bluuebunny/crossref_metadata_2025 huggingface dataset:
R/M, 1953
Authors: Bident Christophe
Published: July 2008

French literary criticism in the twentieth century is marked by two names: those of Roland Barthes andMaurice Blanchot. Each of them cut an individual path through the dense and variegated cultural terrain of their era, and few authors escaped their attention. Their paths generally ran in parallel, and they rarely opposed each other, yet their dialogue was never easy, and the impression remains that between them, there was never really a meeting of minds. Taking 1953 as a crucial year, this article will attempt to situate both the convergences and the divergences which mark their respective careers, by considering them in relation to a single question: that of the neuter.
The Difference Between Science and Philosophy: the Spinoza-Boyle Controversy Revisited
Authors: Duffy Simon
Published: July 2008

This article examines the seventeenth-century debate between the Dutch philosopher Benedict de Spinoza and the British scientist Robert Boyle, with a view to explicating what the twentieth-century French philosopher Gilles Deleuze considers to be the difference between science and philosophy. The two main themes that are usually drawn from the correspondence of Boyle and Spinoza, and used to polarize the exchange, are the different views on scientific methodology and on the nature of matter that are attributed to each correspondent. Commentators have tended to focus on one or the other of these themes in order to champion either Boyle or Spinoza in their assessment of the exchange. This paper draws upon the resources made available by Gilles Deleuze and Felix Guattari in their major work What is Philosophy?, in order to offer a more balanced account of the exchange, which in its turn contributes to our understanding of Deleuze and Guattari's conception of the difference between science and philosophy.
Chaos and Control: Nanotechnology and the Politics of Emergence
Authors: Kearnes Matthew
Published: July 2008

This article looks at the strong links between Deleuze's molecular ontology and the fields of complexity and emergence, and argues that Deleuze's work implies a ‘philosophy of technology’ that is both open and dynamic. Following Simondon and von Uexküll, Deleuze suggests that technical objects are ontologically unstable, and are produced by processes of individuation and self-organization in complex relations with their environment. For Deleuze design is not imposed from without, but emerges from within matter. The fundamental departure for Deleuze, on the basis of such an ontology, is to conceive of modes of relating to the evolution of technology. In this way Deleuze, along with Guattari, provides the basis for an ethics and a politics of becoming and emergent control that constitutes an alternative to the hubris of contemporary reductionist accounts of new areas such as nanotechnology.
Chaosmologies: Quantum Field Theory, Chaos and Thought in Deleuze and Guattari's What is Philosophy?
Authors: Plotnitsky Arkady
Published: July 2008

This article explores the relationships between the philosophical foundations of quantum field theory, the currently dominant form of quantum physics, and Deleuze's concept of the virtual, most especially in relation to the idea of chaos found in Deleuze and Guattari's What is Philosophy?. Deleuze and Guattari appear to derive this idea partly from the philosophical conceptuality of quantum field theory, in particular the concept of virtual particle formation. The article then goes on to discuss, from this perspective, the relationships between philosophy and science, and between their respective ways of confronting chaos, a great enemy but also a great friend of thought, and its greatest ally in its struggle against opinion.
Science and Dialectics in the Philosophies of Deleuze, Bachelard and DeLanda
Authors: Williams James
Published: July 2008

This article charts differences between Gilles Deleuze's and Gaston Bachelard's philosophies of science in order to reflect on different readings of the role of science in Deleuze's philosophy, in particular in relation to Manuel DeLanda's interpretation of Deleuze's work. The questions considered are: Why do Gilles Deleuze and Gaston Bachelard develop radically different philosophical dialectics in relation to science? What is the significance of this difference for current approaches to Deleuze and science, most notably as developed by Manuel DeLanda? It is argued that, despite its great explanatory power, DeLanda's association of Deleuze with a particular set of contemporary scientific theories does not allow for the ontological openness and for the metaphysical sources of Deleuze's work. The argument turns on whether terms such as ‘intensity’ can be given predominantly scientific definitions or whether metaphysical definitions are more consistent with a sceptical relation of philosophy to contemporary science.
Translation and the Lipogram
Authors: Briggs Kate
Published: July 2008

This article argues for a definition of translation as a form of writing under constraint. Quite straightforwardly, the translator must write the original text again in a language other than the one in which it was originally composed. Both inhibiting and enabling, that restriction is also translation's resource, ensuring its distinctiveness as a writing practice and providing the key to its unique transformative possibilities. Like lipogrammatical writing, translation is inaugurated by its constraint. The article explores the affinity between translation and the lipogram with reference to Georges Perec's La Disparition, where the prohibition of the letter e initiates a peculiarly inventive kind of writing. Peculiarly inventive, because the effects generated by writing without a given letter of the alphabet, or by writing a given text again in another, altogether different, language, are essentially unprogrammable: we do not know what is going to happen.
Trauma Theory: Contexts, Politics, Ethics
Authors: Radstone Susannah
Published: July 2008

