bluuebunny/crossref_metadata_2025 huggingface dataset:
Mallarmé, les philosophes et les gestes de la philosophie
Authors: Délègue Yves
Published: October 2008

Henri Meschonnic l'affirme: il y a une «affaire Mallarmé», qu'auraient soulevée les philosophes post-heideggériens, faisant de Mallarmé le Hölderlin français, c'est-à-dire le poète-philosophe qui à ce titre, de Maurice Blanchot à Jacques Rancière ou Alain Badiou, intéresse les professionnels de la pensée. Je ne prends pas ici position sur l'affaire, mais je profite d'elle pour m'interroger sur les rapports entre philosophie et poésie. Si Mallarmé peut [-] être dit philosophe, comment faut-il l'entendre? Parler de sa «philosophie», c'est méconnaître la nature de l'expérience poétique qui le mena à «creuser le vers» et à «penser sa pensée» jusqu'au «néant». Mieux vaut parler des gestes philosophiques qui ont commandé sa pratique poétique, et qu'on retrouve chez d'autres écrivains, qu'ils soient ou non philosophes, parce que ces gestes concernent le rapport de la parole et des choses. C'est par ce biais qu'on peut comprendre ce qui unit et sépare à la fois poésie et philosophie et les rend l'une et l'autre plus que jamais indispensables aujourd'hui.
L'idéalisme fin-de-siècle
Authors: Brix Michel
Published: October 2008

Les divers manifestes du «symbolisme» se sont réclamés de la caution des doctrines esthétiques dérivées du platonisme, dont l'héritage s'est transmis à la fin-de-siècle par la médiation de l'œuvre d'Arthur Schopenhauer. L'examen de l'idéalisme fin-de-siècle laisse apparaître plusieurs données majeures qui intéressent l'histoire littéraire et illustrent de façon exemplaire combien se révèlent étroits les liens qui unissent la littérature et la pensée philosophique. Le présent article insiste principalement sur trois constats: l'idéalisme des symbolistes montre des caractères spécifiques, qui interdisent de le confondre avec le platonisme des romantiques; la pensée de Schopenhauer a été déformée par les esthètes de la fin-de-siècle pour justifier la thèse de l'inexistence du monde; enfin le texte de Nietzsche sur «Le Cas Wagner» témoigne de la parenté qui existe entre ces trois phénomènes littéraires et philosophiques majeurs du temps: l'idéalisme, le symbolisme et la décadence.
La réforme pénitentiaire sous la monarchie de Juillet ou l'indépassable «génie national » français
Authors: Dhaussy Catherine
Published: October 2008

La France de la monarchie de Juillet se passionne pour la réforme pénitentiaire. Les experts préconisent des mesures inspirées par l'exemple américain, notamment l'isolement des détenus et l'usage de la cellule. Mais, en dépit d'un vaste débat et d'une volonté politique manifeste, aucune réforme n'est votée. L'étude des arguments utilisés dans les débats permet de conclure que la principale raison réside dans une incompatibilité d'ordre culturel entre deux nations: il est impossible d'appliquer en France une réforme venue des Etats-Unis. C'est en effet parce que les Français ne peuvent adapter un mode d'organisation américain, pour la seule raison qu'il est américain, que ne sera jamais votée de loi instaurant l'isolement dans les centrales.
Les paradoxes de la cave pénale. De quelques représentations carcérales dans l'œuvre de Victor Hugo
Authors: Gleizes Delphine
Published: October 2008

Le modèle structurel de la prison, central dans l'œuvre de Victor Hugo, apparaît comme l'un des espaces problématiques dans lesquels se dramatisent et s'articulent les questions politiques et métaphysiques. La métaphore carcérale, présente tout à la fois dans la dénonciation des régimes politiques dictatoriaux et dans l'évocation de l'arbitraire de la providence divine, postule implicitement une continuité entre ce que Hugo appelle dans L'Homme qui rit la «loi d'en bas», loi humaine, et la «loi d'en haut», loi divine. Il s'agit dès lors d'étudier la façon dont Hugo construit et exploite ce paradigme carcéral et d'analyser l'ambivalence dont il est le reflet dans la pensée de l'écrivain, entre acceptation et révolte, dénonciation et soumission aux arrêts divins.
« Du jour suffisamment et de l'espace assez.» : Verlaine en prison
Authors: Solal Jérôme
Published: October 2008

La prison est un thème traité par Verlaine dans ses tardives proses autobiographiques. Son parcours de «poète maudit» l'y autorise. Mais l'emprisonnement lui-même est propice à une création littéraire qui en suspend l'infamie. C'est du long séjour carcéral de 1873-1875 que, dans le recueil inédit Cellulairement, jaillissent les vers dispersés plus tard dans d'autres œuvres. Verlaine fait alors l'expérience de la mesure qui dehors lui a tellement manqué. Cette «mesure» se comprend en deux sens. Sens moral: loin de toute récrimination victimaire, il trouve une certaine paix dans «le meilleur des châteaux», il y goûte la tempérance et cette sagesse minimale mais précieuse d'«être bien soi» dans un environnement stable et structuré. Sens musical: avec son émancipateur Art poétique, il trouve son rythme propre dans la claudication de l'Impair, où s'entendent les dissonances de la mélancolie. Avec la conversion de l'été 1874, Verlaine change de cap et rêve de troquer sa malédiction de poète contre la bénédiction de récitant chrétien.
Lignes de fuite. La Bête humaine évadée du naturalisme
Authors: Louapre Muriel
Published: October 2008

