bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plutonium: Radionuclides
Authors: Neu Mary P. , Goff George S. , Runde Wolfgang 
Published: June 2010

AbstractPlutonium is the most debated actinide element because of its dual use in devastating nuclear weapons and beneficial generation of nuclear energy. Plutonium metal exists in several allotropic phases and plutonium in solution exhibits a rich and complex chemistry. The ability to exist in up to four oxidation states makes plutonium unique among all elements. Pu(III) and Pu(VI) form only under reducing or oxidizing conditions, respectively; whereas Pu(IV) and Pu(V) have broad stability ranges within the geochemical bounds of environmental systems. When Pu(IV) is above trace concentration and particulate matter is present, then solids or suspended colloids are the predominant chemical forms. In contrast, Pu(V), as PuO$_{2}^{+}$, has relatively higher solubility as an aquo species or a monomeric complex of natural ligands (hydroxide, chloride, sulfate, etc.). Stronger complexing, polydentate ligands, such as carbonate and organics, tend to increase plutonium solubility by forming very stable Pu(IV) complexes. Minerals, high molecular weight organic matter, and bacteria can either increase or decrease the solubility of plutonium, depending upon their chemical properties, mechanisms of interaction, and the geochemical conditions of the surrounding environment. Plutonium generally has very low solubility, low mobility, and few health consequences from environmental forms, and therefore poses little risk to living systems under nearly all conditions. This article provides a brief overview of the chemistry and behavior of plutonium in aqueous solutions and in the environment.
Americium and Curium: Radionuclides
Authors: Runde Wolfgang 
Published: June 2010

AbstractFollowing the element plutonium, americium and curium are the sixth and seventh elements in the actinide series. The primordial americium and curium isotopes that formed during the creation of the solar system billions of years ago have decayed away. Today, residual amounts of americium and curium isotopes present in nature are anthropogenic, originating from human activities such as nuclear weapons testing or nuclear energy generation. All americium and curium isotopes are highly radioactive and pose extreme health hazards to humans, especially when ingested or inhaled. Complexation reactions with environmentally relevant ligands, separation chemistry, the mechanistic studies of the processes that Am(III) and Cm(III) undergo at the solid–liquid interface in nature, and innovative process applications have been the focus of many studies during recent decades.In general, the trivalent oxidation state of americium and curium is the most stable under environmental conditions. As hard cations, the Am3+and Cm3+ions form strong complexes with hard donor ligands and adsorb readily on surfaces. In the absence of carbonate, hydrolysis leads to sparingly soluble Am(III) and Cm(III) hydroxide complexes. Americium and curium are commonly used in home smoke detectors and for oil‐well logging (241Am), and as radioisotope thermoelectric generators (244Cm).
Oceans and Seas: Radionuclides
Authors: Aoyama Michio 
Published: June 2010

AbstractThe main sources of anthropogenic radioactivity of the world ocean are fallout from atmospheric nuclear weapon testing and the releases from nuclear fuel reprocessing plants and from the Chernobyl accident in 1986. This article summarizes the numbers of tests and the annual fission and fusion yields for the atmospheric weapon tests. The artificial radionuclides137Cs,239, 240Pu,90Sr, and other transuranics are used for monitoring and study by many institutes and organizations in many countries for the following reasons: (i)137Cs and90Sr are conservative in the open sea, the most abundant anthropogenic radionuclides, and the main contributors to biological exposure; and (ii) the very long‐lived239, 240Pu is nonconservative and the most abundant among transuranics. The number of observations of these radionuclides in each sea area is summarized. Global distribution of137Cs decay corrected for accumulative deposition as of January 1, 1970 is described as the initial condition of137Cs inventory in the world ocean. The collective effective dose commitment to the world population from artificial and natural radionulides in the marine food is described. The current radionuclide levels in the world ocean are low and therefore of no concern from the radiological point of view.
IndianOcean: Radionuclides
Authors: Povinec Pavel P. 
Published: June 2010

