Food anaphylaxis

    Figure Avoidance is the primary measure in food allergy confirmed

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A novel Ce<Superscript>III</Superscript>-cyclam type complex and its redox chemistry in aqueous solutions

A new Ce^III complex was synthesized by mixing the ligand “dioxocyclam” with Ce^III ions at pH 8.0 and its redox properties were investigated.

Chemistry, commentary, and community: discussion of “an examination of the vaporization enthalpies and vapor pressures of pyrazine, pyrimidine, pyridazine, and 1,3,5-triazine” by Lipkind and Chickos

Vaporization enthalpies for the isomeric diazines were discussed within the context of recent measurements and estimation techniques. It is suggested that pyridazine shows enigmatic behavior.

Encapsulating of single quantum dots into polymer particles

Single semiconductor quantum dots were embedded into polymer particles with diameters below 0.1 μm by an emulsion polymerization procedure or via a secondary dispersion approach. The photoluminescence properties of the nanocrystals are retained upon encapsulation, as demonstrated by fluorescence confocal microscopy.

Chemistry,commentary and community: Discussion of “The NaDyBr<Subscript>4</Subscript> complex: its molecular structure and thermodynamic properties” by Varga and Hargittai

The molecular geometries, relative stabilities, binding energies, and dissociation energies of NaDyBr₄ and its molecular ion are discussed. Both the bidentate and tridentate isomers are stable for the neutral species, while only the bidentate form is stable for NaDyBr₄ ⁺.

Core-shell effects of functionalized oxide nanoparticles inside long-range meso-ordered spray-dried silica spheres

Core-shell and homogeneous distributions of functionalized cerium oxide nanoparticles within spray-dried mesostructured silica spheres are achieved by modification of synthesis parameters such as the templating agent and nanoparticle capping functions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Kinetics of substitution at [tris(3,5-dimethylpyrazolyl)-hydroborato]molybdenum nitrosyl dihalides by alcohols and by aniline

The kinetics of substitution by alcohols and by aniline at [tris(3,5-dimethylpyrazolyl)hydroborato]molybdenum nitrosyl dihalides in toluene solution at 298.2 K and at atmospheric pressure are reported and interpreted in terms of an associative mechanism.

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A note on Michael Weisberg’s: challenges to the structural conception of chemical bonding

Michael Weisberg’s recent 2007 paper on the chemical bond makes the claim that the chemical notion of the covalent bond is in trouble. This note casts doubts on that claim.

Do we need to rethink collaborative trials?

The currently recommended design of collaborative trials (interlaboratory method performance studies) is examined in relation to the usefulness of the resulting statistics. It is suggested that larger experiments, without duplicate analysis, would be more informative.

Comparison of synthetic procedures for the preparation of sol–gel derived phenoxy-silica hybrid materials

Novel phenoxy-silica hybrid materials (with 3 wt.% SiO₂) have been synthesized using different synthetic procedures. Differential scanning calorimetric (DSC) (T_g), FT-IR and transmission electron microscopy (TEM) results, as well as thermal and mechanical properties, are reported for these hybrids, which can be classified into three different groups, depending on the number of components synthesized in situ. Best results in terms of homogeneity (TEM) and mechanical properties have been obtained when the sol–gel process has been carried out in the presence of a phenoxy resin modified with a pendant alkoxysilane monomer.

Estimation of electrochemical quartz crystal microbalance frequencies from cyclic voltammetric data:—underpotential deposition of metals as an illustration

The estimation of electrochemical quartz crystal microbalance (EQCM) frequencies from a given cyclic voltammetric data is analysed using underpotential deposition (UPD) of metals as an illustrative process. The crucial role played by the surface roughness of electrodes and electrosorption valency of the depositing species is pointed out. The computed EQCM frequency shifts for the UPD of Cd and Tl on polycrystalline Ag electrodes are in satisfactory agreement with the experimental data.

Update on COMAR: the Internet database for certified reference materials

This paper describes the COMAR database for certified reference materials (CRMs). The Web-based version of COMAR is freely accessible via the Internet. COMAR was established to assist laboratories in finding the CRMs needed. The database is maintained in a collaboration of the world’s major CRM producers. The planned changes in the database as agreed at the last COMAR council meeting in Prague in May 2006 are indicated.

