In situ Electron Microscopy Investigation of Fe(III)-doped TiO2 Nanoparticles in an Aqueous Environment

Three-dimensional networks of Fe(III)-doped TiO₂ nanoparticles (2–4 nm) prepared from organic precursors are detected by Cryo-TEM (transmission electron microscopy) in an aqueous environment. High-resolution TEM studies show that the nanoparticles prefer to align along their crystallographic orientation. A novel energy transfer mechanism is suggested in which these three-dimensional networks act as antenna systems thus leading to an enhanced photocatalytic activity of the colloidal preparations.     

Algebraic K-Theory of Two-Dimensional Crystallographic Groups

Abstract. We explicitly compute the lower algebraicK-groups of the two-dimensional crystallographic groups.     

Properly discontinuous actions of subgroups in amenable algebraic groups and its application to affine motions

This note will concern properly discontinuous actions of subgroups in real algebraic groups on contractible manifolds. Let (π,X,ρ) be such an action, where ρ:π→ Diff(X) is a homomorphism. We assume that ? extends to a smooth action of a real algebraic group G containing π. If such π has a nontrivial radical (i.e., unique maximal normal solvable subgroup), then we can apply the method of Seifert construction [14],[17] to yield that the quotient π\X supports the structure of an injective Seifert fibering with typical (resp. exceptional) fiber diffeomorphic to a solv (resp. infrasolv)-manifold (when π acts freely). When G is an amenable algebraic group, we can say about a uniqueness property for such actions. Namely, let (π_i, X_i, ρ_i) be actions as above (i= 1,2). Then, given an isomorphism f of π₁ onto ?₂, there is a diffeomorphism h: X₁→X₂ such that h(ρ₁(r)x)=ρ₂(f(r)h(x).As an application, we try to decide the structure of affine motions of some euclidean space $\text{R}$ⁿ. First we verify the conjecture of [17, 4 5], i.e., a compact complete affinely flat manifold admits a maximal toral action if its fundamental group has a nontrivial center. Second, a compact complete affinity flat manifold whose fundamental group is virtually polycyclic supports the structure of an infrasolvmanifold. This structure varies depending on its solvable kernel (if it is abelian or nilpotent, it must be a euclidean space form or an infranilmanifold respectively). If a group of the affine group A(n) acts properly discontinuously and with compact quotient of $\text{R}$ⁿ, then it is called an affine crystallographic group. Finally, we can say so far as to a uniqueness property that two virtually polycyclic affine crystallographic groups are conjugate inside Diff($\text{R}$ⁿ) if they are isomorphic (cf.[8]).     

Seifert manifolds with fiber spherical space forms

We study the Seifert fiber spaces modeled on the product space . Such spaces are ``fiber bundles' with singularities. The regular fibers are spherical space-forms of , while singular fibers are finite quotients of regular fibers. For each of possible space-form groups of , we obtain a criterion for a group extension of to act on as weakly -equivariant maps, which gives rise to a Seifert fiber space modeled on with weakly -equivariant maps as the universal group. In the course of proving our main results, we also obtain an explicit formula for for a cocompact crystallographic or Fuchsian group . Most of our methods for apply to compact Lie groups with discrete center, and we state some of our results in this general context.

     

A New Approach to Ethyl 1-Aroyl/Aroylmethyl-5-methyl-3-methylthiopyrazole-4-carboxylates： High Regioselectivity in Alkylation and Acylation Reactions between N-1 and N-2 of a Pyrazole Derivative

It has been known that pyrazole ring has two main tautomeric isomers1-3as showed in Scheme1.The proton could migrate at the two nitrogen atoms of the pyrazole ring.Taylor E.C.and Purdum W.R.4first reported the synthesis of2as an isomer of2a.And so far,only a few literatures5-6have reported that this pyrazole derivative was in form2a,rather than2,therefore both acylation or alkylation reaction occurred at N-1of2a.But the regiochemistry of the N-substituted product of pyrazole has not been u…     

Quantification of H, B and F in Kornerupine: Accuracy of SIMS and SREF (X-Ray Single-Crystal Structure-Refinement) Data

