bluuebunny/crossref_metadata_2025 huggingface dataset:
The mDial Formin Is Required for Neutrophil Polarization, Migration, and Activation of the LARG/RhoA/ROCK Signaling Axis during Chemotaxis
Authors: Shi Yongquan , Zhang Jinyi , Mullin Michael , Dong Baoxia , Alberts Arthur S. , Siminovitch Katherine A.
Published: March 2009

Neutrophil chemotaxis depends on actin dynamics, but the roles for specific cytoskeleton regulators in this response remain unclear. By analysis of mammalian diaphanous-related formin 1 (mDia1)-deficient mice, we have identified an essential role for this actin nucleator in neutrophil chemotaxis. Lack of mDia1 was associated with defects in chemoattractant-induced neutrophil actin polymerization, polarization, and directional migration, and also with impaired activation of RhoA, its downstream target p160-Rho-associated coil-containing protein kinase (ROCK), and the leukemia-associated RhoA guanine nucleotide exchange factor (LARG). Our data also revealed mDia1 to be associated with another cytoskeletal regulator, Wiskott-Aldrich syndrome protein (WASp), at the leading edge of chemotaxing neutrophils and revealed polarized morphology and chemotaxis to be more mildly impaired in WAS−/− than in mDia1−/− neutrophils, but essentially abrogated by combined mDia1/WASp deficiency. Thus, mDia1 roles in neutrophil chemotaxis appear to be subserved in concert with WASp and are realized at least in part by activation of the LARG/RhoA/ROCK signaling pathway.
Coordinate Regulation of TLR-Mediated Arachidonic Acid Mobilization in Macrophages by Group IVA and Group V Phospholipase A2s
Authors: Ruipérez Violeta , Astudillo Alma M. , Balboa María A. , Balsinde Jesús
Published: March 2009

Macrophages can be activated through TLRs for a variety of innate immune responses. In contrast with the wealth of data existing on TLR-dependent gene expression and resultant cytokine production, very little is known on the mechanisms governing TLR-mediated arachidonic acid (AA) mobilization and subsequent eicosanoid production. We have previously reported the involvement of both cytosolic group IVA phospholipase A2 (cPLA2) and secreted group V phospholipase A2 (sPLA2-V) in regulating the AA mobilization response of macrophages exposed to bacterial LPS, a TLR4 agonist. In the present study, we have used multiple TLR agonists to define the role of various PLA2s in macrophage AA release via TLRs. Activation of P388D1 and RAW2647.1 macrophage-like cells via TLR1/2, TLR2, TLR3, TLR4, TLR6/2, and TLR7, but not TLR5 or TLR9, resulted in AA mobilization that appears to involve the activation of both cPLA2 and sPLA2 but not of calcium-independent phospholipase A2. Furthermore, inhibition of sPLA2-V by RNA interference or by two cell-permeable compounds, namely scalaradial and manoalide, resulted in a marked reduction of the phosphorylation of ERK1/2 and cPLA2 via TLR1/2, TLR2, TLR3, and TLR4, leading to attenuated AA mobilization. Collectively, the results suggest a model whereby sPLA2-V contributes to the macrophage AA mobilization response via various TLRs by amplifying cPLA2 activation through the ERK1/2 phosphorylation cascade.
Antibiotics: Biosynthesis
Authors: Zotchev Sergey B
Published: March 2009

Antibiotics are synthesized by many bacterial, fungal, plant, and animal species as secondary metabolites not required for normal growth of the producing organisms. Medical usefulness of some antibiotics in treatment of infections and cancer prompted investigations into their biosynthesis, which have revealed great complexity and variability of enzymes and reactions involved. Although antibiotics are represented by compounds that belong to diverse chemical classes, some common themes are observed in their biosynthesis. Those themes comprise assembly of antibiotic scaffolds from activated precursors that originate from primary metabolism, followed by modification of the scaffolds with different chemical moieties. In this review, generalized schemes of antibiotic biosynthesis are discussed, along with the common enzymology, genetics, and methods used for studying antibiotic biosynthesis pathways.
Proteins: Array‐Based Techniques
Authors: Tomizaki Kin‐ya , Usui Kenji , Mihara Hisakazu
Published: March 2009

In recent years, array‐based technologies, including DNA microarrays and protein‐detecting microarrays have been getting more attractive and promising as high‐throughput research/diagnostic tools. DNA microarrays comprise oligo‐DNA immobilized onto solid surfaces. Whereas protein‐detecting microarrays are categorized in several formats depending on classes of capturing agents that selectively bind to proteins of interest. Protein‐based capturing agents such as antibodies and fusion proteins are commonly immobilized onto solid surfaces. Alternatively, DNA/RNA aptamers, synthetic peptides, and small molecules including drugs and carbohydrates also act as capturing agents. In particular, peptides as capturing agents are very versatile, because they are chemically prepared according to the well‐established standard synthetic procedures and enable site‐specific and directed surface modifications. In this review, we describe the basic features of protein‐detecting microarray technologies (capturing agents, surface chemistry, and signal generation/readout); thereafter we suggest that the use of synthetic peptides is a very promising and powerful tool to monitor not only protein–peptide interactions but also enzymatic activities.
Chemotaxis
Authors: Eisenbach Michael
Published: March 2009

