bluuebunny/crossref_metadata_2025 huggingface dataset:
Isoprene‐Assisted Radical Coupling of (Co)polymers Prepared by Cobalt‐Mediated Radical Polymerization
Authors: Debuigne Antoine , Jérôme Christine , Detrembleur Christophe
Published: January 2009

Tackling 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.

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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

Not 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.

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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

Give 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.

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Development of a novel microcompounder for polymer blends and nanocomposite
Authors: Son Younggon
Published: January 2009

In 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

A 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

Using 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

The 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

Polycaprolactone (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

An 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

Poly(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

An 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

Oxidized 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

We 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

Interactions 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

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

The 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.
N‐linked glycosylation is an important parameter for optimal selection of cell lines producing biopharmaceutical human IgG
Authors: van Berkel Patrick H. C. , Gerritsen Jolanda , Perdok Gerrard , Valbjørn Jesper , Vink Tom , van de Winkel Jan G. J. , Parren Paul W. H. I.
Published: January 2009

We studied the variations in N‐linked glycosylation of human IgG molecules derived from 105 different stable cell lines each expressing one of the six different antibodies. Antibody expression was based on glutamine synthetase selection technology in suspension growing CHO‐K1SV cells. The glycans detected on the Fc fragment were mainly of the core‐fucosylated complex type containing zero or one galactose and little to no sialic acid. The glycosylation was highly consistent for the same cell line when grown multiple times, indicating the robustness of the production and glycan analysis procedure. However, a twofold to threefold difference was observed in the level of galactosylation and/or non‐core‐fucosylation between the 105 different cell lines, suggesting clone‐to‐clone variation. These differences may change the Fc‐mediated effector functions by such antibodies. Large variation was also observed in the oligomannose‐5 glycan content, which, when present, may lead to undesired rapid clearance of the antibody in vivo. Statistically significant differences were noticed between the various glycan parameters for the six different antibodies, indicating that the variable domains and/or light chain isotype influence Fc glycosylation. The glycosylation altered when batch production in shaker was changed to fed‐batch production in bioreactor, but was consistent again when the process was scaled from 400 to 5,000 L. Taken together, the observed clone‐to‐clone glycosylation variation but batch‐to‐batch consistency provides a rationale for selection of optimal production cell lines for large‐scale manufacturing of biopharmaceutical human IgG. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Computer imaging: A project for pattern classification with range images
Authors: Umbaugh Scott E. , LeAnder Robert , Solt Patrick , Kharbanda Amit , Deokar Pradyna
Published: January 2009

A series of three laboratory exercises were developed to introduce undergraduate students specializing in computer vision and image processing to three‐dimensional imaging. These lab exercises were consolidated into a term project in the Image Analysis and Computer Vision course at Southern Illinois University Edwardsville. The difficulty encountered in introducing undergraduate students to 3‐D imaging was the expense of the equipment. Because equipment expense placed a limitation on the number of 3‐D cameras available and consequently, the number of students that could use the equipment, the image database used in this project was captured by graduate students only. At the end of the term, the students evaluated the effectiveness of the project. Eighty eight percent of the students strongly agreed or agreed that they “gained insight into the process of developing algorithms for automatic object classification via images.” Additionally, 83% of the students strongly agreed or agreed that “this project is an excellent enhancement to the in‐class lectures.” © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 225–231, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20183
Audio processors as a learning tool for basic acoustics
Authors: Pejuan Arcadi , Novell Montse
Published: January 2009

Audio processors like Audacity provide a “hear‐and‐see” learning tool for basic acoustics, combining sound and image. Activities designed as laboratory experiments with PC (even at home!) have been already successfully implemented, for example, about the dependence of timbre and acoustic spectrum, of pitch and frequency, and of loudness and amplitude. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 379–388, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20207
Live problem solving via computer in the classroom to avoid “Death by PowerPoint”
Authors: Shacham Mordechai , Cutlip Michael B. , Elly Michael
Published: January 2009

The use of live demonstrations in courses related to numerical problem solving combined with PowerPoint presentations is advocated in order to stimulate student interest and involvement and enhance learning. The proposed approach is demonstrated by solving a system of ordinary differential equations as a boundary value problem, utilizing finite difference approximations for solving partial differential equations, and investigating ill‐conditioning in multiple linear regression. The educational benefits of this approach are discussed in detail. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 285–294, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20214
Educational software to develop sheet metal with Solid Edge
Authors: del Río‐Cidoncha Gloria , Martínez‐Palacios Juan , Ortíz‐Marín Rafael , Rojas‐Sola José Ignacio
Published: January 2009

