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Solid-state transformations are important in many areas of science and technology. Herein, a model for predicting the relative energies of stationary points along the reaction pathways for stress-induced solid-state transformations is assessed and applied. The model is based on a second-order expansion of the energy of the system with respect to changes in the unit cell, and requires a small number of parameters that can be obtained through quantum chemical calculations. Comparison of the model with the results of quantum chemical calculations indicates that the model accurately reproduces changes in energy occurring during stress-induced transformations over a reasonable range of stresses. A procedure for applying the model to identify stress tensors that are most likely to promote a desired reaction is illustrated. The results also indicate that this procedure provides insight into the connection between the form of a stress tensor and the changes in energy occurring during a stress-induced solid-state transformation. Key words: mechanochemistry, models, density functional theory, materials, solid state, 1. Introduction Chemical transformations occur in conjunction with changes in energy. For instance, the kinetics of a reaction are influenced by the energy barrier separating the reactants from the products [...]

A preconcentration procedure for heavy metal ions in biological and water samples has been presented. The procedure is based on the sorption of [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+], and [Pb.sup.2+] on cellulose nanoparticles modified with folic acid. The prepared adsorbent was characterized by FT-IR, SEM, TEM, and BET measurements. Potentiometric titration is used to prove the complexation between metal ions and the modified cellulose as well as to calculate the cation-exchange capacity of the sorbent. The influences of the analytical parameters including pH, amount of adsorbent, shaking time, temperature, conditions of desorption, and the effects of matrix ions were studied. Under the optimized conditions, the calibration curves for [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+], and [Pb.sup.2+] were linear in the range of 2.7-200, 0.5-50, 0.37-150, and 10-300 µg [L.sup.-1], respectively. The detection limits (3s, n = 10) for [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+], and [Pb.sup.2+] were 0.81, 0.15, 0.11, and 3.9 µg [L.sup.-1], respectively. The proposed method offers a preconcentration factor of 200 for all of the ions studied and an enhancement factor for [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+], and [Pb.sup.2+] of 40.0, 30.8, 40.4, and 34.2, respectively. The accuracy of the suggested method was tested by analyzing spiked samples. The method was successfully applied to the determination of these metal ions in water and blood samples. Key words: modified cellulose nanoparticles, folic acid, solid-phase extraction, trace metal ions, atomic absorption spectrometry. Nous presentons une procedure de preconcentration d'ions de metaux lourds dans des echantillons biologiques et des echantillons d'eau. La procedure repose sur la sorption d'ions [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+] et [Pb.sup.2+] sur des nanoparticules de cellulose modifiee par l'acide folique. Nous avons caracterise l'adsorbant par des analyses FT-IR, MEB, MET et BET. Nous avons employe la technique de titrage potentiometrique pour faire la preuve de la complexation entre les ions metalliques et la cellulose modifiee ainsi que pour calculer la capacite d'echange cationique du sorbant. Nous avons etudie l'influence de parametres analytiques comme le pH, de la quantite d'adsorbant, du temps d'agitation, de la temperature, des conditions de desorption et des effets des ions de la matrice. En conditions optimisees, les courbes de calibration des ions [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+] et [Pb.sup.2+] etaient lineaires dans les intervalles de concentrations de 2,7 a 200, de 0,5 a 50, de 0,37 a 150 et de 10 a 300 µg [L.sup.-1] respectivement. Les limites de detection (3s, n = 10) des ions [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+] et [Pb.sup.2+] etaient de 0,81, 0,15, 0,11 et 3,9 µg [L.sup.-1] respectivement. La methode proposee permet d'obtenir un facteur de preconcentration de 200 pour tous les ions a l'essai et un facteur d'enrichissement des ions [Cu.sup.2+], [Cd.sup.2+], [Hg.sup.2+] et [Pb.sup.2+] de 40,0, 30,8, 40,4 et 34.2 respectivement. Nous avons mis a l'epreuve l'exactitude de la methode proposee en analysant des echantillons dopes. La methode a permis de doser avec succes ces ions metalliques dans des echantillons d'eau et de sang. [Traduit par la Redaction] Mots-cles: nanoparticules de cellulose modifiee, acide folique, extraction en phase solide, ions de metaux traces, spectrometrie d'absorption atomique., Introduction Trace analysis of metal ions in real samples is still difficult due to their low concentrations as well as the matrix interference. This issue can be resolved by preconcentration [...]