A comparative study of hydrothermal and sol–gel methods in the synthesis of MnO<Subscript>2</Subscript> nanostructures

In this work, MnO₂ nanostructure powders with different crystalline phases have been successfully prepared by hydrothermal and sol–gel methods. The obtained products were characterized by XRD and SEM techniques and their crystallographic phases and morphological properties compared. Results showed that α-MnO₂, β-MnO₂, and δ-MnO₂ nanorods were synthesized by hydrothermal method and γ-MnO₂ polymorph was obtained by sol–gel method.

Blue-emitting mesoporous films prepared via incorporation of luminescent Schiff base zinc(II) complex

Highly fluorescent materials have been prepared by incorporation of a zinc complex in mesoporous silica thin films with ordered pore structure. The zinc complex has been introduced into the mesoporous materials via impregnation in an ethanol solution. The incorporation into the films has been monitored by UV–Vis, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. After 18 h of immersion in the doping solution the films showed strong blue emission, increase in the refractive index. Leaching experiments performed by immersing the samples in ethanol or tetrahydrofuran have shown that the chromophore is retained in the porous matrix.

Electrochemical studies of bi- and polymetallic complexes featuring acetylide based bridging ligands

Acetylide-based bridging ligands have been widely used in the preparation of complexes that display a degree of electronic interaction between metal-based redox groups located at the ligand termini. The electrochemical response of these systems has been selectively reviewed, with a focus on the variation in properties that accompany changes in the structure of the bridging ligand and the nature of the metal groups.

Structure and chromotropic properties of mono- and binuclear mixed-ligand nickel(II) complexes containing 1,3-diketonate and polyamine ligands

Abstract  Mixed-ligand Ni^II complexes have been synthesized with 1,3-diketonate and bulky tri- or tetra-amine ligands. Their structures were determined by X-ray crystallography, and solvatochromic behavior was examined by UV–vis–NIR spectroscopy. Steric effects of the bulky ligands on the coordination distances and spectral properties are discussed. Graphical Abstract  

Properties of the electronic density of states in TiO<Subscript>2</Subscript> nanoparticles surrounded with aqueous electrolyte

Results on the density of sates of nanostructured TiO₂ as a function of particle size and temperature are reported. In TiO₂ nanoparticles with a mean diameter 10 nm, the density of states (DOS) is strongly temperature-dependent, indicating a rearrangement of the bandgap states in which the exponential energy parameter (width of the distribution) increases from 0.080 to 50 °C. For nanoparticles with mean diameters of 20 and 30 nm the DOS is much closer to an exponential distribution, and is much less sensitive to temperature variations. It is suggested that nanometer confinement has a significant influence on the density of electronic states for 10-nm particles, while band tailing is similar to that occurring in bulk semiconductors for the larger particles.

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Vocabulary of terms in protometrology

Protometrology is a new term recently proposed to designate the science of observation. As any field of knowledge needs a terminological system, in this article a system of terms and definitions on protometrology, with examples belonging to clinical laboratory sciences, is presented. This terminological system starts with the definitions of the two primitive concepts “object” and “property”.

Preparation, structural, and optical features of two-dimensional cross-linked DNA/gold-nanoparticle conjugates

The formation and the optical features of two-dimensional aggregates formed by DNA-directed immobilization and cross-linking of bifunctional DNA–gold nanoparticles at flat gold substrates are analyzed. The samples are structurally characterized by atomic force microscopy to evaluate the particle size, the particle densities, and the degree of aggregation. The optical characteristics determined by UV/visible measurements are correlated with the structural features observed.

Modeling of solvent viscosity effects on the electroreduction of Pt(II) aquachlorocomplexes

Solvent dynamics effects on the electroreduction of [PtCl₃(H₂O)]⁻ at a mercury electrode are explored in the framework of Sumi–Marcus model using an efficient computational scheme. According to results of density functional calculations, the second electron transfer step may be regarded as rate controlling. The nonmonotonous influence of solvent viscosity on the reaction rate is predicted and explained in terms of the saddle point avoidance. The results of model calculations are employed to interpret experimental data reported earlier in the literature.