AbstractThe distribution of global fallout radionuclides in Indian Ocean waters about four decades after their main injection from atmospheric nuclear weapons tests on the ocean surface is discussed. Recent data obtained in the framework of the WOMARS (Worldwide Marine Radioactivity Studies) and SHOTS (Southern Hemisphere Ocean Tracer Studies) projects are evaluated and compared with previous investigations carried out in the northern and southern Indian Ocean. The results indicate transport of surface waters labeled with radionuclides from the Mediterranean Sea, as well as from the Northwestern Pacific through the Indonesian Seas to the Indian Ocean. After passing the equator the waters circulate in the South Indian Ocean subtropical gyre, which accumulates radionuclide tracers and other contaminants on timescales of decades. This accumulation of contaminants in the Southern Indian Ocean is of environmental importance for the protection of the marine environment from land‐based contamination sources.
Arctic Ocean: Radionuclides
Authors: Zaborska Agata , Carroll JoLynn 
Published: June 2010

Abstract

This article presents an overview of the major sources, transport pathways, and fate of anthropogenic radionuclides in the Arctic marine environment. The dominant anthropogenic radionuclides present in Arctic seawater, sediments, and marine biota are cesium‐137 (
137
Cs), plutonium‐239 (
239
Pu), plutonium‐240 (
240
Pu), technetium‐99 (
99
Tc), and strontium‐90 (
90
Sr). Major sources contributing to the inventory of radionuclides in the Arctic Ocean and surrounding shelf seas include atmospheric fallout, European nuclear reprocessing facilities, the Chernobyl accident, and discharges from major Arctic rivers. Anthropogenic radionuclides from these sources are supplied to and redistributed within the Arctic Ocean via atmospheric, sea ice, currents, sediment, and river transport pathways. With the exception of a few locations, e.g., the underwater nuclear test site at Chernaya Bay, sediment, seawater, and biota activity concentrations in the Arctic are today very low, posing negligible biological and human‐health risks. However, the rate of warming of the Arctic is three times faster than other parts of the globe, raising the prospect of significant reorganization of system properties and processes with consequent changes to both the sources and fate of radionuclides in the Arctic in the decades to come.
Civilian Nuclear Accidents
Authors: Runde Wolfgang , Neu Mary P. , Goff George S. 
Published: June 2010

AbstractSince the discovery of plutonium and its use for nuclear weapons and nuclear energy radionuclides have been dispersed into the environment and contribute significantly to the global presence of anthropogenic radionuclides. Today, nuclear power plants are controlled by the national radiation protection authorities but are continuously emitting the small amounts of radioactivity permitted by the national health authorities. Other releases originate from the use of radionuclides in medical diagnostic and therapeutic treatments. Although these releases are minor compared to natural radioactivity and anthropogenic radionuclides, they contribute to the current radiation background. The anthropogenic actinides in the northern hemisphere mainly originated during nuclear weapons testing, fallout from the reactor accident at Chernobyl, atmospheric burnup of nuclear satellites, and intentional discharges of liquid waste streams from industrial‐scale nuclear reprocessing facilities. Despite the increasingly sophisticated engineered reactor and processing systems, accidents since the 1950s have resulted in the release of radioactivity to the environment. The most prominent accidents that led to a significant dispersion of radionuclides are the Three Miles Island accident, the Windscale Fire, and the Chernobyl accident. In this article, we discuss these events and other nonweapons related uncontrolled releases of radioactivity into the environment.
Perfluorinated Polymers, Perfluorinated Ethylene–Propylene Copolymers
Authors: Gangal Subhash V. , Brothers Paul D. 
Published: June 2010