This article discusses the current ‘popularity’ of trauma research in the Humanities and examines the ethics and politics of trauma theory, as exemplified in the writings of Caruth and Felman and Laub.Written from a position informed by Laplanchian and object relations psychoanalytic theory, it begins by examining and offering a critique of trauma theory's model of subjectivity, and its relations with theories of referentiality and representation, history and testimony. Next, it proposes that although trauma theory's subject matter—the sufferings of others—makes critique difficult, the theory's politics, its exclusions and inclusions, and its unconscious drives and desires are as deserving of attention as those of any other theory. Arguing that the political and cultural contexts within which this theory has risen to prominence have remained largely unexamined, the article concludes by proposing that trauma theory needs to act as a brake against rather than as a vehicle for cultural and political Manicheanism.
The Duty of Memory: A Solidarity of Voices after the Rwandan Genocide
Authors: Small Audrey
Published: July 2008

In 2000, the publication of ten texts marked the completion of a two-year project entitled Le Devoir de mémoire, which had brought together ten writers from across Africa to write in response to the Rwandan genocide. This article looks at how the project was posited from the outset as a specifically African response, setting this in the context of older problems of voice, selfrepresentation and the renegotiation of miswritten histories in the postcolonial context. This aspect of the project is made all the more urgent by the actuality of the genocide, and the period of residence the writers spent in Rwanda in 1998. This article argues that the project succeeded in creating a space in which Africa as a whole is made part of the genocide, and vice versa, by raising complex questions of responsibility and by drawing on familiar themes in modern African writing, namely history, memory and identity; exile and dislocation.
Flesh, Folds and Texturality: Thinking Visual Ellipsis via Merleau-Ponty, Hélène Cixous and Robert Frank
Authors: Chamarette Jenny
Published: July 2008

Certain forms of art privilege the ellipsis. For example, in poetry, one has only to think of Mallarmé's Un Coup de dés for ellipsis to mark its peculiar trace upon the processes of meaning. Nonetheless, because ellipsis situates itself so curiously between meaning and signification, a formal definition may seem too categorical in explaining what ellipsis can do in its between-state, flanked by visuality, semiotics and signification. This article examines how Merleau- Ponty, Derrida and Deleuze, employ textual-visual and ontological-perceptual strategies for making sense of this slippery signifier. These strategies allow us to think through examples of ellipsis in the writing of Hélène Cixous and in the photographs of Robert Frank, in terms of semantic, affective, aesthetic and material qualities.
Postcolonial Melancholia
Authors: Sorensen Eli
Published: July 2008

The article attempts to identify some of the boundaries and limits of postcolonial studies, with a specific focus on its relationship to the literary. Leading critics have argued that the contemporary field of postcolonial studies has become melancholic, as a consequence of its institutionalization in recent years, and the article suggests reading these signs of melancholia as an expression of the failed attempt to identify with the dimension of the literary in the postcolonial text.
CFD study of mixing characteristics of bubble column and external loop airlift reactor
Authors: Roy S. , Joshi J. B.
Published: July 2008

In the present work, a computational fluid dynamics study has been carried out to bring out the mixing characteristics of bubble column and external loop airlift reactor. A comparison of mixing time for two reactors has been presented on the basis of the same reactor volume as well as the total power input. The CFD model was validated by simulating flow, both in bubble column and external loop airlift reactor. An agreement was observed between the predicted and the experimental data available in the published literature. The validated CFD model has been extended for the simulation of the mixing time for both the reactors. The CFD predictions of mixing time show good agreement with the experimental values published in literature. A systematic numerical study was then carried out to bring out the mixing characteristics of both the reactors. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
CFD modeling of rotary cement kilns
Authors: Mujumdar Kaustubh S. , Ranade Vivek V.
Published: July 2008

Rotary cement kilns are widely used to convert calcineous raw meal into cement clinker, and are key components in the cement industry. In this article, we report a comprehensive computational fluid dynamics (CFD)‐based model to capture key transport processes in rotary cement kilns. Separate but coupled computational models were developed for the bed and the freeboard regions of the rotary kiln. The complex swirling airflow produced by kiln burners, coal combustion, gas‐phase combustion of volatile matter and radiative heat transfer in the freeboard region were modeled. The clinkerization reactions in the bed region were modeled assuming solids as pseudo fluids. Coating formation in cement kilns (for both bed and freeboard regions) was considered. Appropriate source and sink terms were developed to model transfer of CO2 from the bed to the freeboard region due to calcination reaction in the bed region. The developed bed and freeboard models were coupled by mass and energy communication through common interface. These coupled computational models were able to quite satisfactorily predict the available data from industrial kilns and previously published results. The computational models were also able to capture the intricacies of the burning zones of rotary cement kilns for changing burner‐operational parameters like axial to swirl ratio and oxygen enrichment. The developed approach, computational models and simulation results will not only help in developing better understanding of cement kilns but also provide quantitative information about influence of burner design and other design parameters on kiln performance. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
On the hydrodynamics of liquid–liquid slug flow capillary microreactors
Authors: Kashid M. N. , Rivas D. Fernández , Agar D. W. , Turek S.
Published: July 2008

