Recent Reviews. 47

Reviews are listed in order of appearance in the sources indicated. In multidisciplinary review journals, only those reviews which fall within the scope of this Journal are included. Sources are listed alphabetically in three categories: regularly issued review journals and series volumes, contributed volumes, and other monographs. Titles are numbered serially, and these numbers are used for reference in the index. Major English-language sources of critical reviews are covered. Encyclopedic treatises, annual surveys such as Specialist Periodical Reports, and compilations of symposia proceedings are omitted. This installment of Recent Reviews covers principally the middle part of the 1997 literature. Previous installment: J. Org. Chem. 1997, 62(21), 7522-30. These Recent Review articles are now also available in a database form on the ACS Organic Division WWW site http://www.organic.emory.edu/acsorg/     

High-performance liquid chromatographic separation of polyolefin antioxidants and light-stabilisers

Summary A scheme was devised for the identification of 22 common antioxidants and light-stabilisers in polyolefins. The separation of these stabilisers was performed by isocratic reversed phase high-performance liquid chromatography on a RP-18 column. Three different separation conditions have been used: the mobile phase composition was 100% acetonitrile (MeCN), 90/10 meCN/H₂O and 80/20 MeCN/H₂O. The UV₂₅₄/UV₂₈₀ ratio and the elution time of each stabiliser were determined for these three mobile phase compositions. The values of UV₂₅₄/UV₂₈₀ ratios may be used together with the retention time values for the identification of unknown stabilisers in polyolefin samples.     

Evaluation of Series Involving the Product of the Tail of $${\zeta(k)}$$ and $${\zeta(k+1)}$$ζ(k+1)

We aim at evaluating the following class of series involving the product of the tail of two consecutive zeta function values

$$\sum\limits_{n=1}^{\infty}\left(\zeta(k)-1-\frac{1}{2^k}-\cdots-\frac{1}{n^k}\right)\left(\zeta(k+1)-1-\frac{1}{2^{k+1}}-\cdots-\frac{1}{n^{k+1}}\right),$$

where \({k\geq 2}\) is an integer. We show that the series can be expressed in terms of Riemann zeta function values and a special integral involving a polylogarithm function.

     

Minimal submanifolds in ℝ<Superscript>4</Superscript> with a G.C.K. structure

In this paper we obtain all invariant, anti-invariant and CR submanifolds in (?⁴, g, J) endowed with a globally conformal Kähler structure which are minimal and tangent or normal to the Lee vector field of the g.c.K. structure.     

Supramolecular structures based on dimeric combinations of cyclodextrin and adamantane via click chemistry

The cyclic starches α-, β-, and γ-cyclodextrins (CDs) readily form inclusion complexes (ICs) with a large variety of polymers. In polymer-CD-ICs, the CD hosts are threaded by the guest polymers, which must be highly extended, and stacks of polymer threaded host CDs pack closely together and crystallize. When guest polymers are coalesced from their CD-IC crystals, by washing with a solvent good, bad for CD, polymer, or treatment with an amylase enzyme, the guest polymers coalesce into bulk samples whose structures, morphologies, and even conformations are distinct from bulk samples made from their solutions and melts. We generally observe (i) crystallizable homopolymers coalesced from their CD-ICs to evidence increased levels of crystallinity, unusual polymorphs, and higher melting, crystallization, and decomposition temperatures, while coalesced amorphous homopolymers exhibit higher glass-transition temperatures, than samples consolidated from their disordered solutions and melts; (ii) molecularly mixed, intimate blends of two or more polymers that are normally believed to be immiscible can be achieved by coalescence from their common CD-IC crystals, (iii) the phase segregation of incompatible blocks can be controlled (suppressed or increased) when block copolymers are coalesced from their CD-IC crystals, and (iv) the thermal and temporal stabilities of the coalesced and well-mixed homopolymer blends and block copolymers appear to be substantial, thereby suggesting retention of as-coalesced structures and morphologies under normal thermal processing conditions. Furthermore, CDs may be covalently incorporated in polymers both during and after their syntheses, thereby providing a broad range of new functionalities for delivery of additives or to act as sensors or filters. Alternatively, additive-CD-ICs or additives rotaxanated with CDs may be effectively delivered to polymers. As an example, TiO₂—filled polypropylene fibers may be readily dyed in aqueous solution using water soluble CD-rotaxanated azo-dyes.     

