bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mössbauer Spectroscopy
Authors: Schünemann Volker , Paulsen Hauke 
Published: March 2008

AbstractMössbauer spectroscopy offers information about the structural, electronic, and dynamic properties of Mössbauer‐active isotopes. Within this contribution we will limit ourselves to57Fe Mössbauer spectroscopy and discuss how electronic and structural information of iron centers in inorganic and bioinorganic compounds as well as iron proteins can be obtained. An introduction to the basic principles and necessary sample requirements is followed by examples of Mössbauer spectroscopic work on metallic iron, iron nanoparticles, and thin films. The main part of this contribution contains an overview of selected examples of iron compounds in almost all oxidation states known so far, ranging from zero‐valent iron carbonyls to very recently reported ultra‐high‐valent Fe(VI) coordination compounds. In addition, a short overview on the theoretical calculation of Mössbauer parameters like isomer shift and quadrupole splitting by means of density functional theory is given. These calculations have been improved considerably in recent years and are expected to be used by an increasing number of inorganic chemists for the interpretation of spectroscopic results.
Magnetic Circular Dichroism (
MCD
) Spectroscopy
Authors: Mack John , Stillman Martin J. 
Published: March 2008

Abstract
Magnetic circular dichroism (MCD) spectroscopy provides information about the spin and orbital angular momenta associated with ground and excited electronic states. This can provide the key to understanding the optical spectroscopy of high symmetry ions and complexes, which provides an important insight into the electronic structure. MCD spectra contain the same set of spectral bands as the corresponding electronic absorption spectrum, with significantly different band morphologies due to the effect of the applied magnetic field and the use of a differential absorbance intensity scale.

MCD spectra are recorded by mounting a superconducting magnet (
B
≈ 0–11 T), an electromagnet (
B
≈ 0–1 T), or a permanent magnet into the sample compartment of a CD spectrometer with the field applied parallel to the axis of light propagation. Parallel applied fields are often referred to as the Faraday magnet alignment, since it formed the basis of Faraday's pioneering experiments in which plane polarized beams of light were found to be rotated during transmission through certain substances, due to the differential absorbance of left circularly polarized (lcp) and right circularly polarized (rcp) light. The Faraday 𝒜

1

, ℬ

0

, and 𝒞

0

terms form the basis for the analysis of MCD spectra based on the Zeeman splitting of the absorption bands for lcp and rcp light, the field‐induced mixing of zero‐field states, and the Zeeman splitting‐based ground state population adjustment, respectively.
Nuclear Magnetic Resonance (NMR) Spectroscopy of Inorganic/Organometallic Molecules
Authors: Iggo Jonathan A. , Liu Jianke , Khimyak Yaroslav Z. 
Published: March 2008

AbstractNMR spectroscopy is an indispensable spectroscopic tool for the characterization of inorganic compounds. This contribution provides a guide to the application of recent advances in high‐resolution, solid‐state, and high‐pressure NMR spectroscopic methods to organometallic/inorganic molecules and solids. The topics covered include methods for the determination of structure, intermolecular interactions, solid‐state organization, reaction kinetics, and diffusion.
Nuclear Quadrupole Resonance (NQR) Spectroscopy
Authors: Wulfsberg Gary P. 
Published: March 2008