Microreactor technology is an important method of process intensification. Liquid–liquid slug flow capillary microreactors have been used to intensify the reactions with heat and mass transfer limitations. In this type of reactor, either two liquids flow alternate to each other in a capillary or one liquid flows as a continuous flow while the other flows in the form of enclosed drops (slugs) depending on the interfacial tension between two liquids and liquid adhesion with the solid walls. The enhanced mass transfer is due to the internal circulations within the slugs, which rise due to the shearing action between the slug axis and the capillary wall or continuous phase. The slug size and the intensity of internal circulations depend on the type of mixing element and physical properties of the liquids. The proper understanding of physical behaviour of fluids at the microscale is a challenging issue for the growing microreactor application demands. This article highlights the hydrodynamic characteristics of the liquid–liquid slug flow capillary microreactor. Experimental results on flow regime, slug size and particle image velocimetry along with corresponding complementary state‐of‐the‐art computational fluid dynamics (CFD) simulations are discussed in detail. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
CFD modeling of a fluidized bed sewage sludge gasifier for syngas
Authors: Wang Yiqun , Yan Lifeng
Published: July 2008

A three‐dimensional model of a fluidized bed for sewage sludge gasification is presented. The model describes the complex physical and chemical phenomena in the gasifier, including turbulent flow, heat and mass transfer, and chemical reactions. The simulation employs the standard κ− ε turbulence model for the gas phase in an Eulerian framework, and the discrete phase model for the sludge particles in a Lagrangian framework, coupled with the nonpremixed combustion model for chemical reactions. In terms of the Computational Fluid Dynamics (CFD) software Fluent 6.1, the simulations provide detailed information on the gas products' composition and temperature distribution inside the gasifier and at the outlet. The results are compared with the experimental data in literature (Manya et al., 2005). Effects of temperature and equivalence ratio (ER) on the product syngas (H2 + CO) quality are studied. The model shows good agreement with the experimental data. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Simultaneous model of chlorine dosing and decay in drinking water distribution system and model predictive control application
Authors: Muslim Abrar , Li Qin , Tadé Moses O.
Published: July 2008

The most commonly applied active disinfectant in drinking water distribution system (DWDS) is free chlorine residual (FCR) in the form of hypochlorous acid and hypochlorite ion. The concentration of FCR decreases along the transport pipeline. Controlled replenishment of chlorine at various sites in DWDS is critical to maintain the FCR in the safe range of 0.2–0.6 ppm. This study proposed a multiple‐input multiple‐output (MIMO) model (developed in Simulink of Matlab 7.0.1) that simultaneously takes into account chlorine dosing and decay process with the considerations of process disturbances. The model is further implemented into a centralised model predictive control (CMPC) system. The advantages of our CMPC system in controlling multiple outputs are its robustness and short settling time, compared to the conventional process‐data‐based proportional integral (PI) control strategies. Moreover, the simplicity of this reactive‐transport‐model‐based MIMO control system and the use of Matlab promise an easy adaptation to field test and plant implementation. It addresses an important need in water quality management, particularly for developing countries. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Removal of methylene blue from aqueous solution by rubber (Hevea brasiliensis) seed shell in a fixed‐bed column
Authors: Oladoja N. A. , Asia I. O. , Ademoroti C. M. A. , Ogbewe O. A.
Published: July 2008

The present study investigated the dynamic sorption of methylene blue (MB) from solution using rubber seed shell (RSS) in a fixed‐bed column. The process of sorption of MB from solution was analyzed using five different isotherm models (Langmuir, Freundlich, Temkin, Harkins–Jura, and Halsey isotherm equations), and the monolayer sorption capacity (82.64 mg/g) obtained from the Langmuir plot was compared with the bed depth service time (BDST) capacity (703.42 mg/l) obtained from the BDST model plot. The effect of two process variables (RSS bed height and initial MB concentration) on the dynamic sorption of MB on RSS was studied using the breakthrough curve. The total time (tx) for the establishment of primary adsorption zone (PAZ), the time required for the movement of the PAZ down the length of the RSS bed (tδ), the fractional capacity (f), and the length or depth of PAZ (δ) were evaluated. The operating design of the fixed was altered using serial dynamic sorption study, and the sensitivity of the RSS bed to drought was monitored when the Ci/Cf approached 0.5. The operational parameters of these variations were also estimated. The process variables were correlated with the BDST model, and a linear graph with high linear correlation (R2 > 0.9) values was obtained (0.9944 and 1.0000 at Tb10 and Tb50 respectively). The results obtained from the correlation of the process variables with the BDST model were used to predict the effect of changing the process variables on the system by using the BDST approach. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Studies to aid process development for the manufacture of neopentyl glycol from isobutyraldehyde: aldol condensation followed by hydrogenation
Authors: Tike M. A. , Gharde A. M. , Mahajani V. V.
Published: July 2008

In our present research and investigations, attempts were made to study aldol condensation of isobutyraldehyde with formaldehyde, and the subsequent hydrogenation of resultant hydroxypivaldehyde (aldol product) to neopentyl glycol. The kinetics of aldol condensation were studied using a weak basic anion‐exchange resin catalyst, Indion‐860, after screening other heterogeneous catalysts. The initial rate data were analyzed using a power‐law model to aid process design. Further, subsequent hydrogenation of resultant hydroxypivaldehyde was studied using 5% Ru/Al2O3 catalyst. The selectivity towards neopentyl glycol was > 99%. The kinetic data were analyzed using a power‐law model. A dual‐site Langmuir–Hinshelwood‐type model suggesting molecular adsorption (nondissociative) of hydrogen and surface reaction as the rate‐controlling step provided the best fit of the experimental data. The catalyst could be recycled with good selectivity. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Understanding capture of non‐Brownian particles in porous media with network model
Authors: Gao Changhong
Published: July 2008