AbstractPerfluorinated ethylene‐propylene (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). It retains most of the desirable characteristics of polytetrafluoroethylene (PTFE) but with a melt viscosity low enough for conventional melt processing. The introduction of hexafluoropropylene lowers the melting point of PTFE from 327°C to about 260°C. The lower melt viscosity allows melt extrusion of wire insulation of longer continuous lengths than the batchwise paste extrusion of PTFE and allows the injection molding of intricate shaped parts. This polymer has a combination of properties that make it useful in applications that require chemical inertness, excellent dielectric properties, good weatherability, antistick properties, low coefficient of friction and performance in temperature extremes. As a thermoplastic, it can be processed by extrusion and compression, injection and blow molding. Films can be heat bonded and sealed, vacuum formed, and laminated to various substrates. Aqueous and nonaqueous dispersion polymerizations are the most convenient routes to produce these copolymers. The polymerization conditions are similar to those of TFE homopolymer dispersion polymerization. The optimal composition of the copolymer is such that the mechanical properties are retained in the useable range and the melt viscosity is low enough for easy melt processing.
Nuclear Magnetic Resonance for Environmental Monitoring
Authors: Cook Robert L. , Ojwang Loice M. , Poché Caroline L. 
Published: June 2010

AbstractNuclear magnetic resonance (NMR) is one of the most powerful tools available for analytical chemists at present. The power of the technique and its wide applicability come from the fact that it probes isolated nuclei with low‐energy radio waves. The isolation of the probed nuclei allows one to obtain very detailed information on their local electronic and physical environments. The coupling of nuclei also allows for a systematic study of their connectivities. The use of radiofrequency exploits (i) our fundamental understanding and ability to manipulate this form of electromagnetic energy and (ii) the low‐energy nature of this radiation to gently and nondestructively probe nuclei, and hence, molecules in a range of situations, including in vivo. These attributes of NMR allow it to have a wide range of applications within the field of environmental monitoring, from identification and detection to unraveling complex biochemical process due to environmental stressors. The NMR field continues to evolve with advances in theory, practice, and hardware and, as it does so, it expands into applications ranging from monitoring natural organic matter (NOM) in the environment to emerging environmental issues, such as atmospheric organic matter (AOM) characterization or chemical weapon detection and identification, to studying the influence of environmental stressors on a range of living organisms through metabolite profiling.
Laser Ablation in Atomic Spectroscopy
Authors: Horn Ingo 
Published: June 2010

AbstractThis article covers the developments in the field of laser ablation and highlights the current issues under investigation. Fundamental parameters such pulse width, wavelength, elemental and isotopic fractionation, the ablation mechanism, precision, and accuracy as well the the available software packages for calculation and manipulation of the data obtained by laser ablation are discussed. Ongoing research is focused on elemental‐isotopic fractionation and on high‐precision stable isotope ratio determinations and the use of femtosecond pulses for ablation. The recent results obtained using femtosecond pulses for ablation illustrate that this analytical technique is still under development.
Site‐directed Spin Labeling and Pulse Dipolar Electron Paramagnetic Resonance
Authors: Klare Johann P. , Steinhoff Heinz‐Jürgen 
Published: June 2010

Abstract
Structural and functional investigations on biomolecules often rely on the availability of topological information, either to allow building structural models or to characterize conformational changes of these molecules or complexes thereof during function. Site‐directed spin labeling (SDSL) in combination with EPR spectroscopy became a very powerful tool to obtain intra‐ and inter‐molecular distance constraints, as the accessible distances span the interesting range from 0.5–8 nm, crystallization is not required, and the size of the system under investigation is not limited. Especially the development of pulse dipolar EPR methods, in particular double electron–electron resonance (DEER) spectroscopy with its ability to provide interspin distance distributions in the 2–8 nm range, greatly increased the applicability of electron paramagnetic resonance (EPR) spectroscopy for studies on biological systems. This article is intended to give an introduction into SDSL and dipolar EPR. The first part summarizes the state‐of‐the‐art in SDSL, providing an overview of methodologies currently available or under development. In the second part, the technique of DEER spectroscopy is introduced, covering the basic theoretical background as well as selected practical aspects of data acquisition and analysis. Finally, selected examples for the application of SDSL‐DEER from the recent literature are summarized.
Dipolar Recoupling of Heteronuclear Spin Pairs by Rotational‐Echo, Double‐Resonance Nuclear Magnetic Resonance
Authors: Gullion Terry 
Published: June 2010