La fusion, dans le projet zolien, du roman du chemin de fer, conçu comme roman du mouvement, et du roman criminel, ne répond pas qu'à des considérations d'opportunité. L'analyse des séquences d'errance dans le roman met en évidence le rôle dynamique joué par la ligne de chemin de fer, à la fois instrument de clôture qui dévoile la dimension carcérale de l'univers et du système zolien, et vecteur d'un mouvement pathologique car sans objet ni sens. Constitutif du phénomène de naturalisation voire d'incorporation de la prison, ce mouvement apparaît dans un second temps comme la transposition du syndrome contemporain de la dromomanie, signe d'une préoccupation collective pour ceux qui échappent par le mouvement au contrôle social. Tout en reconduisant la doxa en posant le caractère pathologique des conduites de fugue, Zola y découvre un puissant vecteur d'exploration des frontières de l'humain, qui s'opère grâce au motif de la ligne: le rôle dynamique joué par la ligne, à la fois comme voie ferrée et comme schéma géométrique, dans la genèse du roman et son fonctionnement, permet alors de mettre en évidence la puissance d'abstraction qui soutient le naturalisme zolien, et assure la conversion d'une doxa en production symbolique.
Volume Measurement
Authors: Davis Thomas , Zanella Andrew
Published: October 2008

This unit describes the common types of volumetric apparatus used in the life science laboratory, their use, and care. When an experimenter needs to prepare solutions of accurate concentrations and to transfer quantitatively samples of liquid from one container to others, an array of glassware and plasticware is available for these operations ranging from a microliter to a liter in volume. Considerations of temperature, solvent compatibility, and safety also need to be taken into account.
Weight Measurement
Authors: Guzy Michael
Published: October 2008

This unit provides information to aid in the selection and proper use of a laboratory balance. Laboratory balances are used for measuring the mass of an object and come in two main types: mechanical and electronic. Electronic balances generally come with a computer interface to facilitate the collection, storage, and manipulation of the data. In addition to weighing objects, electronic balances also perform a range of computations, including counting objects, measuring density, statistics, and pipet volume calibration. Balances vary widely in terms of their capacity (how heavy an object they can accurately weigh), precision, accuracy, repeatability, and robustness. Understanding the various characteristics of a laboratory balance is necessary in order to be sure that the balance is well suited for your particular scientific or industrial needs. This unit also discusses the proper use and maintenance of a laboratory balance. In general, laboratory balances are relatively easy to use and require little maintenance.
Spectrophotometry
Authors: Morris Rob
Published: October 2008

Spectroscopy is the study of the interaction of light with matter. By observing how light interacts with matter—through reflection, refraction, elastic scattering, absorbance, inelastic scattering, and emission—it is possible to (1) identify the wavelengths of light that interact with atoms and molecules, or (2) quantify the amount of light being absorbed, reflected, scattered, or emitted at a particular wavelength. This unit describes the background and basic principles of spectrophotometry (the study of the reflection or transmission properties of a substance as a function of wavelength, in particular, absorbance spectrophotometry. Also included is discussion of key spectrophotometer components and their functions, the relationship between absorbance and transmittance, experiment considerations, and the steps necessary in preparing a standard curve for determining absorbance concentration.
Reagent Preparation: Theoretical and Practical Discussions
Authors: Chakravarti Deb N. , Chakravarti Bulbul , Mallik Buddhadeb
Published: October 2008

One of the most important requirements for the successful completion of any biochemical protocol is to prepare reagents accurately. This unit describes general guidelines for the preparation of reagents, use of clean glass‐ and plasticware, use of high‐purity reagents, safe handling of chemicals and biochemicals, use of high‐purity distilled or deionized water, accurate weighing, pipetting, and pH measurement, and avoidance of chemical or microbial contamination of reagents and use of sterile reagents. Different units of concentration used for preparation of reagents or buffer solutions are described. This unit also includes a section for the preparation of buffer solutions with a practical example.
Measurement of pH
Authors: Wiley Emily A. , Chakravarti Deb N.
Published: October 2008

The measurement of pH is one of the most basic and necessary skills in a life science laboratory. The function and physical characteristics of biological molecules are highly sensitive to the pH of the environment. Common biological buffers must be prepared with the appropriate pH, usually close to neutral for most biological applications. This unit includes a discussion of the different pH instrumentation, notably pH electrodes, and their applications. It also relates basic pH measurement theory to critical parameters for the technique, and covers the correct use, handling, and storage of pH instruments.
Culture of Escherichia coli and Related Bacteria
Authors: Riley Sean P. , Woodman Michael E. , Stevenson Brian
Published: October 2008

This appendix provides general techniques, equipment, and media used for the growth of many commonly encountered bacteria. For specific growth conditions, readers should refer to units regarding the laboratory maintenance of the organism of interest.
Centrifugation
Authors: Gallagher Sean R.
Published: October 2008

Centrifugation is a ubiquitous technique in the life science laboratory, and uses specialized equipment (centrifuges) to spin or centrifuge samples in rotors, generating centrifugal force for a range of applications that include pelleting of precipitates, isolating organelles, and protein and DNA purification. The unit describes basic applications, definitions, and references, and provides up to date tables for rotor specifications from major suppliers.
Purification and Concentration of Nucleic Acids
Authors: H. Dowhan Dennis
Published: October 2008

