Investigation of 4-acetyl-2,6-dibenzyl-1,5-dihydroxy-2-methylcyclohexa-4,6-dien-3-one by X-ray crystallography and 1H-NMR spectroscopy

Benzylation of 3-methylphloracetophenone [1-(2,4,6-trihydroxy-3-methylphenyl)ethanone] (3) with benzyl chloride gave 4-acetyl-2,6-dibenzyl-1,5-dihydroxy-2-methylcyclohexa-4,6-dien-3-one (5). Compound 5 crystallizes in the orthorhombic space group Fdd2 with a = 17.586(2), b = 42.891(5), c = 10.279(2) Å, V = 7753(2) Å,³ and Z = 16. When crystals of 5 were dissolved in [D₆]acetone the compound underwent tautomerization and a mixture of 5 and its keto form 4 was obtained (keto form/enol form ratio 1:4).     

Specific heat of the elpasolite Pb2MgWO6

The specific heat of Pb₂MgWO₆ has been measured in the temperature interval 83–370 K. An anomaly in the specific heat associated with the phase transition at T ₀=312.8K has been discovered. The thermodynamic parameters of the structural phase transition Fm3m-Pmcn have been determined. Fiz. Tverd. Tela (St. Petersburg) 41, 1686–1688 (September 1999)     

Mechanical characterization and pH response of fibril-reinforced microcapsules prepared by layer-by-layer adsorption

Despite the fair number of microencapsulation principles that have been developed, the actual protection and targeted delivery of sensitive ingredients remains a challenge in the food industry. A suitable technique should use food-grade and inexpensive materials, and ensure tight control over the capsule size and release trigger mechanism. For example, encapsulates may need to survive the low pH of the stomach to release their contents in the neutral environment of the small intestine. In this work we present layer-by-layer (LbL) microcapsules assembled from whey protein isolate (WPI), high-methoxyl pectin (HMP) and WPI-fibrils. The narrow size distribution of these capsules is determined by the oil-in-water droplets used as templates, and their mechanical properties and pH response can be tuned by the number of layers adsorbed. Capsules with more than eight layers have a mechanical strength comparable to chemically cross-linked polymer capsules, because of the reinforcement by the WPI-fibrils in combination with the shell completion. Typically, capsules with five layers survive pH 2 for more than 2 h, but dissolve within 30 min at pH 7. At higher number of layers, the capsules are even more stable. Contrary to other encapsulates, these capsules can be dried and are suitable for application in dry products.     

Spectral multipliers on quotients¶by amenable subgroups

We show that spectral multipliers for operators on quotients by amenable subgroups have holomorphic extension to a strip which is contained in the corresponding one for the group. Received: 16 September 1999     

Long-Range Transport in an Assembly of ZnO Quantum Dots: The Effects of Quantum Confinement,Coulomb Repulsion and Structural Disorder

We have studied the storage and long-range transport of electrons in a porous assembly of weakly coupled ZnO quantum dots permeated with an aqueous and a propylene carbonate electrolyte solution. The number of electrons per ZnO quantum dot is controlled by the electrochemical potential of the assembly; the charge of the electrons is compensated by ions present in the pores. We show with optical and electrical measurements that the injected electrons occupy the S, P, and D type conduction electron levels of the quantum dots; electron storage in surface states is not important. With this method of three-dimensional charge compensation, up to ten electrons per quantum-dot can be stored if the assembly is permeated with an aqueous electrolyte. The screening of the electron charge is less effective in the case of an assembly permeated with a propylene carbonate electrolyte solution. Long-range electron transport is studied with a transistor set-up. In the case of ZnO assemblies permeated with an aqueous electrolyte, two quantum regimes are observed corresponding to multiple tunnelling between the S orbitals (at a low occupation) and P orbitals (at a higher occupation). In a ZnO quantum-dot assembly permeated with a propylene carbonate electrolyte solution, there is a strong overlap between these two regimes.     

Room‐Temperature Electronic Template Effect of the SmSi(111)‐8×2 Interface for Self‐Alignment of Organic Molecules

This work describes an innovative concept for the development of organized molecular systems based on the template effect of the pre‐structured semi‐conductive SmSi(111) interface. This substrate is selected because Sm deposition in the submonolayer range leads to a 8×2‐reconstruction, which is a well‐defined one‐dimensional semi‐metallic structure. Adsorption of aromatic molecules [1,4‐di‐(9‐ethynyltriptycenyl)‐benzene] on SmSi(111)‐ 8×2 and Si(111)‐7×7 interfaces is investigated by scanning tunneling microscopy (STM) at room temperature. Density functional theory (DFT) and semi‐empirical (ASED+) calculations define the nature of the molecular adsorption sites of the target molecule on SmSi as well as their self‐alignment on this interface. Experimental data and theoretical results are in good agreement.     

A practical way of grafting maleic anhydride onto polypropylene providing high anhydride contents without sacrificing excessive molar mass

This study reports a reactive extrusion process leading to very high levels of anhydride grafting (2.5–3 wt %) along polypropylene backbone without recovering grafted PP waxes at the die exit. Such high graftings are attainable without excessive degradation of the PP chain by using a brominated reagent. Simultaneously, this brominated reagent allows the tuning of the grafted PP crystallinity via epimerization of the PP backbone. Indeed, the synthesis of a mainly isotactic/atactic stereoblock polymer containing high levels of grafted succinic anhydride moieties is demonstrated by NMR and melting enthalpies recorded by DSC are definitely observed depressed and broadened. Grafting levels of around 3 wt % have been achieved and ascertained by both chemical titration and NMR spectroscopy. In addition, FTIR spectroscopy reveals an unusual observation: for the first time, only one single pair of symmetric and asymmetric carbonyl stretching bands are observed on those grafted PP, while, in other processes of anhydride grafting, those symmetric and asymmetric bands were both split in at least two bands. This suggests, for the here reported process, the absence of interacting grafted anhydride rings, i.e., absence of closely grafted anhydride moieties and absence of poly(maleic anhydride). All those observations support that this “bromine route” brings a really new grafting process for PP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2936–2947, 2008     

Synthesis and characterization of 2-substituted bornane pharmacophores for novel cannabinergic ligands

Analogously to the fenchyl and adamantyl groups, the bornyl and epimeric isobornyl groups are compact lipophilic substituents that can be incorporated into drug design to improve pharmacological or physicochemical properties. Methods are reported for the synthesis and characterization of 2-substituted norbornanes and bornanes that can serve as novel cannabinergic ligand intermediates.