Chemotaxis is a basic guidance mechanism employed by cells and organisms to move toward beneficial targets or environments and to avoid undesired ones. This mechanism, which is prevalent from bacteria to human beings, consists of two basic processes. One is the formation by diffusion of a concentration gradient of a specific chemical. The other is the sensation of this gradient by a cell/organism and the modification of its direction of movement up or down the chemical gradient (the chemical being defined as chemoattractant or chemorepellent, respectively). Although chemotaxis is a universal mechanism and so are the steps that constitute it (gradient sensing by receptors, signal transduction and amplification, and movement response), the processes that underlie this mechanism are diverse.
Viral Cysteine Peptidases and Cysteine Peptidase Inhibitors
Authors: Yin Jiang , James Michael N. G.
Published: March 2009

Polyprotein processing is a controlled cascade of proteolytic events carried out by virally encoded cysteine proteinases. It plays a central role in the infectious life cycle of animal RNA viruses such as picornaviruses, caliciviruses, and coronaviruses. Furthermore, some of these viral enzymes are vitally important in viral RNA genome replication, virion assembly, and virus–host antagonism. The 3 C
pro
and 3 C‐like (3CL
pro
) peptidases are structurally related to the chymotrypsin branch of the serine proteinase family, but they have the catalytic serine residue replaced by a cysteine. Their uniquely designed yet structurally conserved S1 substrate binding pocket strongly favors a P1‐Glutamine in the substrate. The high level of structural conservation in the active sites of 3 C
pro
and 3CL
pro
and the lack of a mammalian homolog make these enzymes hotly pursued targets for antiviral drug design. The structures of these viral cysteine peptidases in complex with various inhibitors have shed light not only on how different inhibitors work but also on the catalytic mechanisms underlying the hydrolysis of normal peptidyl substrates. Most importantly, the results from the structural studies on Hepatitis A virus (HAV) 3 C
pro
point out possible new directions in the design of therapeutic intervention in a variety of diseases caused by members of these large RNA virus families.
Metals in Medicine: Therapeutic Agents
Authors: Mukherjee Arindam , Sadler Peter J.
Published: March 2009

Within the emerging field of medicinal inorganic chemistry, the realization that metal complexes can be designed as both therapeutic and diagnostic agents with novel mechanisms of action is increasing. Some recent advances are highlighted in this review, beginning with the success of platinum anticancer complexes and attempts to extend such activity to other transition metals, even to arsenic. Lithium is widely used for bipolar affective disorders, and gold is used for the treatment of rheumatoid arthritis. Metal ions also play crucial roles in contrast agents for magnetic resonance imaging and in radiopharmaceuticals used for imaging and therapy. Metal complexes offer flexible design platforms as enzyme inhibitors, and metals in enzyme active sites can be key drug targets. The antimicrobial and antiviral activities of certain metal complexes may prove useful in the fight against antibiotic resistance. Metals play key roles, too, in the control of small signaling molecules such as nitric oxide and carbon monoxide. Control of the uptake and distribution of the essential metals also presents a challenge, which is aided by modern genomic knowledge.
Micro
RNA
Authors: Visone Rosa , Croce Carlo M.
Published: March 2009

miRNAs (microRNAs) are single‐stranded noncoding RNAs 18–29 nucleotides long that were first discovered as critical regulators of developmental timing events in
Caenorhabditis elegans
. Several studies collectively identified ∼3000 mature miRNAs highly conserved in species that range from plants to humans, which suggests that they are ancient players. Recently, poor or not conserved miRNAs were identified by using new software program for miRNAs prediction. miRNAs are processed through a multistep process and confer their regulation at a posttranscriptional level by blocking and causing degradation of target miRNAs. The processing steps are performed by members of the RNAse III enzyme family, whereas gene‐silencing events are mediated by members of the highly conserved Argonaute (AGO) protein family. In mammals, miRNAs are predicted to control the activity of more than 30% of all protein‐coding genes, and they have been shown to participate in the regulation of almost every cellular process investigated so far. Improved bioinformatic programs now can predict the miRNAs targets in a more‐efficient manner, thus facilitating the identification of miRNA function. Recently, new insights have been provided into the role of miRNAs in various biological events, which include development, aging and cancer.
Mass Spectrometry to Identify Posttranslational Modifications
Authors: Eyers Claire E. , Gaskell Simon J.
Published: March 2009

The analysis of posttranslational modifications using mass spectrometric‐based strategies is a rapidly growing area of postgenome science. This article describes an overview of the techniques currently used in the analysis of some common protein modifications. Strategies are described for the selective enrichment of modified peptides to facilitate mass spectrometric analysis. Techniques are also described for the identification of peptides that carry specific modifications by detection of characteristic fragment ions following collision‐induced dissociation.
Protein– Protein Interactions
Authors: Sundberg Eric J.
Published: March 2009

Although proteins have numerous capabilities, one of their most important functions is to bind other proteins. These protein–protein interactions are critical for nearly every cellular process, and when they become corrupted, they often result in a diseased state. Because of the importance of protein–protein interactions in nearly all aspects of biology, efforts to decipher the rules that govern these associations have been underway for many decades. This review provides an overview of the evolution of the study of protein–protein interactions with an emphasis on recent developments in the field that concern the modular architecture of protein–protein interfaces and the networked communications within these binding sites that serve as a driving force for protein complex specificity and affinity. Relationships between biophysical studies performed to quantify the myriad factors that contribute to protein molecular recognition and computational analysis and interaction prediction algorithm development, as well as drug discovery and development, are also highlighted.
Ubiquitin Proteasome Pathway
Authors: Navon Ami , Ciechanover Aaron
Published: March 2009