AbstractThe article concerns the usefulness of nuclear quadrupole resonance (NQR) spectroscopy in inorganic and organometallic chemistry. NQR‐active nuclei have spinI ≥ 1; those of high enough abundance to be commonly useful are found in the odd‐numbered groups of the periodic table. These are tabulated and examples given for each. The number of NQR frequencies observed in a solid‐state compound reflects the number of chemically different quadrupolar atoms in the compound and also the number of crystallographically inequivalent atoms; changes in the latter may indicate phase transitions or different polymorphs of a given compound. More commonly, one uses average NQR frequencies for chemically different atoms, and from these average frequencies, derives atomic parameters such as populations of valence orbitals, partial ionic charges, π‐bond orders, and covalent bond orders of the quadrupolar atom. The article mainly reviews selected applications of halogen (35Cl,79, 81Br,127I) NQR to specific bonding questions in inorganic chemistry, and divides these according to whether the halogen or other atoms are (a) single bonded, (b) single bonded but with secondary bonds with other atoms, or (c) bonded to several atoms. For singly bonded atoms, the applications reviewed include (a1) relativistic effects, (a2) effects of nearby ionic charges on haloacetate ions, (a3) the contrasting effects of nearby ionic charges on halometallate ions, (a4) effects of intramolecular partial charges on chlorines in organosilicon compounds, (a5) cis‐and trans‐ ligand effects in substituted halometallate complexes, and (a6) interpretations of multicentered bonding in trihalide ions. Secondary bonding of single‐bonded halogen atoms are reviewed particularly in the cases of (b1) halocarbons as ligands, (b2) chloroacetates and chlorophenolates as chlorine‐donor ligands, and (b3) in salts of weakly coordinated halogenated anions. Finally, some illustrations are given of NQR studies of central multicoordinated atoms (for example, transition‐metal atoms in complexes).
X‐Ray Absorption Spectroscopy
Authors: Bencze Krisztina Z. , Kondapalli Kalyan C. , Stemmler Timothy L. 
Published: March 2008

Abstract
X‐ray absorption spectroscopy (XAS), often referred to as X‐ray absorption fine structure (XAFS) spectroscopy, is a powerful technique available for determining the local coordination site structure and electronic properties of specific atoms in molecules. XAS can be performed on molecules in the gaseous, solution, or solid states, and generally every element is spectroscopically active. This technique utilizes high intensity X rays supplied by synchrotron radiation sources to selectively excite core electron transitions for a specific element of choice. XAS spectra are divided into two spectral regions, the X‐ray absorption near edge structure (XANES) region and the extended X‐ray absorption fine structure (EXAFS) region. XANES spectra can be utilized to provide: (1) qualitative information regarding the ligands coordinated to the absorbing atom, (2) semi‐quantitative information regarding the redox state of the absorbing atom, and (3) metal‐ligand coordination geometry. Simulations of the EXAFS data can provide information regarding absorber‐scatterer bond length values to extremely high accuracy (ca. ±0.02 Å), as well as coordination numbers and ligand identity at reduced accuracies. The high accuracy in bond lengths achieved from XAS makes this technique extremely sensitive for measuring subtle structural perturbations within molecules under perturbed or turnover conditions. When utilized with other techniques, XAS can supply the metrical parameters required to understand the chemical properties of specific elements in a molecule.
X‐Ray Powder Diffraction
Authors: Clearfield Abraham , Bhuvanesh Nattamai 
Published: March 2008

AbstractCrystalline solids may be described as containing a unit of matter that when repeated in three‐dimensional space reproduces the crystal. Because of the periodic nature of crystals and the fact that the distances between the atoms, that is, bond distances, are of the same order of magnitude as X‐ray wavelengths, the crystals act as diffraction gratings toward X‐ray beams. Diffraction from a small single crystal produces a three‐dimensional array of spots whose geometry can be related to the geometry of the unit cell and the three noncoplanar vectors that describe the periodic arrangement of the unit cells. Knowledge of the intensities of the diffracted radiation allows the determination of the atoms within the unit cell.Many compounds occur as polycrystalline solids or powders. Most solids in nature are present as mixtures of two or more crystalline phases. Such materials still diffract X‐rays but the three‐dimensional array of spots is condensed into a one‐dimensional array of diffraction lines or near Gaussian peaks. Because of this low dimensionality much less data are obtained; however, a great deal of information may still be derived from the powder pattern referred to as X‐ray powder diffraction (XRPD) for XRPD pattern. In its simplest form the XRPD may be used as a fingerprint to identify a particular phase or mixture of phases. The amount of each phase may be determined quantitatively.As the crystallite size decreases, the X‐ray peaks broaden, so it is possible to obtain a measure of the crystallite size. Lattice strain also contributes to peak broadening, requiring that the two effects be separated for accuracy in interpretation of the data. The advent of high speed computers and highly engineered diffractometers allows for rapid accurate analysis of powder mixtures or the study of solid solutions, defects and other complexities of crystalline material. It is, in many cases, possible to determine the crystal structure of compounds from their X‐ray powder data and this aspect of powder diffractometry is included here. Diffraction does not occur from amorphous solids, but X‐rays are scattered and much information on particle size and short range order can be obtained from small angle X‐ray and neutron scattering studies. Furthermore, EXAFS and Atomic Pair Distribution functions provide a means of probing the structures of amorphous and semicrystalline materials.
Circular Dichroism (
CD
) Spectroscopy
Authors: Presta P. Anthony , Stillman Martin J. 
Published: March 2008

