ZnO, aside from TiO2, has been considered as a promising material for purification and disinfection of water and air, and remediation of hazardous waste, owing to its high activity, environment-friendly feature and lower cost. However, their poor visible light utilization greatly limited their practical applications. Herein, we demonstrate the fabrication of different aspect ratios of the ZnO nanorods with surface defects by mechanical-assisted thermal decomposition method. The experiments revealed that ZnO nanorods with higher aspect ratio and surface defects show significantly higher photocatalytic performances.

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Effect of aspect ratio and surface defects on the photocatalytic activity of ZnO nanorods

Angiotensin converting enzyme (ACE) inhibitors augment circulating levels of the vasodilator peptide angiotensin-(1-7) [Ang-(1-7)] in man and animals. Increased concentrations of the peptide may contribute to the antihypertensive effects associated with ACE inhibitors. The rise in Ang-(1-7) following ACE inhibition may result from increased production of the peptide or inhibition of the metabolism of Ang-(1-7)-similar to that observed for bradykinin. To address the latter possibility, we determined whether Ang-(1-7) is a substrate for ACE in vitro. In a pulmonary membrane preparation, the ACE inhibitor lisinopril attenuated the metabolism of low concentrations of 125I-Ang-(1-7). The primary product of 125I-Ang-(1-7) metabolism was identified as Ang-(1-5). Using affinity-purified ACE from canine lung, HPLC separation and amino acid analysis revealed that ACE functioned as a dipeptidyl carboxypeptidase cleaving Ang-(1-7) to the pentapeptide Ang-(1-5). The ACE inhibitors lisinopril and enalaprilat (1 micromol/L), as well as the chelating agents EDTA, o-phenanthroline, and DTT (0.1-1 mmol/L) abolished the generation of Ang-(1-5) and did not yield other metabolic products. Ang-(1-5) was not further hydrolyzed by ACE. Kinetic analysis of the hydrolysis of Ang-(1-7) by ACE revealed a substrate affinity of 0.81 micromol/L and maximal velocity of 0.65 micromols min(-1) mg(-1). The calculated turnover constant for the peptide was 1.8 sec(-1) with a catalytic efficiency (Kcat/Km) of 2200 sec(-1) mmol/L(-1). These findings suggest that increased levels of Ang-(1-7) following ACE inhibition may be due, in part, to decreased metabolism of the peptide.

Metabolism of Angiotensin-(1–7) by Angiotensin-Converting Enzyme

CONTRIBUTORS. INTRODUCTION THE WORLD OF OXIDE NANOMATERIALS (Jose A. Rodriguez and Marcos Fernandez-Garcia). PART I BASIC CONCEPTS. Chapter 1. Theory of Size, Confinement, and Oxidation Effects (Chang Q. Sun). Chapter 2. On Aqueous Interfacial Thermodynamics and the Design of Metal-Oxide Nanostructures (Lionel Vayssieres). PART II SYNTHESIS AND PREPARATION OF NANOSTRUCTURED OXIDES. Chapter 3. Synthesis of Metal-Oxide Nanoparticles: Liquid-Solid Transformations (Lawrence D'Souza and Ryan Richards). Chapter 4. Synthesis of Metal-Oxide Nanoparticles: Gas-Solid Transformations (S. Buzby, S. Franklin, and S. Ismat Shah). PART III STUDY AND CHARACTERIZATION OF NANOSTRUCTURED OXIDES. Chapter 5. Techniques for the Study of the Structural Properties (Jose A. Rodriguez, Marcos Fernandez-Garcia,Arturo Martinez-Arias, and Jonathan C. Hanson). Chapter 6. Techniques for the Study of the Electronic Properties (Marcos Fernandez-Garcia and Jose A. Rodriguez). Chapter 7. Post Hartree-Fock and Density Functional Theory Formalisms (Francesc Illas and Gianfranco Pacchioni). Chapter 8. Parametric Quantum Methods in Modeling Metal Oxide Nanoclusters and Surfaces (F. Ruette and M. Sanchez). Chapter 9. Atomistic Models and Molecular Dynamics (D.C. Sayle and T.X.T. Sayle). PART IV PHYSICOCHEMICAL PROPERTIES OF OXIDE NANOMATERIALS. Chapter 10. Theoretical Aspects of Oxide Particle Stability and Chemical Reactivity (Ye Xu, William A. Shelton, and William F. Schneider). Chapter 11. Adsorption of Probe Molecules on Nanostructured Oxides (James A. Anderson and Russell F. Howe). Chapter 12. Chemical Properties of Oxide Nanoparticles: Surface Adsorption Studies from Gas- and Liquid-Phase Environments (John M. Pettibone, Jonas Baltrusaitis, and Vicki H. Grassian). Chapter 13. Transport Properties and Oxygen Handling (Glenn C. Mather and Arturo Martinez-Arias). PART V INDUSTRIAL/TECHNOLOGICAL APPLICATIONS OF OXIDE NANOMATERIALS. Chapter 14. Adsorbents (Pethaiyan Jeevanandam and Kenneth J. Klabunde). Chapter 15. Gas Sensors (Doina Lutic, Mehri Sanati, and Anita Lloyd Spetz). Chapter 16. Photovoltaic, Photoelectronic, and Electrochemical Devices Based on Metal-Oxide Nanoparticles and Nanostructures (Juan Bisquert). Chapter 17. Nanostructured Oxides in Photo-Catalysis (Gerardo Colon-Ibanez, Carolina Belver-Coldeira, and Marcos Fernandez-Garcia). Chapter 18. Oxide Nanomaterials for the Catalytic Combustion of Hydrocarbons (Ilenia Rossetti and Lucio Forni). Chapter 19. Nanostructured Oxides in DeNOx Technologies (Marcos Fernandez-Garcia, Arturo Martinez-Arias, and Javier Perez-Ramirez). Chapter 20. Chemistry of SO2 and DeSOx Processes on Oxide Nanoparticles (Jose A. Rodriguez). Chapter 21. H2 Production and Fuel Cells (Xianqin Wang and Jose A. Rodriguez). Chapter 22. Oxide Nanomaterials in Ceramics (Vicente Rives, Raquel Trujillano, and Miguel A. Vicente). Index.