 We use a multiple-analytical approach based on secondary-ion mass-spectrometry (SIMS), X-ray single-crystal structure refinement (SREF) and electron-probe micro-analysis (EPMA) to derive the complete crystal-chemical formula of a B-rich kornerupine-group mineral, prismatine, from Hrarigahy, Madagascar: (Ca_0.01Li_0.02Mg_0.20Fe²⁺ _0.10) (Mg_3.57Fe²⁺ _0.06 Al_5.37) (Si_3.84B_0.91Al_0.26)O₂₁ (OH_1.08F_0.07). SIMS matrix effects related to crystal structure were investigated by analyzing two grains with a known crystallographic orientation relative to the ion beam. Boron orders at the T3 site. The refined site-scattering for T3, 6.33 eps (electrons per site) agrees well with the mean bond-length for this site (1.512 ?), which indicates nearly complete occupancy by B (85% rel.). B₂O₃ (∼ 4 wt%), derived by SREF, agrees with the SIMS data within analytical uncertainty using Si as the inner reference for the matrix. The occupancy of the X site obtained by combining the SIMS and EPMA data (5.30 eps; electrons per site) agrees with the refined site-scattering value (5.75 eps). Trace quantities of Li and Ca are ordered at this site. SIMS data for H₂O is in accord with the stoichiometric value, indicating complete occupancy at O10 by OH. Fluorine (∼ 0.17 wt%) orders at O10: it corresponds to ∼ 0.07 atoms per formula unit (apfu) vs. 0.15 apfu (atoms per formula unit) by SREF, indicating a slight overestimation of F with SREF, as previously observed in fluoborite. Our data show that SIMS chemical matrix effects are well-calibrated, and emphasize the usefulness of independent micro-analytical techniques in testing the mutual accuracy and consistency of experimental data.     

Etude du Systeme LiPO3-Pr(PO3)3 Donnees sur LiPr(PO3)4

The LiPO₃-Pr(PO₃)₃ system was studied by micro-differential thermal analysis. The only new compound observed in the system was LiPr(PO₃)₄, melting incongruently at 1246 K. An eutectic appears at 926 K. Crystallographic data and powder diagram of the new compound are given. LiPr(PO₃)₄ crystallizes in the C2/c monoclinic system with unit cell: a=16.428(6), b=7.054(3), c=9.747(4) Å, β=126°31′(3), V=910.2 ų, Z=4. The IR and Raman spectra of this compound are given. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular and crystal structure of 4,6,6-trimethyl-2-oxo-5,6-dihydro-2H-pyran-3-carbonitrile and 4,6,6-trimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitrile

Single crystals of 4,6,6-trimethyl-2-oxo-5,6-dihydro-2H-pyran-3-carbonitrile and 4,6,6-trimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitrile were prepared and submitted to X-ray diffraction analysis. Both compounds have a molecular structure belonging to the C₁ symmetry group. The heterocyclic rings are in a distorted envelope conformation. The crystals belong to the monoclinic system and each contain four molecules in the unit cell. In the crystal the pyridine derivative exists in the form of centrosymmetric dimers stabilized by intermolecular hydrogen bonds between the oxygen atoms of the carbonyl group and the hydrogen atom at the nitrogen atom of the ring. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1620–1624, November, 2007.     

Conformational investigation of phenoxycyclohexan-2-one andp-Cl- andp-NO2-phenoxycyclohexan-2-one by molecular mechanics; x-ray crystallographic analysis ofp-NO2-phenoxycyclohexan-2-one

The preferred conformers of phenoxycyclohexan-2-one and p-Cl- andp-NO₂-phenoxycyclohexan-2-ones were calculated by the MM2(87) method. The results are compared with the data from experimental conformational investigations in solution. According to the calculation, the compounds are described by a multicomponent equilibrium, including thesp-G conformer with a planar orientation of the anisole fragment and a mixture of theac-G andT conformers both with planar and with orthogonal arrangement of the aryl group. The structure ofsp-G(0°)p-NO₂-phenoxycyclohexan-2-one was determined by x-ray crystallographic analysis.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1359–1364, June, 1992.     

Molecular and Crystal Structure of 4,6-Dimethyl-2-(phenylhydrazino)pyrimidine and Its Alkylation and Protonation Products

It was established by X-ray crystallographic analysis that 4,6-dimethyl-2-(phenylhydrazino)pyrimidine forms 2-(2-n-butyl-2-phenylhydrazino)-4,6-dimethylpyrimidine during alkylation with n-butyl bromide and 4,6-dimethyl-2-(phenylhydrazino)-1(H)-pyrimidinium nitrate during protonation with nitric acid. The structure of the molecules and the system of intermolecular hydrogen bonds in the crystals of the compounds are discussed.