Abstract
Circular dichroism (CD) spectroscopy is of fundamental importance as a tool in all areas of chemistry and biochemistry because this technique is the simplest and fastest measure of the presence of the chiral species that lead to optical activity. Chiral centers and chiral species exist from the simplest molecules to complex organic molecules, from inorganic complexes to metal‐based biological molecules, typically metalloproteins; from folded polymers, which are typically peptides and proteins; to the supramolecular organization of the quaternary structure of proteins; including all forms of helical structure typified by the the double helix; to liquid crystals and beyond, to even more massive and organized species. For all these species, CD spectroscopy provides insight into the presence and the extent of the chiral electric field induced by the atomic and molecular organization. The optical activity is detected under electronic and vibrational absorption bands as a result of the differential absorption of left‐ and right‐circularly polarized light. Measurement of mirror images of the CD spectrum is commonly used to determine the enantiomeric purity of small molecules. The measurement of the change, and sometimes loss, of optical activity measured in the spectral region of the chiral chromophores can be used to determine and understand the denaturation of a folded protein as the chirality changes with the change in gross structural features associated with the folding.
We focus particularly in this chapter on the influence of metals on the chiral properties of proteins. Metal binding results in changes in molecular and supramolecular conformations readily measured under metal‐based spectral bands. In cases for which the folding of the protein is almost entirely metal‐induced, the CD spectrum becomes an extremely sensitive marker for structural change as a function of metal loading allowing both the stoichiometry of metal binding and the coordination geometry to be proposed.

Measurement of the chirality of a molecule is easy in the region 190–1000 nm as several relatively inexpensive instruments provide high sensitivity. Time‐resolved CD spectral data are also readily achievable using stopped‐flow devices. Measurement in the infrared regions is also popular and provides invaluable information; instruments can now be purchased “off the shelf”. The new growth area is the use of synchrotron radiation as the light source allowing CD spectral data to be measured in all regions of the electromagnetic spectrum, but particularly, for energies higher than 50 000 cm
−1
(below 200 nm).
Electrochemistry
Authors: Elvington Mark C. , Brewer Karen J. 
Published: March 2008

AbstractThis chapter provides a summary of electrochemical methods with an emphasis on applications to inorganic chemistry. Electrochemical methods include potential sweep, potential step, and bulk methods including coupling of bulk electrolysis methods to characterization methods. Discussions include examples from the literature and important experimental considerations. Techniques discussed include cyclic voltammetry, differential pulse voltammetry and polarography, square wave voltammetry, and bulk electrolysis. The coupling of analysis methods including electronic absorption, IR and EPR spectroscopy to bulk electrolysis are provided. Discussions are tailored to the application of electrochemistry in inorganic chemistry research with practical considerations and illustrative examples provided.
Magnetism and Phase Formation in the Candidate Dilute Magnetic Semiconductor System In2 − xCrxO3: Bulk Materials are Dilute Paramagnets
Authors: Bizo L. , Allix M. , Niu H. , Rosseinsky M. J. 
Published: March 2008

AbstractWell‐characterized bulk materials in the candidate dilute magnetic semiconductor system In2 − xCrxO3 are prepared for 0 ≤ x < 0.15, with cation site preferences in the bixbyite structure identified by diffraction methods. Small ferromagnetic moments are observed; their size (<10−2 µB/dopant ion) is not consistent with bulk ferromagnetism. The resulting bulk materials display dilute paramagnetic behaviour, with all of the moment expected per Cr3+ cation dopant being involved in this paramagnetic response.
Template Synthesis of Aligned Carbon Nanotube Arrays using Glucose as a Carbon Source: Pt Decoration of Inner and Outer Nanotube Surfaces for Fuel‐Cell Catalysts
Authors: Wen Zhenhai , Wang Qiang , Li Jinghong 
Published: March 2008