Synthesis, properties, and applications of oxide nanomaterials

Bioluminescence, the emission of ecologically functional light by living organisms, emerged independently on several occasions, yet the evolutionary origins of most bioluminescent systems remain obscure. We propose that the luminescent substrates of the luminous reactions (luciferins) are the evolutionary core of most systems, while luciferases, the enzymes catalysing the photogenic oxidation of the luciferin, serve to optimise the expression of the endogenous chemiluminescent properties of the luciferin. Coelenterazine, a luciferin occurring in many marine bioluminescent groups, has strong antioxidative properties as it is highly reactive with reactive oxygen species such as the superoxide anion or peroxides. We suggest that the primary function of coelenterazine was originally the detoxification of the deleterious oxygen derivatives. The functional shift from its antioxidative to its light-emitting function might have occurred when the strength of selection for antioxidative defence mechanisms decreased. This might have been made possible when marine organisms began colonising deeper layers of the oceans, where exposure to oxidative stress is considerably reduced because of reduced light irradiance and lower oxygen levels. A reduction in metabolic activity with increasing depth would also have decreased the endogenous production of reactive oxygen species. Therefore, in these organisms, mechanisms for harnessing the chemiluminescence of coelenterazine in specialised organs could have developed, while the beneficial antioxidative properties were maintained in other tissues. The full range of graded irradiance in the mesopelagic zone, where the majority of organisms are bioluminescent, would have provided a continuum for the selection and improvement of proto-bioluminescence. Although the requirement for oxygen or reactive oxygen species observed in bioluminescent systems reflects the high energy required to produce visible light, it may suggest that oxygen-detoxifying mechanisms provided excellent foundations for the emergence of many bioluminescent systems.

https://www.life.illinois.edu/ib/426/handouts/origin%20of%20biolux%20review1998.pdf

The origins of marine bioluminescence: turning oxygen defence mechanisms into deep-sea communication tools.

Lithium titanate and titanium dioxide are two best-known high-performance electrodes that can cycle around 10,000 times in aprotic lithium ion electrolytes. Here we show there exists more lithium titanate hydrates with superfast and stable cycling. That is, water promotes structural diversity and nanostructuring of compounds, but does not necessarily degrade electrochemical cycling stability or performance in aprotic electrolytes. As a lithium ion battery anode, our multi-phase lithium titanate hydrates show a specific capacity of about 130 mA h g−1 at ~35 C (fully charged within ~100 s) and sustain more than 10,000 cycles with capacity fade of only 0.001% per cycle. In situ synchrotron diffraction reveals no 2-phase transformations, but a single solid-solution behavior during battery cycling. So instead of just a nanostructured intermediate to be calcined, lithium titanate hydrates can be the desirable final destination. Water is usually not favorable in high-voltage window aprotic electrolytes. Here the authors discover some lithium titanate hydrates that allow superior power rate and ultralong cycle life in aprotic electrolytes.

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Lithium titanate hydrates with superfast and stable cycling in lithium ion batteries.

This chapter concentrates on the characterization of Langmuir—Blodgett (LB) monolayer and multilayer films on solid surfaces. Experimental techniques to study the properties of monolayers floating on the surface of a subphase have been discussed by Gaines(1) and are, to some extent, covered in the earlier chapters of this book. A review of the properties of LB films could be arranged in a number of ways: subdivisions according to the type of material or to the nature of the experimental technique are probably the most straightforward approaches. In this chapter the latter plan is adopted. It is hoped that this will not only aid the researcher wishing to investigate monolayer and multilayer systems, but also keep the work relevant as more novel LB materials are synthesized. Examples used have generally been chosen from published data on the simpler types of LB assemblies (e.g., longchain fatty acids).

M. C. Petty

Papers

Characterization and Properties