This article presents a useful application for university courses in Engineering Graphics, and for manufacturing processes based on developing sheet metal. From the basis of a three‐dimensional surface, the application can generate its development, as well as its area and perimeter that could be used by a conventional numerical control machine (CNC) to cut the sheet. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 17: 295–304, 2009; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20247
Biochemical Characterization of a Uranyl Ion‐Specific DNAzyme
Authors: Brown Andrea K. , Liu Juewen , He Ying , Lu Yi
Published: January 2009

Uranyl ion‐specific DNAzyme: A DNAzyme (lower strand) cleaves the substrate (upper strand) in the presence of the uranyl ion. The enzyme folds into a bulged three‐way‐junction structure with catalytically important nucleotides residing in the bulge. A highly conserved G⋅A mismatch is also crucial for the enzyme's activity.

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The biochemical characterization of a DNAzyme that is highly specific for uranyl (UO22+) ions is described. Sequence alignment, enzyme truncation, and mutation studies have resulted in a conserved sequence that folds into a bulged stem–loop structure. Interestingly, a G⋅A pair next to the scissile site is important for the uranyl ion‐specific DNAzyme; this is reminiscent of the G⋅T wobble base pair adjacent to the cleavage site that is crucial for the PbII‐specific 8–17 DNAzyme activity. Therefore wobble pairs might be important for formation of metal‐specific metal‐binding sites in DNAzymes. The DNAzyme binds the uranyl ion with a dissociation constant of 469 nM, which is among the strongest metal‐binding affinities in nucleic acid enzymes reported to date. This explains why a catalytic beacon fluorescent sensor based on this enzyme has a detection limit (45 pM) that rivals the most‐sensitive analytical instrument. It also has over 1 000 000‐fold specificity for the uranyl ion over other metal ions. The DNAzyme can carry out multiple turnover reactions that follow the Michaelis–Menten equation, with a kcat of 1.46 min−1 and a KM of 463 nM, similar to that of the 8–17 DNAzyme. The pH profile shows a bell‐shaped curve that reaches a maximum at pH 5.5, at which the in vitro selection was carried out; this suggests that in vitro selection can be performed to obtain DNAzymes with optimal performance under specific conditions under which practical applications are required. These findings enrich our fundamental understanding of metal‐binding sites in nucleic acids and allow the design of sensors with better performance.
Phase Transformation in Titania Nanocrystals by the Oriented Attachment Mechanism: The Role of the pH Value
Authors: Ribeiro Caue , Barrado Cristiano M. , de Camargo Emerson R. , Longo Elson , Leite Edson R.
Published: January 2009

The oriented attachment (OA) mechanism has been investigated as an important process in the formation of anisotropic nanostructures such as depicted. The results showed that the control of a desired phase in this system may be attained by the control of OA mechanism through pH value, obtaining several morphologies.

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A new synthetic method for TiO2 nanocrystals starting from metallic Ti and hydrogen peroxide was developed, in order to obtain minimal interferences to evaluate phase transformation in the system. The results revealed that the crystal morphology appeared to be dictated by the pH value, which shows a strong dependence on the surface energy. The involvement of the oriented attachment (OA) mechanism is important to modify the morphology and, hence, the distribution of the surface energy and confirmed that the mechanism can accelerate certain phase transitions, albeit pH dependence in terms of how the mechanism affects the final particle morphology and direction of crystalline growth. The importance of the mechanism was also apparent in extremely basic conditions, which indicates a possible correlation with the formation of hydrogen titanate nanostructures.
Intramolecular Methylacridan–Methylacridinium Complexes with a Phenanthrene‐4,5‐diyl or Related Skeleton: Geometry–Property Relationships in Isolable CH Bridged Carbocations
Authors: Suzuki Takanori , Yoshimoto Yasuyo , Takeda Takashi , Kawai Hidetoshi , Fujiwara Kenshu
Published: January 2009

Bridging the gap: Snapshots of 1,6‐H‐shift precursors indicate that a narrower CH⋅⋅⋅C+ separation (D in the ORTEP diagram) in the title complexes induces faster degenerate rearrangement of 1+. A contact distance of less than 2.7 Å is necessary to realize the organic three‐center two‐electron bond of [CHC]+, as indicated by extrapolation of the X‐ray data.

