bluuebunny/crossref_metadata_2025 huggingface dataset:
Sol and gel states in peptide hydrogels visualized by Gd(III)‐enhanced magnetic resonance imaging
Authors: Weerasekare Mahika , Taraban Marc B. , Shi Xianfeng , Jeong Eun‐Kee , Trewhella Jill , Yu Yihua Bruce
Published: March 2011

The hydrogels assembled from a pair of self‐repulsive but mutually attractive decapeptides are visualized by magnetic resonance imaging (MRI). It is found that in the absence of Gd(III)‐chelate, gelation has little effect on MRI signal intensity. In the presence of Gd(III)‐chelate, gelation leads to significant changes in water relaxation and MR signal intensity. The sol to gel transition is best visualized by T2‐weighted imaging using large echo time with the sol producing a bright spot and the gel producing a dark spot. MRI studies point to high local Gd(III)‐chelate concentration. Small‐angle X‐ray scattering study indicates that this local enrichment of Gd(III)‐chelate has two contributing processes: first, the aggregation of peptides into fibers; second, within peptide fibers, Gd(III)‐chelate further aggregate into clusters. This work demonstrates that the status of peptide‐based hydrogels can be visualized by MRI with the aid of covalently linked Gd(III)‐chelates. This result has implications for monitoring peptide scaffolds in vivo. © 2011 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 734–743, 2011.
Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase
Authors: Hayes Stuart A. , Berger Raphael J. F. , Mitzel Norbert W. , Bader Julia , Hoge Berthold
Published: March 2011

(C2F5)2PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C2F5)3PF2. (C2F5)3PF2 was reduced in the first step with NaBH4 in a solvent‐free reaction at 120 °C. The product, P(C2F5)3, was treated with an excess of an aqueous sodium hydroxide solution to afford the corresponding phosphinite salt Na+(C2F5)2PO− selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl4 resulted in the selective formation of (C2F5)2PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C2F5)2PCl was recorded and found to be described by a two‐conformer model. A quantum chemical investigation of the potential‐energy surface revealed the possible existence of many low‐energy conformers, each with a number of low‐frequency vibrational modes and therefore large‐amplitude motions. The conformer calculated to be most stable was also found to be most abundant by GED and comprised 61(5) % of the total. The molecular structure parameters determined by GED were in good agreement with those calculated at the MP2/TZVPP level of theory; the only significant difference was a discrepancy of about 3° in the C‐P‐C angle, which, for the lowest‐energy conformer, was refined to 98.2(4)° and was calculated to be 94.9°.
(4+3) Cycloaddition Reactions of Nitrogen‐Stabilized Oxyallyl Cations
Authors: Lohse Andrew G. , Hsung Richard P.
Published: March 2011

The use of heteroatom‐substituted oxyallyl cations in (4+3) cycloadditions has had a tremendous impact on the development of cycloaddition chemistry. Extensive efforts have been exerted toward investigating the effect of oxygen, sulfur, and halogen substituents on the reactivity of oxyallyl cations. Most recently, the use of nitrogen‐stabilized oxyallyl cations has gained prominence in the area of (4+3) cycloadditions. The following article will provide an overview of this concept utilizing nitrogen‐stabilized oxyallyl cations.
ChemInform Abstract: Structure, Properties, and Theoretical Electronic Structure of UCuOP and NpCuOP.
Authors: Wells Daniel M. , Ringe Emilie , Kaczorowski D. , Gnida D. , Andre G. , Haire Richard G. , Ellis Donald E. , Ibers James A.
Published: March 2011

The title compounds are prepared by solid state reaction of U or Np, Cu and/or CuO, and P at 1073—1273 K (evacuated silica tube, 96 h).
ChemInform Abstract: Synthesis of LiNi0.5Mn1.5O4 by Solid‐State Reaction with Improved Electrochemical Performance.
Authors: Feng X. Y. , Shen C. , Fang X. , Chen C. H.
Published: March 2011

The title compound is synthesized from a mixture of Ni(OAc)2 and Mn(OAc)2 (alumina crucible, 500 °C, 5 h) followed by addition of LiOAc (calcination at 500 °C for 5 h, sintering at 900 °C for 10 h, and annealing at 700 °C for 10 h) and in a one‐step reaction directly from a mixture of Ni(OAc)2, Mn(OAc)2, and LiOAc (900 °C).
ChemInform Abstract: A Gallium‐Catalyzed Cycloisomerization/Friedel—Crafts Tandem.
Authors: Li Hui‐Jing , Guillot Regis , Gandon Vincent
Published: March 2011

It is found that GaCl3 efficiently promotes double, triple, and even quadruple hydroarylation of diverse arenynes which allows formation of various valuable polycyclic compounds.
ChemInform Abstract: Regioselectivity in Intermolecular Pauson—Khand Reactions of Dissymmetric Fluorinated Alkynes.
Authors: Kizirian Jean‐Claude , Aiguabella Nuria , Pesquer Albert , Fustero Santos , Bello Paula , Verdaguer Xavier , Riera Antoni
Published: March 2011

The reaction proceeds strictly regioselectively: the fluorinated substituent is always found at the α‐position to the enone.
ChemInform Abstract: Toward a Novel Approach to Bis‐β‐Lactam Synthesis Using Vilsmeier Reagent as an Efficient Entity via Staudinger Cycloaddition Reaction.
Authors: Meshram Jyotsna , Ali Parvez , Tiwari Vandana
Published: March 2011

Vilsmeier reagent is shown to act as acid activator reagent for the direct [2 + 2] ketene—imine cycloaddition of acetic acid (II) and bisimines (I).
ChemInform Abstract: An Efficient Synthesis of α‐Methylene‐γ‐butyrolactones from Baylis—Hillman Adducts via an In‐Mediated Barbier Reaction and Stereoselective Lactonization under MeSO2Cl/Et3N Conditions.
Authors: Park Bo Ram , Kim Ko Hoon , Kim Jae Nyoung
Published: March 2011

syn‐Homoallylic alcohols (I), derived from Baylis—Hillman adducts, are converted into trans‐butyrolactones via an intramolecular mesylate displacement.
ChemInform Abstract: Three‐Component Assembly and Divergent Ring‐Expansion Cascades of Functionalized 2‐Iminooxetanes.
Authors: Yao Weijun , Pan Lianjie , Zhang Yiping , Wang Gang , Wang Xiaoqin , Ma Cheng
Published: March 2011

