Mark C. Biesinger

Plastics and beaches: A degrading relationship

Plastic debris in Earths oceans presents a serious environmental issue because breakdown by chemical weathering and mechanical erosion is minimal at sea. Following deposition on beaches, plastic materials are exposed to UV radiation and physical processes controlled by wind, current, wave and tide action. Plastic particles from Kauais beaches were sampled to determine relationships between composition, surface textures, and plastics degradation. SEM images indicated that beach plastics feature both mechanically eroded and chemically weathered surface textures. Granular oxidation textures were concentrated along mechanically weakened fractures and along the margins of the more rounded plastic particles. Particles with oxidation textures also produced the most intense peaks in the lower wavenumber region of FTIR spectra. The textural results suggest that plastic debris is particularly conducive to both chemical and mechanical breakdown in beach environments, which cannot be said for plastics in other natural settings on Earth.

Facile synthesis of gold nanoparticle (AuNP)–carbon nanotube (CNT) hybrids through an interfacial Michael addition reaction

A CNT-AuNP hybrid has been synthesized through the Michael addition reaction between thiol-functionalized single-wall CNT and small water-soluble Maleimide-AuNP. The resilience and stability of this hybrid nanosystem is ensured by a covalent bond linking the nanoparticle to the CNT and by the fact that the functionalization reaction involves the organic shell of the AuNP and not its metallic core.

Quantitative Chemical State XPS Analysis of First Row Transition Metals, Oxides and Hydroxides

Practical quantitative chemical state X-ray photoelectron spectroscopy (XPS) analysis of first row transition metals, oxides and hydroxides is challenging due to the complexity of their M 2p spectra. Complex multiplet splitting, shake-up and plasmon loss structure can play a role in the interpretation of the chemical states present. This paper will show practical curve fitting procedures for the quantitative measurement of different chemical states for metal oxides and hydroxides from a survey of transition metals. It will also discuss some of the limitations and pitfalls present as well as give practical examples of their successful use. These curve-fitting procedures are based on 1) standard spectra from quality reference samples, 2) a survey of appropriate literature databases and/or a compilation of literature references, 3) fitting of multiplet split spectra based on spectra of numerous reference materials and theoretical modelling, 4) spectral subtractions routines, again using reference spectra, and 5) specific literature references where fitting procedures are available.

The use of XPS, FTIR, SEM/EDX, contact angle, and AFM in the characterization of coatings

Coatings are applied to surfaces for a variety of reasons: to enhance their appearance, to protect the substrate, to augment the adhesion to other layers, or to functionalize them for further reactions. To evaluate the efficacy of the coating, it is often necessary to analyze the substrate and the coating to ensure that the needed characteristics are present. To this end, the use of x-ray photoelectron spectroscopy (XPS), contact angle, and atomic force microscopy (AFM) can provide information about the surface composition, its morphology, and its ability to be wetted with various solvents. Scanning electron microscopy with energy dispersive x-ray analysis (SEM/EDX) and Fourier transform infrared spectroscopy (FTIR) can provide a clear picture of the near surface components as well as the continuity of coatings. All of these aspects are valuable in evaluating a coating and essential when problems are encountered. The application of these techniques to the analysis of coatings is discussed.

Versatile strained alkyne modified water-soluble AuNPs for interfacial strain promoted azide–alkyne cycloaddition (I-SPAAC)

Versatile water- and organic solvent-soluble AuNPs that incorporate an interfacial strained alkyne capable of efficient pour and mix strain promoted interfacial cycloadditions with azide partners have been synthesized and carefully characterized for the first time. The use of XPS to quantitate the loading of the strained alkyne on the AuNPs is noteworthy. The reactivity towards the interfacial strain promoted azide-alkyne cycloaddition reaction was demonstrated by using azide-decorated polymersomes as bioorthogonal reaction partners.

Synthesis and characterization of novel TiO2-poly(propylene fumarate) nanocomposites for bone cementation

This work reports on a new methodology for synthesizing poly(propylene fumarate) (PPF)/titania nanowire composites which would be beneficial in tissue engineering for orthopaedic bone cements. The synthetic procedure reacted PPF with maleic anhydride to create HOOC-PPF-COOH species in a ring-opening reaction at room temperature. These species were then coordinated to titania nanowires by metal carboxylate bonding through the end -COOH groups. These PPF-grafted nano-TiO2 assemblies were then further polymerized and crosslinked in the presence of N-vinylpyrrolidone to produce the bone cements. The synthesis and modification of PPF was confirmed by NMR (1H and 13C) and XPS, while the reaction chemistry of the functionalized PPF and nano-TiO2 was also investigated by XPS and FTIR. Mechanical testing of the resulting composites demonstrated a significant reinforcement of the tensile and flexural properties, showing the utility of this synthetic approach for bone tissue engineering.

Continuous Hydrothermal Decarboxylation of Fatty Acids and Their Derivatives into Liquid Hydrocarbons Using Mo/Al2O3 Catalyst

In this study, we report a single-step continuous production of straight-chain liquid hydrocarbons from oleic acid and other fatty acid derivatives of interest including castor oil, frying oil, and palm oil using Mo, MgO, and Ni on Al2O3 as catalysts in subcritical water. Straight-chain hydrocarbons were obtained via decarboxylation and hydrogenation reactions with no added hydrogen. Mo/Al2O3 catalyst was found to exhibit a higher degree of decarboxylation (92%) and liquid yield (71%) compared to the other two examined catalysts (MgO/Al2O3, Ni/Al2O3) at the maximized conditions of 375 °C, 4 h of space time, and a volume ratio of 5:1 of water to oleic acid. The obtained liquid product has a similar density (0.85 kg/m3 at 15.6 °C) and high heating value (44.7 MJ/kg) as commercial fuels including kerosene (0.78–0.82 kg/m3 and 46.2 MJ/kg), jet fuel (0.78–0.84 kg/m3 and 43.5 MJ/kg), and diesel fuel (0.80–0.96 kg/m3 and 44.8 MJ/kg). The reaction conditions including temperature, volume ratio of water-to-feed, and space time were maximized for the Mo/Al2O3 catalyst. Characterization of the spent catalysts showed that a significant amount of amorphous carbon deposited on the catalyst could be removed by simple carbon burning in air with the catalyst recycled and reused.

The Influence of Final-State Effects on XPS Spectra from First-Row Transition-Metals

The first row transition metals (FRTM) and their compounds are of immense importance to the worldwide economy. In 2009, 2.3 billion (metric) tonnes of iron ore, 21.5 million tonnes (Mt) of chromium, 11.1 Mt of zinc, 9.6 Mt of manganese, 6.2 Mt of titanium, 1.6 Mt of nickel, 1.6 Mt of copper, 62,000 tonnes of cobalt and 54,000 tonnes of vanadium were produced from mining operations around the world [1].