bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein Detection in Gels Without Fixation
Authors: Joo Won‐A , Speicher David W.
Published: April 2007

A number of alternative methods are described for detecting proteins in polyacrylamide gels that do not require fixation of the protein either prior to staining or in conjunction with staining. The primary advantage of avoiding fixation is that this makes it easier to remove proteins of interest from the gels for subsequent analysis. In general, the sensitivity of protein detection methods that avoid fixation is lower than for detection methods using fixation. For any given method, sensitivity is dependent on the volume of the protein band within the gel; hence, sensitivity is highest for sharp, narrow bands. Techniques described in this unit include protocols for protein detection in gels by SDS precipitation, preparation of contact blots, staining with imidazole‐zinc, and use of the fluorescent labels IAEDANS and fluorescamine. Several additional methods, including the use of tryptophan fluorescence, guide strips, and minimal protein staining, are discussed in the Commentary.
Identification of Newly Transcribed RNA
Authors: Greenberg Michael E. , Bender Timothy P.
Published: April 2007

Newly transcribed RNA can be identified using the nuclear runoff transcription assay. In this assay, isolated nuclei, free of membranes and cytoplasmic debris, are used in an in vitro transcription reaction in the presence of 32P‐labeled UTP. The labeled RNA can then be hybridized to cDNAs immobilized on nitrocellulose. This unit describes three methods for isolating suitable nuclei by detergent lysis, Dounce homogenization, and centrifugation on a sucrose gradient. Two Support Protocols describe the preparation of nitrocellulose filter strips containing double‐stranded and single‐stranded DNAs, which are used to detect the presence of specific transcripts in the nuclear runoff transcription assay.
Large‐Scale BAC Clone Restriction Digest Fingerprinting
Authors: Mathewson Carrie A. , Schein Jacqueline E. , Marra Marco A.
Published: April 2007

Restriction digest fingerprinting is a common method for characterizing large insert genomic clones, e.g., bacterial artificial chromosome (BAC), P1 artificial chromosome (PAC) and Fosmid clones. This clone fingerprinting method has been widely applied in the construction of clone‐based physical maps, which have been used as positional cloning resources as well as to support directed and genome‐wide sequencing efforts. This unit describes a robust, large‐scale procedure for generation of agarose gel–based clone fingerprints from BAC clones.
Serial Analysis of Gene Expression (SAGE): Experimental Method and Data Analysis
Authors: Blackshaw Seth , Croix Brad St. , Polyak Kornelia , Kim Jae Bum , Cai Li
Published: April 2007

This unit provides a protocol for performing serial analysis of gene expression (SAGE). SAGE involves the generation of short fragments of DNA, or tags, from a defined point in the sequence of all cDNAs in the sample analyzed. This short tag, because of its presence in a defined point in the sequence, is typically sufficient to uniquely identify every transcript in the sample. SAGE allows one to generate a comprehensive profile of gene expression in any sample desired from as little as 100,000 cells or 1 µg of total RNA. SAGE generates absolute, rather than relative, measurements of RNA abundance levels, and this fact allows an investigator to readily and reliably compare data to those produced by other laboratories, making the SAGE data set increasingly useful as more data is generated and shared. Software tools have also been specifically adapted for SAGE tags to allow cluster analysis of both public and user‐generated data.
Production of Recombinant Adeno‐Associated Viral Vectors
Authors: Choi Vivian W. , Asokan Aravind , Haberman Rebecca A. , Samulski Richard Jude
Published: April 2007

Adeno‐associated virus is a nonpathogenic human virus that has been developed into a gene‐delivery vector due to its high efficiency of infection for many different cell types and its ability to persist and lead to long‐term gene expression. This unit describes efficient methods to generate high‐titer, research‐grade, adenovirus‐free recombinant single‐stranded and self‐complementary adeno‐associated virus in various serotypes, along with methods to quantify the viral vectors.
Quantitation of DNA and RNA with Absorption and Fluorescence Spectroscopy
Authors: Gallagher Sean R. , Desjardins Philippe R.
Published: April 2007

Quantitation of nucleic acids is a fundamental tool in molecular biology that requires accuracy, reliability, and the use of increasingly smaller sample volumes. This unit describes the traditional absorbance measurement at 260 nm and three more sensitive fluorescence techniques, as well as three microvolume methods that use fiber optic technology in specialized cells or instrumentation. These procedures allow quantitation of DNA solutions ranging from 1 pg/µl to 50 mg/ml.
Reactor diameter impact on hot zone dynamics in an adiabatic packed bed reactor
Authors: Sundarram Sandhya , Viswanathan Ganesh A. , Luss Dan
Published: April 2007