Polyazomethines derived from polynuclear dihydroxyquinones and siloxane diamines

New polyazomethines have been synthesized based on polynuclear dihydroxy quinones (5,8-dihydroxy-1,4-naphthoquinone and 1,4-dihydroxyanthraquinone) and siloxane diamines differing by the siloxane sequence length (1,3-bis(3-aminopropyl)tetramethyldisiloxane and α,ω-bis(3-aminopropyl)oligodimethylsiloxane having about 12 siloxane units/sequence). The structures were verified by spectral analyses. Solubility tests, GPC and viscosity measurements were performed. Some properties of the resulted polymers were investigated by thermal (TGA and DSC), electrical, spectral (UV-Vis) and electrochemical (differential pulse voltammetry) methods.     

New heteroleptic lanthanide complexes as multimodal drugs: Cytotoxicity studies,apoptosis, cell cycle analysis,DNA interactions,and protein binding

We report herein the synthesis and characterization of four new heteroleptic complexes of Sm(III), Eu(III), Gd(III), and Tb(III) with the natural flavonoid 5‐hydroxyflavone (primuletin) and 1,10‐phenanthroline. According to the physicochemical characterization, the mononuclear complexes correspond to the general formula [Ln(OH) ₂ L ₁ L ₂ ]·nH ₂ O , where L₁ = C₁₅H₉O₃ (deprotonated 5‐hydroxyflavone) and L₂ = C₁₂H₈N₂ (1,10‐phenanthroline), Ln is the lanthanide cation, and n = 4 for Sm(III), 3.5 for Eu(III), 2 for Gd(III), and 3 for Tb(III). A six‐coordinated distorted octahedron geometry was proposed for the complexes, and density functional theory (DFT) studies were used to calculate their optimized geometry. Cytotoxicity was studied using MTS assay on cervical, colorectal, colon, breast, and ovarian adenocarcinoma cell lines. Flow cytometry data were consistent with apoptotic cell death and disruption of the cell cycle in cervical and colon cancer cells. As a means to investigate the mechanism underlying the cytotoxic effects, the abilities of the complexes to interact with calf thymus DNA, human serum albumin, and transferrin have also been assessed. According to experimental and computational studies, the four lanthanide complexes act as DNA intercalators and bind strongly to serum proteins.     

Shaft design: A semi-analytical finite element approach

This work deals with the practical use of semi-analytical finite elements in the machine design. The case of mechanical shafts is considered. The most usual loading condition characterized by the presence of axial, torsional, bending, and shear loads can be modeled by over imposing an axi-symmetric, an axi-antisymmetric and a harmonic load, corresponding to the first three terms of the Fourier series expansion, if semi-analytical plane finite element is used. A practical case is presented and the advantages, with respect to the three-dimensional approach in terms of computational time and accuracy for stress and displacement evaluation, is put in evidence.     

Effects and Characterization of Some Topical Ointments Based on Vegetal Extracts on Incision,Excision, and Thermal Wound Models

The present paper aims to formulate and characterize four phytotherapeutic ointments based on Hippophae fructus, Calendulae flos, Bardanae folium, and Millefolii herba, which are included in a novel ointment base. In order to investigate the healing properties of the ointments, in vivo experimental wound models of linear incision, circular excision, and thermal burn were performed on Wistar rats. Topical treatment was performed daily for 21 days. Determination of the wound contraction rate (WCR), the period of reepithelization, and histopathological examination were achieved. Additionally, for the tested ointments, oscillatory and rotational rheological tests were carried out, and for the extracts, HPLC analysis was performed. The results demonstrate that the tested novel ointments are safe for use and the most effective ointment proved to be the one based on Arctium lappa, followed by that of Calendulae flos.