Reactions of α‐keto esters with N‐sulfonylketimines, prepared in situ from terminal alkynes and azide (III), proceeds via 2‐iminooxetane intermediates such as (VII) which are transformed into maleimide derivatives or 5‐iminopyrrolidinones.
ChemInform Abstract: A Mild, Efficient and Eco‐Friendly Synthesis of 1,3‐Bis(4‐arylthiazol‐2‐yl)benzenes in PEG‐400.
Authors: Noie Jalil , Khosropour Reza
Published: March 2011

A selective and green synthesis which proceeds in the recycable and reusable reaction medium PEG is presented.
ChemInform Abstract: Concise Synthesis of Tetrahydropyrans by a Tandem Oxa‐Michael/Tsuji—Trost Reaction.
Authors: Wang Liang , Li Pengfei , Menche Dirk
Published: March 2011

A novel domino process is developed for the synthesis of polysubstituted title compounds.
ChemInform Abstract: Application of Biphasic Reaction Procedure Using Ferric Chloride Dissolved in an Imidazolium Salt and Benzotrifluoride (FeIm‐BTF Procedure) to Aza‐Prins Cyclization Reaction.
Authors: Hasegawa Eietsu , Hiroi Nohara , Osawa Chika , Tayama Eiji , Iwamoto Hajime
Published: March 2011

A combination of FeCl3 and [bmim]FeCl4 (or [bmim]PF6) promotes the cyclization of homoallylic N‐tosylamine (I) with aldehydes using benzotrifluoride as the solvent.
ChemInform Abstract: One‐Pot Synthesis and Antimicrobial Activity of Novel Quinolone Heterocyclic Derivatives (V).
Authors: Zheng Hui , Liu Juan , Zhang Pengfei
Published: March 2011

Preliminary tests of title compounds (V) show that they possess certain antibacterial and antifungal activities.
ChemInform Abstract: Rhodium(III)‐Catalyzed Synthesis of Isoquinolines from Aryl Ketone O‐Acyloxime Derivatives and Internal Alkynes.
Authors: Too Pei Chun , Wang Yi‐Feng , Chiba Shunsuke
Published: March 2011

The method allows the preparation of a broad spectrum of highly functionalized isoquinolines.
ChemInform Abstract: 1,3‐Dichloro‐5,5‐dimethylhydantoin as a Novel and Efficient Homogeneous Catalyst in Biginelli Reaction.
Authors: Hojati Seyedeh Fatemeh , Gholizadeh Mostafa , Haghdoust Mahnaz , Shafiezadeh Fatemeh
Published: March 2011

The use of a stable, easily available and efficient catalyst in the title reaction is established.
ChemInform Abstract: Reactions of 1‐Amino‐5‐morpholino‐6,7,8,9‐tetrahydrothieno [2,3‐c]isoquinoline‐2‐carbonitrile.
Authors: El‐Dean Adel M. Kamal , Radwan Shaban M. , Zaki Remon M.
Published: March 2011

A variety of fused heterocyclic compounds including triazolopyrimidothienotetrahydroisoquinolines is synthesized starting from the title carbonitrile (I).
ChemInform Abstract: Design, Synthesis and Biotest of a Bicyclo[3.3.1]nonane Analogue (V) of 2‐Amino‐5,6‐dihydro‐4H‐1,3‐thiazine.
Authors: Zefirova Olga N. , Nurieva Evgeniya V. , Chupakhin Vladimir I. , Semenova Irina S. , Peregud Danil I. , Onufriev Mikhail V. , Gulyaeva Natalia V.
Published: March 2011

With the aim to enhance the lipophilicity of the title thiazine NO‐synthase inhibitor, its bridgehead analogue (V) is synthesized.
ChemInform Abstract: Generation and Reactions of an Unsubstituted N‐Heterocyclic Carbene Boryl Anion.
Authors: Monot Julien , Solovyev Andrey , Bonin‐Dubarle Helene , Derat Etienne , Curran Dennis P. , Robert Marc , Fensterbank Louis , Malacria Max , Lacote Emmanuel
Published: March 2011

Reduction of boryl iodide (I) with LDBB and subsequent trapping of the resulting N‐heterocyclic carbene boryl anion with various electrophiles yields derivatives that would be difficult to access with existing methods.
ChemInform Abstract: A Borylative Cyclization Towards Indole Boronic Esters.
Authors: Huang Jianhui , Macdonald Simon J. F. , Harrity Joseph P. A.
Published: March 2011

A convenient procedure for the synthesis of indole boronic esters is developed using palladium‐catalyzed borylative cyclization of 2‐alkynylanilines with bis(pinacolato)diboron.
ChemInform Abstract: Palladium‐Catalyzed Asymmetric Synthesis of Axially Chiral Allenylsilanes and Their Application to SE2′ Chirality Transfer Reactions.
Authors: Ogasawara Masamichi , Okada Atsushi , Subbarayan Velusamy , Soergel Sebastian , Takahashi Tamotsu
Published: March 2011

The desilylative SE2′ reactions of the axially chiral allenylsilanes proceed with complete transfer of the chirality to the newly formed tertiary and quaternary stereocenters of the resulting propargylic derivatives.
ChemInform Abstract: Rongalite®‐Promoted Odorless and Highly Regioselective Synthesis of β‐Hydroxyselenides under Solvent‐Free Conditions.
Authors: Lv Guangshu , Li Ting , Hu Ruijia , Chen Jiuxi , Ding Jinchang , Wu Huayue
Published: March 2011

An efficient and simple procedure reenders possible the highly regioselective synthesis of β‐hydroxyselenides by ring‐opening of epoxides with 1,2‐diphenylselenide under solvent‐free conditions.
ChemInform Abstract: Glycerol as a Promoting Medium for Cross‐Coupling Reactions of Diaryl Diselenides with Vinyl Bromides.
Authors: Goncalves Loren C. , Fiss Gabriela F. , Perin Gelson , Alves Diego , Jacob Raquel G. , Lenardao Eder J.
Published: March 2011

