bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aluminiumbasen für die hoch chemoselektive Synthese von Aryl‐ und Heteroarylaluminiumverbindungen
Authors: Wunderlich Stefan H. , Knochel Paul 
Published: January 2009

AbstractO am Steuer: Vielfältige funktionalisierte (hetero)aromatische Aluminiumreagentien wurden in THF effizient über eine dirigierte Aluminierung mithilfe neuartiger, neutraler Aluminiumtrisamidbasen hergestellt. Ester‐ und Cyanfunktionen werden gut toleriert. Bemerkenswerterweise sind Donor‐Sauerstoffsubstituenten effektive dirigierende Gruppen für diese Aluminierungen. An O,S‐ und N,S‐Heterocyclen werden bei der Metallierung hohe Regioselektivitäten beobachtet.magnified image
Nanomedicine—Challenge and Perspectives
Authors: Riehemann Kristina , Schneider Stefan W. , Luger Thomas A. , Godin Biana , Ferrari Mauro , Fuchs Harald 
Published: January 2009

AbstractThe application of nanotechnology concepts to medicine joins two large cross‐disciplinary fields with an unprecedented societal and economical potential arising from the natural combination of specific achievements in the respective fields. The common basis evolves from the molecular‐scale properties relevant to the two fields. Local probes and molecular imaging techniques allow surface and interface properties to be characterized on a nanometer scale at predefined locations, while chemical approaches offer the opportunity to elaborate and address surfaces, for example, for targeted drug delivery, enhanced biocompatibility, and neuroprosthetic purposes. However, concerns arise in this cross‐disciplinary area about toxicological aspects and ethical implications. This Review gives an overview of selected recent developments and applications of nanomedicine.
Palladium‐Catalyzed Substitution of Allylic Fluorides
Authors: Hazari Amaruka , Gouverneur Véronique , Brown John M. 
Published: January 2009

AbstractAs unusual substrates for the Tsuji–Trost allylation reaction, allylic fluorides are responsive to palladium‐catalyzed substitution. Their activity towards this reaction fits in the series OCO2Me>OBz≫F≫OAc. The classic stereoretention mechanism that involves sequential inversions does not operate in this case. Several distinct cases are considered.magnified image
Transition‐Metal‐Catalyzed Diamination of Olefins
Authors: de Figueiredo Renata Marcia 
Published: January 2009

AbstractDiaminations are a girl's best friend: New reactions in the field of transition‐metal‐catalyzed diamination of olefins provide a powerful tool for the elaboration of more complex molecules bearing the 1,2‐diamine moiety. An overview of these methods, including asymmetric versions, is given.magnified image
High‐Purity Discrete PEG‐Oligomer Crystals Allow Structural Insight
Authors: French Alister C. , Thompson Amber L. , Davis Benjamin G. 
Published: January 2009

AbstractTo great (monodisperse) lengths: An improved synthesis of purer ethylene glycol (EG) oligomers allows access to 16‐ and 32‐mers pure enough for multiple incorporation, and also to the longest (48‐mer) discrete EG oligomer yet reported. The high purity enables the first crystallizations and hence the first glimpses of secondary 310‐helical PEG structures.magnified image
Isoprene‐Assisted Radical Coupling of (Co)polymers Prepared by Cobalt‐Mediated Radical Polymerization
Authors: Debuigne Antoine , Jérôme Christine , Detrembleur Christophe 
Published: January 2009

AbstractTackling blocks: The isoprene‐assisted radical coupling (I‐ARC) of polymers prepared by cobalt‐mediated radical polymerization (see picture) is the first efficient radical coupling method that is not restricted to short chains. When applied to AB diblock copolymers, I‐ARC constitutes a straightforward approach to the preparation of novel symmetrical ABA triblock copolymers.magnified image
Compartmentalization of Chemically Separated Components into Droplets
Authors: Edgar J. Scott , Milne Graham , Zhao Yiqiong , Pabbati Chaitanya P. , Lim David S. W. , Chiu Daniel T. 
Published: January 2009