AbstractA facile method is developed to synthesize aligned arrays of open‐ended carbon nanotubes (CNTs) via in situ glucose polymerization in the inner pores of anodic aluminum oxide templates under hydrothermal conditions, followed by carbonization at high temperature. Pt nanoparticles are decorated on the surfaces of the as‐prepared CNTs using the incipient wet method based on the use of NaBH4 as a reductant. Characterization of the resulting structures by transmission electron microscopy and field‐emission scanning electron microscopy demonstrates that the Pt nanoparticles are anchored on both the inner and outer walls of CNTs, thus giving rise to a shell–core–shell‐like nanotube composite. The electrocatalytic properties of the Pt–CNT–Pt electrodes are investigated for methanol oxidation by cyclic voltammetry and chronoamperometric measurements. It is found that the hybrid electrodes show superior catalytic performance compared to commercial carbon‐black‐supported Pt. The increased catalytic efficiency of Pt might be a result of the unique morphology of these structures.
Two‐Dimensional Hexagonally‐Ordered Mesoporous Carbon Nitrides with Tunable Pore Diameter, Surface Area and Nitrogen Content
Authors: Vinu Ajayan 
Published: March 2008

AbstractTwo‐dimensional mesoporous carbon nitride (MCN) with tunable pore diameters have been successfully prepared for the first time using SBA‐15 materials with different pore diameters as templates through a simple polymerization reaction between ethylenediamine (EDA) and carbon tetrachloride (CTC) by a nano hard‐templating approach. The obtained materials have been unambiguously characterized using X‐ray diffraction (XRD), N2 adsorption, high‐resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), high‐resolution scanning electron microscopy (HRSEM), X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT‐IR) spectroscopy, and CHN analysis. The results show that the pore diameter of the MCN materials can be easily tuned from 4.2 to 6.4 nm without affecting their structural order. XRD, HRTEM and N2 adsorption results reveal that the materials are structurally well ordered with a two‐dimensional porous structure, a high surface area and a large pore volume. It is also demonstrated for the first time that the textural parameters such as the specific pore volume, the specific surface area and the pore diameter, and the nitrogen content of the MCN materials can be controlled by the simple adjustment of the EDA to CTC weight ratio. The carbon to nitrogen ratio of the MCN decreases from 4.3 to 3.3 with increasing EDA to CTC weight ratio from 0.3 to 0.9. The optimum EDA to CTC weight ratio required for fabricating the well‐ordered MCN materials with excellent textural parameters and high nitrogen content is around 0.45. The catalytic activity of the materials has been tested in the Friedel‐Crafts acylation of benzene using hexanoyl chloride as the acylating agent. The materials are highly active and show a high conversion and 100 % product selectivity to caprophenone.
Optimization of a pulsed operation of gas separation by membrane
Authors: Corriou Jean‐Pierre , Fonteix Christian , Favre Eric 
Published: March 2008

AbstractA pulsed cyclic membrane process, originally proposed by Paul for gas separations, has been investigated through a simulation and optimization study. For carbon dioxide hydrogen separation, it is shown that cyclic operation, based on an already reported material, could potentially compete with the most selective, still virtual, polymers, both in terms of selectivity and productivity. The use of asynchronous cycling operation, unexplored up to now, has been more specifically investigated. This mode of operation offers an extended range of performances from the point of view of the selectivity‐productivity trade‐off. A dedicated optimization study based on either nonlinear or genetic algorithm approach shows that, for this system, synchronous operation offers the best performances. These results have been confirmed by multiobjective optimization by means of the genetic algorithm. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Principles for hearing grievances, and an effective response
Authors: Rees Caroline 
Published: March 2008

AbstractTwo CPR Fall 2007 Meeting panelists re‐team to expand their focus on corporate social responsibility and its relationship to conflict resolution. First, John Sherman, of Westborough, Mass., describes why his employer, energy provider National Grid, focuses substantial business efforts on giving communities a voice in its efforts. Caroline Rees, of Cambridge, Mass., examines the need for grievance mechanisms to address inevitable local conflicts. Both authors provide practical advice based on adaptable existing models.
Graft copolymerization of acrylamide onto tamarind kernel powder in the presence of ceric ion
Authors: Goyal Puja , Kumar Vineet , Sharma Pradeep 
Published: March 2008