The purification and concentration of nucleic acids have become routine procedures in most biology and molecular biology laboratories. This unit covers the basic principles and procedures for the isolation, purification, and manipulation of solutions of DNA or RNA. The basic DNA protocol, using phenol extraction and ethanol precipitation, is appropriate for the purification of DNA from small volumes (<0.4 ml) at concentrations ≤1 mg/ml. Purification of DNA using commercially available silica membrane spin columns is presented as an alternate protocol. Isolation and purification of RNA from mammalian cells or tissues is also examined. Use of the protein denaturant guanidine thiocyanate and water‐saturated phenol, followed by concentration by isopropanol precipitation, for producing small samples of RNA is illustrated in the basic RNA protocol.
Overview of Chromatography
Authors: Mallik Buddhadeb , Chakravarti Bulbul , Chakravarti Deb N.
Published: October 2008

Chromatography in its many different forms is an indispensable separation technique for purification or analysis of one or multiple components from a mixture that may contain a variety of simple as well as complex molecules. This unit is focused on a specific type of chromatography known as liquid chromatography (LC), with particular reference to separation of proteins. Theory of chromatography is discussed in the context of partition of the components of a mixture between a solid stationary phase and a liquid mobile phase. Although very useful for chromatographic separation of small molecules, there is, however, considerable deviation observed in the case of separation of proteins. Principles of three commonly used chromatographic techniques for separation of proteins, such as size exclusion, ion exchange, and affinity chromatography are discussed. The unit is expected to be useful for biologists and biochemists, as well as engineers.
Column Chromatography
Authors: Chakravarti Bulbul , Mallik Buddhadeb , Chakravarti Deb N.
Published: October 2008

Chromatography is a widely used technique of separation which depends on the differential interaction of molecules between a stationary phase and a mobile phase. In most modern life science laboratories, purification of proteins plays an important role. Almost all types of laboratory‐based liquid chromatography techniques used for purification of proteins are carried out using the stationary phase contained in tubular columns. Although individual methods for sample loading or elution of these columns are usually different depending on the specific technique used, this general experimental procedure that uses tubular columns is known as column chromatography. This unit is focused on setting up laboratory‐based column chromatography methods for separation of proteins using three commonly used chromatographic techniques for separation of proteins, such as size exclusion, ion exchange, and affinity chromatography.
Overview of Electrophoresis
Authors: R. Gallagher Sean
Published: October 2008

This unit is an overview of the following units on protein and nucleic acid electrophoresis separation techniques.
Agarose Gel Electrophoresis
Authors: Armstrong Jennifer A. , Schulz Joseph R.
Published: October 2008

Agarose gel electrophoresis, which separates and sizes linear DNA and RNA fragments, is arguably the most basic and essential technique in molecular biology. It is commonly employed for analysis of PCR products, plasmid DNA, and products of restriction enzyme digestion. It is the first step for analysis of specific DNA and RNA fragments by northern and Southern blots. In this unit, we provide both written instructions and photographic images to take the reader from preparing a first agarose gel to analyzing results and determining the size of sample DNA. We include two protocols: agarose gel electrophoresis (commonly used to analyze DNA), and denaturing gel electrophoresis (for analyzing RNA). We have divided each protocol into four basic steps: (1) preparing and pouring the agarose gel; (2) preparing and loading samples; (3) running the agarose gel; and (4) staining the gel using the fluorescent stain ethidium bromide to visualize DNA and RNA.
SDS‐Polyacrylamide Gel Electrophoresis (SDS‐PAGE)
Authors: Gallagher Sean R.
Published: October 2008

Electrophoresis is used to separate complex mixtures of proteins (e.g., from cells, subcellular fractions, column fractions, or immunoprecipitates), investigate subunit compositions, verify homogeneity of protein samples, and purify proteins for use in further applications. In polyacrylamide gel electrophoresis, proteins migrate in response to an electrical field through pores in a polyacrylamide gel matrix; pore size decreases with increasing acrylamide concentration. The combination of pore size and protein charge, size, and shape determines the migration rate of the protein. In this unit, the standard Laemmli method is described for discontinuous gel electrophoresis under denaturing conditions, i.e., in the presence of sodium dodecyl sulfate (SDS). Support protocols cover the casting of gels, calculation of molecular mass using the electrophoretic mobility of a protein, and purification of SDS by recrystallization.
Staining Proteins in Gels
Authors: Gallagher Sean R. , Sasse Joachim
Published: October 2008

This unit describes protocols for detecting proteins in SDS‐polyacrylamide gels. It describes methods for Coomassie blue and silver staining, as well as the fluorescent stains SYPRO orange and red. Staining with Coomassie blue is easier and more rapid; however, silver staining methods are considerably more sensitive and can thus be used to detect smaller amounts of protein. Alternative rapid staining procedures are provided for each method. Fluorescent staining is a popular alternative to the traditional staining procedures, mainly because it is more sensitive than Coomassie staining, and often as sensitive as silver staining.
Overview of Blotting
Authors: Negritto Maria Cristina , Manthey Glenn M.
Published: October 2008