AbstractNot merely a drop in the ocean: The integration of capillary electrophoresis (CE) with droplet generation driven by electroosmotic flow enabled the compartimentalization of molecular components separated by CE in a series of droplets (see picture; the green bars represent the separated analytes). The droplet‐confined bands can be docked and studied on a chip.magnified image
Water as an Oxygen Source in the Generation of Mononuclear Nonheme Iron(IV) Oxo Complexes
Authors: Lee Yong‐Min , Dhuri Sunder N. , Sawant Sarvesh C. , Cho Jaeheung , Kubo Minoru , Ogura Takashi , Fukuzumi Shunichi , Nam Wonwoo 
Published: January 2009

AbstractGive me an “O”! Mononuclear nonheme iron(IV) oxo complexes have been generated using water as an oxygen source and cerium(IV) as an oxidant. The high‐yield oxygenation of organic substrates in this system (see picture, Fe green, O red, N blue, C gray) is catalyzed by iron(II) complexes. The source of oxygen in the iron(IV) oxo complexes and the oxygenated products has been assigned unambiguously by isotopic labeling experiments.magnified image
Development of a novel microcompounder for polymer blends and nanocomposite
Authors: Son Younggon 
Published: January 2009

AbstractIn this article, we introduce a new type of small scale compounder. The compounder developed is for mixing of polymeric samples of 0.5–10 g. It consists of a heated cylindrical metal having two cylindrical cavities connected through a narrow channel and two cylindrical pistons, which squeeze molten polymers from one cavity to the other cavity through the narrow channel. During mixing procedure, the molten polymers flow from one cavity to the other cavity, repeatedly, and this operation generates the extensional flow in the converging and the diverging geometry. Because the compounder has mixing chamber of very simple geometry, the cleaning is very easy and the material lost is very small. We evaluated the mixing efficiency of the compounder by comparing with the commercialized small‐scale mixers including a cup and rotor batch mixer, an internal batch mixer, and a recirculating conical twin‐screw extruder. It was found that the compounder developed has many advantages over the existing small‐scale mixers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
New polymer syntheses, Part 44: Synthesis, characterization, and corrosion inhibition behavior of new polyurea derivatives based on diaryl ether in the polymers backbone
Authors: Aly Kamal I. , Abbady M. A. , Mahgoub S. A. , Hussein M. A. 
Published: January 2009

AbstractA new interesting class of polyurea derivatives 5a‐c was synthesized using solution polycondensation technique by the interaction of 1 mol of 4,4′‐bis(2″‐aminothiazol‐4″‐yl)diphenyl ether monomer 3 with 1 mol of diisocyanate compounds in pyridine. The model compound 4 was synthesized by the interaction of 1 mol of monomers 3 with 2 mol of phenylisocyanate in pyridine, and the structure was confirmed by correct elemental and spectral analyses. The resulting polymers were characterized by elemental and spectral analyses besides solubility and viscometry measurements. The thermal properties of those polymers were evaluated by TGA, DTG, and DTA measurements and correlated to their structural units. In addition, the morphological properties of a selected example were tested by SEM, and the electrical properties of these polymers were measured. On the other hand, the corrosion inhibition properties of selected example of polyurea derivatives were carried out on steel in 0.5M H2SO4 at 40°C giving cathodic inhibition. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Rheological analysis of the degradation of HDPE during consecutive processing steps and for different processing conditions
Authors: Kealy Tim 
Published: January 2009

AbstractUsing a twin‐screw extruder, HDPE has been processed six times consecutively under a range of processing conditions (changing barrel temperature, screw speed, and feed rate). After each pass, the product has been analyzed in terms of the melt flow index (MFI) and GC(ωC), the crossover point of the viscoelastic moduli as a function of the angular velocity at which it occurs. MFI data show changes in the structure of the HDPE after each processing step, but this information is limited in quality and quantity. GC data show the mechanism for degradation (side‐chain branching and chain scission) and allow us to track relative changes in mean molecular weight (MMW) and molecular weight distribution (MWD). MMW and MWD both increase as a result of continued reprocessing. The apparent changes in MWD are substantial indicating significant chain scission initially, accompanied and followed during subsequent processing by a combination of side‐chain branching and further chain scission. A relative measure of the polydispersity index (PI) of the melt is calculated and the PI increases as the HDPE is further reprocessed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Evaluation of postpolymerization as a function of the storage time of triethylene glycol dimethacrylate/2,2‐bis[4‐(2‐hydroxy‐3‐methacryloxy‐prop‐1‐oxy)‐phenyl]propane bisphenyl‐α‐glycidyl ether dimethacrylate copolymers used in dental resins by differential scanning calorimetry and dynamic mechanical analysis
Authors: Rigoli Isabel C. , Cavalheiro Carla C. S. , Neumann Miguel G. 
Published: January 2009