The 26S proteasome is responsible for the rapid destruction of damaged polypeptides and the controlled removal of critical regulatory proteins. This ATP‐dependent system is highly regulated and generally recognizes and processes substrates covalently attached to polyubiquitin chains. In eukaryotes, the proteasome is also essential for the cellular immune response as it generates most of the peptides used for class 1 MHC presentation. We review herein; the ubiquitin tagging system, the general architecture of the 26S proteasome, as well as some none canonical functions of the 26S proteasome.
ATPSynthesis, Chemistry of
Authors: Wilkens Stephan
Published: March 2009

The universal carrier of free energy in all living organisms is adenosine triphosphate (ATP). Virtually all energy‐requiring biological processes are coupled to the enzymatic hydrolysis of ATP to adenosine diphosphate (ADP) and inorganic phosphate (Pi). The enzyme complex that synthesizes the bulk of the cellular ATP is called F1F0–ATP synthase. F1F0–ATP synthase is found in energy‐converting membranes, such as the inner membrane of mitochondria, the plasma membrane of bacteria, and the thylakoid membrane of chloroplasts, where it harnesses the potential energy of a transmembrane electrochemical gradient that is generated during oxidation of foodstuffs or photosynthesis. F1F0–ATP synthase is a rotary molecular motor enzyme: The energy released in the membrane‐bound part (F0) of the enzyme during ion translocation is transmitted to the catalytic sites on the membrane extrinsic part (F1) via rotation of a central domain made of polypeptides from both F0and F1. This specialized topics review summarizes our current understanding of the biological process of ATP synthesis and emphasizes recent insights into the atomic structure of ATP synthase and the fascinating mechanism of subunit‐rotation‐induced energy coupling.
Biocatalysis and Biotransformation
Authors: Roberts Stan , Turner Nicholas John
Published: March 2009

Biocatalysis and biotransformations are two expressions that relate to the use of enzymes as catalysts for reactions that introduce or modify functional groups in organic compounds. Enzymes are proteins that consist of one or more chains of condensed amino acids. Because all 20 natural amino acids (with the exception of glycine) are chiral, these biological catalysts are also chiral; as such, they are often used to prepare optically active organic molecules, which may be difficult to obtain by chemical means. The biocatalyst can be used as isolated, partially purified protein or as a constituent of a cell, usually a bacterium or fungus. Moreover, isolated enzymes can be used in free, soluble form or more often they are immobilized by conjugation to an insoluble support, for example an ion‐exchange resin. Immobilization of enzymes is often found to improve their stability when used under process‐related conditions. It also facilitates recovery and reuse of the biocatalyst.
Second Messengers in Cellular Signaling
Authors: DiPilato Lisa M. , Zhang Jin
Published: March 2009

Second messengers are a class of highly ubiquitous signaling molecules, which play important roles in nearly all cellular processes, which range from fertilization and development to cell death. These signaling molecules include the cyclic nucleotides cAMP and cGMP, calcium, and lipid‐derived second messengers, such as diacylglycerol, IP3, and PIP3. Although biochemically different in structure and activity, these signaling molecules share key features that are required for second‐messenger action and necessary for efficient and specific signaling. The use of fluorescent sensors to monitor second messengers in real time as well as small molecules to manipulate and perturb signaling has greatly advanced our understanding of these dynamic signaling molecules. These tools and methods should continue to provide insights into the nuances of cell signaling and their related diseases as well as aid the development of new therapeutics. This article reviews the molecular mechanisms that govern second‐messenger action and the current approaches to studying them.
14‐3‐3 Proteins
Authors: Cockrell Lisa M. , Du Yuhong , Acker Timothy M. , Fu Haian
Published: March 2009

The 14‐3‐3 proteins are a family of multifunctional regulators in eukaryotic organisms. Through binding to over 200 client proteins, 14‐3‐3 proteins regulate numerous cellular functions, which include metabolic pathways, molecular trafficking, and cell‐cycle progression. Most 14‐3‐3 interactions are mediated by defined phosphoserine/threonine motifs within the target protein sequence. The presence of these phosphorylated motifs allows for integration of 14‐3‐3 interactions with client proteins into a diverse cellular signaling network, through the actions of various protein kinases and phosphatases. As evidence of its vital role in cell function, 14‐3‐3 has been implicated in human diseases, such as cancer and neuronal disorders. Thus, development of small‐molecule 14‐3‐3 modulators will allow the continued discovery of the critical importance of 14‐3‐3 in normal physiology and lead to future use as targeted therapies in human disease.
Integrated and Organized Cellular Energetic Systems
Authors: Saks Valdur , Monge Claire , Guzun Rita , Dzeja Petras , Wallimann Theo
Published: March 2009