Recent analysis revealed that a pseudohomogeneous model of a uniformly active, adiabatic packed bed reactor can predict formation of stable hot zones in the cross‐section of the reactor if the kinetic rate expression can lead to isothermal rate oscillations. This prediction was confirmed by simulations of CO oxidation. We show that hot zone formation in a shallow reactor can be predicted also for C2H4 hydrogenation, the kinetic model of which is structurally different from that of CO oxidation. Qualitatively different spatiotemporal temperature patterns may form under the same operating conditions. Their number increases as the reactor diameter is increased. An increase in the reactor diameter increases the time constant of the transversal heat dispersion and decreases the temperature synchronization among points on the same reactor cross‐section. The interaction and conjugation among qualitatively different moving temperature patterns can lead to formation of complex motions. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Preparation and properties of deep dye fibers from poly(ethylene terephthalate)/SiO2 nanocomposites by in situ polymerization
Authors: Yang Yongzhe , Gu Hongchen
Published: April 2007

In this study, poly(ethylene terephthalate) (PET)/SiO2 nanocomposites were synthesized by in situ polymerization and melt‐spun to fibers. The superfine structure and properties of PET/SiO2 fibers were studied in detail by means of TEM, DSC, SEM, and a universal tensile machine. According to the TEM, SiO2 nanoparticles were well dispersed in the PET matrix at a size level of 10–20 nm. The DSC results indicated that the SiO2 nanoparticles might act as a marked nucleating agent promoting the crystallization of the PET matrix from melt but which inhibited the crystallization from the glassy state, owing to the “crosslink” interaction between the PET and SiO2 nanoparticles. The tensile strength of 5.73 MPa was obtained for the fiber from PET/0.1 wt % SiO2, which was 17% higher than that of the pure PET. The fibers were treated with aqueous NaOH. SEM photographs showed that more and deeper pits were introduced onto PET fibers, which provided shortcuts for disperse dye and diffused the reflection to a great extent. According to the K/S values, the color strength of the dyeing increased with increasing SiO2 content. It is found that the deep dyeability of PET fibers was improved greatly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Differential microemulsion polymerization of styrene: A mathematical kinetic model
Authors: He Guangwei , Pan Qinmin , Rempel Garry L.
Published: April 2007

A mathematical model has been developed for the differential microemulsion polymerization of styrene. In the model, both homogeneous and heterogeneous nucleation mechanisms are considered. It is confirmed that the predictions of the particle size and the fractional conversion by the model are in good agreement with the experimental data. It is indicated that the particle size of polystyrene decreases with an increase in the amount of the initiator or surfactant. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Role of fluorocarbon surfactant in the preparation of polytetrafluoroethylene‐modified polyacrylate emulsion
Authors: Cui Xuejun , Chen Zhengxia , Li Qiushun , Zhong Shuangling , Wang Yinghua , Wang Hongyan
Published: April 2007

Role of fluorocarbon surfactant in the preparation of polytetrafluoroethylene‐modified polyacrylate emulsion is investigated. The fluorocarbon surfactant has an efficient preemulsification to polytetrafluoroethylene (PTFE) powder. It enables PTFE powder to be introduced into the copolymer of n‐butyl acrylate, n‐methyl methacrylate, n‐styrene, and α‐methacrylic acid. Thereby, stable PTFE‐modified polyacrylate emulsion can be formed. The effects of fluorocarbon surfactant on the surface tension, particle size and particle size distribution of the emulsion, as well as the relation between fluorocarbon surfactant and the amount of PTFE powder are fully investigated. The particle size and the surface tension of emulsion strongly depend on the fluorocarbon surfactant concentration in the reaction system. The particle size distribution becomes narrower and the stability of the emulsion is improved with the increasing of the fluorocarbon surfactant concentration. According to the experiments, a possible mechanism of fluorocarbon surfactant in polymerization is proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis and characterization of novel functional inorganic–organic hybrid material with macromolecule–metal complex by atom transfer radical polymerization
Authors: Xu Yaxin , Li Hongtu , Wang Di , Li Yapeng , Song Yantao , Ai Peng , Wang Jingyuan
Published: April 2007

