bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiresidue Pesticide Analysis in Ginseng and Spinach by Nontargeted and Targeted Screening Procedures
Authors: Hayward Douglas G , Wong Jon W , Zhang Kai , Chang James , Shi Feng , Banerjee Kaushik , Yang Paul 
Published: December 2011

Abstract
Five different mass spectrometers interfaced to GC or LC were evaluated for their application to targeted and nontargeted screening of pesticides in two foods, spinach and ginseng. The five MS systems were capillary GC/MS/MS, GC-high resolution time-of-flight (GC/HR-TOF)-MS, TOF-MS interfaced with a comprehensive multidimensional GC (GCxGC/TOF-MS), an MS/MS ion trap hybrid mass (qTrap) system interfaced with an ultra-performance liquid chromatograph (UPLC-qTrap), and UPLC interfaced to an orbital trap high resolution mass spectrometer (UPLC/Orbitrap HR-MS). Each MS system was tested with spinach and ginseng extracts prepared through a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure. Each matrix was fortified at 10 and 50 ng/g for spinach or 25 and 100 ng/g for ginseng with subsets of 486 pesticides, isomers, and metabolites representing most pesticide classes. HR-TOF-MS was effective in a targeted search for characteristic accurate mass ions and identified 97% of 170 pesticides in ginseng at 25 ng/g. A targeted screen of either ginseng or spinach found 94–95% of pesticides fortified for analysis at 10 ng/g with GC/MS/MS or LC/MS/MS using multiple reaction monitoring (MRM) procedures. Orbitrap-MS successfully found 89% of 177 fortified pesticides in spinach at 25 ng/g using a targeted search of accurate mass pseudomolecular ions in the positive electrospray ionization mode. A comprehensive GCxGC/TOF-MS system provided separation and identification of 342 pesticides and metabolites in a single 32 min acquisition with standards. Only 67 or 81% of the pesticides were identified in ginseng and spinach matrixes at 25 ng/g or 10 ng/g, respectively. MS/MS or qTrap-MS operated in the MRM mode produced the lowest false-negative rates, at 10 ng/g. Improvements to instrumentation, methods, and software are needed for efficient use of nontargeted screens in parallel with triple quadrupole MS.
Applications of LC/ESI-MS/MS and UHPLC/Qq-TOF-MS for the Determination of 141 Pesticides in Tea
Authors: Wang Jian , Chow Willis , Leung Daniel 
Published: December 2011

Abstract
This paper presents the applications of LC-electrospray ionization (ESI)/MS/MS and ultra-HPLC (UHPLC)/ESI quadrupole (Qq)-time-of-flight (TOF) MS for the determination of 141 pesticides in tea. Pesticides were extracted and cleaned up from tea with a modified quick, easy, cheap, effective, rugged, and safe method using graphitized carbon black and primary-secondary amine sorbents. Quantification was achieved using matrix-matched standard calibration curves with isotopically labeled standards or a chemical analog as internal standards in an analytical range from 5 to 500 μg/kg. The LC/ESI-MS/MS served as a reliable tool to quantify the pesticides due to its superior sensitivity and good repeatability. Its method performance characteristics that include overall recovery, intermediate precision, and measurement uncertainty were evaluated according to a statistically designed experiment, i.e., a nested design. About 87% of the pesticides had recoveries between 81 and 110%; 94% had an intermediate precision ≤20%; and 90% showed measurement uncertainty ≤40%. About 92% of the pesticides were able to be detected at 5 μg/kg with an S/N ≥3. The UHPLC/Qq-TOF-MS showed much less sensitivity and poorer repeatability compared to the LC/ESI-MS/MS, and, therefore, it was primarily used for confirmatory purposes based on the accurate mass measurement and isotopic patterns.
Using the scan‐x Web Site to Predict Protein Post‐Translational Modifications
Authors: Chou Michael F. , Schwartz Daniel 
Published: December 2011

