Determination of heavy metals in selected drug substances by inductively coupled plasma – mass spectrometry

229-231Heavy metal contents in dicyclomineHCl, ethambutol, pyrazinamide and furazolidone drugs were determined by inductively coupled plasma (ICP) - mass spectrometry (MS). The drugs were analyzed for Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Hg, Pb metals by selecting a suitable isotope. Cr, Fe, Ti and Cu were observed to be highest in dicyclomineHCl, ethambutol, pyrazinamide and furazolidone respectively. Ni and Hg were absent in all the four drugs, while traces of Cd were present in ethambutol and pyrazinamide. Analytical results showed that ICP-MS method is useful for monitoring inorganic impurities present in such drugs

Self-assembly of PEGylated tetra-phenylalanine derivatives: Structural insights from solution and solid state studies

Water soluble fibers of PEGylated tetra-phenylalanine (F4), chemically modified at the N-terminus with the DOTA chelating agent, have been proposed as innovative contrast agent (CA) in Magnetic Resonance Imaging (MRI) upon complexation of the gadolinium ion. An in-depth structural characterization of PEGylated F4-fibers, in presence (DOTA-L6-F4) and in absence of DOTA (L6-F4), is reported in solution and at the solid state, by a multiplicity of techniques including CD, FTIR, NMR, DLS, WAXS and SAXS. This study aims to better understand how the aggregation process influences the performance of nanostructures as MRI CAs. Critical aggregation concentrations for L6-F4 (43 μM) and DOTA-L6-F4 (75 μM) indicate that self-aggregation process occurs in the same concentration range, independently of the presence of the CA. The driving force for the aggregation is the π-stacking between the side chains of the aromatic framework. CD, FTIR and WAXS measurements indicate an antiparallel β-sheet organization of the monomers in the resulting fibers. Moreover, WAXS and FTIR experiments point out that in solution the nanomaterials retain the same morphology and monomer organizations of the solid state, although the addition of the DOTA chelating agent affects the size and the degree of order of the fibers

Biological hydrogen production from lignocellulosic biomass

Biologically derived hydrogen (biohydrogen) from lignocellulosic biomass has the potential to be an ideal renewable fuel as its combustion does not produce carbon-based emissions and it can be derived from sources which do not affect food production. Moreover, the by-products of biohydrogen production can be fed to an anaerobic digester producing biogas. Thus, a two-step process involving biohydrogen production followed by biogas production is emerging as a viable option for conversion of lignocellulosic biomass. Essential aspects of designing a viable hydrogen production system such as biomass selection, inhibitory compounds in the biomass, removal and salvage of hydrogen and the desirable qualities in any hydrogen producing organism are discussed in this chapter

Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A

International audienceWe report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2.2$^\circ$ away from the best-fit position of the IceCube neutrino event IceCube-211208A detected on December 8, 2021. The source was in a high-flux state in the optical, ultraviolet, X-ray, and GeV gamma-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ray flux. The X-ray data from Swift-XRT and NuSTAR characterize the transition between the low-energy and high-energy components of the broadband spectral energy distribution (SED), and the gamma-ray data from Fermi -LAT, VERITAS, and H.E.S.S. require a spectral cut-off near 100 GeV. Both X-ray and gamma-ray measurements provide strong constraints on the leptonic and hadronic models. We analytically explore a synchrotron self-Compton model, an external Compton model, and a lepto-hadronic model. Models that are entirely based on internal photon fields face serious difficulties in matching the observed SED. The existence of an external photon field in the source would instead explain the observed gamma-ray spectral cut-off in both leptonic and lepto-hadronic models and allow a proton jet power that marginally agrees with the Eddington limit in the lepto-hadronic model. We show a numerical lepto-hadronic model with external target photons that reproduces the observed SED and is reasonably consistent with the neutrino event despite requiring a high jet power