The hydrophilic homopolymer brushes of poly(acrylamide) (PAAM) and poly(2‐hydroxyethyl methacrylate) (PHEMA) were prepared by means of atom transfer radical polymerization (ATRP) on the modified silicon gel by the initiator that was prepared by vapor method. The block copolymer brushes consisting of PAAM and PHEMA blocks were obtained by using the homopolymer brush as the macroinitiator for the second ATRP polymerization of another monomer. The structures of the homopolymer brushes and the block copolymer brushes were characterized by IR and X‐ray photoelectron spectroscopy (XPS). XPS revealed that the first polymer layer of the surface was partly covered with the second polymer layer after being block‐copolymerized with the second monomer. SEM showed that the silicon gel particles with polymer brushes were made up of the silicon gel particles as the core and the polymer as the shell. Under appropriate conditions, the copper or cadmium ion was introduced into the silicon gel with the homopolymer brushes and the block copolymer brushes to form the inorganic–organic hybrid material. TGA analysis showed that the inorganic–organic hybrid material is more stable. The results of ESR indicated that the inorganic–organic hybrid material with the polymer metal complex basing on the silicon gel particle possessed well paramagnetism. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis and characterization of methoxypolyethyleneglycol and lauric acid grafted novel polyurethanes for controlled release of nifedipine
Authors: Shelke Namdev B. , Aminabhavi Tejraj M.
Published: April 2007

Novel polyurethanes (PUs) grafted with methoxypolyethyleneglycol (mPEG) and lauric acid (LA) were synthesized by solution polymerization using dibutyl tin dilaurate as a catalyst, taking different molar ratios of LA‐trimethylol propane (LA‐TMP) with respect to mPEG‐trimethylol propane (mPEG‐TMP). The polymers obtained were characterized by Fourier transform infrared spectroscopy and gel permeation chromatography to confirm, respectively, the PU formation and molecular weight. Moderate molecular‐weight PUs were obtained, and nifedipine (NFD)‐loaded microspheres were prepared by solvent evaporation method. The size of the microspheres as measured by laser light scattering technique ranged between 10 and 50 μm. An increase in the size of particles was observed with an increasing molar ratio of mPEG‐TMP with respect to LA‐TMP. The % encapsulation efficiency was found to vary between 65 and 92. The surface morphology of microspheres as studied by scanning electron microscopy revealed the spherical nature of the particles with wrinkles on their surfaces. Crystalline nature of the drug in the microspheres after loading was studied by X‐ray diffraction technique. The release of NFD through the matrix microspheres was investigated in pH‐7.4 phosphate buffer. An increase in release rate was observed with increasing molar ratio of mPEG‐TMP with respect to LA‐TMP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Graft copolymerization of vinyl monomers onto silk fibers initiated by a semiconductor‐based photocatalyst
Authors: Ojah Raju , Dolui Swapan K.
Published: April 2007

Graft copolymerization onto silk (Bombyx mori) was carried out with vinyl monomers (methyl methacrylate and acrylamide) and initiated by a semiconductor‐based photocatalyst (cadmium sulfide). The utility of a semiconductor as an initiator in free‐radical photografting and the effects of ethylene glycol and triethylamine with cadmium sulfide on graft copolymerization were explored. Depending on the reaction conditions, 10–48% grafting with methyl methacrylate and 4–26% grafting with acrylamide were achieved. The reaction conditions were optimized, and the grafted fibers were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetry analysis, and tensile strength measurements. The chemical resistance and water absorption of the grafted fibers were compared with those ungrafted fibers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Preparation and cell compatibility evaluation of chitosan/collagen composite scaffolds using amino acids as crosslinking bridges
Authors: Tsai Sung‐Pei , Hsieh Chien‐Yang , Hsieh Chung‐Yu , Wang Da‐Ming , Huang Lynn Ling‐Huei , Lai Juin‐Yih , Hsieh Hsyue‐Jen
Published: April 2007

