bluuebunny/crossref_metadata_2025_split huggingface dataset:
Working with Enzymes
Authors: Skrincosky David , Santangelo Cindy 
Published: October 2008

AbstractThis 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

AbstractAs 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

AbstractDNA 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

AbstractPersons 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

AbstractThe 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

AbstractWorldwide, 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

AbstractIn 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractPolymeric 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

AbstractImide 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

AbstractEPM/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

AbstractWell‐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

AbstractWe 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

AbstractCommercial 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

AbstractWheat 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

AbstractPartially 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

AbstractThe 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