A glycerol/CuI/Zn mixture efficiently catalyzes the title reaction and can be completely reused at least four times.
ChemInform Abstract: Synthesis and Structure of m‐Terphenyl Thio‐, Seleno‐, and Telluroethers.
Authors: Zakai Uzma I. , Bloch‐Mechkour Anna , Jacobsen Neil E. , Abrell Leif , Lin Guangxin , Nichol Gary S. , Bally Thomas , Glass Richard S.
Published: March 2011

The structures of the title compounds are determined by spectroscopic means and X‐ray analysis.
ChemInform Abstract: Synthesis of Some Novel Glucosyl Triazoles from 2,3,4,6‐Tetra‐O‐pivaloyl‐D‐glucopyranosyl Azide.
Authors: Shen Chao , Zheng Hui , Zhang Pengfei , Chen Xinzhi
Published: March 2011

A series of novel glycosyl triazoles (IV) is synthesized using “click chemistry”.
ChemInform Abstract: Convertible Formation of Different Glycoside Using Molecular Iodine.
Authors: Saeeng Rungnapha , Sirion Uthaiwan , Sirichan Yada , Trakulsujaritchok Thanida , Sahakitpichan Poolsak
Published: March 2011

A convertible formation between 2,3‐unsaturated glycosides and 2‐deoxy‐2‐iodoglycosides is observed if the glycosylation is performed using iodine as a versatile reagent under different conditions.
ChemInform Abstract: Microwave‐Accelerated Click Chemistry: Expeditious Synthesis of Novel Triazole‐Linked Salicylic β‐D‐O‐Glycosides with PTP1B Inhibitory Activity.
Authors: Yang Jin‐Wei , Li Cui , He Xiao‐Peng , Zhao Hong , Gao Li‐Xin , Zhang Wei , Shi Xiao‐Xin , Tang Yun , Li Jia , Chen Guo‐Rong
Published: March 2011

Glycosides (IIIb) and (IVa) demonstrate potent inhibitory activity against protein tyrosine phosphatase 1B.
ChemInform Abstract: Formal Total Synthesis of Enantiopure Tricyclic (S)‐Myrmicarin Alkaloids 217, 215A and 215B.
Authors: Santarem Marco , Vanucci‐Bacque Corinne , Lhommet Gerard
Published: March 2011

The formal synthesis of (S)‐myrmicarin alkaloids is achieved by the preparation of pyrroloindolizidine (IV) in 12 steps and 7% overall yield starting from pyrrolidine (I).
ChemInform Abstract: Synthesis Analogues of Milbemycin and Their Bioactivity Evaluation.
Authors: Zhao Jin Hao , Ji Ming Hua , Xu Xu Hui , Cheng Jing Li , Zhu Guo Nian
Published: March 2011

Eight novel analogues of milbemycin are synthesized and evaluated for their bioactivity.
ChemInform Abstract: Synthesis of Acinetobactin.
Authors: Takeuchi Yasuo , Ozaki Satoru , Satoh Masahiro , Mimura Ken‐ichiro , Hara Sei‐ichi , Abe Hitoshi , Nishioka Hiromi , Harayama Takashi
Published: March 2011

Acinetobactin (II) is synthesized and its absolute configuration is clarified.
ChemInform Abstract: Synthesis and in vitro Inotropic Evaluation of 2‐(4‐Substitutedbenzyl‐1,4‐diazepan‐1‐yl)‐N‐(4,5‐dihydro‐1‐phenyl [1,2,4]triazolo[4,3‐a]quinolin‐7‐yl)acetamides.
Authors: Jiang Sheng‐Ming , Ye Bai‐Jun , Liu Xue‐Kun , Zhang Tian‐Yi , Cui Xun , Piao Hu‐Ri
Published: March 2011

16 Compounds of type (I) are prepared and evaluated for their positive inotropic activities.
ChemInform Abstract: Metal Nanocrystals with Highly Branched Morphologies
Authors: Lim Byungkwon , Xia Younan
Published: March 2011

Review: < 100 refs.
ChemInform Abstract: Magnetic Surface Nanostructures
Authors: Enders A. , Skomski R. , Honolka J.
Published: March 2011

Review: 292 refs.
ChemInform Abstract: Synthesis and Reactivity of Iridacycles Containing the TpMe2Ir Moiety
Authors: Paneque Margarita , Poveda Manuel L. , Rendon Nuria
Published: March 2011

Review: ca. 100 refs.
ChemInform Abstract: Recent Advances in the Study of Mesoporous Metal—Organic Frameworks
Authors: Fang Qian‐Rong , Makal Trevor A. , Young Mark D. , Zhou Hong‐Cai
Published: March 2011

Review: 112 refs.
ChemInform Abstract: Ozonolysis of Unsaturated Carbonyl Compounds and Alcohols
Authors: Zvereva T. I. , Kasradze V. G. , Kazakova O. B. , Kukovinets O. S.
Published: March 2011

Review: 52 refs.
ChemInform Abstract: Synthesis of Heteroaromatics via Rearrangement Reactions
Authors: Vivona Nicolo , Buscemi Silvestre , Pibiri Ivana , Piccionello Antonio Palumbo , Pace Andrea
Published: March 2011

Review: 100 refs.
ChemInform Abstract: Synthesis of Indole Derivatives with Biological Activity by Reactions Between Unsaturated Hydrocarbons and N‐Aromatic Precursors
Authors: Palmisano Giovanni , Penoni Andrea , Sisti Massimo , Tibiletti Francesco , Tollari Stefano , Nicholas Kenneth M.
Published: March 2011

Review: 362 refs.
ChemInform Abstract: Multiple Bond‐Forming Transformations: The Key Concept Toward Ecocompatible Synthetic Organic Chemistry
Authors: Coquerel Yoann , Boddaert Thomas , Presset Marc , Mailhol Damien , Rodriguez Jean
Published: March 2011