In this study, a novel freeze‐gelation method instead of the conventional freeze‐drying method was used to fabricate porous chitosan/collagen‐based composite scaffolds for skin‐related tissue engineering applications. To improve the performance of chitosan/collagen composite scaffolds, we added 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) and amino acids (including alanine, glycine, and glutamic acid) in the fabrication procedure of the composite scaffolds, in which amino acid molecules act as crosslinking bridges to enhance the EDC‐mediated crosslinking. This novel combination enhanced the tensile strength of the scaffolds from 0.70 N/g for uncrosslinked scaffolds to 2.2 N/g for crosslinked ones; the crosslinked scaffolds also exhibited slower degradation rates. The hydrophilicity of the scaffolds was also significantly enhanced by the addition of amino acids to the scaffolds. Cell compatibility was demonstrated by thein vitroculture of human skin fibroblasts on the scaffolds. The fibroblasts attached and proliferated well on the chitosan/collagen composite scaffolds, especially the one with glutamic acid molecules as crosslinking bridges, whereas cells did not grow on the chitosan scaffolds. Our results suggest that the collagen‐modified chitosan scaffolds with glutamic acid molecules as crosslinking bridges are very promising biomaterials for skin‐related tissue engineering applications because of their enhanced tensile strength and improved cell compatibility with skin fibroblasts. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Surface‐modified silica nanoparticles for reinforcement of PMMA
Authors: Hong R. Y. , Fu H. P. , Zhang Y. J. , Liu L. , Wang J. , Li H. Z. , Zheng Y.
Published: April 2007

Polymethyl methacrylate (PMMA) was introduced onto the surface of silica nanoparticles by particle pretreatment using silane coupling agent (γ‐methacryloxypropyl trimethoxy silane, KH570) followed by solution polymerization. The modified silica nanoparticles were characterized by Fourier‐transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Sedimentation tests and lipophilic degree (LD) measurements were also performed to observe the compatibility between the modified silica nanoparticles and organic solvents. Thereafter, the PMMA slices reinforced by silica‐nanoparticle were prepared by in situ bulk polymerization using modified silica nanoparticles accompanied with an initiator. The resultant polymers were characterized by UV–vis, Sclerometer, differential scanning calorimetry (DSC). The mechanical properties of the hybrid materials were measured. The results showed that the glass transition temperature, surface hardness, flexural strength as well as impact strength of the silica‐nanoparticle reinforced PMMA slices were improved. Moreover, the tensile properties of PMMA films doped with silica nanoparticles via solution blending were enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Poly(acrylamide‐allyl glycidyl ether) cryogel as a novel stationary phase in dye‐affinity chromatography
Authors: Demiryas Nazan , Tüzmen Nalan , Galaev Igor Yu , Pişkin Erhan , Denizli Adil
Published: April 2007

Poly(acrylamide‐allyl glycidyl ether) [poly(AAm‐AGE)] cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomers frozen inside a glass column (cryo‐polymerization). After thawing, the monolithic cryogel contains a continuous polymeric matrix having interconnected pores of 10–100 μm size. Cibacron Blue F3GA was immobilized by covalent binding onto poly(AAm‐AGE) cryogel via epoxy groups. Poly(AAm‐AGE) cryogel was characterized by swelling studies, FTIR, scanning electron microscopy, and elemental analysis. The equilibrium swelling degree of the poly(AAm‐AGE) monolithic cryogel was 6.84 g H2O/g cryogel. Poly(AAm‐AGE) cryogel containing 68.9 μmol Cibacron Blue F3GA/g was used in the adsorption/desorption of human serum albumin (HSA) from aqueous solutions and human plasma. The nonspecific adsorption of HSA was very low (0.2 mg/g). The maximum amount of HSA adsorption from aqueous solution in acetate buffer was 27 mg/g at pH 5.0. Higher HSA adsorption value was obtained from human plasma (up to 74.2 mg/g). Desorption of HSA with a purity of 92% from Cibacron Blue F3GA attached poly(AAm‐AGE) cryogel was achieved using 0.1M Tris/HCl buffer containing 0.5M NaCl. It was observed that HSA could be repeatedly adsorbed and desorbed with poly(AAm‐AGE) cryogel without significant loss in the adsorption capacity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Carboxyl‐terminated butadiene acrylonitrile rubber/epoxy polymer alloys as damping adhesives and energy absorbable resins
Authors: Kishi Hajime , Nagao Atsushi , Kobayashi Yusaku , Matsuda Satoshi , Asami Toshihiko , Murakami Atsushi
Published: April 2007