AbstractTamarind kernel powder (TKP), a natural xyloglucan polysaccharide is derived from the seeds of Tamarindus indica Linn., a common and most important tree of India and South East Asia. TKP is used in cotton sizing, as a wet‐end additive in the paper industry, as a thickening, stabilizing, and gelling agent in the food industry. Chemical modification of TKP through grafting has received considerable attention to impart new functional groups for different applications. Keeping this in view, graft copolymerization of acrylamide (AA) onto TKP was carried out in an aqueous medium using a ceric ammonium nitrate (CAN)‐nitric acid initiation system. The reaction conditions were optimized for grafting with respect to the effect of the concentrations of CAN, nitric acid, TKP, AA, time, and reaction temperature. The maximum percentage grafting (%G) and percentage grafting efficiency (%GE) were found to be 231.45 and 93.66%, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Hydrogel–hydrogel composites: The interfacial structure and interaction between water and polymer chains
Authors: Li Xinming , Cui Yingde , Xiao Jianliang , Liao Liewen 
Published: March 2008

AbstractThis work examines the interfacial structure and interaction between water and polymer chains in the hydrogel–hydrogel composites with the goal of establishing foundations for further investigation of drug diffusion from one hydrogel to another in the soft contact lens. This is based on the ability of the hydrogel–hydrogel composites to release ophthalmic drugs in a sustained manner. The hydrogel–hydrogel composites were synthesized by immersing the glycerol‐swollen particles of crosslinked N‐vinyl‐2‐pyrrolidone (NVP) into the monomer of hydroxyethylmethacrylate (HEMA) containing initiator benzoylperoxide (BPO) that polymerizes to form a matrix in the presence of the first networks. The hydrogel–hydrogel composites were characterized by UV/Vis spectrophotometer, scanning electronic micrography (SEM), and differential scanning calorimetry (DSC). The results showed that the samples of hydrogel–hydrogel composites of the particles of crosslinked NVP and poly‐HEMA were transparent and glassy and suitable for soft contact lens. Three types of the interfacial structure, no interpenetrating interface, partly interpenetrating interface, and fully interpenetrating interface, of the hydrogel–hydrogel composites existed, and the type of the interfacial structure was determined by the degree to which the monomer of HEMA penetrated into the first networks before formation of the matrix. Different from poly‐HEMA hydrogels, the peaks near 0°C on DSC curves of the hydrogel–hydrogel composites did not split while they were kept acute, and the amount of freezable‐bound water was less. This shows that the water incorporated in the hydrogel–hydrogel composites does not strongly interact with polymer matrix, so the hydrogel–hydrogel composites cannot keep their shape during the phase transition of water. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Mathematik, Naturwissenschaften und Technik als Bestandteile der Kultur der Gegenwart
Authors: Tobies Renate 
Published: March 2008

AbstractMathematics, Natural Sciences and Technology – Parts of the Encyclopedia Die Kultur der Gegenwart (The culture of today). The paper explores the trend of the early 20th century to consolidate mathematics, natural sciences, medicine and technology under the umbrella of one integrative culture – a tendency which contrasts with the increasing mainstream trend of separating the humanities from the natural sciences. The unifying umbrella was framed by the great encyclopedia Die Kultur der Gegenwart which was published by B. G. Teubner from 1905 to 1925 and was planned to run up to 62 volumes. We analyze the quantitative rate of the parts devoted to the humanities, the natural sciences and technology, respectively, the degree to which these parts were completed in this encyclopedia. In particular, we investigate the role of mathematicians and their reasons to find a classification for the mathematical, natural scientific and engineering parts of culture as well as their reasons, to win Nobel prize winners and other famous scientists to become co‐editors and authors. We examine the published volumes in the fields of mathematics, chemistry, physics, astronomy and technology in order to show what type of publication – professional or popular – was intended. Furthermore, we illuminate how the educational reform of mathematics, natural sciences and technology of this period – which included a reform of girls' and women's education – was reflected in the encyclopedia Die Kultur der Gegenwart.