Bioenergetics as a part of biophysical chemistry and biophysics is a quantitative science that is based on several fundamental theories. The definition of energy itself is given by the first law of thermodynamics, and application of the second law of thermodynamics shows that the living cells can only function as open systems in which internal order (low entropy state) is maintained by increasing the entropy in surrounding medium (Schrödinger's principle of negentropy). For this mechanism, exchange of mass is needed that yields metabolism as the sum of catabolism and anabolism. The free‐energy changes taking place during metabolic reactions obey rules of chemical thermodynamics, which deals with Gibbs free energy of chemical reactions and with electrochemical potentials. For application of these theories to the integrated systemsin vivo, complex cellular organization should be accounted for: macromolecular crowding, metabolic channeling and functional coupling mechanisms caused by close and tight protein–protein interactions, compartmentation of enzymes, as well as both macrocompartmentation and microcompartmentation of substrates and metabolites in cells should be considered. For integration of these system components, effective methods of communication, including compartmentalized energy transfer systems, are required. These systems are represented in muscle cells by phosphotransfer networks, mostly by creatine kinase and adenylate kinase systems. System analysis of these networks shows their central role both in energy transfer and metabolic feedback regulation of mitochondrial function, in regulation of ion fluxes and cellular energetics during increased workload by synchronizing the cellular electrical and mechanical activities with energy supply and substrate oxidation.
Alberti's Paradigm
Authors: Garber Richard
Published: March 2009

Could the advent of building information modelling (BIM) see the architect's status return to that of his medieval counterpart, the master builder? Guest‐editor Richard Garber examines the work of Filippo Brunelleschi, who did the seemingly impossible in early 15th‐century Florence by spanning the massive opening of the dome of Santa Maria del Fiore, the city's cathedral, through an adept use of physical models. Copyright © 2009 John Wiley & Sons, Ltd.
McLean's Nuggets
Authors: McLean Will
Published: March 2009

The development of a clean, plentiful and low‐cost alternative energy source is the holy grail of the 21st century. Ken Yeang looks into his crystal ball and asks whether the future could lie in nanoenergy and the proliferation of numerous personal nanogenerators ‐ attached to buildings, individuals or under bridges. Copyright © 2009 John Wiley & Sons, Ltd.
Nanoparticle formation through solid‐fed flame synthesis: Experiment and modeling
Authors: Widiyastuti W. , Purwanto Agus , Wang Wei‐Ning , Iskandar Ferry , Setyawan Heru , Okuyama Kikuo
Published: March 2009

The preparation of silica nanoparticles through solid‐fed flame synthesis was investigated experimentally and theoretically. Monodispersed submicrometer‐ and micrometer‐sized silica powders were selected as solid precursors for feeding into a flame reactor. The effects of flame temperature, residence time, and precursor particle size were investigated systematically. Silica nanoparticles were formed by the nucleation, coagulation, and surface growth of the generated silica vapors due to the solid precursor evaporation. Numerical modeling was conducted to describe the mechanism of nanoparticle formation. Evaporation of the initial silica particles was considered in the modeling, accounting for its size evolution. Simultaneous mass transfer modeling due to the silica evaporation was solved in combination with a general dynamics equation solution. The modeling and experimental results were in agreement. Both results showed that the methane flow rate, carrier gas flow rate, and initial particle size influenced the effectiveness of nanoparticle formation in solid‐fed flame synthesis. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Risk management for a global supply chain planning under uncertainty: Models and algorithms
Authors: You Fengqi , Wassick John M. , Grossmann Ignacio E.
Published: March 2009

In this article, we consider the risk management for mid‐term planning of a global multi‐product chemical supply chain under demand and freight rate uncertainty. A two‐stage stochastic linear programming approach is proposed within a multi‐period planning model that takes into account the production and inventory levels, transportation modes, times of shipments, and customer service levels. To investigate the potential improvement by using stochastic programming, we describe a simulation framework that relies on a rolling horizon approach. The studies suggest that at least 5% savings in the total real cost can be achieved compared with the deterministic case. In addition, an algorithm based on the multi‐cut L‐shaped method is proposed to effectively solve the resulting large scale industrial size problems. We also introduce risk management models by incorporating risk measures into the stochastic programming model, and multi‐objective optimization schemes are implemented to establish the tradeoffs between cost and risk. To demonstrate the effectiveness of the proposed stochastic models and decomposition algorithms, a case study of a realistic global chemical supply chain problem is presented. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Cohort study for the effect of chronic noise exposure on blood pressure among male workers in Busan, Korea
Authors: Lee Ji Ho , Kang Weechang , Yaang Seung Rim , Choy Nari , Lee Choong Ryeol
Published: March 2009

Objective

It has not yet been established whether exposure to chronic noise induces an increase in blood pressure or an increase in the development of hypertension. Therefore, a cohort study was performed to identify the effects of chronic noise exposure on blood pressure.

Methods

Five hundred thirty male workers at a metal manufacturing factory in Busan, Korea, were enrolled in the study. They were monitored with an annual health check‐ups for nine consecutive years from 1991 to 1999. The subjects were divided into four groups which were determined by noise level categories (NLCs) according to the exposure of noise intensity; NLC‐I: office workers who were exposed to <60 dBA at work; NLC‐II: worksite technical supporters or inspectors who were intermittently exposed to noise and were not using hearing protection devices; NLC‐III: worksite workers exposed to a noise below 85 dBA (TWA) and used one type of hearing protection device, earplug or earmuff; NLC‐IV: worksite workers who were exposed to a noise level of 85 dBA or higher in average and used both earplug and earmuff.

Results

After controlling the possible confounders, such as baseline age, smoking, alcohol intake, exercise, family history of hypertension, systolic blood pressure (SBP), or diastolic blood pressure (DBP), and changes in body mass index (BMI), we determined that the mean values for the SBP over the duration of this study were 3.8, 2.0, and 1.7 mmHg higher in groups NLC‐IV, NLC‐III, and NLC‐II, respectively, in comparison to that of the NLC‐I group. There was no significant difference in DBP among the groups.

