Mereologies as the grammars of chemical discourses

Mereology is the logic of part—whole concepts as they are used in many different contexts. The old chemical metaphysics of atoms and molecules seems to fit classical mereology very well. However, when functional attributes are added to part specifications and quantum mechanical considerations are also added, the rules of classical mereology are breached in chemical discourses. A set theoretical alternative mereology is also found wanting. Molecular orbital theory requires a metaphysics of affordances that also stands outside classical mereology.     

Transfer hydrogenation processes to mu(3)-alkylidyne groups on the organotitanium oxide [Ti(3)Cp*O(3)

The photochemical treatment of mu(3)-alkylidyne complexes [[TiCp*(mu-O)](3)(mu(3)-CR)] (R=H (1), Me (2), Cp*=eta(5)-C(5)Me(5)) with the amines (2,6-Me(2)C(6)H(3))NH(2), Et(2)NH, and Ph(2)NH and the imine Ph(2)C=NH leads to the partial hydrogenation of the alkylidyne moiety that is supported on the organometallic oxide, [Ti(3)Cp*O(3)], and the formation of new oxoderivatives [[TiCp*(3)(mu-CHR)(R'NR")] (R"=2,6-Me(2)C(6)H(3), R'=H, R=H (3), Me (4); R'=R"=Et, R=H (5), Me (6); R'=R"=Ph, R=H (7), Me (8)) and [[TiCp*(mu-O)](3)(mu-CHR)(N=CPh(2))] (R=H (9), R=Me (10)), respectively. A sequential transfer hydrogenation process occurs when complex 1 is treated with tBuNH(2), which initially gives the mu-methylene [[TiCp*(mu-O)](3)(mu-CH(2))(HNtBu)] (11) complex and finally, the alkyl derivative [[TiCp*(mu-O)](3)(mu-NtBu)Me] (12). Furthermore, irradiation of solutions of the mu(3)-alkylidyne complexes 1 or 2 in the presence of diamines o-C(6)H(4)(NH(2))(2) and H(2)NCH(2)CH(2)NH(2) (en) affords [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(6)H(4)NH)] (13) and [[TiCp*(mu-O)](3)(mu(3)-eta(2)-NC(2)H(4)NH)] (14) by either methane or ethane elimination, respectively. In the reaction of 1 with en, an intermediate complex [[TiCp*(mu-O)](3)(mu-CH(2))(NHCH(2)CH(2)NH(2))] (15) is detected by (1)H NMR spectroscopy. Thermal treatment of the complexes 4-10 quantitatively regenerates the starting mu(3)-alkylidyne compounds and the amine R'(2)NH or the imine Ph(2)C=NH; however, heating of solutions of 3 or 4 in [D(6)]benzene or a equimolecular mixture of both at 170 degrees C produces methane, ethane, or both, and the complex [[TiCp*(mu-O)](3)[mu(3)-eta(2)-NC(6)H(3)(Me)CH(2)]] (16). The molecular structure of 8 has been established by single-crystal X-ray analysis.     

Pickering emulsion polymerization kinetics of styrene: Comparison of bare and surface modified SiO2 nanoparticles

A step towards the understanding of some mechanistic events occurring in the styrene Pickering emulsions, using a SiO₂ dispersion, is presented. Polymerizations at 80°C with different levels of a water soluble initiator were performed. The emulsion polymer content was ca. 15% with conversions close to 90%. With conversion and particle size measurements, the particle density was estimated for bare and surface modified SiO₂ particles. Then, the average number of radicals per particle was inferred, yielding a pseudo-bulk type polymerization. It was found that bare SiO₂ nanoparticles do not participate in the nucleation mechanism; however, they, along with the initiator, promote an enhanced oligomer coagulation. On the other hand, the hexadecyltrimethylammonium bromide modified SiO₂ nanoparticles do participate in the nucleation and coagulation mechanisms, yielding more stable and smaller poorly-covered polymer particles. This approach allowed untangling some events such as: particle nucleation, radical entry to particles, particle density, coagulation and vitreous and Trommsdorff effects.     

A stereotypic,transplantable liver tissue-culture system

A method of coculturing adult rat hepatic parenchymal cells (PC) and stromal cells in a three-dimensional framework of nylon filtration screens or biodegradable polymer meshes was developed in our laboratory. Rat liver stroma, which includes vascular and bile duct endothelial cells, fat-storing cells, fibroblasts, and Kupffer cells, were isolated by gradient centrifugation afterin situ liver perfusion and expanded in monolayer culture prior to seeding onto nylon screens or bioresorbable polyglycolic acid (PGA) polymers oriented into a felt-like construct. A second inoculum of freshly isolated PC was applied after the stromal cells became established. Histological analyses revealed that PC proliferation occurred until all available space for expansion within the template was exhausted. These cells retained their rounded morphology, and after 4–5 wk 7–9 “layers” of PC filled the 140-μm deep template. Dioxin-inducible cytochrome P450 activity was detected for up to 58 d in culture, and albumin, fibrinogen, transferrin, and soluble fibronectin were detected in the medium by enzyme-linked immunosorbent assay (ELISA) for 48 d in vitro. Immunohistochemical analysis of sections through the cultures confirmed the presence of these proteins as well as cytokeratin at the cellular level; the extracellular matrix stained for both collagen type III and laminin. Long-term PC proliferation and function were enhanced by the presence of stromal cells as well as by a meshwork template whose geometry allows the interaction of PC with stroma and matrix on several different planes. To permit transplantation, co-cultures of hepatic PC and stromal cells were established on PGA felt constructs instead of nylon screens. After 24 d in vitro, these constructs were grafted into sites in the mesentery, omentum, and sub-cutaneous tissues of adult Long-Evans rats. The growth of hepatocytes after 30 din situ was evident by histological analysis; grafts of co-cultures regenerated a liver-like architecture consisting of sinusoids and putative biliary structures. In addition, PC at these extrahepatic graft sites were positive for albumin, transferrin, and fibrinogen synthesis by immunohistochemistry. Graft survival was enhanced when recipients were subjected to 40% hepatectomy. Hepatic PC:stromal cell cocultures may prove useful in the restoration of liver function either by direct transplantation using PGA or similar templates, or as extracorporeal devices, using nylon screens.     

