Measurement of Redox Potential in Nanoecotoxicological Investigations

Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO2)) dispersions were measured using an oxidation-reduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe

The certification of the mass fraction of carbon in cementite grains in a Fe-C matrix: IRMM-471

The report describes the production and certification of IRMM-471, a reference material certified for the carbon mass fraction of its cementite (Fe3C) grains. The Fe3C grains are dispersed within an iron pearlite matrix and present an average grain diameter between 20 µm and 50 μm. IRMM-471 has been produced and certified in order to be used as calibrant in electron probe micro-analyser (EPMA) for carbon determination in iron and steel products.JRC.D.2-Standards for Innovation and sustainable Developmen

Measurement of redox potential in nanoecotoxicological investigations

Redox potential has been identified by the Organisation for Economic Co-operation and Development (OECD) as one of the parameters that should be investigated for the testing of manufactured nanomaterials. There is still some ambiguity concerning this parameter, i.e., as to what and how to measure, particularly when in a nanoecotoxicological context. In this study the redox potentials of six nanomaterials (either zinc oxide (ZnO) or cerium oxide (CeO 2 )) dispersions were measured using an oxidationreduction potential (ORP) electrode probe. The particles under testing differed in terms of their particle size and dispersion stability in deionised water and in various ecotox media. The ORP values of the various dispersions and how they fluctuate relative to each other are discussed. Results show that the ORP values are mainly governed by the type of liquid media employed, with little contributions from the nanoparticles. Seawater was shown to have reduced the ORP value, which was attributed to an increase in the concentration of reducing agents such as sulphites or the reduction of dissolved oxygen concentration. The lack of redox potential value contribution from the particles themselves is thought to be due to insufficient interaction of the particles at the Pt electrode of the ORP probe

Rapid response to syphilis outbreak among female sex workers

Background: Outbreak of syphilis, i.e., 16 cases of rapid plasma reagin (RPR) reactive cases of syphilis was reported in Community Based Organization (CBO) Sahyog of Surat, India, from April to August 2014. The aim of the study was to find risk factors and take immediate actions to prevent spread. Materials and Methods: Outbreak investigation of 16 Female Sex Workers of CBO Sahyog in Surat who were found Rapid Plasma Reagin (RPR) and Treponema Pallidum Hemagglutination Assay (TPHA) positive from April to August 2014; was carried out. Clinico-epidemiological and laboratory-based evidence for different sexually transmitted infections (STIs) conducted at Government Medical College, New Civil Hospital, Surat. Root cause analysis (RCA) of index case was carried out. Results: Desk review for the past 3 years data of STI revealed total STI cases as 88 (2011), 95 (2012), and 130 (2013), of which 4, 2, and 2 found RPR reactive, respectively. Data from April to August 2014 revealed 16 RPR reactive cases and confirmed by TPHA. On examination, one had ulcerative cervical lesion, rest did not have any symptoms of syphilis. Eleven had vaginal/cervical discharge, 11 had lower abdominal pain. A total of 11 had unprotected sex, 7 encountered condom tear in the past 6 months, and 5 reported sexual violence. Seven had sexual activity under influence of alcohol. Laboratory investigation revealed two as HIV-positive. RPR reactivity reported highest (9 out of 16) from same area of hotspot. RCA of probable index case revealed factors responsible as violence and nonuse of condoms. Conclusions: Outbreak investigation revealed one probable index case. All 16 treated with injection Penidure. Violence or condom tear is responsible for the spread. Crisis management team should be strengthened

Dibromocarbene Functionalization of Boron Nitride Nanosheets: Toward Band Gap Manipulation and Nanocomposite Applications

We report the covalent functionalization of exfoliated boron nitride nanosheets (BNNSs) using dibromocarbene (DBC) species. The functionalization of BNNSs is enabled as the nanosheets are utilized as two-dimensional phase-transfer catalysts for the migration of carbenes across the organic–aqueous phase boundary. We postulate that BNNSs stabilize carbenes by forming B-CBr₂ ylides and in turn act as the reaction substrate. DBC functionalization of BNNSs results in the formation of B–C and B–N bonds to the sp²-hybridized BNNS lattice via the formation of dibromo-bridged bicyclo BCN systems. The covalent functionalization was characterized using HR-TEM, AFM, EELS, XRD, EDX, ToF-SIMS, TGA, Raman, XPS, FTIR, and UV–vis techniques. Utilization of CBr₂ groups as a means by which BNNSs may be integrated and interfaced with solvents, molecular species, and condensed-phase materials was demonstrated by grafting alkyl chains from the functional groups via alkyl/halogen exchange. Alkyl-functionalized BNNSs were integrated within polyethylene (LDPE) and extruded to form BNNS-nanocomposite fibers. Implications of the covalent functionalization of h-BN are considered in the context of band gap manipulation and the versatility of the CBr₂ functional groups to enable subsequent chemical derivatization