Conclusion

This study suggests that chronic noise exposure increases SBP independently, among male workers. Am. J. Ind. Med. 52:509–517, 2009. © 2009 Wiley‐Liss, Inc.
Self‐Assembly of a Four‐Helix Bundle on a DNA Quadruplex
Authors: Rosenzweig Brooke A. , Hamilton Andrew D.
Published: March 2009

Eine neuartige Methode zur Selbstorganisation von Monomeren und zur Steuerung der Struktur eines De‐novo‐Helixbündelproteins wird beschrieben. Ein Guanin(G)‐reiches Oligodesoxynucleotidgerüst bildet einen H‐verbrückten DNA‐Quadruplex in Gegenwart von K+‐Gegenionen und induziert so eine helicale Struktur und eine vierfache Stöchiometrie in konjugierten, amphiphilen Peptidsequenzen. Das DNA‐Gerüst ist vielversprechend für den schnellen Aufbau künstlicher Proteine.

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Elektrochemische Abscheidung von dreidimensional geordnetem makroporösem Germanium aus ionischen Flüssigkeiten: eine Methode zur Herstellung von photonischen Kristallen mit hoher Dielektrizitätskonstante
Authors: Meng Xiangdong , Al‐Salman Rihab , Zhao Jiupeng , Borissenko Natalia , Li Yao , Endres Frank
Published: March 2009

Eine vielversprechende Methode für die Synthese von photonischen Germanium‐Kristallen umfasst die elektrochemische Abscheidung von Ge aus GeCl4‐haltigen ionischen Flüssigkeiten in ein kolloidales Polystyrol‐Templat und das anschließende Entfernen der Matrix. Die Methode arbeitet bei Raumtemperatur und führt zu dreidimensional geordneten makroporösen Germanium‐Nanostrukturen (siehe Bild; Skalierung: 2μm) als Prototyp eines photonischen Kristalls.

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Sonochemical Synthesis of Highly Luminescent Zinc Oxide Nanoparticles Doped with Magnesium(II)
Authors: Xiong Huan‐Ming , Shchukin Dmitry G. , Möhwald Helmuth , Xu Yang , Xia Yong‐Yao
Published: March 2009

Mut zur Lücke: Mg/ZnO‐Nanopartikel mit heller, stabiler Photolumineszenz in kolloidalen Dispersionen wie im Festkörper bilden sich durch Dotierung von Mg2+‐Ionen in ZnO‐Nanopartikel durch sonochemische Synthese. Ihre Bandlücken und Lumineszenzeigenschaften verändern sich mit der Defektkonzentration in den ZnO‐Nanopartikeln. Diese Konzentration hängt vom molaren Mg/Zn‐Verhältnis ab (siehe Bild).

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Probing the Bioactive Conformation of an Archetypal Natural Product HDAC Inhibitor with Conformationally Homogeneous Triazole‐Modified Cyclic Tetrapeptides
Authors: Horne W. Seth , Olsen Christian A. , Beierle John M. , Montero Ana , Ghadiri M. Reza
Published: March 2009

Besser als das Original: Neuartige Analoga von Apicidin, einem cyclischen Tetrapeptidinhibitor der Histon‐Desacetylase (HDAC), enthalten ein 1,4‐ oder 1,5‐disubstituiertes 1,2,3‐Triazol anstelle einer Gerüst‐Amidbindung, um die entsprechende Bindung in trans‐ oder cis‐Konfiguration zu fixieren. So ließ sich die Bindungsaffinität unterschiedlicher Peptidkonformationen (siehe Bild) untersuchen. Ein Analogon erwies sich in einigen Fällen als ein dem Apicidin überlegener HDAC‐Inhibitor.

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Photomagnetic Switching of the Complex [Nd(dmf)4(H2O)3(μ‐CN)Fe(CN)5]⋅H2O Analyzed by Single‐Crystal X‐Ray Diffraction
Authors: Svendsen Helle , Overgaard Jacob , Chevallier Marie , Collet Eric , Iversen Bo B.
Published: March 2009

Röntgenblick: Einkristall‐XRD‐Experimente (siehe Bild) belegen, dass der photomagnetische Heterodimetalltitelkomplex im angeregten Zustand vorliegt. Das System zeigt eine Verkürzung sämtlicher Eisen‐Ligand‐Bindungen, was dafür spricht, dass die Photoanregung mit einem Ladungstransfer vom Liganden zum Metall oder einer Änderung der Superaustauschkopplung zwischen den Metallzentren einhergeht.

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Synthesis of 1,3‐Diamines Through Rhodium‐Catalyzed CH Insertion
Authors: Kurokawa Toshiki , Kim Mihyong , Du Bois J.
Published: March 2009

Schließen und öffnen: N‐Boc‐N‐alkylsulfamide sind geeignete Substrate für die Titelreaktion. Die oxidative Cyclisierung im ersten Schritt ist hoch chemoselektiv sowie stereospezifisch und diastereoselektiv. Mit neuen Verfahren zur Öffnung der dabei erhaltenen Sechsringheterocyclen werden unterschiedlich geschützte 1,3‐Diamine zugänglich (siehe Schema).