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The isolation and low‐temperature X‐ray analyses of a series of intramolecular methylacridan–methylacridinium complexes have been achieved. The two chromophores are in close proximity due to an arylene spacer, such as a phenanthrene‐4,5‐diyl or biphenyl‐2,2′‐diyl unit. These bridged carbocations prefer the CH localized structure both in solution and in the solid state. The bridging hydrogen atom undergoes a facile intramolecular hydride shift from one carbon atom to another in solution, and the energy barrier is linearly correlated with the intramolecular C⋅⋅⋅C+ distance in the solid‐state geometry, as determined by single‐crystal X‐ray analyses. By extrapolation from the data, the delocalized three‐center bond of [CHC]+ would be formed when the C⋅⋅⋅C+ distance is less than 2.7 Å.
Highly Water‐Soluble, Fluorescent, Conjugated Fluorene‐Based Glycopolymers with Poly(ethylene glycol)‐Tethered Spacers for Sensitive Detection of Escherichia coli
Authors: Xue Cuihua , Velayudham Singaravelu , Johnson Steve , Saha Ratul , Smith Adrian , Brewer Wilbel , Murthy Pushpalatha , Bagley Susan T. , Liu Haiying
Published: January 2009

Know your bacteria! Two fluorene‐based, conjugated polymers with oligo(ethylene glycol)‐ and poly(ethylene glycol)‐tethered spacers have been prepared by the Suzuki coupling polymerization reactions. β‐Glucose and α‐mannose residues were covalently attached to the conjugated polymers by post‐polymerization functionalization with thiol‐functionalized carbohydrates under basic conditions. Investigations on their use as biosensing materials for the detection of Escherichia coli are reported (see figure).

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Two bromide‐bearing, fluorene‐based, conjugated polymers with oligo(ethylene glycol)‐ and poly(ethylene glycol)‐tethered spacers have been prepared by the Suzuki coupling polymerization of bromide‐bearing, fluorene monomers. β‐Glucose and α‐mannose residues have been covalently attached to the conjugated polymers by post‐polymerization functionalization of the precursor polymers with thiol‐functionalized carbohydrates under basic conditions through thioether linkage. A glucose‐bearing glycopolymer with oligo(ethylene glycol)‐tethered spacers (polymer A) displays poor water solubility. However, glycopolymers with poly(ethylene glycol)‐tethered spacers (polymers B and C) are highly water‐soluble due to their long, flexible, hydrophilic spacers. Incubation of the ORN178 strain of Escherichia coli (E. coli) with α‐mannose‐bearing glycopolymer (polymer C) results in the formation of fluorescent cell clusters, causing significant red shifts in UV/Vis absorption and fluorescent spectra of the polymer through multivalent cooperative interactions of the polymeric carbohydrates with the bacterial pili. In contrast, polymer C displays no interactions with a mutant ORN208 strain of E. coli.
A General Route to Construct Diverse Multifunctional Fe3O4/Metal Hybrid Nanostructures
Authors: Guo Shaojun , Dong Shaojun , Wang Erkang
Published: January 2009

Multifunctional nanostructures: By using 3‐aminopropyltrimethoxysilane as a linker, Au nanoparticles (NPs), Au shells, flowerlike Au/Pt hybrid NPs, and Ag or Au/Ag core/shell NPs could be supported on the surface of superparamagnetic Fe3O4 spheres to construct hybrid nanostructures that display near‐IR absorption, high catalytic activity towards an electron‐transfer reaction, or excellent surface‐enhanced Raman scattering activity. The picture shows SEM images of Fe3O4 spheres coated with Au shells (top) and with Au/Pt hybrid NPs (bottom).