Blotting techniques are among the most common approaches used in a molecular biology laboratory. These techniques, Southern, northern, and immunoblotting, are applicable to a variety of macromolecules including DNA, RNA, and protein, respectively. Each of the techniques are dependent on the ability to resolve the individual macromolecules in a size‐dependant manner, transfer the molecules to a solid support, and finally use a defined probe to detect the specific molecule of interest. The utilization of the blotting technology over the last 30 years has been instrumental to the elucidation of many fundamental biological processes. The continued use of blotting technology holds promise for even greater discovery over the next 30 years.
Nucleic Acid Blotting: Southern and Northern
Authors: Mays Hoopes Laura L.
Published: October 2008

E.M. Southern invented blotting of DNA in 1975; the method was extended to RNA in 1977. Standard Southern blotting includes limited depurination, denaturation, and neutralization of the DNA in gels (where they have been separated in size by electrophoresis) and capillary transfer of the DNA onto nitrocellulose or nylon blotting membranes. For northern blotting, RNA is guarded from base and RNase, denatured, separated by electrophoresis, and then blotted to nylon blotting membranes. Both types of blots are then blocked to prevent nonspecific binding, hybridized with probe, and washed. Next the sequences of interest are located by detecting labeled probes. Alternative methods involve dot/slot blotting when the size of the nucleic acid being probed is not of interest. Electrophoretic transfer from polyacrylamide gels can be used when the nucleic acid fragments of interest are too small to be effectively resolved on agarose gels. Artifacts in Southern blot can result from incomplete digestion, overloading the blotting membrane, incomplete blocking, damaged blot media, and air bubbles. In northern blotting, RNA quality must be monitored, and RNA that is degraded or contaminated with excess DNA should be avoided.
Labeling DNA and Preparing Probes
Authors: Haushalter Karl A.
Published: October 2008

Labeling nucleic acids with radioisotopes, fluorophores, biotin, or digoxigenin enables their detection and analysis. When designing a labeling strategy, consider the intended application, the source of nucleic acid, and the type of label to incorporate. DNA oligonucleotides can be 5′ end‐labeled with radioisotopes in a reaction catalyzed by T4 polynucleotide kinase, or nonisotopic labels can be incorporated into oligonucleotides during DNA synthesis. Larger DNA substrates can be labeled by 5′ end labeling (radioisotopes) or labeled uniformly along the length of the DNA by nick translation or random primed synthesis (using radioisotope or nonisotopic labels). The labeled DNA can be used for a variety of applications, including probing Southern blots, probing northern blots, in situ hybridization, quantifying real‐time PCR results, and gel shift assays.
Immunofluorescence Microscopy
Authors: J. Asai David
Published: October 2008

The visualization of fluorescently tagged molecules is a powerful strategy that can contribute to the understanding of the complex dynamics of the cell. A particularly robust and broadly applicable method is immunofluorescence microscopy, in which a specific fluorescently labeled antibody binds the molecule of interest and then the location of the antibody is determined by fluorescence microscopy. The effective application of this technique includes several considerations, including the nature of the antigen, specificity of the antibody, permeabilization and fixation of the specimen, and fluorescence imaging of the cell. Although each protocol will require fine‐tuning depending on the cell type, the antibody, and the antigen, there are steps common to nearly all applications. This unit provides protocols for visualization of the cytoskeleton in two very different kinds of cells: flat, adherent fibroblasts and thick, free‐swimming Tetrahymena cells.
Working with Enzymes
Authors: Skrincosky David , Santangelo Cindy
Published: October 2008

This unit briefly describes the history, theory, and biochemical principles of enzymes. The enzyme classification system, which is based upon the reactions enzymes catalyze, is explained. Several factors affecting enzyme activity including concentration, temperature, pH, and substrate choices are reviewed. While it is difficult to make generalizations since each enzyme is unique, we have compiled useful tips on enzyme storage and commonly encountered forms. This unit also applies the basic general principles of enzymes to a specific class of enzymes, called restriction endonucleases, in order to demonstrate how to correctly set up an enzymatic reaction.
Overview of PCR
Authors: Kuslich Christine D. , Chui Buena , Yamashiro Carl T.
Published: October 2008

As a means of rapidly copying and amplifying a selected template sequence from a pool of DNA in vitro, the polymerase chain reaction (PCR) as a stand‐alone technique and in combinations with other methods has a vast range of applications. This chapter provides an overview of the theory and applications for this powerful and versatile laboratory method. A generic protocol for the broadest application is described in this unit along with the basic theory underpinning PCR to foster an understanding of how to make modifications to the protocol that can be applied to specific applications of the PCR technique. There is a troubleshooting table provided to describe and resolve the most common problems associated with PCR, as well as a table for suppliers and manufacturers of thermal cycling instruments. A detailed discussion of various DNA polymerases and suppliers is also provided.
DNA Sequencing: An Outsourcing Guide
Authors: W. Touchman Jeffrey , D. Mastrian Stephen
Published: October 2008

DNA sequencing, the process of determining the precise order of nucleotides in a DNA strand, is a fundamental and ubiquitous method in molecular biology. Examples of its many uses include characterization of unknown DNA, mutation detection, allele identification, and clone construct confirmation. Advances in sequencing technology, motivated by the successful International Human Genome Project, have resulted in unprecedented access to high‐quality and cost‐effective automated analysis. It is increasingly common for researchers to delegate routine DNA sequencing needs to dedicated laboratories or companies specializing in this technology. In this unit, we discuss key protocols for maximizing the success of DNA sequencing when working with such service providers and describe detailed troubleshooting advice for analyzing anomalous results.
General Laboratory Safety and Working with Hazardous Chemicals
Authors: Lunn George , Strober Warren
Published: October 2008