AbstractThe recent plethora of proteomic mass spectrometry data is providing evidence that almost every protein in the cell undergoes some form of post‐translational modification. We describe a protocol to use the scan‐x Web site to view predicted acetylation sites in the human proteome and predicted phosphorylation sites in the human, mouse, fly, and yeast proteomes with high specificity. This tool is accessible from virtually any computer with a Web browser. The only requirement is a means of searching for a protein of interest in one of the represented organisms. Curr. Protoc. Bioinform. 36:13.16.1‐13.16.8. © 2011 by John Wiley & Sons, Inc.
Arsenic: Inorganic ChemistryBased in part on the article Arsenic: Inorganic Chemistry by Ralph A. Zingaro which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Muñoz‐Hernández Miguel‐Ángel 
Published: December 2011

AbstractThis article reflects the importance and development of the chemistry of inorganic arsenic compounds. Throughout the text the reader will be taken from the chemistry of simple arsenic species found in minerals to such as those arsenic species that reflect the breath of modern inorganic chemistry. Efforts have been made to show developments in fundamental chemistry, materials science, and aspects of arsenic in the environment. Accordingly, Section 2 covers aspects of the preparation of simple arsenic species like the chalcogenides and halogenides. In Section 3 the important arsenic intermetallic and Zintl phases are discussed emphasizing important technological aspects. The chemistry of inorganic arsenic hydrides and halides is presented in Sections 4 and 5 with many important fundamental issues that are difficult to find in one single textbook. Inorganic simple arsenic compounds that bear pnictogen and/or chalcogen atoms are discussed in Sections 6 and 8. In these two sections the chemistry is presented starting from species that are found in minerals to complexes that have arsenic as the central atom introducing exciting discrete arsenic molecules and aspects of supramolecular chemistry. The chemistry of arsenic–carbon species where the carbon atom is strictly inorganic is shown in Section 7. Finally, Section 9 intends to give a brief introduction of the impact of arsenic in the environment, especially focusing on issues related to living organisms.
BiomineralizationBased in part on the article Biomineralization by Richard B. Frankel which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Dauphin Yannicke 
Published: December 2011

Abstract
Three main categories are involved in biominerals: silica, calcium carbonates, and calcium phosphates. The calcium biominerals are usually crystalline, but amorphous types are also known. Within these categories, the shapes and chemical contents of structural units are variable. Moreover, the chemical and physical properties of biominerals are very different from the crystal habits produced inorganically: they depend on the producing plants and animals and the environmental conditions. Biomineral development is permanently controlled by specifically produced organic molecules that remain entrapped within the mineral units. Although biomineralization has been widely studied in the past, the growth mechanisms are still poorly understood, and the most elaborated model is based on the nacreous layer of mollusk shells. Studies on biominerals and biomineralization have various applications, from biology and geology to biomimetics.
Carbonyl Complexes of the Transition Metals
Authors: Calderazzo Fausto 
Published: December 2011

AbstractCarbon monoxide is a versatile ligand as it forms compounds with both transition metals and main group elements. Transition d metals of electronic configuration dn(0 < n < 10) form the most numerous class of these compounds, although recent progress has been made in expanding the area of existence toward main group, lanthanide (4f) and actinide (5f) metals. The most extensively studied series of carbonyl derivatives have the general formula [M(CO)n]m, withnrepresenting the coordination number of the central metal atom M, andmbeing the nuclearity of the system. In these compounds, the central metal atom is in the zero oxidation state. Starting from readily available inorganic derivatives in a positive oxidation state, the synthesis of these compounds normally requires a reducing agent capable of acting in the presence of carbon monoxide: in fact, only nickel metal, as a finely divided activated powder, is reactive toward CO leading to the corresponding derivative Ni(CO)4. The selection of the reducing agent varies as a function of the position of the metal M within the periodic table. There is a general trend of an increase in the nuclearitymtoward the end of the transition d series, the nuclearity being related to the bonding arrangements of the CO ligand, which may act as terminal, doubly bridging or triply bridging. Metal carbonyls are characterized by IR‐active vibrations around 2000 cm−1associated with the carbonyl groups. Vibrational spectra in solution give important information about: (a) the electronic distribution within the M–CO bond in terminally bonded carbonyl groups; (b) the molecular structure associated with the number of bands observed; (c) the type of bonding in dinuclear or polynuclear compounds. X‐ray diffraction data have been extensively used in order to define the molecular structure in the solid state. The metal–CO combinations span a wide range of oxidation states, derivatives being known for oxidation states from +III to −IV. Metal carbonyls undergo three types of reaction: (a) substitution of the carbonyl groups, whereby the oxidation state of the central metal atom remains unchanged, (b) oxidation, and (c) reduction. Carbonyl derivatives of early‐ and late transition metals present specific bonding and spectroscopic properties. Concerning the transition elements of groups 6–9, the M–CO bond dissociation enthalpy increases down the group, and is normally greater than the metal–metal bond enthalpy, the latter being estimated from the heat of atomization. From a mechanistic viewpoint, substitution and redox reactions have been studied extensively. A special case of substitution is the migratory carbonyl insertion, by which an M–R bond to a carbyl group R is converted by CO into the M–(CO)R sequence.
Iron: Heme Proteins & Dioxygen Transport & StorageBased in part on the article Iron: Heme Proteins & Dioxygen Transport by Harold M. Goff which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Hayashi Takashi 
Published: December 2011