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We have developed a simple, efficient, economical, and general approach to construct diverse multifunctional Fe3O4/metal hybrid nanostructures displaying magnetization using 3‐aminopropyltrimethoxysilane (APTMS) as a linker. High‐density Au nanoparticles (NPs) could be supported on the surface of superparamagnetic Fe3O4 spheres and used as seeds to construct Au shell‐coated magnetic spheres displaying near‐infrared (NIR) absorption, which may make them promising in biosensor and biomedicine applications. High‐density flowerlike Au/Pt hybrid NPs could be supported on the surface of Fe3O4 spheres to construct multifunctional hybrid spheres with high catalytic activity towards the electron‐transfer reaction between potassium ferricyanide and sodium thiosulfate. High‐density Ag or Au/Ag core/shell NPs could also be supported on the surface of Fe3O4 spheres and exhibited pronounced surface‐enhanced Raman scattering (SERS), which may possibly be used as an optical probe with magnetic function for application in high‐sensitivity bioassays.
Asymmetrically Substituted Benzene‐1,3,5‐tricarboxamides: Self‐Assembly and Odd–Even Effects in the Solid State and in Dilute Solution
Authors: Stals Patrick J. M. , Smulders Maarten M. J. , Martín‐Rapún Rafael , Palmans Anja R. A. , Meijer E. W.
Published: January 2009

Molecular organization: Chiral benzene tricarboxamides with methyl substituents at defined positions self‐assemble into supramolecular polymers of preferred helicity by three‐fold α‐helical‐type hydrogen bonding. The odd–even effect is operative and all derivatives are liquid crystalline showing a Colho phase (see figure).

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Asymmetric benzene‐1,3,5‐tricarboxamides (aBTAs) comprising two n‐octyl and one chiral methyl–alkyl side chain were synthesised and characterised. The influence of the position and the configuration of the chiral methyl group (methyl at the α, β or γ position) in the aliphatic side chains on the liquid‐crystalline properties and the aggregation behaviour of the aBTAs was systematically studied and compared to symmetrical benzene‐1,3,5‐tricarboxamides (sBTAs). Solid‐state characterisation (polarised optical microscopy, IR spectroscopy, X‐ray diffraction and differential scanning calorimetry) revealed that all aBTAs show threefold, α‐helical‐type intermolecular hydrogen bonding between neighbouring molecules and exhibit a columnar hexagonal organisation from room temperature to well above 200 °C. Moving the chiral methyl group closer to the amide group stabilises the liquid‐crystalline state, as evidenced by a higher clearing temperature and corresponding enthalpy. The self‐assembly of dilute solutions of the aBTAs in methylcyclohexane (≈10−5 mol L−1) was investigated with circular dichroism (CD) spectroscopy. The sign of the Cotton effect demonstrated a pronounced odd–even effect, whereas the value of the molar ellipticity, Δε, in the aBTAs was independent of the position of the methyl group. Subsequent temperature‐dependent CD measurements showed that the aggregation of all aBTAs can quantitatively be described by the nucleation‐growth model and that the stability of the aggregates increases when the chiral methyl group is closer to the amide moiety. The results presented herein illustrate that even small changes in the molecular structure of substituted benzene‐1,3,5‐tri‐carboxamides affect their solid‐state properties and their self‐assembly behaviour in dilute solutions.
ChemInform Abstract: Synthesis of Novel Amino Acid Derived Sulfinamides and Their Evaluation as Ligands for the Enantioselective Transfer Hydrogenation of Ketones.
Authors: Zani Lorenzo , Eriksson Lars , Adolfsson Hans
Published: January 2009

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ChemInform Abstract: TBOxCrIIICl‐Catalyzed Enantioselective Synthesis of 1,3‐Butadien‐2‐ylcarbinols.
Authors: Naodovic Marina , Xia Guoyao , Yamamoto Hisashi
Published: January 2009

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ChemInform Abstract: 5‐Substituted 3‐Nitro‐1‐trinitromethyl‐1,2,4‐triazoles.
Authors: Kofman T. P. , Kartseva G. Yu. , Glazkova E. Yu.
Published: January 2009

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ChemInform Abstract: Synthesis and Properties of 5‐Substituted 1‐Dinitromethyl‐3‐nitro‐1H‐1,2,4‐triazoles.
Authors: Kofman T. P. , Trubitsin A. E. , Dmitrienko I. V. , Glazkova E. Yu.
Published: January 2009

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ChemInform Abstract: Copper Catalyzed 1,3‐Dipolar Cycloaddition Reaction of Azides with N‐(2‐Trifluoroacetylaryl)propargylamines. A Mild Entry to Novel 1,4‐Disubstituted‐[1,2,3]‐triazole Derivatives.
Authors: Medebielle Maurice , et al. et al.
Published: January 2009