Abstract

Nuclear magnetic resonance (NMR)‐active nuclear spins interact through the dipolar interaction, an important source of structural information because of the
r
−3
dependence of this interaction on the internuclear distance. Fast random molecular reorientation averages the dipolar interaction to zero in solutions, and there is no direct evidence of the dipolar interaction in solution‐state NMR spectra under typical laboratory conditions. In static solids with no significant molecular motion, measuring the dipolar coupling provides an important source of structural information. In high‐resolution spectra of solids obtained through magic‐angle spinning (MAS), however, the dipolar interaction is coherently averaged to zero, with concomitant loss of the information inherent to this interaction. Dipolar‐recoupling experiments measure the dipolar coupling in MAS NMR. They are designed to produce a nonzero average effect of the dipolar interaction. Measured dipolar couplings obtained by dipolar‐recoupling experiments can be used to determine the distance between coupled pairs of spins. One such dipolar‐recoupling experiment is rotational‐echo, double‐resonance (REDOR) NMR, a commonly used technique to measure dipolar couplings between heteronuclear spin pairs. This article describes the REDOR experiment.
Micro‐X‐Ray Fluorescence
Authors: Tsuji Kouichi 
Published: June 2010

AbstractX‐ray fluorescence (XRF) is a well‐known analytical technique that enables nondestructive elemental quantitative analysis of various kinds of samples without requiring the use of high vacuum. In conventional XRF, the analysis area on the sample is typically 10 mm in diameter. However, advances in X‐ray technology of X‐ray sources, X‐ray optics, and X‐ray detectors have changed the performance of XRF analysis. X‐ray microbeams of a few micrometers up to several tens of micrometers have been obtained with a reasonable intensity for X‐ray elemental analysis in the laboratory. The use of such a micro‐X‐ray beam enables XRF analysis of small regions. This micro‐XRF method opens new application fields for XRF analysis. In addition, scanning the sample enables the production of two‐dimensional XRF images. This method of chemical X‐ray imaging provides very useful information. In addition, a confocal configuration for X‐ray excitation and X‐ray detection also provides the opportunity for three‐dimensional XRF images. These topics related to recent developments in micro‐XRF are introduced.
Laser Ablation Inductively Coupled Plasma Mass Spectrometry in Forensic Science
Authors: Trejos Tatiana , Almirall José R. 
Published: June 2010

AbstractThe application of laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) to the elemental analysis of forensic matrices offers many advantages for solid sampling, including direct characterization of solids, the elimination of the need for chemical procedures for dissolution, minimal sample consumption, and a reduced risk of contamination from the sample preparation procedures associated with sample digestion. This article aims at summarizing the recent literature describing the use of LA‐ICP‐MS in the field of forensic examinations with selected applications, highlighting the forensic analyses of a variety of matrices and analytes of interest and including the advantages, limitations, and future trends in this field. A critical evaluation of the parameters of forensic interest is discussed in detail, including the analytical performance of the technique, discrimination potential (when comparing samples), the impact of sample homogeneity/heterogeneity at the microscale, reproducibility, quality control, sampling strategies, sampling size requirements, availability of matrix‐matched standards, data analysis, and the interpretation of results. Practical considerations such as the selection of laser wavelength and carrier gas, the use of internal standardization, and quantification strategies are discussed as also the unique requirements of quality control and method validation and acceptance in court.
Mass Spectrometry Applications in Forensic Science
Authors: Smith Darrin L. 
Published: June 2010