Review: 66 refs.
ChemInform Abstract: Catalysis Using β‐Diketonato Metal Complexes
Authors: Westcott Stephen A.
Published: March 2011

Review: 297 refs.
ChemInform Abstract: The Nanoscale Integration of Heterostructures in Chemo‐ and Biocatalysis
Authors: Stucky Galen D.
Published: March 2011

Review: 50 refs.
ChemInform Abstract: Insects and Their Chemical Weaponry: New Potential for Drug Discovery
Authors: Dossey Aaron T.
Published: March 2011

Review: 280 refs.
ChemInform Abstract: Theory of Coupled Electron and Proton Transfer Reactions
Authors: Hammes‐Schiffer Sharon , Stuchebrukhov Alexei A.
Published: March 2011

Review: 180 refs.
ChemInform Abstract: Infrared and Raman Imaging of Heterogeneous Catalysts
Authors: Stavitski Eli , Weckhuysen Bert M.
Published: March 2011

Review: 72 refs.
Activation of dendritic cells via TLR7 reduces Foxp3 expression and suppressive function in induced Tregs
Authors: Hackl Daniela , Loschko Jakob , Sparwasser Tim , Reindl Wolfgang , Krug Anne B.
Published: March 2011

Exogenous and endogenous RNA ligands of Toll‐like receptor (TLR) 7 which are present during viral infection or autoimmune diseases such as systemic lupus erythematosus (SLE) directly activate DCs and B cells and thus support the generation of effector T and B lymphocytes. However, the generation of effective antiviral or autoreactive adaptive immune responses requires blocking of immunosuppression by Tregs. In this study, we show that TLR7 ligands reduce the number of Tregs generated de novo from naïve murine T cells in vitro and in vivo. In the presence of TLR7‐activated splenic DCs, Foxp3 was transiently induced in naïve T cells by TGF‐β but was downregulated at later time points. Neutralization experiments revealed that loss of Foxp3 after initial induction was mostly dependent on IL‐6 produced in the DC–T‐cell cocultures containing TLR7 ligands. Thus, under the influence of TLR7 ligands fewer Tregs were generated and these expressed lower levels of Foxp3 correlating with a reduced capacity to suppress responder T‐cell proliferation. Thus, we provide evidence that TLR7 ligands affect Treg‐dependent immune regulation and may thereby contribute to the development of autoimmune diseases such as systemic lupus erythematosus.
ApoB (XbaI) polymorphism and lipid variation in Teharnian population
Authors: Daneshpour Maryam S , Faam Bita , Hedayati Mehdi , Eshraghi Parisa , Azizi Fereidoun
Published: March 2011

This study examines the association of XbaI apolipoprotein B polymorphism with lipid related variables in Tehran lipid and glucose study. 809 subjects from the TLGS population were selected, anthropometrical and biochemical factors were measured. A segment of the apo B gene in exon 26 was amplified by PCR and the polymorphism was revealed by RFLP using XbaI restriction enzyme. Allele frequencies obtained for X+ and X− were 27.6 and 72.4%, respectively. Presence of the X+ allele was significantly associated with increased levels of total cholesterol (p 0.048), apolipoprotein B (p 0.018), and low‐density lipoprotein (p 0.022). The associations were significant even after adjustment for age, BMI, smoking, and history of diabetes. There are some relationships between the presence of different alleles of XbaI polymorphism with serum cholesterol, apoB, and LDL‐C concentration. These findings highlight the importance of variation in this gene on some lipid related factors levels.
FEM‐BEM coupling for the exterior Stokes problem with non‐conforming finite elements and an application to small droplet deformation dynamics
Authors: Radcliffe A. J.
Published: March 2011

A non‐conforming, discontinuous Galerkin finite element–boundary element coupling procedure is presented for the exterior planar Stokes problem. The novel coupled formulation is developed using that for the conforming case as a guide to the introduction of extra mortar variables used to couple a discontinuous interior finite element solution with a continuous exterior boundary element solution. Convergence results for the new scheme are presented, for a range of different interior penalties, on computational domains discretized with regular structured meshes.

To illustrate an application, the excitations required to model two‐phase droplet deformations in an extensional flow, under simple surface tension, with the new scheme are also presented. For a selection of different drop viscocities and exterior flows, with and without a rotational component, the progression to a steady‐state deformation of initially undeformed circular drops is calculated and the results compared with those from both a conforming FEM‐BEM equivalent scheme and from a small perturbation analysis where available. Copyright © 2011 John Wiley & Sons, Ltd.
An empirical analysis of dynamic multiscale hedging using wavelet decomposition
Authors: Conlon Thomas , Cotter John
Published: March 2011

This study investigates the hedging effectiveness of a dynamic moving‐window OLS hedging model, formed using wavelet decomposed time‐series. The wavelet transform is applied to calculate the appropriate dynamic minimum‐variance hedge ratio for various hedging horizons for a number of assets. The effectiveness of the dynamic multiscale hedging strategy is then tested, both in‐ and out‐of‐sample, using standard variance reduction and expanded to include a downside risk metric, the scale‐dependent Value‐at‐Risk. Measured using variance reduction, the effectiveness converges to one at longer scales, while a measure of VaR reduction indicates a portion of residual risk remains at all scales. Analysis of the hedge portfolio distributions indicate that this unhedged tail risk is related to excess portfolio kurtosis found at all scales.
AST-120 (spherical carbon adsorbent) lowers ammonia levels and attenuates brain edema in bile duct–ligated rats
Authors: Bosoi Cristina R. , Parent-Robitaille Christian , Anderson Keith , Tremblay Mélanie , Rose Christopher F.
Published: March 2011