(Super 51)V solid-state NMR spectroscopy as a direct and sensitive reporter of the vanadium site in vanadium chloroperoxidases (VCPO) is introduced. Quantum mechanical DFT calculations of the NMR parameters for an extensive series of VCPO active site models indicate that the vanadate cofactor is most likely anionic with one axial hydroxo ligand, one equatorial hydroxo-, and two equatorial oxo- groups.

The nanoporous platinum oxide ([H.sub.1]-ePtO) as a hydrogen ion-selective sensing material is reported. Bare nanoporous platinum oxides exhibit near-Nernstian behavior (e.g., -55 mV/pH in PBS), ignorable hysteresis, a short response time, and high precision, which are remarkably better than those of flat platinum oxides. The electrode potential of a nanoporous platinum oxide responds exclusively to hydrogen ion, which implies its usefulness as a solid-state pH sensor. In the present study, the performance of nanoporous platinum oxide was investigated and compared with that of Ir[O.sub.x] in terms of selectivity and the influences of ionic strength, temperature, complexing ligands, and surfactants. HrePtO functions well as a pH-sensing solid-state material, and it is viewed as a promising alternative to Ir[O.sub.x]. Interference by redox couples was successfully suppressed by covering the [H.sub.1]-ePtO surface with a protective layer, e.g., an electropolymerized polyphenol thin film. Since the nanoporous platinum oxide with such a protective layer is particularly suitable for miniaturization and micropatterning, our findings suggest its usefulness in applications such as solid-state pH sensors embedded in chip-based microanalysis systems.

We present a new method for the determination of 29 endocrine-disrupting compounds in marine water. This method is based on a solid-phase extraction preconcentration technique, followed by a nanoscale liquid chromatography/ direct-electron ionization (EI) mass spectrometric analysis. Direct-EI is a novel technique for the rapid conversion of a GC/MS into an efficient and reliable LC/MS for EI detection. The capability to acquire EI mass spectra of the analytes, and to operate in selected ion monitoring mode during real sample analyses, allows certain identification and precise quantification. In addition, this method is not influenced by the polarity of the analytes and does not require different detection modes (positive and negative) for identification with API techniques. Limits of detection of the method span from 0.4 to 118.7 ng*L-1, corresponding to an instrumental detection limit of 0.005-1.260 ng. Linear regression and recovery experiment data, together with their standard deviations, are also presented. Marine water samples were collected along the middle-western ,adriatic Coast (Italy), near the shore and at the mouth of rivers and canals.

Research has been conducted on the dimethyl sulfoxide solvated thallium(III) ion. The vibrational spectra and the structure of this ion have been investigated in the dimethyl sulfoxide solution and in a solid state, and the results of the comparison of the coordination and bonding of solvated thallium(III) ions with those of the other solvated metal ions with the d (super)10 electronic configuration are presented.

Research has been conducted on the phosphine derivatives of bisphenoxide zinc and cadmium complexes. The solution and solid-state structural chemistry associated with these complexes have been investigated and the results are described.

Byline: A. Sobaszek (1), L. Adamowicz (1) Abstract: The calculations leading to the differential equations of statistical kinematics inside a solid and near the boundary between a solid and vacuum are given. The influence of the transmission coefficient of the boundary on the concentration of the diffusing material in solids is taken into account by introducing the length of extrapolation expressed by the polynomial of arbitrary order depending on the needed accuracy. The obtained length of extrapolation is influenced not only by the diffusion parameters and the boundary's characteristic feature but also by the initial distribution of concentration and by the time of diffusion. The presence of an external force is neglected. The numerical calculation for the planar diffusion of hydrogen in a palladium monocrystal is given as an example. The present method may be particularly useful for diffusion in thin layers and membranes, or when the detailed information on the distribution of diffusing material near the boundary between a solid and vacuum is needed. Author Affiliation: (1) Institute of Physics, Warsaw University of Technology, Koszykowa, 75, 00a662, Warsaw, Poland Article History: Registration Date: 23/09/2004

A series of potassium- and carbonate-containing apatites were prepared by solid state reactions at high temperature, keeping the CO2 atmosphere dry. Analyses of physical and chemical properties showed that the samples are single phase and contain 4-12 wt percent carbonate. The differences in the size of the K+ and Na+ is probably responsible for small differences in the physical properties of K+- and Na+-containing carbonated apatites.