AbstractThe aim of this work was to evaluate the effect of the storage time on the thermal properties of triethylene glycol dimethacrylate/2,2‐bis[4‐(2‐hydroxy‐3‐methacryloxy‐prop‐1‐oxy)‐phenyl]propane bisphenyl‐α‐glycidyl ether dimethacrylate (TB) copolymers used in formulations of dental resins after photopolymerization. The TB copolymers were prepared by photopolymerization with an Ultrablue IS light‐emitting diode, stored in the dark for 1–60 days at 37°C, and characterized with differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy with attenuated total reflection. DSC curves indicated the presence of an exothermic peak, confirming that the reaction was not completed during the photopolymerization process. This exothermic peak became smaller as a function of the storage time and was shifted at higher temperatures. In DMA studies, a plot of the loss tangent versus the temperature initially showed the presence of two well‐defined peaks. The presence of both peaks confirmed the presence of residual monomers that were not converted during the photopolymerization process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Simultaneous enhancement of the strength and elongation of polycaprolactone: The role of chitosan‐graft‐polycaprolactone
Authors: Zhou Ziyan , Huang Haitao , Xu Peihu , Fan Lihong , Yu Jiahui , Huang Jin 
Published: January 2009

AbstractPolycaprolactone (PCL) is a basic substance for biomedical materials and especially for scaffolds in tissue engineering. To improve the performance of PCL‐based materials, we filled a PCL matrix with a biocompatible polysaccharide‐grafted PCL, chitosan‐g‐polycaprolactone (CS‐g‐PCL). The results showed that the strength, elongation, and Young's modulus of the resultant composites were simultaneously enhanced in contrast with those of neat PCL. The structures of the PCL/CS‐g‐PCL blends were investigated with Fourier transform infrared, X‐ray diffraction, differential scanning calorimetry, dynamic mechanical analysis, and scanning electron microscopy, and the effects of the chitosan (CS) content in CS‐g‐PCL and the CS‐g‐PCL content in the blends on the mechanical properties and structures of the blends were examined. The rigidity of CS chains and the increasing crystallinity induced by the nucleation of CS‐g‐PCL contributed to the enhancement of the strength, whereas the cocontinuous interfacial structure and improved miscibility between CS and PCL matrix mediated with grafted PCL chains greatly enhanced the elongation of the composite materials. This work presents a strategy for enhancing the mechanical performance of PCL as a biomaterial. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Amidation of acrylic acid grafted polyethylene film with isopropylamine and temperature‐responsive character of the resulting amidated film
Authors: Wang Tao , Shi Shan , Li Li , Zhao Liqun , Kuroda Shin‐ichi , Kubota Hitoshi 
Published: January 2009

AbstractAn acrylic acid (AA) grafted polyethylene (PE) film with a homogeneous distribution of grafted chains was prepared by the photografting of AA onto a low‐density PE film with a thickness of 30 μm. The AA‐grafted PE film was subjected to amidation with isopropylamine (IPA) at 25°C in water as a solvent. Up to 80 mol % of the carboxyl groups of the AA‐grafted chains could be successfully converted to N‐isopropylacrylamide (NIPAAm) residues through the control of the amidation conditions, such as the reaction time, amount of the condensation reagent, and concentration of IPA. The resulting amidated PE film exhibited a temperature‐responsive character: the film swelled and shrank in water below and above a temperature range of about 40–60°C, respectively. The extent of the character of the amidated PE film was greater than that of NIPAAm‐ and NIPAAm/AA‐grafted PE films prepared by the photografting of NIPAAm monomer and NIPAAm/AA binary monomers, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Swelling properties of superabsorbent poly(acrylic acid‐co‐acrylamide) with different crosslinkers
Authors: Xie Jianjun , Liu Xinrong , Liang Jifu , Luo Yingshe 
Published: January 2009