The pathogenesis of hepatic encephalopathy is multifactorial, involving gut-derived toxins such as ammonia, which has been demonstrated to induce oxidative stress. Therefore, a primary hepatic encephalopathy treatment target is reducing ammonia production in the gastrointestinal tract. AST-120, an oral adsorbent of engineered activated carbon microspheres with surface areas exceeding 1600 m2/g, acts as a sink for neurotoxins and hepatotoxins present in the gut. We evaluated the capacity of AST-120 to adsorb ammonia in vitro and to lower blood ammonia, oxidative stress and brain edema in cirrhotic rats. Cirrhosis was induced in rats by bile duct ligation for 6 weeks. AST-120 was administered by gavage preventively for 6 weeks (0.1, 1, and 4 g/kg/day). In addition, AST-120 was evaluated as a short-term treatment for 2 weeks and 3 days (1 g/kg/day) and as a sink to adsorb intravenously infused ammonium acetate. In vitro, AST-120 efficiently adsorbed ammonia. Ammonia levels significantly decreased in a dose-dependent manner for all AST-120–treated bile duct-ligated rats (nontreated: 177.3 ± 30.8 μM; AST-120, 0.1 g/kg/day: 121.9 ± 13.8 μM; AST-120, 1 g/kg/day: 80.9 ± 30.0 μM; AST-120, 4 g/kg/day: 48.8 ± 19.6 μM) and significantly correlated with doses of AST-120 ( r = −0.6603). Brain water content and locomotor activity normalized after AST-120 treatments, whereas arterial reactive oxygen species levels remained unchanged. Furthermore, AST-120 significantly attenuated a rise in arterial ammonia after ammonium acetate administration (intravenously).

Conclusion:

AST-120 treatment decreased arterial ammonia levels, normalized brain water content and locomotor activity but did not demonstrate an effect on systemic oxidative stress. Also, AST-120 acts as an ammonia sink, efficiently removing blood-derived ammonia. Additional studies are warranted to evaluate the effects of AST-120 on hepatic encephalopathy in patients with advanced liver disease. (HEPATOLOGY 2011;)
Synthesis of novel pyrazolopyridine and pyridopyrimidine derivatives
Authors: Soliman A. M.
Published: March 2011

2‐Amino‐6‐chloropyridine‐3,5‐dicarbonitrile was used as an intermediate for synthesis of new pyrazolopyridine, pyridopyrimidine, benzodiazepine, and benzothiazipine derivatives. J. Heterocyclic Chem., (2011).
Ammonium metavanadate as an efficient catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazoles
Authors: Niralwad Kirti S. , Shingate Bapurao B. , Shingare Murlidhar S.
Published: March 2011

Ammonium metavanadate (NH4VO3) is an inexpensive, efficient and mild catalyst for the synthesis of 2,4,5‐triaryl‐1H‐imidazole from the one‐pot three‐component condensation of benzil/benzoin, an aldehyde and ammonium acetate in excellent yield. This method has the advantages of good yield, green catalyst, simple procedure, much faster reactions. J. Heterocyclic Chem., (2011).
Ligand Accessibility to Receptor Binding Sites Enhanced by Movable Polyrotaxanes
Authors: Hyun Hoon , Yui Nobuhiko
Published: March 2011

Functionalized polyrotaxanes are utilized to investigate the relation to multivalent interactions between the mannose moiety and Con A immobilized surfaces. According to the results of SPR spectroscopy, the mannose‐conjugated polyrotaxanes show a higher response than any other mannose conjugate on both surfaces of high‐ and low‐density Con A. Moreover, the results of the FRET analysis suggest that the mobility of α‐cyclodextrins in the polyrotaxane more efficiently contributes to their binding interactions in a multivalent manner. This well‐defined polyrotaxane system provides control over ligand density, ligand mobility, and gives an efficient response to the biological interaction receptor, which has not been easy to achieve in covalently bound polymeric systems.

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Blue‐Emitting Polymers Based on 4‐Hydroxythiazoles Incorporated in a Methacrylate Backbone
Authors: Menzel Roberto , Breul Alexander , Pietsch Christian , Schäfer Johann , Friebe Christian , Täuscher Eric , Weiß Dieter , Dietzek Benjamin , Popp Jürgen , Beckert Rainer , Schubert Ulrich S.
Published: March 2011

The synthesis of two new monomers based on 4‐hydroxythiazoles, with a non‐classical chromophore structure similar to the luciferin dye of glowworms, is presented. These dyes are functionalized with methacrylates and copolymerized with methyl methacrylate using a RAFT polymerization process. The obtained polymers reveal PDI values below 1.2 and are characterized by NMR spectroscopy, SEC including a diode‐array detector, UV‐vis and fluorescence spectroscopy. In addition, thin films of the polymers are prepared by spin‐coating and investigated regarding their optical properties.

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Synthesis of Thermo‐Responsive Polymers With Both Tunable UCST and LCST
Authors: Tian Hai‐Ying , Yan Jun‐Jie , Wang Di , Gu Chen , You Ye‐Zi , Chen Xue‐Si
Published: March 2011

New water‐soluble block copolymers of 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA), oligo(ethylene glycol) methacrylate (OEGMA), and N‐(3‐(dimethylamino) propyl) methacrylamide (DMAPMA) (poly(OEGMA‐co‐MEO2MA)‐b‐poly(DMAPMA)) were prepared via sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization. Selective quaternization of poly(DMAPMA) block gives poly(OEGMA‐co‐MEO2MA)‐b‐poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide), such block copolymer exhibits double thermo‐responsive behavior in water, poly(MEO2MA‐co‐OEGMA) block shows a lower critical solution temperature (LCST), and poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide) block shows a upper critical solution temperature (UCST). Both of LCST and UCST can be controlled: LCST could be tuned by the fraction of OEGMA units in poly(OEGMA‐co‐MEO2MA), and UCST was found to be dependent on the degree of quaternization (DQ).

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Fluorescent Core‐Shell Star Polymers Based Bioassays for Ultrasensitive DNA Detection by Surface Plasmon Fluorescence Spectroscopy
Authors: Feng Chuan Liang , Yin Meizhen , Zhang Di , Zhu Shenmin , Caminade Anne Marie , Majoral Jean Pierre , Müllen Klaus
Published: March 2011

Multilayers containing a perylene diimide labelled star polymers (FSP) donor adjacent to phosphorus dendrimer layer on a silver substrate were constructed by layer by layer (LBL) approach. Using Surface Plasmon Enhanced Fluorescence Spectroscopy (SPFS) technique, a time‐resolved ultrasensitive and selective detection of DNA targets relying on enhanced optical fields associated with energy transfer (ET) were achieved under the excitation at 543 nm. The detection limit is about 8 orders of magnitude better than the achieved one under the excitation at 632 nm, which is ascribed to no energy transfer from the donor to the acceptor under the excitation at 632 nm, resulting in much weak detection signal in turn.