Ricke zinc mediates the systematic regiocontrolled synthesis of regioregular and regiorandom films of poly(3-alkylthiophenes) (P3AT). Regioregular P3ATs are self-organized, flexible, crystalline, exhibit metallic luster and are bronze-colored, but regiorandom P3ATs are amorphous and orange-colored. The small bandgap of regioregular films is 0.4 eV lower than that of regiorandom P3ATs. Electroconductivity and physical properties of regioregular films are superior to that of regiorandom P3ATs.

Computational studies assuming single particle rotations help determine the hindered rotational energy levels of ammonium ion in crystalline environments in all directions. Energy levels help calculate heat capacity, thermal expansion, librational and tunneling frequencies and activation energies of ammonium ions. Various instrumental techniques help determine these parameters and two approaches help determine the energy levels due to hindered rotation of a tetrahedron. Rotational properties of ammonium compounds are discussed. Hindered rotational energies of symmetric tops and asymmetric tops are determined.

Low-valent iron complex bis(cyclooctatetraene)iron reacts with triethylphosphine telluride, TePEt3, to form extended inorganic solid-state tellurides of iron, FexTey. Various phosphine ligands produce different Fe/Te-containing compounds that are intermediates in the process. Structures of these intermediates are related to the final extended solid products. Use of larger ligands leads to the formation of smaller clusters and molecular structure of the complex influences the coupling characteristics of the Fe centers.

Complexation of mono and dinuclear Pd fragments yields neutral mixed-valence trinuclear palladium clusters, which demonstrate excellent stability in solution and solid-state. These complexes react strongly with weak proton donors, which convert phosphido ligands to secondary phosphines. Multinuclear NMR analysis characterizes these complexes.

Study of charge-transfer (CT) excitation of solid-state molecular complexes that induced single crystal-to-single transformation revealed the electron transfer (ET) process to be the initiator of solid state chemical reactions. Excitation of CT bands produced certain photoreactions characteristic of solid-state reactions. CT crystals exhibit electrical conduction and ferromagnetic behavior.

A corrole ring is synthesized by self-condensation of a monopyrrolic precursor. CO(OMTPC)PPh3 is formed from a porphyrinogen-like species through a ring-contraction reaction. Catalytic activity of the cobalt atom and steric release permitted by a corrole group are the main elements of this reaction. The complex exhibits a significant planar structure in the solid state.

Self-propagating solid-state precursor reactions between MoCl5.WCl6 and Na2S involve the rapid synthesis of high-quality molybdenum-tungsten disulfide solid solutions, (Mo,W)S2. The precursor methodology provides mixed-metal dichalcogenide products with a better metal dispersion than the products of long-term, high-temperature reactions between the elements.

Stereochemical analysis of benzoylformate azines, in solid, solution and gas states, reveals that azines adopt a Z,Z configuration and an N-N s-trans conformation. Phenyl groups exist in the molecular plane of the Ci-symmetric azine, and carboxyl groups are situated in almost perpendicular planes. Azines favor the same stereochemistry in the solid state and in the gas phase.

Bond lengths are enhanced, particularly in axial ligands, due to the stereochemically active solitary couple in (HB(3-But-5-Mepz)3)SnCl, as against that seen in (HB(3-But(pz)3))CdCl, by examining the geometries of two four-coordinates. Intramolecular steric influences do not cause the enhanced bond lengths, which are related to the effects of the single couple that modifies the total structure of the tin(II) complex. A stereochemically inactive lone pair cannot be a part of a tin(II) poly(pyrazolyl)borate compound when it is synthesized.

An experiment was conducted to develop and define homoleptic tin(II) and lead(II) tellurolates, selenolates and thiolates, which possess ESi(SiMe3)3 ligands. Elementary examination and x-ray powder diffraction corroborated the structure and crystallinity of these complexes. Due to thermolysis, UV irradiation or combination of Lewis bases with hydrocarbon solutions related decomposition reactions may occur at low temperatures.