AbstractMost organisms require dioxygen (O2) to survive; however, simple O2diffusion in blood does not supply a sufficient amount of oxygen for respiration. Thus, in all mammals, O2is carried and stored by O2‐binding heme proteins, myoglobin, and hemoglobin. Myoglobin is a single‐chain globular protein with heme as a prosthetic group, while hemoglobin consists of four heme‐containing subunits. O2binds to ferrous pentacoordinated heme‐iron and is stabilized by distal and proximal amino acid residues in the heme pocket. The O2pathway in the protein matrix and the binding mechanisms are discussed in detail by O2‐binding kinetic data for a series of myoglobin and hemoglobin mutants. Particularly, several residues, B10, E7, E10, E11, F7, and F8, mainly regulate the O2binding in the vertebrate heme proteins. In contrast, invertebrate and plant hemoglobins with unusually high O2affinities have been found in nature. InAscarishemoglobin, O2dissociation is very slow, whereas leghemoglobin shows a large O2association rate constant. In the case of trematode hemoglobin fromParamphistonum epiclitum, both kinetic parameters are improved. Artificial molecular design to modify O2affinity is another way to understand the O2binding mechanisms of the heme proteins. The strategy of heme protein modification can be divided into at least two approaches: One is a point mutation at distal or proximal amino acid residues, and the other is reconstitution by replacement of the native heme with an artificial heme. The physiological function of vertebrate hemoglobins is O2transport from the lungs or gills to the tissues; thus, they are required to exhibit cooperative interactions in binding O2to heme‐iron in the protein matrix. Although it is well known that a Hill coefficient of approximately 3.0 has been observed for tetrameric human hemoglobin, the mechanism of allosteric interaction is still discussed based on theoretical and experimental data. At present, an a two‐state (MWC) model proposed by Monod, Wyman, and Changeux for cooperative ligand binding is preferred to a sequential model. In addition, a study on the allosteric effectors for hemoglobins seems to be attractive from physiological aspects. The conventional effectors such as organic polyphosphate for human hemoglobin reduce the O2affinity of the T‐state, while it has been found that bezafibrate (BZF) or inositol hexaphosphate (IHP) can regulate O2binding not only for the T‐state but also for the R‐state. Finally, the interaction of NO with the heme proteins and modification of myoglobin for conversion into a new oxidase are briefly described.
Nitrogen Monoxide (Nitric Oxide): Bioinorganic Chemistry
Authors: Lancaster Jack R. , Giles Gregory I. 
Published: December 2011