Persons carrying out the protocols in this manual may encounter the following hazardous or potentially hazardous materials: (1) radioactive substances; (2) toxic chemicals and carcinogenic, mutagenic, or teratogenic reagents; and (3) pathogenic and infectious biological agents. Most governments regulate the use of these materials; it is essential that they be used in strict accordance with local and national regulations. Cautionary notes are included in many instances throughout the manual, and some specific guidelines are also provided in this appendix. However, users must proceed with the prudence and precautions associated with good laboratory practice, under the supervision of personnel responsible for implementing laboratory safety programs at their institutions and in compliance with designated guidelines of federal, state, and local officials.
Laboratory Notebooks and Data Storage
Authors: Williams Michael , Bozyczko‐Coyne Donna , Dorsey Bruce , Larsen Scott
Published: October 2008

The laboratory notebook, whether in hardcopy or electronic (ELN) format, represents a true, chronological record of a scientist's bench work, incorporating the primary source of all materials and information related to the design, execution, and outcomes (data) for a specific experiment. The notebook content thus represents a precise, legible record of what was done, why, and by whom. It also describes the outcome of the experiment and how this is related to the initial hypothesis on which performing the experiment was based. As an archive, a laboratory notebook allows others previously unassociated with the work to understand what was done and, if necessary, independently recreate the experiments. A laboratory notebook and its associated records (e.g., computer printouts or HPLC traces) also represent the vital record of the conception date of an invention and its reduction to practice, providing a timely and necessary legal record to support and defend patent applications.
Practical Considerations When Altering Digital Images
Authors: Sedgewick Jerry
Published: October 2008

Worldwide, Adobe Photoshop is the primary means in research for altering images. Training on the use of this powerful tool most often is peer to peer within a laboratory, or it is self‐taught through trial and error. As a result, varying amounts of visual data can be removed unwittingly; contrast‐ and brightness‐enhancement of images can be done without adjusting color and grayscale levels to conform to the output (which includes publication, projection, web placement, and inclusion into Microsoft Word and Adobe Acrobat); images can be unethically altered; and pixelation can be introduced. Correct methods for use of Adobe Photoshop are outlined in this unit so that these errors can be avoided.
Statistical Analysis
Authors: Kloke John , Hardin Johanna
Published: October 2008

In this Appendix, we provide an outline of methods used in analyzing molecular biology data. We give a summary of types of data encountered and the appropriate methods to apply for the questions of interest. Statistical techniques described include the t test, the Wilcoxon rank sum test, the Mann‐Whitney‐Wilcoxon test, ANOVA, regression, and the chi‐square test. For each method, we give the appropriate assumptions, the details of the test, and a complete concrete example to follow. We also discuss related ideas such as multiple comparisons and why correlation does not imply causation.
Hydrogen storage in several metal‐phosphate molecular sieves
Authors: Dong Jinxiang , Ban Guizhi , Zhao Qiang , Liu Lei , Li Jinping
Published: October 2008

The hydrogen storage properties of metal‐phosphate molecular sieves AlPO4‐5, AlPO4‐53, SAPO‐34, (NH4)ZnPO4‐HEX, and ZrPO‐Py have been investigated at 77 K and 195 K and at pressures of 0–1.7 MPa. The hydrogen storage capacity is up to 1.0 wt % on AlPO4‐5, 1.30 wt % on AlPO4‐53, 1.42 wt % on SAPO‐34, 0.68 wt % on (NH4)ZnPO4‐HEX, and 0.72 wt % on ZrPO‐Py at 77 K and 1.7 MPa. At 195 K and 1.7 MPa, the hydrogen storage capacity is 0.50 wt % on AlPO4‐5, 0.48 wt % on AlPO4‐53, 0.55 wt % on SAPO‐34, 0.50 wt % on (NH4)ZnPO4‐HEX, and 0.54 wt % on ZrPO‐Py. The hydrogen storage capacities of samples increase with decreasing temperature. © 2008 American Institute of Chemical Engineers AIChE J, 54: 3017–3025, 2008
Preparation of a novel alloy composed of fluorene‐based polyester and polycarbonate and their properties for the optical uses
Authors: Kawasaki Shinichi , Yamada Masahiro , Kobori Kana , Sakamoto Hiroki , Kondo Yoshikazu , Jin Fengzhe , Takata Toshikazu
Published: October 2008