AbstractPoly(ethylene glycol) diacrylate (PEGDA) was synthesized and characterized with Fourier transform infrared. A superabsorbent based on poly(acrylic acid‐co‐acrylamide) (PAAM) was prepared by free‐radical solution polymerization with various crosslinkers. The relationship between the absorbency of PAAM in distilled water and in 0.9% NaCl solutions and the swelling time was explored. The order of the equilibrium absorbency of PAAM with different crosslinkers in 0.9% NaCl solutions was glutaraldehyde (GDA) < PEGDA < N,N′‐methylene bisacrylamide (NMBA) < divinylbenzene (DVB). Some swelling models were used to fit the swelling data. The second‐order kinetic model was best for describing the water absorption of PAAM with water absorption rate constants in the order of DVB < PEGDA < NMBA < GDA. The repeated absorbencies of PAAM in 0.9% NaCl solutions were also investigated. The repeated absorbency of PAAM with PEGDA as the crosslinker was better that that of PAAM with other crosslinkers. The repeated absorbency of PAAM was rather poor when DVB was used as the crosslinker, although the maximum absorbency was obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Deposition of disinfectant poly(methyl acrylate) nanocapsules onto natural rubber film via the layer‐by‐layer technique
Authors: Paiphansiri Umaporn , Tangboriboonrat Pramuan 
Published: January 2009

AbstractAn aqueous core containing a disinfectant agent (chlorhexidine digluconate) was encapsulated in a poly(methyl acrylate) shell with a modified nanoprecipitation technique. After redispersion of the capsules in an aqueous medium, the remaining amount of the disinfectant agent was as high as 90%. The nanocapsules were successfully adsorbed via the layer‐by‐layer technique onto a γ‐radiation‐vulcanized natural rubber latex sheet. Water contact angle measurements and scanning electron microscopy confirmed the presence of nanocapsules on the rubber surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Oxidized cellulose: An application in the form of sorption filter materials
Authors: Foglarova Marcela , Prokop Jiri , Milichovsky Miloslav 
Published: January 2009

AbstractOxidized cellulose (oxycellulose) was very effectively used in the form of filter sheets to remove some metal ions from water and from aqueous solutions. Furthermore, oxycellulose was applied in an ion‐exchange column and in a batch process. The mechanisms of the sorption process inside oxycellulose as well as the kinetics of sorption were studied. A comparison of oxycellulose and other adsorption components such as zeolites and ion‐exchange resins was made. The affinity of oxycellulose to metal ions was determined to be in the following order: Cd2+, Zn2+ > Ni2+ ≫ Ca2+ > Mg2+ ≫ Na+. The use of oxycellulose was very effective, especially in the form of sorption filters, because this allowed us to use a simple filtration process. Moreover, the specific loading amount of the filter cake was higher for filtration than for the column process under comparable conditions. Oxycellulose in a glass column behaved similarly to an ion‐exchange resin. It showed approximately constant efficiency until the sorption capacity of the adsorbent was exhausted, and then it suddenly dropped. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Electrochemical measurements for studying the polymerization process and critical point behaviors of hydrogels
Authors: Yildiz Gulcemal , Yilmaz Yasar 
Published: January 2009

AbstractWe propose a new technique based on electrochemical measurements for studying the critical point behaviors of the sol–gel transition of acrylamide–N,N′‐methylene bisacrylamide hydrogels. In this technique, no chemical activator is used for accelerating the polymerization reaction. However, a potential difference is applied by means of silver and calomel electrodes placed in the reaction mixture. The silver electrode begins to be ionized and loses its electrons. The free radicals, −O3SO•, H•, and •OH, form on the silver electrode via persulfate dissociation. The polymerization is initiated by means of these free radicals. The current measured during the gelation processes passes through a maximum (a Gaussian‐like behavior) and varies linearly with the reaction time during linear polymerization. All the parameters (the monomer, initiator, and crosslinker concentrations, the applied voltage, and the stirring rate of the reacting mixture) affecting the current have been studied in detail. We show that the maxima appearing in the current–time plots correspond to the gelation thresholds, the so‐called sol–gel transition points. We also analytically prove that the current monitors the weight‐average degree of polymerization (DPw) and the gel fraction (G) below and above the threshold, respectively. The scaling behaviors of DPw and G have been tested near the gelation thresholds, and we have observed that the critical exponents γ and β, defined for DPw and G, agree with the predictions by mean‐field theory. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Interaction of dis‐azo dyes with quaternized poly(dimethylaminoethyl methacrylate) as a function of the dye structure and polycation charge density
Authors: Dragan Ecaterina Stela , Dinu Ionel Adrian 
Published: January 2009