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Blends of poly(2,6–dimethyl–1,4–phenylene oxide) with styrene copolymers
Authors: Gottschalk Axel , Mühlbach Klaus , Seitz Friedrich , Stadler Reimund , Auschra Clemens
Published: March 2011

Binary blends of poly(2,6–dimethyl–1,4–phenylene oxide) (PPE) with various styrene copolymers were investigated. Poly(styrene–co–acrylonitrile) (SAN), poly[styrene–co–(methyl methacrylate)] (SMMA), poly[styrene–co–(acrylic acid)] (SAA) and poly[styrene–co–(maleic anhydride)] (SMA) are only miscible with PPE when the amount of comonomer is rather small. From calculated binary interaction densities it can be concluded that the strong repulsion between PPE and comonomer limits miscibility. In blends of PPE with SAN, as well as with ABS, the inter‐facial tension between the blend components is significantly reduced upon addition of polystyrene–block–poly–(methyl methacrylate) diblock copolymers (PS–b–PMMA) and polystyrene–block–poly (ethylene–co–butylene)–block–poly–(methyl methacrylate) triblock copolymers (PS–b–PEB–b–PMMA). They show a profound influence on morphology, phase adhesion and mechanical blend properties.
Characterization of the segmental mobility of liquid‐crystalline side‐chain polyesters by fourier‐transform infrared spectroscopy
Authors: Kulinna Ch. , Zebger I. , Hvilsted S. , Ramanujam P. S. , Siesler H.W.
Published: March 2011

Fourier‐Transform infrared (FTIR) polarization spectroscopy has been applied to study segmental orientation of a new class of liquid‐crystalline side‐chain (LCSC) polyesters as a function of laser irradiation. From the experimental results qualitative structural models and quantitative results in terms of an order parameter were derived. Time‐dependent investigations yielded a detailed insight into the orientational response of the mesogens, and temperature‐dependent studies were applied to monitor the erasure of the induced orientation.
Polymer blends: Structure and specific interaction of components ‐ poly(phenylene sulfide) and its oligomers
Authors: Kryszewski Marian
Published: March 2011

Poly(phenylene sulfide) (PPS) and its blends with oligomers of PPS have been investigated. It was shown that such a system shows changes in the crystallization behaviour, in the amount of rigid amorphous phase, in the glass transition temperature and in the electrical conductivity (after doping).
Investigations on the structure of regenerated cellulose fibers; Herrn Professor Janeschitz‐Kriegl zum 70. Geburtstag mit den besten Wünschen gewidmet
Authors: Schurz Josef , Lenz Jürgen
Published: March 2011

A review is given on comparative investigations onto the structure of regenerated cellulose fibers of the regular viscose type (modal) and of solvent spun fibers of the lyocell type, namely the NMMO fiber spun from a solution of cellulose in N–methylmorpholine N–oxide and water. It was found that in the lyocell fiber the mechanical properties in the wet state detoriate less. This is explained by an increased length of the crystallites, less clustering of the crystalline regions, and a shorter and better oriented amorphous portion. These structural features could be caused by a different spinning mechanism due to a preordered spinning solution in which the stiff complexed cellulose molecules are oriented lengthwise in the spinning direction. This will greatly facilitate their orientation during fiber formation in the elongtional deformation velocity field of the draw down zone.
Fascinated by a chain molecule review of 35 years' research on cellulose
Authors: Fengel Dietrich
Published: March 2011

For over 35 years the author has been involved in cellulose research and his retirement next year is the reason why he has undertaken to present a review on some aspects of his investigations on the fascinating substance cellulose. One topic of his research activities is electron microscopy. At the very start, at the Institute for Cellulose Chemistry (T.H. Darmstadt), observations were made on bordered pits and structural details on the walls of wood and pulp fibres. He was able to continue his teacher's, Georg Jayme's, traditional basic research on cellulose at the Institute for Wood Research (University of Munich) where “dreams” of the fifties and sixties such as the visualization of individual molecules and the growing of macrocrystals of cellulose could be realized. Here, the electron microscope became a vital instrument for the study of cellulose chemistry.
Spontaneous copolymerizations in the reactions of electron‐rich dienes with electrophilic olefins
Authors: Hall H. K. , Padias Anne Buyle
Published: March 2011

The spontaneous thermal reactions of electron‐rich dienes with electrophilic olefins lead to both [4+2] cycloadducts and copolymers. The mechanism proposed for the initiation of the copolymerization involves the formation of a 2‐hexene‐1,6‐diradical. Structure‐reactivity relationships are discussed.
Polymerization of surface‐active monomers and applications
Authors: Nagai Katsutoshi
Published: March 2011

The results on radical polymerization and copolymerization of alkyl bromide salts of 2‐dimethylaminoethyl methacrylate having a different alkyl chain length in various solvents giving micellar and isotropic solutions are summarized to obtain an insight into micellar polymerization. The monomer micellization of the cationic surface‐active monomers at concentrations far above their critical micelle concentration (cmc) leads to great increases in the rate of polymerization and the molecular weight of the resulting polymers for both aqueous and inverse micellar systems and the tendency toward alternation of the copolymerization for aqueous micellar systems, whereas it has little influence on the tacticity of the resulting polymers. Applications of the polimerization and the copolymerization of the surface‐active monomer to the polymer encapsulation of silica particles are also reported.
Synthesis and structure of polyisopeptides
Authors: Sekiguchi Hikaru , Coutin Bernard , And Soufiane Bechaouch , Gachard Isabelle
Published: March 2011