This paper is concerned with the structures and properties for fluorene‐based polyester‐polycarbonate (FBP/PC) alloys. Obtained alloys were characterized thermodynamically, optically, and viscoelastically, and the relationship between drawing behavior and molecular dynamics were also investigated. FBP/PC alloys showed transparent and a single glass transition temperature (Tg) for all compositions that indicated the complete compatibility in FBP/PC alloy systems. Tendency of the maximum draw ratios for alloy sheets was very similar to the profile of Tg versus FBP content. Maximum draw ratio was increased linearly with FBP content, demonstrating the intimate relationship between the large deformation and the molecular motion. A large amount of orientational birefringence occurred in PC sheet, but in the case of FBP/PC alloys and FBP, orientational birefringence was drastically decreased or not observed at all. This meant that positive birefringence of PC molecules was compensated by the absolutely smaller birefringence of FBP molecules. From a molecular mobility perspective, relaxation time (T2) for PC was smaller even at 200°C. However, for FBP and its alloys, T2 were much larger, showing the considerably enhanced molecular mobility in FBP or FBP/PC alloys. In this study, we could first reveal that the relationship between Tg and FBP content was very similar to the behaviors of birefringence (Δn)/draw ratio (λ) versus FBP content, T2 versus FBP content and 1/maximum draw ratio (λmax) versus FBP content. Based on these results, we were able to propose a novel alloy with high refractive index, low orientational birefringence, and higher processability by alloying FBP with PC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
New hyperdispersant agent for polypropylene/CaSO4 composites
Authors: Wang Shaohui , Xu Weibing , Zhou Zhengfa , Ren Fengmei
Published: October 2008

A new hyperdispersant agent with SiOH as an anchoring group and poly(butyl acrylate) as a solvatable chain was synthesized, and its effect on the properties of polypropylene (PP)/CaSO4 composites was investigated. Fourier transform infrared spectroscopy results showed that the hyperdispersant agent reacted on the CaSO4 surface and the modified CaSO4 particles. The tensile strength and impact strength of the PP/CaSO4 composites increased about 14 and 34%, respectively, versus that of PP/CaSO4 (filled with the same unmodified fraction). According to surface analysis by scanning electron microscopy, the CaSO4 particles were buried well in the PP matrix when CaSO4 was coated with the hyperdispersant agent. CaSO4 significantly increased the crystallization temperature and crystallization rate of PP by differential scanning calorimetry, but the addition of hyperdispersant‐agent‐modified CaSO4 did not lead to the formation of crystalline PP through X‐ray diffraction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of polymeric curing agent modified with silazanes on the mechanical properties of silicone rubber
Authors: Dai Lina , Zhang Zhijie , Zhao Yunfeng , Liu Hongming , Xie Zemin
Published: October 2008

Polymeric curing agent modified with hexamethyldisilazane (PCA‐D), or with hexamethylcyclotrisilazane (PCA‐T), was used to improve the mechanical properties of hydroxyl‐teminated polydimethylsiloxane (PDMS) rubber. The structure and the gel time of PCA were characterized by 29Si NMR and shear viscosity measurement, respectively. The PCA modified with silazanes was more stable in storage than that without treatment (PCA‐0). Chemical bonds were formed during the reaction of silazanes and PCA according to 29Si NMR results. The crosslink density (γe) and the mechanical properties of PCA/PDMS rubber were determined by swelling equilibrium and stress–strain tests. It was found that PCA treated with both silazanes could better enhance the mechanical properties of PCA/PDMS rubber compared with PCA‐0. PCA‐T/PDMS rubber, with additional crosslinks, was the best among the three types of PCA/PDMS rubber on the mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of novel poly(urethane‐imide) dispersions based on 2,2‐bis[N‐(3‐hydroxyphenyl)phthalimidyl]hexafluoropropane
Authors: Chen Ruei‐Shin , Cheng Ya‐Ling , Chang Kai‐Wen
Published: October 2008

Imide units are incorporated into thermoplastic and solvent‐based polyurethane (PU) chains to improve the thermal stability of PU. However, these poly(urethane‐imide) (PUI) materials have poor processablity and suffer from solvent emission. To prepare easily processable and environmentally friendly PUI products, some waterborne PUIs are synthesized using a prepolymer process. A series of PUI dispersions with 25 wt % solid content, viscosities of 7.5–11.5 cps, and particle sizes of 63–207 nm was prepared. The composition–property relationship of PUIs, including the solubility behavior of PUI cast films, and their thermal and mechanical properties were established. The solvent resistance and tensile strength of PUI film increased with the number of imide groups. All PUIs exhibited improved thermal stability but not char yield as the temperature increased. The inclusion of a little imide increased the decomposition temperature of PUI while maintaining the elasticity of the polymer, revealing successful translation of PUI into the water‐based form. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Optimization of power cable production lines for EPM/EPDM elastomers by genetic algorithm with different peroxides
Authors: Milani G. , Milani F.
Published: October 2008

EPM/EPDM elastomers are widely used for the insulation of high and medium voltage electric cables. Insulator mechanical properties depend on the extent of vulcanization, which is obtained by manufactures using a number of different peroxides as cross‐linking agents. Vulcanization occurs in the continuous vulcanization tube, a pressurized tube filled with nitrogen at high temperatures. Then, water and/or air are used to cool the cable at ambient temperature. Changes of process variables cause considerable changes in insulator physical properties. In the present article, a genetic algorithm with zooming and elitist strategy is used for the determination of optimal production lines parameters to use to maximize rubber output mechanical properties. Nitrogen temperature Ts and exposition time t are assumed as production parameters to optimize, whereas two different output mechanical properties (tensile strength and tear resistance) are considered as objective functions. Several optimization problems are analyzed both for medium and high voltage cables. A final multiobjective optimization is presented with the corresponding Pareto frontier, where objective functions are represented by tear resistance and tensile strength. Optimal production Ts and t are obtained for all the cases analyzed. Numerical simulations show how different peroxides and insulator thicknesses sensibly influence optimal production variables. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A new synthetic approach to asymmetric amphiphilic ABA′ block copolymers by ATRP and click reactions
Authors: He Xiaohua , Liang Liyuan , Wang Kai , Lin Shaoliang , Yan Deyue , Zhang Yiqun
Published: October 2008