Particles can invade porous media such as reservoir rocks and deep‐bed filters, causing severe damage to their permeabilities. The mechanisms of permeability decline are attributed to surface deposition, bridging and size exclusion of particles in porous media. Traditional models are empirical correlations heavily dependent on filtration data. In this paper, a 2D square network model incorporating the damaging mechanisms is used to study the capture of non‐Brownian particles in porous media and the resultant permeability damage. The model employs certain assumptions to imitate the characteristics of real porous media. The proposed procedure applies force analysis to obtain particle invasion depth, and determines damaging mechanisms by pore size to particle size ratio. The method is validated with test data and reasonably good results are obtained. The new model provides more insights into the capture process and does not rely on core flooding data. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Friction between co‐current upward gas–solid flow and column wall
Authors: Qi Xiaobo , Huang Weixing , Zhu Jesse
Published: July 2008

Friction between co‐current upflow gas–solid flow and column wall was investigated by measuring apparent solids concentrations and actual ones in two circulating fluidized bed (CFB) risers with fluid catalytic cracking (FCC) and sand particles, respectively. A new model to predict frictional‐pressure drops between the gas–solid flow in the fully developed zone and the column wall was developed. The results show that the friction between the gas–solid flow and the riser wall causes a significant deviation of the apparent solids concentration from the actual ones, especially under those operating conditions with higher superficial gas velocities and solids‐circulation rates. When superficial gas velocities are greater than 8 m/s, the apparent solids concentrations in the fully developed zone of the risers can be greater than 60% of the actual ones. Particle diameters have different influences on the frictional‐pressure loss under different superficial gas velocities. After the frictional‐pressure drops predicted by the proposed model are deducted from the measured total pressure drops, the predicted actual solids concentrations agree well with the measured actual ones. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Optimized experimental design for the inhibition of calcium oxalate using a turbidimetrical model
Authors: Driouch Aouatef , Djelloul Abdelkader , Kaid‐Omar Zohra , Semmoud Ahmed , Rais Abdelmajid , Addou Ahmed
Published: July 2008

In this work, we studied the individual and combined effect of inhibitors such as citrate ions and magnesium ions on crystallization of calcium oxalate. It is the main constituent of more than 70% of urinary stones. In order to optimize the number of experiments with the help of a suitable mathematical model, an experimental design was developed. The crystallization of CaC2O4 with and without inhibitors, at physiological concentrations, was studied by turbidimetry at 37 °C. The inhibition effect was evaluated through the induction time (nucleation) and the turbidimetrical slope (crystalline growth). The experimental design enabled the investigation of the effect of citrate ions, magnesium ions, and their combination on the inhibition rate. The obtained results showed that the inhibition power increases with inhibitor concentration when it is tested alone. This inhibition also affected the delay on nucleation. Thus, the induction time varied from 0.22 min without inhibitor to 4.73 min with citrate ions and 1.96 min with magnesium ions. The two inhibitors were more effective on nucleation and on crystalline growth when they were used in combination compared to one of them tested alone. The mathematical model fitted the experimental results well with a minimum of trials. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Spina bifida before and after folic acid fortification in Canada
Authors: De Wals Philippe , Tairou Fassiatou , Van Allen Margot I. , Lowry R. Brian , Evans Jane A. , Van den Hof Michiel C. , Crowley Marian , Uh Soo‐Hong , Zimmer Pamela , Sibbald Barbara , Fernandez Bridget , Lee Nora S. , Niyonsenga Theophile
Published: July 2008

BACKGROUND:

In 1998, fortification of a large variety of cereal products with folic acid became mandatory in Canada. A multicentric study was carried out to assess the impact of this policy on the frequency of NTDs. The present analysis focused on spina bifida.

METHODS:

The study population included approximately 2 million livebirths, stillbirths, and terminations of pregnancies because of fetal anomalies among women residing in seven Canadian provinces, from 1993 to 2002. Spina bifida cases were divided according to the upper limit of the defect: upper (cranial, cervical, or thoracic) and lower (lumbar or sacral) defects. Based on published results of red blood cell folate tests, the study period was divided into prefortification, partial fortification, and full fortification periods.

RESULTS:

A total of 1,286 spina bifida cases were identified: 51% livebirths, 3% stillbirths, and 46% terminations. Prevalence decreased from 0.86/1,000 in the prefortification to 0.40 in the full fortification period, while the proportion of upper defects decreased from 32% to 13%. Following fortification, regional variations in the prevalence and distribution of sites almost disappeared.