AbstractIn only the last 20 years, Nitric oxide (NO, nitrogen monoxide), one of the smallest and simplest molecules in Nature, has been found to be involved in an astounding number of mammalian physiological and pathophysiological phenomena. The importance of NO as a messenger molecule in the cardiovascular system was recognized in 1998 by the awarding of the Nobel Prize in Physiology or Medicine and over 70000 papers have appeared involving NO in biology. The simplicity of its chemical structure stands in stark contrast to the complexity of its biological actions, including its “Janus‐faced” character as both beneficial and detrimental. This chapter is an overview of the history of this discovery, the fundamental chemistry of NO and its derivatives in the biological environment, and the multiple biological actions of NO.
Alkane Carbon–Hydrogen Bond Activation
Authors: Crabtree Robert H. 
Published: December 2011

AbstractThe title topic is reviewed with attention to alkane complexes, Shilov chemistry, alkane functionalization, Fenton reagents, oxidative addition pathways, sigma bond metathesis pathways, and surface‐bound reagents. Methane to methanol chemistry is discussed and attempts to commercialize the reaction are described in connection with Periana systems. Some organic synthetic applications are also covered. Future challenges are posed.
Nuclear Magnetic Resonance (
NMR
) Spectroscopy of Metallobiomolecules
Authors: Bren Kara L. 
Published: December 2011

Abstract
Nuclear magnetic resonance (NMR) spectroscopy provides information on the structure and dynamics of metallobiomolecules at atomic resolution. A range of metal‐binding sites in biomolecules can be studied by NMR, although the methods used require consideration of the properties of the metal site. Diamagnetic metal‐binding sites are probed using conventional NMR approaches appropriate for analyzing interactions between ions and macromolecules. Weak metal binding as is common in RNAs may require use of mimics that bind more strongly and/or that provide a specific spectroscopic handle. Paramagnetic metals induce hyperfine shifting and linebroadening that serve as signals of metal binding, but may also require adjustments to standard NMR methodologies. Hyperfine shifting takes place through scalar or dipolar mechanisms, and these effects in turn reveal details of metal site structure and metal electronic structure. Paramagnetic effects on chemical shifts are also used to refine structures of metallobiomolecules. Resonance broadening resulting from the hyperfine interaction is related to unpaired electron–nucleus distance as well as properties of the metal ion and thus can be a restraint on structure. The high magnetic anisotropy of some paramagnetic biomolecules can cause the molecule to take a preferential orientation within the applied magnetic field to allow observation of residual dipolar couplings, which reveal relative angular orientations of bond vectors. The study of the many effects of paramagnetic centers on NMR spectra has advanced the field of biomolecular solution structure determination as these efforts have introduced new restraints used in calculating structures. NMR is also valuable for analyzing biomolecule dynamics and chemical exchange processes. A related application is analysis of interactions between metallobiomolecules and ligands, or other macromolecules. Application of NMR to metallobiomolecules has provided a means to study phenomena difficult to observe using other methods such as interactions between proteins, electron self‐exchange reactions, and biomolecule dynamics over a wide range of time scales. NMR methodology continues to advance rapidly and is expected to continue to exert a large influence on our understanding of metal sites in biomolecules.
Nano/Microporous Materials: Transition Metal Cyanides
Authors: Lu Tong‐Bu , Collins David J. , Zhou Hong‐Cai 
Published: December 2011

Abstract
Transition metal–cyanide clusters, in which the cyanide anion acts as a bridging ligand, exhibit a rich variety of shapes and sizes, from simple squares to high‐nuclearity cubes and octahedra. Clusters may be homometallic or heterometallic, and a significant fraction of the transition metals are represented among these materials. Magnetic coupling in these clusters is widespread owing to the proximity of the metals and short length of the bridging cyanide. This review examines the structures and magnetic properties of the major types of transition metal–cyanide cluster materials.
Inorganic Nanocrystals: Patterning and Assembling
Authors: Curri Maria Lucia , Comparelli Roberto , Striccoli Marinella , Depalo Nicoletta , Fanizza Elisabetta 
Published: December 2011