Polyisopeptides are non‐peptidic polymers formed by α,ω‐polycondensation of tri‐ or multi‐functional α‐amino acids. They are expected to possess physical and mechanical properties of synthetic polyamides (or polyesters) and to be biodegradable. In the present paper, the methods of polyisopeptide synthesis are reviewed. Many of them are specific to a given α‐amino acid (and sometimes its derivatives, too). We discuss here about two methods giving satisfactory results. One is the polymerization of L‐aspartic β‐lactam α‐esters, in which the structure of a resulting polymer varies according to the solvent used. A new interpretation on the basis of the nature of catalyst anion species (free ion, ion pair) is presented. The other subject is the active ester polycondensation method applied to the amino‐ and carboxyl‐ protected L‐cystine polyisopeptide and its selective deprotection successively until total deprotection to free amino‐ and free carboxylic groups. The final polymer is the first poly‐L‐cystine ever reported in the literature.
Styrene and methyl methacrylate polymerization using diphenylzinc‐cocatalyst systems. part II.
Authors: Rabagliati Franco M. , Terraza Claudio A. , Ramirez Luis A. , Contreras Jesús M.
Published: March 2011

Various diphenylzinc–additive systems were used to initiate homopolymerization of styrene and of methyl methacrylate. The polymers obtained were characterized by size exclusion chromatography, by 1H– and 13C–NMR and measurements of intrinsic viscosities [η]. These data indicated that polymerization is much influenced by: The nature of the additive employed, the proportion of the additive relative to diphenylzinc and the condition of polymerization.
Synthetic routes to block copolymerization by changing mechanism from cationic polymerization to free radical polymerisation
Authors: Yagoi Yusuf , Hizal Gürkan , Önen Ayşen , Serhatli İErsin
Published: March 2011

Polymers containing thermolabile groups were synthesized by various cationic polymerization initiation mechanisms, namely; oxo–carbenium, promoted cationic and activated monomer polymerization. These polymers used in a subsequent blocking step in which azo groups were decomposed and converted into initiating centres from which blocks were grown by means of free radical polymerization. This procedure was applied to specific systems in which cationic polymerizable monomers are tetrahydrofuran (THF), cyclohexene oxide (CHO) and epichlorohydrin (ECH), respectively, and the free radical polymerizable monomer is styrene (St).
New polymers for biomedical applications: Synthesis and characterization of acrylic systems with pharmacological activity
Authors: Román Julio San , Gallardo Alberto , Levenfeld Belén
Published: March 2011

The synthesis and characterization of new biocompatible “Polymeric Drugs” on the basis of poly (methacrylic esters) and poly (methacrylamides) with side substituents of pharmacological interest, with analgesic, antiinflammatory, antipyretic and antiaggregating activities, is reported. The preparation of these systems was carried out following the universal model suggested by Ringsdorf, and the polymers prepared by the free radical polymerization of the corresponding acrylic monomers were characterized by 1H‐ and 13C‐NMR spectroscopies. Biocompatible hydrogels were prepared by free radical copolymerization of these monomers with HEMA. The characteristic copolymerization parameters and the microstructural distribution of comonomeric sequences were determined by NMR spectroscopy. The swelling behaviour of copolymer films was followed gravimetrically. Applications of polymer and copolymer systems are being tested in the fields of pharmacology and vascular surgery.
Microporous polymeric materials by microemulsion terpolymerization
Authors: Gan L. M. , Chew C. H. , Chieng T. H.
Published: March 2011

Transparent microstructural solid polymers have been prepared by polymerization of methyl methacrylate, 2‐hydroxyethyl methacrylate and reactive sodium 11‐(N‐ethylacrylamido) undecanoate in microemulsions. The transparent polymeric solids could be formed from fluid microemulsions within 10 minutes by photoinitiated polymerization. SEM micrographs of the polymerized samples reveal the existence of microporous structures. The results seem to indicate that the open‐cell porous structures of transparent polymers could be obtained from those precursor microemulsions with water content higher than 20% or the closed‐cell structures from those with less than 20%.
Δχ effects on the miscibility of polymer blends
Authors: Ha Chang Sik , Ki Lee Won , Cho Won Jei
Published: March 2011

The Δχ effect on the miscibility of polymer blends prepared by solution‐casting has been investigated using the mixture of poly(methyl methacrylate)(PMMA) with poly(vinyl acetate) (PVAc). The PMMA/PVAc blends have been prepared by casting from eleven different solutions. The Δχ effect of the solution–cast PMMA/PVAc blends was discussed in terms of Hansen's specified solubility parameters. It was found that the miscibility of the blends could be defined mainly by the solubility parameter contributed by the hydrogen–bonding of a solvent.
Porous structure formation and swelling properties of styrene–divinylbenzene copolymers – effect of diluent nature
Authors: Rabelo D. , Coutinho F. M. B.
Published: March 2011

The effect of the diluent solvating power on the porosity and swelling properties of styrene–divinylbenzene copolymers was investigated. A mechanism for the swelling of macroporous copolymers in good and poor solvent was proposed. The porous structures were classified according to kinetic data of a poor solvent sorption. When the diluent–copolymer affinity was reduced, the fixed pore volume increased, but the nuclei swelling and the elasticity of internuclear chains diminished.
Determination of structure and concentration of growing species in ionic polymerizations: The 31P NMR method
Authors: Penczek Stanislaw , Brzezinska Krystyna
Published: March 2011

The quantitative transformation of the ionic growing species (∼ ∼ ∼*) into the P atom containing end‐groups (∼ ∼ ∼P) allows to determine by 31P NMR their structures and concentrations, down to 10−4 mol‐L−1, or even lower with a further progress of the NMR equipment:

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The P atoms are exclusively located at the chain ends, the known excess of the reagent “P” being used as an internal standard. The chemical shifts of thus prepared chain ends, when compared with models, give information on the chemical structure of the parent active species. This paper reviews the earlier work on ionic ring‐opening polymerization and more recent work, concerning cationic and anionic vinyl polymerization, particularly polymerization of vinyl ethers, styrene, methacrylates and some diene monomers. In the polymerization of vinyl ethers the stereochemistry of the chain ends was studied; it has also been shown, that chemical shift changes with the polymerization degree; thus the first addition products could separately be observed.
Some new developments in vinyl ether polymerization
Authors: Goethals Eric J. , Haucourt Nancy , Peng Li‐Bing
Published: March 2011

Different combinations of acetals with trimethylsilyl iodide have been explored as new initiating systems for the vinyl ether polymerization. The resulting polymers are characterized by controlled molecular weights and narrow molecular weight distributions, confirming the living polymerization mechanism.