Well‐defined asymmetric amphiphilic ABA′ block copolymers composed of poly(ethylene oxide) monomethylene ether (MPEO) with different molecular weights as A or A′ block and poly(styrene) (PS) as B block were synthesized by the combination of atom transfer radical polymerization (ATRP) and click reactions. First, bromine‐terminated diblock copolymer poly(ethylene oxide) monomethylene ether‐block‐poly(styrene) (MPEO‐PS‐Br) was prepared by ATRP of styrene initiated with macroinitiator MPEO‐Br, which was prepared from the esterification of MPEO and 2‐bromoisobutyryl bromide. Then, the azido‐terminated diblock copolymers MPEO‐PS‐N3 were prepared through the bromine substitution reaction with sodium azide. Propargyl‐terminated MPEO with a different molecular weight was prepared under the basic condition from propargyl alcohol and p‐toluenesulfonyl‐terminated MPEO, which was prepared through the esterification of MPEO and p‐toluenesulfochloride using pyridine as solvent. Asymmetric amphiphilic ABA′ block copolymers, with a wide range of number–average molecular weights from 1.92 × 104 to 2.47 × 104 and a narrow polydispersity from 1.03 to 1.05, were synthesized via a click reaction of the azido‐terminated diblock copolymers and the propargyl‐terminated MPEO in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. The structures of these ABA′ block copolymers and corresponding precursors were characterized by NMR, IR, and GPC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Biodegradability and degrading microbes of low‐density polyethylene
Authors: Watanabe Tomoko , Ohtake Yoshito , Asabe Hitoshi , Murakami Nobunao , Furukawa Mutsuhisa
Published: October 2008

We have isolated and identified three types of low‐density polyethylene (LDPE) degrading microbes, for the first time, from soil which was sampled from the field. It has been studied that thermooxidized or UV irradiation LDPE are degraded when incubated with mold (Volke‐sepulveda et al., J Appl Polym Sci 2002, 83, 305; Yamada‐Onodera et al., Polym Degrad Stab 2001, 72, 323); however, there was no article so far reporting the isolation of these particular microbes from the environment. Here, the mechanism of biodegradation of LDPE by the three microbes is described. We used LDPE film, which was buried in soil and biodegraded, and the surrounding soil, located at Nogi Town, Tochigi Prefecture, Japan as the sources of sample for this study. The sample was added to a liquid medium, together with powder of a photodegraded, antioxidant‐free LDPE film, as the sole source of carbon. After enriched cultivation, three strains of microbes were separated from the medium. They were classified on the basis of LDPE degrading capabilities, confirmed by OH generation and degradation traces. Using “Bergey's Manual of Determinative Bacteriology,” the genera of the microbes were identified as Bacillus circulans, Bacillus brevies, and Bacillus sphaericus, which belong among the Natto bacteria, common in soil. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Migration of additives in simulated landfills and soil burial degradation of plasticized PVC
Authors: Lardjane N. , Belhaneche‐Bensemra N.
Published: October 2008

Commercial sunflower oil was epoxidized, and epoxidized sunflower oil (ESO) was used as a thermal stabilizer for polyvinyl chloride (PVC). Semirigid and plasticized formulations stabilized with ESO were realized. Three plasticizers were used: dioctyle phthalate (DOP), diisodecycle phthalate (DIDP), and diisononyle adipate (DINA). Leaching tests simulating real landfill conditions were performed. The two model leachates selected for laboratory leaching tests were solution of acetic acid and distilled water, respectively, corresponding to simulants for domestic waste leachates and rainfall on wastes deposited in bulk. The leaching tests were carried out at 25 and 50°C during 15 days. The variation of the mass of the samples was followed as a function of time. On the other hand, the ageing of the PVC samples was investigated in a landfill soil for 6 months. The modifications of the structure of the polymer were followed by Fourier transform infrared spectroscopy (FTIR). Furthermore, the variation of density and mechanical properties (tensile and shore D hardness) were considered. The results showed that both nature and content of plasticizer influence the migration of the PVC additives used. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Liquefaction of wheat straw and preparation of rigid polyurethane foam from the liquefaction products
Authors: Chen Fangeng , Lu Zhuomin
Published: October 2008

Wheat straw was liquefied in the mixture of polyethylene glycol (PEG 400) and glycerin in the presence of acid at the temperature 130–160°C. The final liquefaction products having the hydroxyl number of 250–430 mg KOH/g and the $ \overline M_n $ of about 1050 can be used as the polyol component to manufacture polyurethane. A kind of polyurethane foam was prepared from liquefied wheat straw, commercial polyol, and diisocyanates in the presence of organotin catalysts and foaming agents. The polyurethane foam presented better compressive strength and thermal stability than that manufactured from diisocyanate and polyol alone. The thermal stability of PU foam was improved with the increase of [NCO]/[OH] ratio and the addition of liquefied wheat straw. The polyurethane foam presented faster biodegradation at ambient temperature than normal polyurethane foam did. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Free radical scavenging activity of cellulase‐treated chitosan
Authors: Feng Tao , Gong Jian , Du Yumin , Huang Zili
Published: October 2008