Carboxyl‐terminated butadiene acrylonitrile (CTBN) liquid rubber/epoxy (diglycidyl ether of bisphenol‐A: DGEBA) / diamino diphenyl methane (DDM) resins, in which CTBN was 60 wt % as the major component, were formulated to evaluate the damping and adhesive properties. In cases where acrylonitrile (AN) was 10∼18 mol % as copolymerization ratio in CTBN, the blend resins showed micro‐phase separated morphologies with rubber‐rich continuous phases and epoxy‐rich dispersed phases. The composite loss factors (η) for steel laminates, which consisted of two steel plates with a resin layer in between, depended highly on the environmental temperature and the resonant frequencies. On the other hand, in the case where AN was 26 mol % in CTBN, the cured resin did not show clear micro‐phase separation, which means the components achieve good compatibility in nano‐scale. This polymer alloy had a broad glass‐transition temperature range, which resulted in the high loss factor (η > 0.1) for the steel laminates and excellent energy absorbability as the bulk resin in a broad temperature range. Also the resin indicated high adhesive strengths to aluminum substrates under both shear and peel stress modes. The high adhesive strengths of the CTBN/epoxy polymer alloy originated in the high strength and the high strain energy to failure of the bulk resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Determination of some physical and mechanical properties of laminated veneer lumber impregnated with boron compounds
Authors: Özçifçi Ayhan , örs Yalçın , Uysal Burhanettin
Published: April 2007

The aim of this study was to determine the effects of Tanalith‐C 3310 (T‐C 3310), borax (Bo), boric acid (Ba), borax + boric acid (Bo + Ba), and diammonium phosphate (D) impregnations for some physical and mechanical properties of laminated veneer lumber (LVL). The veneers used for the LVL samples (based on BS EN 204) were cut from Scots pine (Pinus sylvestris L.), oriental beech (Fagus orientalis L.), and poplar (Populus nigra). They were impregnated with full‐cell method according to ASTM‐D 1413 standards and bonded with phenol formaldehyde (PF) and melamine formaldehyde (MF) adhesives. The following parameters have been tested: density, compression strength, bending strength, modulus of elasticity (MOE) in bending, and shear strength tests. Test results obtained from this study showed that impregnation with Boric acid and Tanalith‐C 3310 (based acidic characteristic) affected the strength of LVL negatively, when the wood material is impregnated with acidic impregnations and bonded with PF, which is an alkali, the glue‐line becomes more elastic, the bonding strength of adhesive weakens. Boric acid and Tanalith‐C 3310 impregnations could not be recommended for LVL elements exposed to bending or shear strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Electrodeposition of NiOx/PANI composite film and its catalytic properties towards electrooxidations of polyhydroxyl compounds
Authors: Peng Xu‐Yuan , Li Wei , Liu Xiao‐Xia , Hua Pei‐Jie
Published: April 2007

Electrocodeposition of nickel oxide (NiOx) and polyaniline (PANI) was conducted through cyclic voltammetric scans in an aqueous solution of NiSO4 and aniline. Characterizations of the obtained NiOx/PANI composite film by XRD and FTIR indicated that the film composed of NiOx and PANI, in which nickel oxide was in the form of Ni2O2(OH). Ni(II)/Ni(III) redox couple appeared at 0.30 V versus SCE on the cyclic voltammogram (CV) of the composite film. Electrooxidations of glucose and fructose occurred at the potential where nickel oxide existed in higher oxidation state. The anodic current densities at 0.46 V for the electrooxidations were linearly dependent on the concentration of polyhydroxyl compounds from 1 to 100 mM for glucose and 10 to 100 mM for fructose, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
New solvent for polyrotaxane. III. Dissolution of a poly(ethylene glycol)/cyclodextrin polyrotaxane in a calcium thiocyanate aqueous solution or N‐methylmorpholine‐N‐oxide monohydrate
Authors: Araki Jun , Kataoka Toshiyuki , Ito Kohzo
Published: April 2007