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Synthesis of Natural Product Inspired Compound Collections
Authors: Kumar Kamal , Waldmann Herbert
Published: March 2009

Mimicking nature synthetically: The successful development of multistep stereoselective syntheses gives access to natural product inspired compound collections having carbo‐, oxa‐,and azacyclic scaffold structures which promise to provide sources for new reagents in medicinal chemistry and chemical biology research.

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Natural products, their derivatives, and their analogues are among the most important sources for new drug candidates and tools for chemical biology and medicinal chemistry research. Therefore, there is a need for the development of efficient synthesis methods which give access to natural product derived and inspired compound collections. To meet this challenge, the requirements of multistep stereoselective syntheses, and the logic and methodology of natural product total synthesis need to be translated and adapted to the methods and formats for the synthesis of compound collections. Recent developments in the synthesis of natural product inspired compound collections having carbocyclic and heterocyclic scaffolds highlight the fact that this goal can be successfully attained. The progress made has paved the way for the integration of natural product inspired compound collections into medicinal chemistry and chemical biology research.
Probing the Bioactive Conformation of an Archetypal Natural Product HDAC Inhibitor with Conformationally Homogeneous Triazole‐Modified Cyclic Tetrapeptides
Authors: Horne W. Seth , Olsen Christian A. , Beierle John M. , Montero Ana , Ghadiri M. Reza
Published: March 2009

Fooling enzymes with mock amides: Analogues of apicidin, a cyclic‐tetrapeptide inhibitor of histone deacetylase (HDAC), were designed with a 1,4‐ or 1,5‐disubstituted 1,2,3‐triazole in place of a backbone amide bond to fix the bond in question in either a trans‐like or a cis‐like configuration. Thus, the binding affinity of distinct peptide conformations (see picture) could be probed. One analogue proved in some cases to be superior to apicidin as an HDAC inhibitor.

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Synthesis and application of some oligopolyamines as adhesives for road bitumens
Authors: Nikolov N.
Published: March 2009

By the amination of a fraction of n‐polychloroparaffins (C13–19) with 1,2‐ethylenediamine in a basic medium, oligopolyamines were obtained. The obtained products were characterized with spectroscopic, titrimetric, and elemental analyses and tested as adhesives for road bitumens. The samples, containing over 7.0% bound nitrogen in a concentration of 1.0 mass % with respect to the bitumen mixtures, were characterized by maximum effectiveness, that is, 100% adhesion between the bitumen and the mineral fillers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of novel oligomeric poly(styrene‐co‐acrylonitrile)–clay complexes
Authors: Chen Ruyi , Chen Dan , Su Shengpei
Published: March 2009

Oligomeric poly(styrene‐co‐acrylonitrile) quaternary ammonium salts were prepared through reactions of trimethylamine with corresponding poly(styrene–acrylonitrile–vinyl benzyl chloride)s, which were synthesized by the free‐radical polymerization of a mixture of styrene, acrylonitrile, and vinyl benzyl chloride. Then, oligomeric poly(styrene‐co‐acrylonitrile)‐modified clays were prepared through the cation exchange of the sodium ions in the clay with the corresponding poly(styrene‐co‐acrylonitrile) quaternary ammonium salts. The poly(styrene–acrylonitrile–vinyl benzyl chloride)s, poly(styrene‐co‐acrylonitrile) quaternary ammonium salts, and their clay complexes were characterized with infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, proton nuclear magnetic resonance, X‐ray diffraction, and transmission electron microscopy. X‐ray diffraction and transmission electron microscopy studies showed that these novel clay complexes were well intercalated. Furthermore, thermogravimetric analysis data indicated that this series of polymerically modified clays had high enough thermal stability for nanocomposites by melt blending. The thermal treatment of one of these novel clays at 250°C under nitrogen was also conducted. Solubility and infrared studies of this thermally treated clay complex revealed that a novel polyimine/enamine structure clay complex had been formed in the gallery of the clay. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of biodegradable block copolymer pluronic‐b‐poly(L‐lysine)
Authors: Yu Hui , Gu Xiaohua , Shen Xinyuan , Li Yaogang , Duan Yourong
Published: March 2009

This study presented the investigations on the synthesis of a novel biodegradable block copolymer of pluronic‐b‐poly(L‐lysine) (pluronic‐b‐PLL), which combined the characteristics of aliphatic polyester and poly(amino acids). The synthesis work started with end‐capping of pluronic with N‐t‐butoxycarbonyl‐L‐phenylalanine using dicyclohexylcarbodiimide in the presence of 4‐dimethylaminopyridine, followed by a deprotection process to obtain the amino‐terminated pluronic; the new primary amino group in the modified pluronic initiated ring‐opening polymerization of amino acid N‐carboxyanhydride, which afforded the pluronic‐b‐poly(Nε‐(Z)‐L‐lysine) block copolymer. Finally, removal of the side‐chain Nε‐(carbonybenzoxy) end protecting groups yields the block copolymer of pluronic‐b‐PLL. The products were characterized by 1H‐NMR, FTIR, DSC, and GPC. The block copolymer micelle containing the anticancer drug paclitaxel was prepared by the double emulsion method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The reinforcement of red clay on natural rubber and its reinforcing mechanism
Authors: Deng Hua , Ao Ningjian , Yan Tuo , Zhang Li , Huang Chubo
Published: March 2009