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ChemInform Abstract: Synthesis of α‐[5‐(5‐Amino‐1,3,4‐thiadiazol‐2‐yl)‐2‐imidazolylthio]acetic Acids.
Authors: Hadizadeh Farzin , Vosooghi Rahil
Published: January 2009

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ChemInform Abstract: Multicomponent Reactions in Chiral Ionic Liquids: A Stereocontrolled Route to Mercaptopyranothiazoles.
Authors: Yadav Lal Dhar S. , Yadav Beerendra S. , Rai Vijai K.
Published: January 2009

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ChemInform Abstract: Synthesis of 1,3‐Dioxanes Catalyzed by TsOH—SiO2 under Solvent‐Free Conditions.
Authors: Borah Kalyan Jyoti , Phukan Mridula , Borah Ruli
Published: January 2009

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ChemInform Abstract: A One‐Pot Biginelli Synthesis of 3,4‐Dihydropyrimidin‐2‐(1H)‐ones/thiones Catalyzed by Triphenylphosphine as Lewis Base.
Authors: Debache Abdelmadjid , Amimour Mouna , Belfaitah Ali , Rhouati Salah , Carboni Bertrand
Published: January 2009

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ChemInform Abstract: Design of Multi‐Binding‐Site Inhibitors, Ligand Efficiency, and Consensus Screening of Avian Influenza H5N1 Wild‐Type Neuraminidase and of the Oseltamivir‐Resistant H274Y Variant.
Authors: Garcia‐Sosa Alfonso T. , Sild Sulev , Maran Uko
Published: January 2009

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ChemInform Abstract: Morphology of and Catalysis in Single Crystals of Zeolites
Authors: Schoonheydt Robert A.
Published: January 2009

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ChemInform Abstract: Palladium and Gold—Palladium Catalysts for the Direct Synthesis of Hydrogen Peroxide
Authors: Edwards Jennifer K. , Hutchings Graham J.
Published: January 2009

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ChemInform Abstract: A Neutron Diffraction Study of Multiferroics LnMn2O5
Authors: Radaelli P. G. , Chapon L. C.
Published: January 2009

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ChemInform Abstract: Catalytic Synthesis of Indoles from Alkynes.
Authors: Krueger Karolin , Tillack Annegret , Beller Matthias
Published: January 2009

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ChemInform Abstract: Enantiocomplementary Enzymes: Classification, Molecular Basis for Their Enantiopreference, and Prospects for Mirror‐Image Biotransformations
Authors: Mugford Paul F. , Wagner Ulrike G. , Jiang Yun , Faber Kurt , Kazlauskas Romas J.
Published: January 2009

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ChemInform Abstract: Other Bisphosphine Ligands for Enantioselective Alkene Hydrogenation
Authors: Chi Yongxiang , Tang Wenjun , Zhang Xumu
Published: January 2009

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ChemInform Abstract: A Catalytic Foothold for Fluorocarbon Reactions
Authors: Perutz Robin N.
Published: January 2009

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ChemInform Abstract: Metal Nitride Cluster Fullerenes: Their Current State and Future Prospects
Authors: Dunsch Lothar , Yang Shangfeng
Published: January 2009

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ChemInform Abstract: Syntheses and Biological Activities of Glycosphingolipids from Invertebrate Species
Authors: Hada Noriyasu
Published: January 2009

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ChemInform Abstract: Enantioselective Hydrogenation of Alkenes with Ferrocene‐Based Ligands
Authors: Blaser Hans‐Ulrich , Lotz Matthias , Spindler Felix
Published: January 2009

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ChemInform Abstract: Two‐Phase Aqueous Hydrogenations
Authors: Joo Ferenc , Katho Agnes
Published: January 2009

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ChemInform Abstract: The Chemistry of the C‐2 Position of Imidazolium Room‐Temperature Ionic Liquids
Authors: Ennis Elliot , Handy Scott T.
Published: January 2009

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ChemInform Abstract: Guanidinylated Dendritic Molecular Transporters: Prospective Drug Delivery Systems and Application in Cell Transfection.
Authors: Theodossiou T. A. , Pantos A. , Tsogas I. , Paleos C. M.
Published: January 2009

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