AbstractRecently, increasing interest has been devoted to the study of the size‐dependent properties of inorganic nanocrystals and nanoparticles, in order to investigate and exploit their original potential. The ability to access nanoparticle properties for device fabrication is based on their organization in morphologically controlled assembly and/or ordered arrays, with suitable patterning, in order to bridge the gap between nanoscopic and mesoscopic scale.Assembly procedures allow the formation of original ordered state of matter and the fabrication of 2‐/3‐D patterned micro‐ and nanostructure, representing a promising route for producing functional materials and for processing and integrating the nanoparticles in macroscopic systems to fully develop their unprecedented functionality for materials and devices for biomedical, electronic, catalytic, and separation process technologies. Top‐down technological methods and techniques, conventional and emerging, have been cleverly and ingenuously combined and matched with dedicated bottom‐up approaches, paying attention to the peculiarity of the nanoparticle size regime. In most approaches, a precise control on the size and shape of the nanoparticles is crucial for driving the assembling and the extent to which the building blocks can be engineered, designed, and fabricated with desired features, including encoded instructions for assembling, has been greatly progressing in the last years. This article focuses on the potential of exploitation of inorganic nanocrystals and nanoparticles for assembling. An overview of the inorganic nanocrystal functions in the different and complementary strategies is outlined, highlighting the novelty and originality of the specific results and placing them in the scenario of the emerging material science, toward the envisioned creation of materials by design.
Quantum‐Chemistry‐Centered Normal Coordinate Analysis (
QCC
‐
NCA
): Application of
NCA
for the Simulation of the Vibrational Spectra of Large Molecules
Authors: Lehnert Nicolai 
Published: December 2011

Abstract

Vibrational spectroscopy is a powerful spectroscopic method that provides detailed information about the geometric and electronic structural properties of materials, compounds, and biomolecules. In the case of transition‐metal complexes, for example, vibrational spectra allow for the determination of the oxidation and spin state of the metal. In addition, vibrational spectroscopy is of great value in monitoring the binding and activation of small molecules, especially diatomics X–Y (O
2
, N
2
, CO, NO, etc.) and their derivatives, by transition‐metal complexes. Here, the coordination, reduction, protonation, derivatization, etc., of the diatomic can be monitored via the X–Y and metal‐XY bond strengths. Usually, the corresponding X–Y and metal‐XY vibrational frequencies are used for such correlations. This, however, is problematic because the energies of normal modes in general do not correlate directly with bond strengths, as they also depend on mode mixing and atomic masses. Because of this, it is much better to compare the X–Y and metal‐XY force constants along a reaction coordinate or between different species to identify chemically important changes/differences in bond strengths. This poses one problem: force constants are obtained from normal coordinate analysis (NCA), but how can this type of analysis be performed routinely for large molecules with many vibrational degrees of freedom, especially if the interest is focused on a small subunit of the molecule (the metal‐XY bond), whereas the other organic ligands L of the metal are of limited interest? The quantum chemistry centered normal coordinate analysis (QCC‐NCA) provides a solution to this problem by using density functional theory (DFT) calculations to generate an initial force field, followed by refinement of the limited number of force constants of the metal‐XY subunit only, whereas all other force constants remain unchanged. The available QCC‐NCA software allows one to perform this kind of analysis with minimal effort. This article provides a general introduction to the QCC‐NCA method and the underlying principles of vibrational analysis, combined with illustrative examples for applications from the area of the transition‐metal mediated activation of N
2
, O
2
, and NO. Special focus is put on the electronic structures and reactivities of ferrous‐heme nitrosyls, where the Fe–NO and N–O force constants have provided key insight into the activation of NO as a function of the trans ligand. The latest development with respect to the QCC‐NCA method is the calculation of nuclear resonance vibrational spectroscopy (NRVS) intensities, which is described in the final sections of this article.
Reaction Coordinate of Pyranopterin Molybdenum Enzymes
Authors: Kirk Martin L. , Knottenbelt Sushilla , Habtegabre Abebe 
Published: December 2011

Abstract
Spectroscopic studies on two pyranopterin molybdenum enzymes, sulfite oxidase and xanthine oxidase, have been used to evaluate the results of detailed bonding calculations and provide insight into the reductive half reaction of these enzymes. Specifically, the nature of the reaction coordinate with respect to substrate oxidation appears to be under orbital control, with the inherent electronic structure of the active site playing a key role in the reactivity of these metalloenzymes.