A multifaceted approach to hydrogen storage

The widespread adoption of hydrogen as an energy carrier could bring significant benefits, but only if a number of currently intractable problems can be overcome. Not the least of these is the problem of storage, particularly when aimed at use onboard light-vehicles. The aim of this overview is to look in depth at a number of areas linked by the recently concluded HYDROGEN research network, representing an intentionally multi-faceted selection with the goal of advancing the field on a number of fronts simultaneously. For the general reader we provide a concise outline of the main approaches to storing hydrogen before moving on to detailed reviews of recent research in the solid chemical storage of hydrogen, and so provide an entry point for the interested reader on these diverse topics. The subjects covered include: the mechanisms of Ti catalysis in alanates; the kinetics of the borohydrides and the resulting limitations; novel transition metal catalysts for use with complex hydrides; less common borohydrides; protic-hydridic stores; metal ammines and novel approaches to nano-confined metal hydrides.     

Vanadium(V) environments in bismuth vanadates: A structural investigation using Raman spectroscopy and solid state V NMR

The Bi₂O₃---V₂O₅ system was examined using Raman spectroscopy and solid state ⁵¹V wideline, magic-angle spinning (MAS), and nutation NMR spectroscopy. The methods are shown to be complementary in the identification of the various phases and in the characterization of their vanadium site symmetries. Most of the compositions examined (1:1 ≤ Bi:V ≤ 60:1) are multiphasic. Depending on the Bi:V ratio, the following phases have been identified: BiVO₄, Bi₄V₂O₁₁, a triclinic type-II phase, a cubic type-I phase, γ-Bi₂O₃ doped with V(V) (sillenite), and β-Bi₂O₃. Detailed spectroscopic characterization reveals that vanadium is tetrahedrally coordinated in all these compounds, and that the degree of symmetry increases with increasing Bi:V ratio. At the highest Bi:V ratios, the combined interpretation of the Raman and NMR data provides strong evidence for the presence of Bi⁵⁺O₄ tetrahedra.     

Preliminary test for nitrogen- and oxygen-containing groups in organic compounds

Summary Organic Compounds carrying groups containing both nitrogen and oxygen, such as nitro- and nitroso compounds, oximes, hydroxamic acids, azoxy compounds, and amine oxides yield nitrous acid when they are heated dry (pyrolysis). This product can be readily detected in the gas phase by theGriess nitrite reaction. This behavior provides a rapid preliminary test for members of these classes of compounds. Micro analytical limits of identification are readily obtained within the technique of spot test analysis.

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Zusammenfassung Organische Verbindungen mit Stickstoff- und sauerstoffhaltigen Atomgruppen, demnach Nitro- und Nitrosoverbindungen, Oxime, Hydroxamsäuren, Azoxy verbindungen und Aminoxyde spalten bei trockenem Erhitzen (Pyrolyse) salpetrige Säure ab, die in der Gasphase durch dieGriesssche Nitritreaktion empfindlich nachweisbar ist. Dieses Verhalten ermöglicht eine schnelle Vorprüfung auf Angehörige der genannten Verbindungsklassen. In der Technik der Tüpfelanalyse werden mikroanalytische Erfassungsgrenzen erreicht.

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Résumé Les combinaisons organiques porteuses d'un groupement azoté et oxygéné telles que les combinaisons nitrées et nitrosées, les oximes, les acides hydroxamiques, les composés azoxy et les oxydes d'aminés, libèrent de l'acide nitreux par chauffage à sec (pyrolyse); cet acide peut être identifié en phase gazeuse par la sensible réaction deGriess des nitrites. Ce comportement permet d'effectuer un essai préliminaire rapide sur les composés appartenant aux classes précédentes. Lorsqu'on met en oeuvre la technique de l'analyse à la touche, les limites de sensibilité atteintes permettent de travailler dans le domaine microanalytique.

     

General correlation model for some physical properties of saturated pure fluids

In this work, we use a general expression to accurately correlate the liquid density, the vaporization enthalpy, the surface tension, and the isobaric heat capacity of a saturated liquid versus temperature along the whole coexistence curve. The general expression used is the same for the four thermodynamic properties, and uses both critical and triple point values as reference. As representative examples of the use of the model, results are given for a set of 22 pure substances. We find that this general expression correlates the data with smaller or similar overall deviations when compared with other published models whose number of coefficients are the same or greater.