Partially N‐acetylated chitosan was hydrolyzed by the cheap, commercially available, and efficient cellulase. The products, with different molecular weight, were comparatively investigated by GPC, FT‐IR, XRD, and NMR. The results show that the decrease of molecular weight led to transformation of crystal structure and increase of water‐solubility, but the chemical structures of residues were not modified. Superoxide anion radical and hydroxyl radical quenching assay were used for the evaluation of free radical scavenging activity of cellulase‐treated chitosan in vitro. Low molecular weight chitosan (LMWC3, Mw 1.7 × 103) exhibited high scavenging activity against free radical. It scavenged 79.3% superoxide radical at 0.1 mg mL−1. At 2.0 mg mL−1, scavenging percentage of initial chitiosan, LMWC1 (Mw 27.3 × 103), LMWC2 (Mw 5.9 × 103), and LMWC3 (Mw 1.7 × 103) against hydroxyl radical was 14.3%, 33.1%, 47.4%, and 65.9%, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermooxidative aging of polyoxymethylene, part 2: Embrittlement mechanisms
Authors: Fayolle B. , Verdu J. , Piccoz D. , Dahoun A. , Hiver J. M. , G'sell C.
Published: October 2008

The thermal oxidation at 130°C of polyoxymethylene homopolymer (H) and copolymer (C) samples of close initial molar masses has been studied by gravimetry, rheometry, X ray scattering, and tensile testing. Both samples undergo random chain scission and depolymerization. Their crystallinity ratio increases, whereas their long period decreases. All these changes are faster for H than for C. Tensile tests reveal that there is no significant change of behavior law except for the ultimate strain, which decreases abruptly when the weight average molar mass reaches a value of the order of 70 kg mol−1 for H and 90 kg mol−1 for C. At these molar masses values, the entanglement network of the amorphous phase has undergone only small damagement. In contrast, a chemi‐crystallization process has induced significant morphological changes, especially a decrease of the interlamellar thickness. It is suggested that this latter phenomenon could be responsible for embrittlement. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparative study on water structures in polyHEMA and polyMEA by XRD‐DSC simultaneous measurement
Authors: Kishi Akira , Tanaka Masaru , Mochizuki Akira
Published: October 2008

We have found that poly(2‐methoxyethylacrylate) (polyMEA) has excellent blood compatibility and proposed that the property is due to freezing bound water in the polymer. This water is defined as that which cold‐crystallizes at around −45°C in the heating process of differential scanning calorimetry (DSC). In addition, we have already reported that the water in polyMEA is classified into three types, nonfreezing, freezing bound, and free waters, whereas the water in other polymers is just classified into two types: free and nonfreezing waters. (J Biomed Mater Res 68A, 2004, 684) However, the phenomenon observed by DSC is the enthalpy change and is not a direct evidence for crystallization. To confirm cold‐crystallization, a comparative investigation of the thermal and crystallographical properties of water in hydrated polyMEA and poly(2‐hydroxyethylmethacrylate) (polyHEMA) as a control was carried out using simultaneous measurements by X‐ray diffractometer (XRD) and DSC. In addition, the effect of the water content in the polymers on the properties was studied. As for polyMEA, the finding that XRD crystalline peaks appearing in the heating process were assigned to hexagonal ice indicated cold‐crystallization. On the other hand, in the case of polyHEMA, the crystal due to ice was formed only in the cooling process, and during the heating process, the growth of crystal ice was not observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Understanding the mechanism of β‐sheet folding from a chemical and biological perspective
Authors: Jager Marcus , Deechongkit Songpon , Koepf Edward K. , Nguyen Houbi , Gao Jianmin , Powers Evan T. , Gruebele Martin , Kelly Jeffery W.
Published: October 2008

Perturbing the structure of the Pin1 WW domain, a 34‐residue protein comprised of three β‐strands and two intervening loops has provided significant insight into the structural and energetic basis of β‐sheet folding. We will review our current perspective on how structure acquisition is influenced by the sequence, which determines local conformational propensities and mediates the hydrophobic effect, hydrogen bonding, and analogous intramolecular interactions. We have utilized both traditional site‐directed mutagenesis and backbone mutagenesis approaches to alter the primary structure of this β‐sheet protein. Traditional site‐directed mutagenesis experiments are excellent for altering side‐chain structure, whereas amide‐to‐ester backbone mutagenesis experiments modify backbone‐backbone hydrogen bonding capacity. The transition state structure associated with the folding of the Pin1 WW domain features a partially H‐bonded, near‐native reverse turn secondary structure in loop 1 that has little influence on thermodynamic stability. The thermodynamic stability of the Pin1 WW domain is largely determined by the formation of a small hydrophobic core and by the formation of desolvated backbone‐backbone H‐bonds enveloped by this hydrophobic core. Loop 1 engineering to the consensus five‐residue β‐bulge‐turn found in most WW domains or a four‐residue β‐turn found in most β‐hairpins accelerates folding substantially relative to the six‐residue turn found in the wild type Pin1 WW domain. Furthermore, the more efficient five‐ and four‐residue reverse turns now contribute to the stability of the three‐stranded β‐sheet. These insights have allowed the design of Pin1 WW domains that fold at rates that approach the theoretical speed limit of folding. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 751–758, 2008.

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