Acetals can also be used as transfer agents in the polymerization of vinyl ethers. When using 1,1‐diethoxyethane (DEE) as transfer agent and isobutyl vinyl ether (IBVE) as monomer, a transfer constant of 0.2 was obtained (at −40°C in toluene). This method, transposed to functional acetals, provides a new way to prepare polyvinyl ethers with one or two functional end groups.

The cationic polymerization of isobutyl vinyl ether initiated with the combination triflic acid/thietane, where thietane acts as electron donating moderator, leads to star‐shaped polyvinylether‐polythietane block‐copolymers (at −40°C in dichloromethane). The block‐copolymer structure is obtained because the vinyl ether polymerization is stopped when the α‐alkoxy thietanium ion (active species) is attacked by a thietane molecule, which is at the same time an initiation reaction for the thietane polymerization. The star‐shaped structure of the block‐polymer is the result of the intermolecular termination in the cationic polymerization of thietane. When using a bifunctional initiator system, a polymer network is obtained consisting of linear polyIBVE‐segments interconnected by branched polythietane segments. These findings support the sulfonium ion structure of the active species in the cationic polymerization of vinyl ethers initiated by the acid‐sulfide system.
Tailor‐made polymers and copolymers from aziridines and 1,3‐oxacyclanes
Authors: Velichkova Rumiana , Christova Darina , Gancheva Valeria
Published: March 2011

Telechelic poly(tert‐butylaziridine)s (polyTBA) and poly(1,3,6‐trioxocane)s (polyTOC) and macromonomers were synthesized mainly by living cationic polymerization. Both, molecular weight and end‐functionality distributions of polyTOC oligomers and polymers were studied using a combination of HPLC under “critical conditions”, gradient HPLC and SEC with double detection following a preparative HPLC fractionation.

Monofunctional and bifunctional polyTBA with various end‐groups were synthesized by the end‐capping method. Several modification reactions were examined for terminal transformation of polyTBA and polyTOC hydroxy‐telechelics into mono‐ and bifunctional vinyl ether macromonomers. Various tailor‐made polymers based on uniform size telechelics and macromonomers were prepared using: 1. polymer‐polymer coupling to produce block copolymers; 2. polyaddition of amino‐functionalized telechelics to bisacrylamides; 3. addition of amino‐polyTBA to polydienes; 4. synthesis of graft copolymers with well‐defined graft component and networks.
Functionalization of poly(1,3‐dioxolane)
Authors: Franta E. , Lutz P. , Reibel L. , Sahli N. , Kada S. Ould. , Belbachir M.
Published: March 2011

1,3‐Dioxolane was polymerized in the presence of ethylene glycol in order to prepare α,ω‐dihydroxylated polymers which, upon reaction with pluriisocyanates yielded networks swellable in water. The crosslinks were made of urethane groups, which are bulky and hydrophobic. In order to expand the scope of the networks that can be envisioned, we have studied the replacement of the two end‐standing hydroxylic groups by unsaturated polymerizable groups. Several methods are presented which allow successfully the quantitative endowment of the polymer endings with methacryloyl‐ or styryl‐ or vinylether‐type groups.

α,ω‐dihydroxylated poly(1,3‐dioxolane) was also metallated and used as a macroinitiator for the polymerization of ethylene oxide: the α,ω‐dihydroxylated triblock copolymer obtained is made of a central poly(1,3‐dioxolane) block flanked by two poly(ethylene oxide) ones.

Several methods are also shown to be efficient in the characterization of the hydroxylic end‐standing functions of the polymer.
Block and graft copolymers of 2‐oxazolines
Authors: Schulz Rolf Christian. , Dworak Andrzej
Published: March 2011

The cationic ring‐opening polymerization of 2‐oxazolines is known to be initiated by alkyl halides, Lewis acids and esters of strong acids. The polymerization proceeds by a living mechanism. Numerous block and graft copolymers have already been described. Recently it was found that chloroformates (R‐O‐CO‐CI) are also useful initiators. The mechanism of the initiation and propagation is discussed. This type of initiators allows the synthesis of different novel two‐block and three‐block copolymers, star‐shape polymers, and a graft copolymer with a polyvinylacetate backbone.
Synthetic strategies to well‐defined polymers by ionic polymerization
Authors: Faust Rudolf
Published: March 2011

The living cationic polymerization and sequential copolymerization of isobutylene and styrene has been achieved. Polymethylmethacrylate‐g‐polyisobutylene graft copolymers have been prepared by the combination of living cationic and group transfer polymerization.
Kinetics and mechanism of group transfer polymerization of N‐butyl acrylate catalyzed by Hgl2/(CH3)3Sil in toluene
Authors: Zhuang Rugang , H. E. Müller Axel
Published: March 2011

The group transfer polymerization (GTP) of n‐butyl acrylate (nBuA) using 1‐methoxy‐1‐(trimethylsiloxy)‐2‐methyl‐1‐propene (MTS) as an initiator, mercuric iodide (HgI2) as a catalyst in toluene at room temperature gives a very good control of molecular weight and narrow molecular weight distribution. (M̄w/M̄n < 1.2). Kinetic studies in this system reveal that this reaction is rather slow, half‐lives being in the range of hours. The kinetic order of the apparent rate constant of propagation with respect to initiator and catalyst concentrations were found to be near to unity. However, the first‐order time‐conversion plots exhibit considerable induction periods. Upon addition of trimethylsilyl iodide (TMSI) the induction periods vanish and the rates are increased by two orders of magnitude. The reaction is first‐order with respect to TMSI indicating that it takes part in the reaction by activating the catalyst. The complex from HgI2 and TMSI acts as a nucleophilic catalyst, similar to oxyanions in the GTP of MMA in THF. It is proposed that the induction periods are due to the formation of TMSI from MTS and HgI2.