CONCLUSIONS:

Results confirmed the etiologic heterogeneity of spina bifida and the more pronounced effect of folic acid in decreasing the risk of the more severe clinical presentations. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Genome‐wide pathway analysis of folate‐responsive genes to unravel the pathogenesis of orofacial clefting in man
Authors: Bliek Bart J. B. , Steegers‐Theunissen Régine P. M. , Blok Leen J. , Santegoets Lindy A. M. , Lindemans Jan , Oostra Ben A. , Steegers Eric A. P. , de Klein Annelies
Published: July 2008

BACKGROUND:

A cleft of the lip with or without the palate (CLP) is a frequent congenital malformation with a heterogeneous etiology, for which folic acid supplementation has a protective effect. To gain more insight into the molecular pathways affected by natural folate, we examined gene expression profiles of cultured B‐lymphoblasts from CLP patients before and after the addition of 5‐methyltetrahydrofolate (5‐mTHF) to the cultures.

METHODS:

Immortalized B‐lymphoblasts from five children with CLP were cultured in folate‐deficient medium for 5 days. 5‐mTHF was added to a concentration of 30 nM. Gene expression patterns were then evaluated before and after supplementation using Human Genome U133 Plus 2.0 arrays. Data analysis was performed with Omniviz and the GEPAS analysis suite. Differential genes were categorized into biological pathways with Ingenuity Pathway systems. Differential expression was validated by quantitative RT‐PCR.

RESULTS:

Using supervised clustering, with a false discovery rate <1%, we identified 144 and 409 significantly up‐regulated and down‐regulated probesets, respectively, after 5‐mTHF addition. The regulated genes were involved in a variety of biological pathways, including one carbon pool and cell cycle regulation, biosynthesis of amino acids and DNA/RNA nucleotides, protein processing, apoptosis, and DNA repair.

CONCLUSIONS:

The large variety of the identified folate responsive pathways fits with the modifying role of folate via the methylation pathway. From the present data we may conclude that folate deficiency deranges normal cell development, which might contribute to the development of CLP. The role of these folate responsive genes in CLP development is intriguing and needs further investigation. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Development of a chitosan‐based nanoparticle formulation for delivery of a hydrophilic hexapeptide, dalargin
Authors: Chen Yan , Siddalingappa Basavaraj , Chan Phoebe H. H. , Benson Heather A. E.
Published: July 2008

Nanoparticle based delivery systems can offer opportunities for targeting, controlled release, and enhanced stability of their drug, protein, or gene therapy payload. This study investigated the use of chitosan in combination with the ionic additives sulfobutyl‐ether‐7‐β‐cyclodextrin (SB‐CD) or SB‐CD/dextran sulfate (SB‐CD/DS) mixture in comparison with chitosan: DS in the formulation of nanoparticles incorporating the hexapeptide dalargin. The physical characteristics (particle size, zeta potential), entrapment and loading efficiency, and release of dalargin were quantified. It was demonstrated that anionic cyclodextrin, SB‐CD, can be used in complex coacervation with chitosan, with and without the presence of DS, to form nanoparticles. The presence of SB‐CD or DS in the nanoparticle formulation and the weight ratio of chitosan to anionic additive(s) influenced the physical properties of the nanoparticles and their ability to carry dalargin. In addition, the particle size of nanoparticles was also affected by the molecular weight of chitosan and DS. The use of either DS or SB‐CD/DS mixture produced chitosan nanoparticles with small particle size, high dalargin entrapment efficiency, enhanced peptide stability, and sustained release characteristics. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 663–670, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Conformational studies of the α‐helical 28–43 fragment of the B3 domain of the immunoglobulin binding protein G from Streptococcus
Authors: Skwierawska Agnieszka , Rodziewicz‐Motowidło Sylwia , Ołdziej Stanisław , Liwo Adam , Scheraga Harold A.
Published: July 2008

To determine whether the α‐helix in the B3 immunoglobulin binding domain of protein G from group G Streptococcus has conformational stability as an isolated fragment, we carried out a CD and NMR study of the 16‐residue peptide in solution corresponding to this α‐helix. Based on two‐dimensional H‐NMR spectra recorded at three different temperatures (283, 305, and 313 K), it was found that this peptide is mostly unstructured in water at these temperatures. Weak signals corresponding to i,i+3 or i,i+4 interactions, which are characteristic of formation of turn‐like structures, were observed in the ROE spectra at all temperatures. The absence of a stable three‐dimensional structure of the investigated peptide supports an earlier study (Blanco and Serrano, Eur J Biochem 1995, 230, 634–649) of a possible mechanism for folding of other (B1 and B2) immunoglobulin binding domains of Protein G. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1032–1044, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Defining resonance Raman spectral responses to substrate binding by cytochrome P450 from Pseudomonas putida
Authors: Mak Piotr J. , Kaluka Daniel , Manyumwa Munyaradzi Edith , Zhang Haiqing , Deng Tianjing , Kincaid James R.
Published: July 2008