AbstractThe role of mass spectrometry (MS) in forensic science can be characterized as either molecular or elemental analysis. Relatively small, volatile, nonpolar molecules found in a variety of forensic samples can be analyzed with electron and chemical ionization (CI) routinely coupled with single‐stage mass analyzers that provide molecular weight and structural information. Nonvolatile and polar molecules including drugs, poisons, and/or their metabolites routinely found in biological matrices along with other analytes of forensic interest can be determined using electrospray or related soft ionization techniques coupled to tandem mass analyzer systems to identify a molecule through structure elucidation and provide excellent screening and quantitative results. New ambient ionization sources now allow the direct analysis of molecules from a forensic sample surface, with minimal prior preparation or separation. In addition, the sequencing of deoxyribonucleic acid (DNA) has also been difficult with most ionization sources until matrix‐assisted laser desorption ionization (MALDI), which has the potential to provide quick and dependable results, was utilized. Elemental profiles also provide reliable methods for characterizing and distinguishing forensic samples. This article aims at providing information about MS and its uses in the field of forensic science.
Liquid Chromatography‐Infrared and Size Exclusion Chromatography‐infrared Analysis for Polymer Characterization
Authors: Plass Monika , Albrecht Andreas , Brüll Robert 
Published: June 2010

Abstract
Fourier transform infrared spectroscopy (FTIR) can be used as a detector in liquid chromatography, giving detailed information on the molecular structure of the effluents after separation. Achieving structural details of chemical compounds after their separation makes the coupling of interactive liquid chromatography (IC) and size exclusion chromatography (SEC) with IR spectroscopy a versatile analytical tool superior to refractive index (RI), ultraviolet (UV), and evaporative light scattering detectors (ELSDs). LC/IR offers an alternative to LC/MS and LC/NMR to study the chemical composition of the eluted compounds. The hyphenation can be realized in two ways, namely, the on flow with an IR flow cell and off‐line via solvent elimination. Both approaches are discussed with regard to their advantages and limitations and different solvent‐elimination interfaces are compared. The coupling of LC with FTIR using the IR flow cell and the solvent‐elimination interfaces is demonstrated on selected samples, including interactive and size exclusion models at ambient and high temperatures.
Structural Studies and the Correlation with the Stress–Strain Response in Polyurethanes
Authors: Prisacariu Cristina , Scortanu Elena 
Published: June 2010

AbstractThe purpose of this article is to review and bring new contributions in understanding the relationship between molecular/supramolecular architecture at the nanometer scale and macroscopic mechanical properties in polyurethanes. In this article, this problem is addressed by studying numerous conventional segmented polyurethanes, based on several diisocyanates, macrodiols, and chain extenders. In order to widen the range of structures achievable beyond those normally available, in this review, we have also included recent developments that have been made in polyurethane materials by producing polymers based on isocyanates of variable geometry, giving hard segments that allow the variation of hard‐domain crystallinity as a key structural variable. They were used to probe the sensitivity of inelastic effects to structural details of the materials. Mechanical responses studied were large strain, constant strain rate, and cyclic strain responses, including interrupted tests. Results were related to microstructural changes, on the basis of evidence from small‐angle X‐ray scattering (SAXS) and wide‐angle X‐ray scattering (WAXS) and infrared (IR) dichroic measurements. Inelastic effects were most pronounced when the hard segment crystallized, and when the phase segregation was more pronounced. Thermal techniques such as differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to study the thermal behavior of the materials. There were tendencies to phase separation, with a characteristic length of ca. 20 nm, and, when isocyanates of variable geometry were employed with certain chain extenders, to crystallization of the hard phase. Such materials display higher flow stress in the hard phase caused by stronger phase segregation. This has clearly revealed that inelastic features in the constitutive response of polyurethane elastomers are sensitive to microstructural detail on length scales of the order of nanometers. Hard‐domain crystallinity exerts a strong effect on inelasticity of the elastomers. There is a clear indication that the physical origin of the flow stress is the relative displacement of the hydrogen‐bonded hard segments. Inelasticity, as measured by hysteresis and unrecovered strain, was increased by increased phase separation.