The introduction of chromium(III) nitrate (Cr NO3 3), ytterbium chloride (YbCl3) and copper chloride (CuCl2) in (calix 4 arenesulfonate)4+ solutions follows three distinct interaction procedures. First, the addition of Cr(NO3)3 leads to the intercalation of the compound into the inter-calix layered structure without the formation of Cr(III)-sulfonate oxygen bonds. The addition reaction of YbCl3 results in the interaction of the ytterbium ion with sulfonate groups of one calixarene, while CuCl2 reactions involve interaction with more than one calixarene units.

A property called entanglement entropy helps to describe the quantum states of interacting particles, and it has at last been measured. The findings open the door to a deeper understanding [...]

Polymer single crystal solid-state grafting-to and grafting-from methods are used for achieving Janus gold nanoparticles (AuNPs) with two different polymer chains decorated on the opposite sides of the NPs. This approach might serve as a generic method for preparing polymer-functionalized Janus NPs and this system holds promises for achieving controlled assembly and tunable optic and electronic properties of NPs.

A high-temperature solid-state reaction method was used to prepare [Sm.sup.2+] ions doped KSrP[O.sub.4] and its crystal structure was analyzed by x-ray diffraction (XRD). The crystallographic sites and the energy structure were found to be associated with 4f->5d transitions of [Sm.sup.2+] ions in KSrP[O.sub.4].

The study explains the importance of various acid supports in several heterogeneous organic base-catalyzed reactions taking place on a solid surface. The supports are found to enhance such reactions and hence can be used in the creation of new heterogeneous catalysts.

The synthetic methods and physical properties of molecule bowls based on the corannulene motif which was first characterized bowl-shaped polynuclear aromatic hydrocarbon (PAH) is presented. The molecule stacking and alignment of the bowl-shaped aromatic compounds in the solid state affect the dipoles and electronic properties.

The crystal structure, multinuclear solid-state NMR spectra and high optical birefringence of Pb[Au(CN)(sub 2)](sub 2)(H2O)(sub x) (x = 0, 1) are reported. The results show that Pb(H2O)[Au(CN)(sub 2)](sub 2) has high optical birefringence that is attributed to the anisotropy of the 2-dimensional slabs of 1, with all C triple bond N bonds aligned in the same direction by the polarization lead(II) center.

The conditions for microwave power generation with hot-electron transport are investigated in a submicron GaN diode when it operates in the limited space-charge accumulation (LSA) mode. Applying a transport model based on local quasistatic approximation, the analysis shows that the nitride diodes can support the LSA mode of oscillation in the terahertz-frequency range.

The polymorphic form of sodium acetate (SA) obtained by dehydration of sodium acetate trihydrate (SA.3H2O) is altered by carrying out the dehydration process under conditions of rapid sample rotation in a solid-state magic-angle-spinning (MAS) NMR probe. Sample rotation produces a centrifugal force in the radial direction with respect to the rotation axis, and the magnitude of this force is higher as distance from the rotation axis increases.

Annealing of the Ga2O3/ZnO core-shell nanowires is done to achieve the formation of well-aligned and single-crystalline ZnGa2O4 nanowires on sapphire (0001) substrates. Structural analysis of the annealed nanowires reveals the existence of an epitaxial relationship between ZnGa2O4 and Ga2O3 phases during the solid-state reaction.

Growth-induced polarity formation in solid solutions composed of dipolar 4-chloro-4'-nitrostilbene molecules and nonpolar 4,4'-dinitrostilbene molecules is investigated by means of two molecular modeling procedures. The study highlights the fact that a solid solution crystal may not be a homogenous entity and that surface effects arising during slow growth can have an impact on solid state properties.

A nearly exhaustive examination is performed throughout the fluoro[60]fullerene family, describing the influence of the intercalated element considered, stoichiometry, structural type, and fluorine content on the potential stability of an intercalated phase. An insight into the solid state properties of this class of materials, combined with a widespread range of potential applications, is provided.

The cyclic bis(amido)tin(II) compound Sn[1,8-((super i)PrN)2C10H6] is isolated from the reaction of Li2[1,8-((super iPrN)2C10H6] and SnCl2. Solid-state structural analysis of Sn[1,8-((super i)PrN)2C10H6] showed it to be a mononuclear species with a pyramidal Sn center as part of a nonplanar metallaheterocycle.