Resonance Raman spectra are reported for substrate‐free and camphor‐bound cytochrome P450cam and its isotopically labeled analogues that have been reconstituted with protoheme derivatives that bear ‐CD3 groups at the 1, 3, 5, and 8‐positions (d12‐protoheme) or deuterated methine carbons (d4‐protoheme). In agreement with previous studies of this and similar enzymes, substrate binding induces changes in the high frequency and low frequency spectral regions, with the most dramatic effect in the low frequency region being activation of a new mode near 367 cm−1. This substrate‐activated mode had been previously assigned as a second “propionate bending” mode (Chen et al., Biochemistry, 2004, 43, 1798–1808), arising in addition to the single propionate bending mode observed for the substrate‐free form at 380 cm−1. In this work, this newly activated mode is observed to shift by 8 cm−1 to lower frequency in the d12‐protoheme reconstituted enzyme (i.e., the same shift as that observed for the higher frequency “propionate bending” mode) and is therefore consistent with the suggested assignment. However, the newly acquired data for the d4‐protoheme substituted analogue also support an earlier alternate suggestion (Deng et al., Biochemistry, 1999, 38, 13699–13706) that substrate binding activates several heme out‐of‐plane modes, one of which (γ6) is accidentally degenerate with the 367 cm−1 propionate bending mode. Finally, the study of the enzyme reconstituted with the protoheme‐d4, which shifts the macrocycle ν10 mode, has now allowed a definitive identification of the vinyl CC stretching modes. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1045–1053, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Relating Chemical and Biological Diversity Space: A Tunable System for Efficient Gene Transfection
Authors: Van Vliet Liisa D. , Chapman Michael R. , Avenier Frédéric , Kitson Chris Z. , Hollfelder Florian
Published: July 2008

Polyethyleneimine (PEI), a well‐established nonviral transfection reagent, was combinatorially modified with varying proportions of methyl, benzyl, and n‐dodecyl groups to create a library of 435 derivatized polymers. Screening of this library for transfection, DNA binding, and toxicity allows systematic correlation of the biological properties of our polymers to their derivatizations. Combinations of derivatizations bring about a 100‐fold variation in transfection efficiency between library members. The best PEI derivatives exhibit increases in transfection efficiency of more than 80‐fold over unmodified PEI (up to 28±7 % of cells transfected) and rival commercial reagents such as Lipofectamine 2000 (21±10 %) and JetPEI (32±5.0 %). In addition, we can identify compounds that are specifically tuned for efficient transfection in CHO‐K1 over Ishikawa cells and vice versa, demonstrating that the approach can lead to cell‐type selectivity of at least one order of magnitude. This work demonstrates that multivalent derivatization of a polymeric framework can create functional diversity substantially greater than the structural diversity of the derivatization building blocks and suggests an approach to a better understanding of the molecular underpinnings of transfection as well as their exploitation.
Synthesis of Novel DC‐SIGN Ligands with an α‐Fucosylamide Anchor
Authors: Timpano Gabriele , Tabarani Georges , Anderluh Marko , Invernizzi Donatella , Vasile Francesca , Potenza Donatella , Nieto Pedro M. , Rojo Javier , Fieschi Franck , Bernardi Anna
Published: July 2008

The dendritic cell‐specific intercellular adhesion molecule (ICAM) 3‐grabbing nonintegrin (DC‐SIGN) is a C‐type lectin that appears to perform several different functions. Besides mediating adhesion between dendritic cells and T lymphocytes, DC‐SIGN recognizes several pathogens some of which, including HIV, appear to exploit it to invade host organisms. The intriguing diversity of the roles attributed to DC‐SIGN and their therapeutic implications have stimulated the search for new ligands that could be used as biological probes and possibly as lead compounds for drug development. The natural ligands of DC‐SIGN consist of mannose oligosaccharides or fucose‐containing Lewis‐type determinants. Using the known 3D structure of the Lewis‐x trisaccharide, we have identified some monovalent α‐fucosylamides that bind to DC‐SIGN with inhibitory constants 0.4–0.5 mM, as determined by SPR, and have characterized their interaction with the protein by STD NMR spectroscopy. This work establishes for the first time α‐fucosylamides as functional mimics of chemically and enzymatically unstable α‐fucosides and describes interesting candidates for the preparation of multivalent systems able to block the receptor DC‐SIGN with high affinity and with potential biomedical applications.
Chemistry in Confining Reaction Fields with Special Emphasis on Nanoporous Materials
Authors: Polarz Sebastian , Kuschel Andreas
Published: July 2008

The everyday routine of most chemists is dictated by large numbers. The chemical rules for ensembles of molar size (N≈NA=6.022×1023) are well known and can be understood in most cases by using Boltzmann distribution. It is an interesting question how a small ensemble of a chemical system behaves and if it differs from the respective large‐ensemble counterpart. The experimental approach presented in the current paper involves the division of a macroscopic volume into compartments that contain only a small number of reactants. The compartments represent the pores of tailor‐made nanoporous materials.
Increasing chiral recognition in acetal formation
Authors: Noe Christian R. , Knollmüller Max , Jangg Edith , Gmeiner Günter P. , Urban Ernst , Eppacher Simon
Published: July 2008

The design of substituted lactols is described, which in their reaction with racemic alkyl aryl carbinols react preferentially with one of the enantiomers exhibiting selectivities up to 14:1. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
The posssible role of enantiodiscrimination in bilirubin toxicity
Authors: Bernardini Carlotta , D'Arrigo Paola , Elemento Gioia , Mancini Giovanna , Servi Stefano , Sorrenti Alessandro
Published: July 2008