Three kinds of red clay were fractionated according to the particle size using ultrasonic and centrifugal method. The mechanical properties of the clay‐rubber composite with various clay fractions were determined. At the same time, both the content of the metal components in the clay and the affect to the aging properties were determined. The result shows that within a certain range, the clay particle size only affects some of the mechanical properties of clay‐rubber composite. The characteristic morphological structure of the clay provides a significant reinforcing action on clay‐rubber composite. We speculate that mechanism of the reinforcement of clay on rubber is that the clay forms a rigid or semi‐rigid chain aggregation structure in rubber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparison of fibroblast and nerve cells response on plasma treated poly (L‐lactide) surface
Authors: Khorasani M. T. , Mirzadeh H. , Irani S.
Published: March 2009

Plasma technique can easily be used to introduce desired functional groups or chains onto the surface of materials, and so it has a special application to improve the cell affinity of polymers surfaces. The purpose of this study is to elucidate the interaction between the cells and the surface of crystalline poly (L‐lactide) (PLLA) samples, which were modified using a low‐temperature plasma treatment apparatus. The plasma treatments were carried out in the carbon dioxide (CO2) gas. The results showed that the contact angle of the samples, which was plasma treated in CO2 gas, decreased compared with that of the untreated samples. The hydrophilicity increased because of the introduction of oxygen‐containing functional groups onto the PLLA surfaces according to the spectroscopy for chemical analysis. High quantities of CO groups, such as hydroxyl and carboxyl could be in corporate into the surface of PLLA. The surface wettability, topography, and chemistry of treated PLLA samples were characterized by contact angle measurement, scanning electron microscope (SEM), and ATR‐FTIR spectroscopy. The origin and plasma‐treated samples were used to investigate the interaction of two different types of cells namely, B65 glial nervous, and L929 fibroblast cells. The nervous cell response on the PLLA plasma treated in the CO2 gas were significantly superior to that of the L929 fibroblast cells and untreated one. The surface modification technique used in this study may be applicable to tissue engineering for the improvement of nerve tissue compatibility of polymer and scaffold‐type substrates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The interchange reaction between poly(ethylene terephthalate) and poly(m‐xylylene adipamide)
Authors: Xie Fei , Kim Yong Wah , Jabarin Saleh A.
Published: March 2009

The interchange reaction in blends of poly(ethylene terephthalate) (PET) and poly(m‐xylylene adipamide) (MXD6) has been characterized in terms of changes observed in spectra obtained with a 600‐MHz 1H‐NMR. The selective degradation of PET components in the blends was carried out in the NMR tubes prior to evaluation. Results indicate that there is no chemical reaction between the PET and MXD6 in the absence of sodium p‐toluenesulfonate catalyst. The presence of the catalyst activates the interchange reaction between these two resins. A mathematical method was applied to calculate the degree of randomness of PET‐MXD6 copolymer. In addition, the reaction degree was found to be affected by exposure temperature, time, shear rate, and catalyst concentration. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Adsorptive removal of methylene blue from simulated dyeing wastewater with melamine‐formaldehyde‐urea resin
Authors: Ozdemir F. Ayca , Demirata Birsen , Apak R.
Published: March 2009

A melamine‐formaldehyde‐urea (MFU) resin was used as adsorbent to clean wastewater containing a basic dye (methylene blue) used to simulate leather and textile processing dyes. Dye removal was followed by measuring the initial and final dye concentration in solution by UV‐Vis spectroscopy using the analytical wavelength of λ = 665 nm and the molar absorptivity of ε = (8.43 ± 0.05) × 104 L mol−1 cm−1. The concentration range of methylene blue in solution for adsorption experiments was between 10−7 and 10−5 M so as to avoid dye polymerization reactions in solution that would give rise to apparent deviations from Beer's law. Batch and column methods were used for investigating adsorptive removal of dye. Parameters such as pH and contact time were optimized. The capacity of the sorbent for the dye was found by classical adsorption modeling (15.0 mg g−1) with the aid of a Langmuir isotherm. The optimal pH for adsorption was 7–8. Adsorption is thought to proceed mainly through cation exchange of methylene blue (MB+) with the RCOO− exchange groups of the sorbent. Adsorption was fast, and reached an equilibrium within 30 min. Color removal of simulated leather dyeing wastewater was shown to be feasible under optimal conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A novel hydrogen peroxide sensor based on multiwalled carbon nanotubes/poly(pyrocatechol violet)‐modified glassy carbon electrode
Authors: Fang Bin , Zhang Na , Zhang Wei , Gu Aixia , Wang Guangfeng
Published: March 2009

In this work, a new hydrogen peroxide (H2O2) sensor was reported based on electropolymerizing pyrocatechol violet (PCV) on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNTs). The modified electrode was characterized by cyclic voltammetry (CV) and scanning electron micrography. The result of electrochemical experiments showed a favorable catalytic activity toward the reduction of H2O2 at −0.4 V with a linear response range from 2.0 μM to 2.4 mM and a detection limit of 0.7 μM (at a S/N = 3). The well catalytic activity of proposed sensor could be attributed to the poly‐PCV/MWCNTs composite film on the electrocatalytic reduction of H2O2. In addition, the sensor also exhibited a high sensitivity, good stability, and reproducibility. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Surface modification of carbon nanofibers via deposition of an ultrathin coating of plasma‐polymerized poly(acrylic acid) and its effect on the properties of polyamide 6/CNF nanocomposites
Authors: Hernández‐Hernández E. , Neira‐Velázquez M. G. , Mendez‐Nonell J. , Ramos‐deValle L. F.
Published: March 2009