Neutral trinuclear metal complexes L2Cd3.2H2O, L2Mn3.MeOH, and L2Zn3.MeOH is isolated in the reaction between the phosphorus-centered achiral tris(hydrazone) P(S)[N(Me)N=CHC6H4-o-OH]3 (LH3) and the corresponding divalent metal ions. It is found that the tricadmium complex is luminescent in the solid state as well as in solution.

A simple combination pH electrode consisting of a solid-state quinhydrone sensor and a solid-state quinhydrone reference electrode is described. Both electrodes are essentially rubber stoppers that are inserted into a special doublewalled holder.

Packing efficiency and crystal density can be calculated from basic geometric principles employing the Pythagorean theorem, if the unit-cell structure is known. The procedures illustrated have applicability in courses such as general chemistry, intermediate and advanced inorganic, materials science, and solid-state physics.

The history of the discovery and development of the periodic mesoporous organosilicas (PMOs) emphasizing the most important advancements regarding compositions and structures, morphologies, and properties are discussed. An outlook about the promising future perspectives of PMOs that result from the latest developments in this field is presented.

The influence of pH and Ca(super 2+) ions on the conformational transition from silk I to silk II in regenerated (redissolved) Bombyx mori fibroin is investigated using Raman spectroscopy and C solid-state NMR. The results suggest that regenerated silk fibrion is a useful model system for analyzing the role of calcium ions and pH in controlling the aggregation, orientation and formation of intermolecular beta-sheets in clinically important proteins.

Magic-angle spinning (MAS) NMR is used to study solid powder samples of complexes of the endometallofullerenes (EMF) La@C82 and Y@C82 with hexamethylphosphoramide (HMPA). It is concluded that paramagnetic La@C82 and Y@C82 in the solid state form clusters or nanoparticles.

The kinetics of 'nucleation-and-branching' rate-limited solid-state reactions are studied. Coupled rate equations are used for this purpose.

(super 17)O NMR data can be easily collected at reasonably high fields (14.1T) from amino acids with good signal to noise ratios from samples where only 10-20 atom percent (super 17)O enriched water was used in the sample preparation. Typical (super 17)O MAS NMR spectra consists of well-separated second-order quadrupolar line shapes from carbonyl and hydroxyl oxygens.

The time profiles of the intensities, line widths and chemical shifts if (super 1)H NMR signals of adsorbed water at 358k were investigated for six different TiO2 photocatalysts with different properties solid-state (super 1)H NMR spectroscopy. The apparent single water peak was found to comprise the signals with different line widths and chemical shifts which corresponded to those of water molecules with different structures and mobility.

EXAFS and XANES at the Pd and/or Sn K-edge are used to characterize pure and palladium doped spherical particles of a novel Sn/SnO(sub x) nanocomposite. These organic precursors are useful in a new type of high performance solid-state gas sensor.

An experiment was conducted, using solid-state (super 129)Xe and (super 19)F nuclear magnetic resonance (NMR) spectroscopy and nonrelativistic and spin-orbit relativistic zeroth-order regular approximation density functional theory (ZORA DFT), to characterize the xenon and fluorine magnetic shielding tensors, alpha, of XeF2. The result demonstrates that relativistic effects play an important role in the nuclear magnetic shielding for xenon.

A study was conducted, using solid-state (super 13)C nuclear magnetic resonance (NMR) spectroscopy, with a well-defined signal-to-noise ratio, to investigate the B2 and B4 phases of the classic banana-shaped molecule called P-14-O-PIMB. The result reveals that twisted conformations are preserved in both the phases, and suggests that the twisted conformation is the origin of the chirality in the B2 and B4 phases.

A successful application of variable-temperature diffuse reflectance spectroscopy is reported for the study of the solid-state thermo- and photochromism of salicylideneanilines that belong to a class of the most well-know chromic organic compounds. It is demonstrated that the color of the materials is controlled by a trace of colored species and that the variable-temperature diffuse reflectance spectroscopy is quite an effective tool for its detention and therefore the study of the chromism in the solid state.

The preparation of monolayers of 11-azido-undecylisiloxane on powdered silica and on silicon wafers by the substitution of 11-bromo-undecylisiloxane and were subsequently coupled with three substituted acetylenes to yield 1,2,3 triazoles via the Huisgen 1,3-dipolar cycloaddition reaction is shown. A test was also conducted to examine the reactions for their suitability to modify and functionalize solid-state surfaces.