The possibility that enantiodiscrimination of bilirubin might be involved in neuronal membrane destabilization, and therefore in bilirubin toxicity, was investigated, by circular dichroism, on model membranes composed of phospholipids. The equilibrium between bilirubin enantiomers is displaced at some extent by the interaction with certain phospholipids. The extent of equilibrium displacement depends on the molecular structure of phospholipids and on the state of charge of bilirubin. The results obtained validate the hypothesis of a possible involvement of chirality in bilirubin toxicity and support a previously suggested model for the molecular mechanism of the interaction of bilirubin with the synaptic membrane. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Interactions of Λ and Δ enantiomers of ruthenium(II) cationic complexes with achiral anionic porphyrins
Authors: Randazzo Rosalba , Lauceri Rosaria , Mammana Angela , D'Urso Alessandro , Purrello Roberto
Published: July 2008

The interactions between Λ and Δ enantiomers of ruthenium(II)‐phenanthroline cationic complex ([Ru(phen)3]2+) and three anionic porphyrins have been characterized by absorption, circular dichroism (CD), fluorescence, and resonance light scattering (RLS). The three porphyrins used in this study have been chosen for the different number (two or four) and reciprocal (symmetrical, cis or trans) disposition of the anionic (4‐sulphonatophenyl) peripheral groups in the meso positions. All the techniques evidence the formation of inorganic–organic hybrids. In particular, CD and fluorescence measurements show that the inorganic moiety is able to transfer to porphyrins not only chirality (as shown from the appearance of an induced CD signal (ICD) in the absorption region of porphyrins) but, most likely, also energy. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Dynamic HPLC of stereolabile iron(II) complexes on chiral stationary phases
Authors: Villani Claudio , Gasparrini Francesco , Pierini Marco , Mortera Stefano Levi , D'Acquarica Ilaria , Ciogli Alessia , Zappia Giovanni
Published: July 2008

A series of chiral tris‐(1,10)‐phenanthroline iron(II) complexes have been resolved by HPLC on chiral stationary phases based on either cellulose tris‐(3,5‐dimethylphenylcarbamate) or teicoplanin. At sub ambient temperatures, baseline separation of the enantiomers was observed for five different iron(II) complexes featuring substituted phenanthroline ligands. Dynamic HPLC profiles were observed near or above room temperature, indicating on‐column Δ/Λ enantiomerization. Rate constants for the Δ/Λ interconversion in free solution and during chromatography were obtained by thermal racemization experiments and by computer simulation of the HPLC dynamic plots, respectively. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Supramolecular enantiodifferentiating photoisomerization of (Z)‐cyclooctene in lyotropic and thermotropic liquid crystals
Authors: Xiao Debao , Wada Takehiko , Inoue Yoshihisa
Published: July 2008

In order to understand the roles of moderately organized media and the factors controlling the chirality transfer in supramolecular photochirogenesis, enantiodifferentiating photoisomerization of (Z)‐cyclooctene to the chiral (E)‐isomer (1E) has been performed for the first time in liquid crystal (LC) systems such as lyotropic LCs of poly(γ‐benzyl‐L‐glutamate) (PBLG), difluorobenzene derivatives mixture, and thermotropic cholesteryl oleyl carbonate LCs. Basically, the as‐employed LCs provided small enantiomer excess (<5%). It is interesting that lyotropic PBLG LCs give contrasting results in cholesteric and nematic mesophases, revealing the importance of the relevant mesophase structure of LC. Selective excitation in achiral difluorobenzene LC doped with a chiral sensitizer facilitates us to conclude that the LC's chiral spatial arrangement is not sufficient or suitable to induce appreciable enantiomeric excess (ee) in the product, but the existence of molecular chirality (of a chiral sensitizer) is essential to afford an optically active (nonracemic) product at least in the present photosensitization system. The photosensitizations in thermotropic LCs further reveal that the product's ee can be manipulated by the LC mesophase not directly but through the sensitizer's conformational changes induced by the supramolecular interactions with the surrounding LC structure. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Alteration of kynurenic acid concentration in rat plasma following optically pure kynurenine administration: A comparative study between enantiomers
Authors: Fukushima Takeshi , Sone Yukiko , Mitsuhashi Shogo , Tomiya Masayuki , Toyo'oka Toshimasa
Published: July 2008

L‐Kynurenine (KYN), a tryptophan metabolite, is metabolized to kynurenic acid (KYNA), which is an antagonist of N‐methyl‐D‐aspartate and α7 nicotinic acetylcholine receptors, by kynurenine aminotransferase (KAT) I and KAT II. In this study, optically pure KYN, namely L‐KYN or D‐KYN, was administered intraperitoneally to male Sprague‐Dawley rats (16.3 μmol kg−1), and the change in plasma KYNA was investigated by using column‐switching high‐performance liquid chromatography (HPLC) with fluorescence detection. Unexpectedly, no remarkable alteration in the plasma KYNA was observed when a natural isomer, L‐KYN, was administered, whereas plasma KYNA concentration was unequivocally increased when an unnatural isomer, D‐KYN, was administered. Serum protein bindings of L‐KYN and D‐KYN were also studied, and the protein binding of L‐KYN (∼65%) in rat serum was larger than that of D‐KYN (∼12%), suggesting that D‐KYN may be easily incorporated and metabolized in tissues during blood circulation to generate KYNA in mammals. In addition, the increase in plasma KYNA by the administration of D‐KYN was suppressed in rats pretreated with a selective inhibitor of D‐amino acid oxidase (DAAO), 5‐methylpyrazole‐3‐carboxylic acid (80 mg/kg). These results suggest that DAAO might be responsible for the production of KYNA from D‐KYN in vivo. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Configuration of the vitamin E analogue garcinoic acid extracted from garcinia kola seeds
Authors: Mazzini Francesco , Betti Michele , Netscher Thomas , Galli Francesco , Salvadori Piero
Published: July 2008