Calcium thiocyanate [Ca(SCN)2] aqueous solutions above 40 wt % and N‐methylmorpholine N‐oxide (NMMO) monohydrate, which are known to dissolve cellulose, were found to be good solvents for a polyrotaxane comprising α‐cyclodextrin and poly(ethylene glycol). The polyrotaxane could be dissolved up to 12 and 10 wt % in a 40 wt % Ca(SCN)2 aqueous solution and NMMO, respectively. These are the first instances of a neutral aqueous solution and a cyclic amine oxide, respectively, that readily dissolve the polyrotaxane. These new good solvents, as well as other solvents of the polyrotaxane, except for dimethyl sulfoxide, are identical to those of cellulose, indicating that the dissolution mechanism of the polyrotaxane is dominated by intra‐ and intermolecular hydrogen bonding of the molecule similar to that of cellulose dissolution. The concentrated polyrotaxane solution in a 40 wt % Ca(SCN)2 aqueous solution showed apparent thixotropy and spontaneous gelation of the solution caused by a gradual increase in its viscosity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Triblock poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid)/paclitaxel conjugates: Synthesis, micellization, and cytotoxicity
Authors: Xie Zhigang , Lu Tiancheng , Chen Xuesi , Lu Changhai , Zheng Yonghui , Jing Xiabin
Published: April 2007

A triblock poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) (PLA–PEG–PLA)/paclitaxel (PTX) conjugate was synthesized by the reaction of carboxyl‐terminated copolymer PLA–PEG–PLA with PTX in the presence of dicyclohexylcarbodiimide and dimethylaminopyridine. Carboxyl‐terminated copolymer PLA–PEG–PLA was prepared by the reaction of the hydroxyl end groups in copolymer PLA–PEG–PLA with succinic anhydride. Its structure was confirmed by NMR and gel permeation chromatography. The PLA–PEG–PLA/PTX conjugates could self‐assemble into micelles in aqueous solutions with a low critical micelle concentration. Dynamic light scattering and environmental scanning electron microscopy analyses of the PLA–PEG–PLA/PTX micelles revealed their spherical structure and size of 220 nm. The antitumor activity of the conjugate against woman Hela cancer cells, evaluated by the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide method, showed that the conjugates had an antitumor activity similar to that of pure PTX. The obtained PLA–PEG–PLA/PTX conjugates are expected to be used in clinical practice. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of minor addition of xanthan on cross‐linking of rice starches by dry heating with phosphate salts
Authors: Chung Hyun‐Jung , Min Deulre , Kim Jong‐Yea , Lim Seung‐Taik
Published: April 2007

Effects of xanthan on the crosslinking of normal and waxy rice starches using a mixture of phosphate salts (sodium trimetaphosphate and sodium tripolyphosphate, 99 : 1, dry solid basis) were investigated. The starch (158.4 g, dry solids) was dispersed in an aqueous solution containing xanthan and phosphate salts (1.6 and 0.6 g in 280 mL water, respectively), and the slurry was dried overnight at 45°C until the moisture content was less than 10%. The dry cake was then ground into powders and heated for 2 h at 130°C in a convection oven. The pasting viscosity, paste clarity, melting and in vitro digestion behaviors of the starches with modifying agents (xanthan and phosphate salts) were investigated. The heat treated starches displayed enhanced shear stability and reduced breakdown, as evidences of crosslinking. Xanthan (1.0% based on starch solids) enhanced the crosslinking effects in the viscosity profile. Waxy rice starch evidenced more profound viscosity changes than did normal rice starch, indicating it was more susceptible to the heat treatment. The waxy rice starch heated with the mixture of phosphate salts and xanthan exhibited a continuous increase in pasting viscosity without any breakdown. Under a DSC analysis, melting enthalpy decreased but melting temperature increased somewhat as results of the heat treatment with xanthan. In an in vitro digestion analysis, the starches treated with xanthan exhibited decreases in the maximum digestion level, and increases in the resistant starch (RS) content. Dry heating, however, increased the digestion rate and glycemic index (GI) regardless of the presence of phosphate salts or xanthan indicating that the starches were thermally degraded. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Characterization of phase morphology of polymer melts (PP/PE blends) via rheology
Authors: Vincze‐Minya Krisztina A. , Schausberger Alois
Published: April 2007

The viscoelastic behavior of high impact polypropylene (PP) melts, a multiphase system with an isotactic PP matrix and inclusions consisting of mainly amorphous ethylene–propylene copolymer (EP), is strongly influenced by the size of small inclusions. The dynamic moduli of such two‐phase systems (reactor products) are well described by Palierne's emulsion model. For this analysis the reactor product is separated into matrix and dispersed phase via the different solubility in xylene. This analysis also provides information on the ratio interfacial tension to particle size of the dispersed phase. With morphology data (particle size) of the solidified heterophasic samples (Transmission Electron Microscopy), we estimate the interfacial tension between PP and EP copolymer via the emulsion model of Palierne and from the relaxation time spectra according to Gramespacher and Meissner. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Effect of natural rubber on wood‐reinforced tannin composites
Authors: Mosiewicki M. A. , Aranguren M. I. , Curvelo A. A. S. , Borrajo J.
Published: April 2007

