS 5039 well within the 95% conficence contour of the Unidentified EGRET Source (UES) 3EG J1824-1514 was a major step towards the possible association between microquasars (MQs) and UESs. The recent discovery of precessing relativistic radio jets in LS I +61 303, a source associated for long time with 2CG 135+01 and with the UES 3EG J0241+6103, has given further support to this idea. Finally, the very recently proposed association between the microquasar candidate AX J1639.0-4642 and the UES 3EG J1639-4702 points towards a population of High Mass X-ray Binary (HMXB)/Neutron Star (NS) microquasars as counterparts of low-latitude unidentified EGRET sources.Comment: 12 pages, 7 figures. Proceedings of the Conference "The Multiwavelength Approach to Unidentified Gamma-ray Sources", to appear in the journal Astrophysics and Space Scienc

Use of tocilizumab in kidney transplant recipients with COVID-1

Acute respiratory distress syndrome associated with coronavirus infection is related to a cytokine storm with large interleukin-6 (IL-6) release. The IL-6-receptor blocker tocilizumab may control the aberrant host immune response in patients with coronavirus disease 2019 (COVID-19) . In this pandemic, kidney transplant (KT) recipients are a high-risk population for severe infection and showed poor outcomes. We present a multicenter cohort study of 80 KT patients with severe COVID-19 treated with tocilizumab during hospital admission. High mortality rate was identified (32.5%), related with older age (hazard ratio [HR] 3.12 for those older than 60 years, P = .039). IL-6 and other inflammatory markers, including lactic acid dehydrogenase, ferritin, and D-dimer increased early after tocilizumab administration and their values were higher in nonsurvivors. Instead, C-reactive protein (CRP) levels decreased after tocilizumab, and this decrease positively correlated with survival (mean 12.3 mg/L in survivors vs. 33 mg/L in nonsurvivors). Each mg/L of CRP soon after tocilizumab increased the risk of death by 1% (HR 1.01 [confidence interval 1.004-1.024], P = .003). Although patients who died presented with worse respiratory situation at admission, this was not significantly different at tocilizumab administration and did not have an impact on outcome in the multivariate analysis. Tocilizumab may be effective in controlling cytokine storm in COVID-19 but randomized trials are needed

Solid phase synthesis and immunogenicity of a VP3 peptide from hepatitis A virus

The synthesis of a peptide belonging to the VP3 capsid protein of Hepatitis A virus has been accomplished by the continuous flow Fmoc-polyamide solid phase method. The use of methoxytrimethylbenzenesulphonyl (Mtr) and pentamethylchromansulphonyl (Pmc) as arginine side-chain protecting groups in the presence of tryptophan without lateral protection or protected with t-Boc is discussed. The synthetic VP3 peptide has been administered to mice in different forms: (i) free, (ii) coupled to keyhole limpet hemocyanin, (iii) encapsulated in multilamellar (MLV) liposomes, and (iv) incorporated to a tetrameric branched lysine core. The immune response induced by these preparation is reported.Peer reviewe