Carbon nanofibers (CNFs) were coated with an ultrathin layer of poly(acrylic acid) (PAA) via plasma polymerization. The effect of the plasma reactor parameters on the extent of the CNF modification was studied. SEM micrographs showed that surface roughness increased with the plasma treatment. The thickness of the ultrathin PAA layer deposited on the CNF was determined by STEM to be ca. 8 nm. Untreated and treated CNF were melt‐mixed with polyamide 6 (PA6) in a Brabender mixing chamber to obtain PA6/CNF nanocomposites. The effect of the plasma treatment on the dispersion and compatibility was examined and found to improve markedly. Fractured tensile specimens showed that the CNF seemed to be completely embedded in the polymer matrix, indicating high compatibility between the PA6 and the PAA‐coated CNF. Tensile stress and tensile modulus of PA6 nanocomposites with treated CNF were found to increase by 30 and 48%, respectively, when compared with those with untreated CNF. However, the increase in tensile stress and modulus with respect to pure PA6 was 52 and 88%, respectively. Finally, XRD showed that the CNF induce the formation of the α (alpha)‐crystalline phase in PA6. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Solid state mechano‐chemical grafting copolymerization of hydroxyethyl cellulose with acrylic acid
Authors: Chen Rong , Yi Chuanbin , Wu Hong , Guo Shaoyun
Published: March 2009

The effects of mechanochemical treatment on hydroxyethyl cellulose (HEC) and its grafting reaction with acrylic acid (AA) under solvent‐free conditions were studied through a vibratory ball‐milling machine, which was developed in our laboratory. Fourier transform infrared (FTIR) spectroscopy and 13C‐NMR analysis were used to investigate the structural development of HEC during vibromilling and the grafting mechanism. Further development of the structure and properties of the graft copolymer was characterized by viscosity measurement, wide‐angle X‐ray diffraction (WAXD), and thermal gravity (TG) analysis. The FTIR results showed a new peak at 1720 cm−1, corresponding to the CO absorbance peak of AA, which indicated that AA was successfully grafted onto HEC during the high‐energy vibromilling of the HEC/AA mixture at ambient temperature in the absence of a solvent and a catalyst. The WAXD showed the destruction of crystals of HEC during the milling, and the TG analysis demonstrated the improvement of the thermal stability of the copolymer. The effects of the processing conditions on the grafting rate and grafting efficiency were studied by chemical titration to determine the optimum grafting conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Invasive species shifts ontogenetic resource partitioning and microhabitat use of a threatened native amphibian
Authors: D'Amore Antonia , Kirby Erik , McNicholas Michael
Published: March 2009

Invasive species may have direct effects on native species, such as predation or competition, as well as indirect effects such as altering habitat or the behaviour of a native species. Indirect effects can be difficult to detect, but whole‐system removal of invasive species presents an excellent opportunity for revealing these more subtle effects.

American bullfrogs were introduced to California in the late 1800s and have been implicated in the declines of native ranid species. Invasive American bullfrogs were removed from a series of 12 ponds to test for changes in microhabitat use of federally threatened California red‐legged frogs, using a neighbouring field site with six ponds as a control.

There was a marked increase in the total number of adult California red‐legged frogs seen in all of the ponds after the first year of bullfrog removal, suggesting that these adults were in the ponds, but hiding when invaders were present. Ontogenetic partitioning of habitat in this species was documented, as well as a shift in that partitioning and increased hiding behaviour with adult bullfrog presence. California red‐legged frogs used willows significantly more as cover, and were found on bare shores half as often when adult bullfrogs were present.

These results support recent suggestions that behavioural responses of prey to predators can play a substantial role in total predator effects and suggest that careful management of invasive species may be necessary to accurately evaluate population sizes of this threatened amphibian species.

Copyright © 2009 John Wiley & Sons, Ltd.
The delineation of an interdisciplinary specialty in terms of a journal set: The case of communication studies
Authors: Leydesdorff Loet , Probst Carole
Published: March 2009

A journal set in an interdisciplinary or newly developing area can be determined by including the journals classified under the most relevant ISI Subject Categories into a journal–journal citation matrix. Despite the fuzzy character of borders, factor analysis of the citation patterns enables us to delineate the specific set by discarding the noise. This methodology is illustrated using communication studies as a hybrid development between political science and social psychology. The development can be visualized using animations which support the claim that a specific journal set in communication studies is increasingly developing, notably in the “being cited” patterns. The resulting set of 28 journals in communication studies is smaller and more focused than the 45 journals classified by the ISI Subject Categories as “Communication.” The proposed method is tested for its robustness by extending the relevant environments to sets including many more journals.
Are Web‐based informational queries changing?
Authors: Tann Chadwyn , Sanderson Mark
Published: March 2009

This brief communication describes the results of a questionnaire examining certain aspects of the Web‐based information seeking practices of university students. The results are contrasted with past work showing that queries to Web search engines can be assigned to one of a series of categories: navigational, informational, and transactional. The survey results suggest that a large group of queries, which in the past would have been classified as informational, have become at least partially navigational. We contend that this change has occurred because of the rise of large Web sites holding particular types of information, such as Wikipedia and the Internet Movie Database.