Natural rubber latex was added to composite materials formulated from a quebracho tannin adhesive crosslinked with hexamethylenetetramine and wood flour as a reinforcing filler. The final microstructure of the thermoset modified by the addition of different concentrations of latex was observed by scanning electron microscopy. The flexural and impact behavior of the modified materials was analyzed and related to the final microstructure of the composites. The effect of exposing the materials to humid environments was also evaluated. The measurements indicated that the addition of latex did not significantly reduce water absorption. However, it facilitated the preparation process of samples with low filler contents because of the increased viscosity of the mixture, which inhibited particle settling. On the other hand, the flexural properties increased with the addition of latex‐containing proteins through a reaction similar to tanning in leathers. The impact properties presented a similar trend, with the largest change occurring between 0 and 5% natural rubber in the matrix formulation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis and characterization of polyamide powders for sorption of reactive dyes from aqueous solutions
Authors: Suteu Daniela , Bilba Doina , Dan Florin
Published: April 2007

Polyamide (PA) fine powders or granules, obtained by anionic solution/suspension polymerization of lactams, were used for the sorption of reactive dye Brilliant Red HE‐3B from aqueous solutions. They provided a relatively large surface area and porosity that allowed an increased sorption rate. The visible molecular absorption spectroscopy was used to evaluate the performance of the investigated systems. Under the same conditions, the sorption capacity of polyamide particles decreases in the following manner: PA6‐powders > PA12‐powders > PA4‐granules. The effect of pH, initial dye concentration, temperature, and sorption duration on dye removal was studied for the PA6‐powder/reactive dye system. The equilibrium sorption isotherms have been analyzed by the linear, Freundlich, and Langmuir models. The data conform to a Langmuir isotherm and a pseudosecond order kinetic model, respectively. In addition, the apparent thermodynamic parameters were calculated and the obtained values support the conclusion that the reactive dye molecules are adsorbed onto PA‐powders by an entropy‐driven, endothermic process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Characterization of acrylic acid‐grafted PP membranes prepared by plasma‐induced graft polymerization
Authors: Choi Eun‐Young , Moon Seung‐Hyeon
Published: April 2007

Acrylic acid (AA)‐g‐polypropylene (PP) membranes were prepared by grafting AA on to a microporous PP membrane via plasma‐induced graft polymerization. The grafting of AA to the PP membrane was investigated using Fourier transform infrared spectroscopy (FTIR). Pore‐filling of the membranes was confirmed by field emission‐scanning electron microscopy (FESEM) and energy dispersing X‐ray (EDX). Ion exchange capacity (IEC), membrane electric resistance, transport number and water content were measured and analyzed as a function of grafting reaction time. The prepared AA‐g‐PP membranes showed moderate electrochemical properties as a cation‐exchange membrane. In particular, membranes with a degree of grafting of 155% showed good electrical properties, with an IEC of 2.77 mmol/g dry membrane, an electric resistance of 0.4 Ω cm2 and a transport number of 0.96. Chronopotentiometric measurements indicated that AA‐g‐PP membranes, with a high IEC had a sufficient conducting region in the membrane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Impact of impregnation with boron compounds on the surface hardness of varnished wood
Authors: Ors Yalçın , Atar Musa , Çolakoğlu Mustafa H.
Published: April 2007

This study was performed to determine the impact of impregnation with boron compounds on the surface hardness of varnished wood materials. For this purpose, test specimens prepared from Oriental beech (Fagus orientalis Lipsky) and oak (Quercus petreae Lipsky), which met the requirements of ASTM D 358, were impregnated according to ASTM D 1413 with boric acid and borax by a vacuum technique. After impregnation, the surfaces were coated by cellulosic, synthetic, polyurethane, waterborne, acrylic, and acid hardening varnishes in accordance with ASTM D 3023. The surface hardness of the specimens after the varnishing process was determined in accordance with ASTM D 4366. According to the wood type, impregnation material, and varnish type, the surface hardness was highest for the oak impregnated with borax and acrylic varnish and lowest for the oak impregnated with borax and synthetic varnish. Therefore, impregnation with boron compounds showed an increasing impact on the surface hardness of the varnished wood. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Amidine Analogues of Melphalan: Synthesis, Cytotoxic Activity, and DNA Binding Properties
Authors: Bielawska Anna , Bielawski Krzysztof , Anchim Tomasz
Published: April 2007