AbstractInteractions between some dis‐azo dyes, different by either the position of their sulfonic groups or their number (Ponceau SS, Crocein Scarlet MOO, Congo Red, and Direct Blue 1), and some strong polycations (PCs), with cationic centers in their side chains and dye removal from artificial wastewaters were systematically investigated in this study. PCs with variable charge densities (CDs) were prepared from poly(dimethylaminoethyl methacrylate) by controlled quaternization with benzyl chloride. Even when the main process in the dye removal was charge neutralization (coagulation) for all of the dyes, significant effects of the CD and dis‐azo dye structure on the metachromatic behavior of the dyes in dilute aqueous solutions and on the dye removal efficiency were observed. The stability of the PC/azo dye complex and, connected with this, the flocculation window were higher when the PC with the highest CD was used. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Distinctiveness of macroinvertebrate communities in turloughs (temporary ponds) and their response to environmental variables
Authors: Porst Gwendolin , Irvine Kenneth 
Published: January 2009

Abstract
Turloughs are a prime example of a water body type that interfaces with both the European Habitats Directive (92/43/EEC) and Water Framework Directive (2000/60/EC) (WFD), highlighting the need for an integrated strategy to protect and manage surface waters and groundwaters. To date, research on turloughs, including their invertebrate communities is limited.
Eight turloughs were sampled for their macroinvertebrate communities and water chemistry in April 2007. Faunal samples were collected by means of a simple box sampler.
Replicate samples within each turlough clustered together, indicating that a single sample can provide a meaningful description of the turlough invertebrate community. Variation of invertebrate communities within turloughs was nested among turloughs.
Hydroperiod influenced mean abundance and taxon richness of macroinvertebrates, but no correlation was found between nutrient status and either mean abundance or taxon richness.
Turloughs are priority habitats under the EC Habitats Directive, requiring maintenance of ‘favourable conservation status’, which needs to be assessed through monitoring, and effected through appropriate management plans. While the distinctiveness of macroinvertebrate communities across turloughs is conducive to simple and cost‐effective monitoring, this also challenges the applicability of the concept of type‐specific communities across these highly dynamic ecosystems.
Copyright © 2009 John Wiley & Sons Ltd.
Differential Expression of PTEN in Normal Adult Rat Brain and Upregulation of PTEN and p‐Akt in the Ischemic Cerebral Cortex
Authors: Cai Qi‐Yan , Chen Xing‐Shu , Zhong Shan‐Chuan , Luo Xue , Yao Zhong‐Xiang 
Published: January 2009

AbstractThe tumor suppressor phosphatase and tensin homologue (PTEN) is a protein and lipid phosphatase. PTEN mutations have been associated with a large number of human cancers. To understand the physiological role of PTEN in the brain and its relationship to Akt in ischemic injury, we first investigated the localization of PTEN immunoreactivity in the brains of normal adult rats using immunohistochemistry. We then detected the modulation of PTEN and p‐Akt following transient global ischemia by Western blot and immunohistochemistry analyses. Our observation of normal brains showed that PTEN was heterogeneously distributed in the cytoplasm, nuclei, and processes in different regions. It was shown immunohistochemically that PTEN was distributed differentially in rat brain, with the highest levels in the anterior olfactory nucleus, cerebral cortex, amygdaloid nucleus, hippocampus, Purkinje's cells, and several nuclei in the basal ganglia, thalamus, midbrain, and pons. After global cerebral ischemia, PTEN and p‐Akt immunoreactivities were increased in the cerebral cortex. This was accompanied by the nuclear translocation of p‐Akt. Double‐labeling experiments revealed that PTEN and p‐Akt were most likely localized to neurons. These results suggest a role for PTEN in normal adult brain and that the PTEN/Akt pathway may be involved in neuronal survival or plasticity after ischemic injury. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.