Glossary of terms used in photocatalysis and radiation catalysis (IUPAC recommendations 2011)

This glossary of terms covers phenomena considered under the very wide terms photocatalysis and radiation catalysis. A clear distinction is made between phenomena related to either photochemistry and photocatalysis or radiation chemistry and radiation catalysis. The term "radiation" is used here as embracing electromagnetic radiation of all wavelengths, but in general excluding fast-moving particles. Consistent definitions are given of terms in the areas mentioned above, as well as definitions of the most important parameters used for the quantitative description of the phenomena. Terms related to the up-scaling of photocatalytic processes for industrial applications have been included. This Glossary should be used together with the Glossary of terms used in photochemistry, 3rd edition, IUPAC Recommendations 2006: (doi:10.1351/pac200779030293) as well as with the IUPAC Compendium of Chemical Terminology, 2nd ed. (the "Gold Book" 2006-; doi:10.1351/goldbook), because many terms used in photocatalysis are defined in these documents. © 2011 IUPAC

Cytotoxicity of ZnO Nanoparticles Can Be Tailored by Modifying Their Surface Structure: A Green Chemistry Approach for Safer Nanomaterials

ZnO nanoparticles (NP) are extensively used in numerous nanotechnology applications; however, they also happen to be one of the most toxic nanomaterials. This raises significant environmental and health concerns and calls for the need to develop new synthetic approaches to produce safer ZnO NP, while preserving their attractive optical, electronic, and structural properties. In this work, we demonstrate that the cytotoxicity of ZnO NP can be tailored by modifying their surface-bound chemical groups, while maintaining the core ZnO structure and related properties. Two equally sized (9.26 ± 0.11 nm) ZnO NP samples were synthesized from the same zinc acetate precursor using a forced hydrolysis process, and their surface chemical structures were modified by using different reaction solvents. X-ray diffraction and optical studies showed that the lattice parameters, optical properties, and band gap (3.44 eV) of the two ZnO NP samples were similar. However, FTIR spectroscopy showed significant differences in the surface structures and surface-bound chemical groups. This led to major differences in the zeta potential, hydrodynamic size, photocatalytic rate constant, and more importantly, their cytotoxic effects on Hut-78 cancer cells. The ZnO NP sample with the higher zeta potential and catalytic activity displayed a 1.5-fold stronger cytotoxic effect on cancer cells. These results suggest that by modifying the synthesis parameters/conditions and the surface chemical structures of the nanocrystals, their surface charge density, catalytic activity, and cytotoxicity can be tailored. This provides a green chemistry approach to produce safer ZnO NP

Nanoscale Metallic Iron for Environmental Remediation: Prospects and Limitations

The amendment of the subsurface with nanoscale metallic iron particles (nano-Fe0) has been discussed in the literature as an efficient in situ technology for groundwater remediation. However, the introduction of this technology was controversial and its efficiency has never been univocally established. This unsatisfying situation has motivated this communication whose objective was a comprehensive discussion of the intrinsic reactivity of nano-Fe0 based on the contemporary knowledge on the mechanism of contaminant removal by Fe0 and a mathematical model. It is showed that due to limitations of the mass transfer of nano-Fe0 to contaminants, available concepts cannot explain the success of nano-Fe0 injection for in situ groundwater remediation. It is recommended to test the possibility of introducing nano-Fe0 to initiate the formation of roll-fronts which propagation would induce the reductive transformation of both dissolved and adsorbed contaminants. Within a roll-front, FeII from nano-Fe0 is the reducing agent for contaminants. FeII is recycled by biotic or abiotic FeIII reduction. While the roll-front concept could explain the success of already implemented reaction zones, more research is needed for a science-based recommendation of nano- Fe0 for subsurface treatment by roll-front

Estudios sobre la valoración del principio ocitócico del lóbulo posterior de hipófisis. Análisis matemático de los resultados y determinación del error del método

Fil: Torino, A. Ministerio del Interior; Instituto Bacteriológico "Dr. Carlos G. Malbrán"; Argentin

Estudios sobre la valoración del principio ocitócico del lóbulo posterior de hipófisis. Análisis matemático de los resultados y determinación del error del método

Fil: Torino, A. Ministerio del Interior; Instituto Bacteriológico "Dr. Carlos G. Malbrán"; Argentin

Estudios de farmacología cuantitativa : 1. Curvas de la toxicidad de la dolantina

Fil: Litter, M. Ministerio del Interior; Instituto Bacteriológico "Dr. Carlos G. Malbrán"; Argentinal° — Se ha estudiado la toxicidad de la dolantina para el ratón blanco y por vía intravenosa, empleando én total 805 animales. 2° — Se ha construido la curva característica de toxicidad y la línea de regresión; esta última también se ha obtenido por cálculo. 3° — La dosis mortal 50 % (DL 50) oscila entre 42,5 y 50,0 mg/kg (método de Trevan, 1929), éntre 44,2 y 55,3 mg/kg (método gráfico de Gaddum, 1933) y entré 44,3 y 55,1 mg/kg (cálculo por el método de Gaddum, 1933). 4° — Nuestros resultados están de acuerdo con lo establecido por Gaddum (1933), a saber, qué los logaritmos de las dosis mortales individuales están distribuidos en forma aproximadamente normal. 5° — La dosis mortal 50 % (DL 50), no representa una constante biológica, sino que varía aún empleando en las experiencias un gran numéro de animales