Vitamin E derivatives bearing a carboxylic group have recently gained great attention because of their antitumoral properties. Garcinoic acid (trans‐13′‐carboxy‐δ‐tocotrienol) is a vitamin E analog extracted from Garcinia Kola seeds in which the carboxylic group is at the end of the aliphatic side chain and reported to be a racemate based on the optical rotation measurements. However, CD determination of a sample of the acid analyzed by us gave a positive peak at 208 nm, indicating that it is not a racemate. To assess the enantiomeric composition of garcinoic acid, it was thus transformed to α‐tocopherol and analyzed by chiral HPLC on column OD‐H. On the basis of the elution order of α‐tocopherol stereoisomers, the garcinoic acid sample resulted to be enantiopure with R configuration at carbon 2 of the chroman ring. Moreover, in a preliminary test, the acid and some of its derivatives showed a marked antiproliferative effect on glioma C6 cancer cells. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Stereoselective analysis of tiopronin enantiomers in rat plasma using high‐performance liquid chromatography‐electrospray ionization mass spectrometry after chiral derivatization
Authors: Wang Huan , Ma Chen , Zhou Jia , Liu Xiao Quan
Published: July 2008

A specific and relatively sensitive high‐performance liquid chromatography‐electrospray ionization mass spectrometry (HPLC‐ESI‐MS) was developed for the quantitative analysis of tiopronin enantiomers in rat plasma. The method is based on the derivatization of (+)‐tiopronin and (−)‐tiopronin with 2,3,4,6‐tetra‐O‐acetyl‐β‐glucopyranosyl isothiocyanate (GITC) in acetonitrile. The separation of resulting diastereomic derivatives was performed on C18 column (150 mm × 2.0 mm ID, packed with 5.0 μm C18 silica RP particle), using a mobile phase of methanol/water (containing 5.3 mM formic acid) with gradient elution. LC–MS was performed in the selected ion monitoring and positive ion mode using target ions at m/z: 575 for the diastereomic derivatives of tiopronin and m/z: 603 for the derivative of N‐isobutyryl‐D‐cysteine (internal standard). The method was validated in terms of specificity, linearity, sensitivity, precision, accuracy, matrix effect, and stability. The calibration curves were linear over the concentration range of 0.025–5 μg/ml for both enantiomers of tiopronin. For both enantiomers of tiopronin, the interbatch and intrabatch variability values were less than 15%, and the accuracy was within ±17% in terms of relative error. The method was successfully applied to a pharmacokinetic study of rac‐tiopronin in rat. Chirality, 2009. © 2008 Wiley‐Liss, Inc.
Stereoselective synthesis of 2,3,7‐trimethylcyclooctanone and related compounds and determination of their relative and absolute configurations by the MαNP acid method
Authors: Naito Junpei , Kuwahara Shunsuke , Watanabe Masataka , Decatur John , Bos Pieter H. , Van Summeren Ruben P. , Horst Bjorn Ter , Feringa Ben L. , Minnaard Adriaan J. , Harada Nobuyuki
Published: July 2008

The copper/chiral phosphoramidite (L1)‐catalyzed conjugate addition of dimethylzinc to cycloocta‐2,7‐dienone 4, followed by the methylation of the intermediate enolate, yielded a single isomer of 7,8‐dimethylcyclooct‐2‐enone (+)‐5. Compound (+)‐5 was subjected to the second conjugate addition with ent‐L1 giving only one stereoisomer of 2,3,7‐trimethylcyclooctanone (+)‐6, which was converted to 2,3,7‐trimethylcyclooctanol 7. To determine the relative and absolute configurations of these compounds, the 1H NMR anisotropy method using (S)‐(+)‐2‐methoxy‐2‐(1‐naphthyl)propionic acid {(S)‐(+)‐MαNP acid} 1 was applied. Racemic alcohol (±)‐7 was esterified with (S)‐(+)‐MαNP acid 1 yielding diastereomeric esters, which were efficiently separated by HPLC on silica gel affording the first‐eluted MαNP ester (–)‐10a and the second‐eluted one (–)‐10b. The relative and absolute configurations of ester (–)‐10a were determined to be (S;1R,2S,3R,7S) by analyzing the 1H and 13C NMR spectra of (–)‐10a and (–)‐10b, especially their HSQC‐TOCSY and NOESY spectra, and by applying the MαNP anisotropy method. The alcohol 7 formed from (+)‐6 was similarly esterified with (S)‐(+)‐MαNP acid 1 yielding an MαNP ester, which was identical with (–)‐10a, and the relative and absolute configurations of 2,3,7‐trimethylcyclooctanone (+)‐6 were determined to be (2S,3R,7S). Chirality, 2008. © 2008 Wiley‐Liss, Inc.