Design, synthesis, and cytotoxic activity of amidine derivatives of melphalan are described and structure‐activity relationships are discussed. Evaluation of the cytotoxicity of these compounds employing a MTT assay and inhibition of [3H]thymidine incorporation into DNA in both MDA‐MB‐231 and MCF‐7 human breast cancer cells demonstrated that these compounds were more active than melphalan. Data from the ethidium displacement assay showed that these compounds were able to bind in the minor groove‐binding mode in AT sequences of DNA. The cytotoxic properties of the amidine analogues of melphalan towards cultured human breast cancer cells correlate with topoisomerase II inhibitory properties but not with DNA‐binding properties.
Synthesis of Pyrazolo[4′,3′:5,6]pyrano[2,3‐d]pyrimidine Derivatives for Antiviral Evaluation
Authors: Shamroukh Ahmed H. , Zaki Magdi E. A. , Morsy Eman M. H. , Abdel‐Motti Faiza M. , Abdel‐Megeid Farouk M. E.
Published: April 2007

6‐Amino‐3‐methyl‐4‐(4‐nitrophenyl)‐2,4‐dihydropyrano[2,3‐c]pyrazole‐5‐carbonitrile (1) was used as a precursor for preparation of some novel 3,7‐dimethyl‐4‐(4‐nitrophenyl)‐2,4‐dihydropyrazolo[4′,3′:5,6]pyrano[2,3‐d]pyrimidine derivatives 3–6, and some of their corresponding N2‐ and C5‐S‐acyclic nucleosides 7 and 8. Furthermore, the preparation of 5‐amino‐1‐[3,7‐dimethyl‐4‐(4‐nitrophenyl)‐2,4‐dihydropyrazolo[4′,3′:5,6]pyrano[2,3‐d]pyrimidin‐5‐yl]‐1H‐pyrazole derivatives 10–16 were described. Some of the prepared products were selected and tested for antiviral activity against Herpes Simplex Virus type‐1 (HSV‐1).
Triazole: the Keystone in Glycosylated Molecular Architectures Constructed by a Click Reaction
Authors: Dondoni Alessandro
Published: April 2007

The copper(I)‐catalyzed modern version of the Huisgen‐type azide–alkyne cycloaddition to give a 1,4‐disubstituted 1,2,3‐triazole unit is introduced as a powerful ligation method for glycoconjugation. Owing to its high chemoselectivity and tolerance of a variety of reaction conditions, this highly atom‐economic and efficient coupling reaction is especially useful for the effective construction of complex glycosylated structures such as clusters, dendrimers, polymers, peptides, and macrocycles. In all cases the triazole ring plays a key role by locking into position the various parts of these molecular architectures. The examples reported and briefly discussed in this short review highlight the use of this reaction in carbohydrate chemistry and pave the way to further developments and applications.
A Comparison of Parametric and Nonparametric Methods for Normalising cDNA Microarray Data
Authors: Khondoker Mizanur R. , Glasbey Chris A. , Worton Bruce J.
Published: April 2007

Normalisation is an essential first step in the analysis of most cDNA microarray data, to correct for effects arising from imperfections in the technology. Loess smoothing is commonly used to correct for trends in log‐ratio data. However, parametric models, such as the additive plus multiplicative variance model, have been preferred for scale normalisation, though the variance structure of microarray data may be of a more complex nature than can be accommodated by a parametric model. We propose a new nonparametric approach that incorporates location and scale normalisation simultaneously using a Generalised Additive Model for Location, Scale and Shape (GAMLSS, Rigby and Stasinopoulos, 2005, Applied Statistics, 54, 507–554). We compare its performance in inferring differential expression with Huber et al.'s (2002, Bioinformatics, 18, 96–104) arsinh variance stabilising transformation (AVST) using real and simulated data. We show GAMLSS to be as powerful as AVST when the parametric model is correct, and more powerful when the model is wrong. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evidence for a Role of the Membrane‐Proximal Region of Herpes Simplex Virus Type 1 Glycoprotein H in Membrane Fusion and Virus Inhibition
Authors: Galdiero Stefania , Falanga Annarita , Vitiello Mariateresa , D'Isanto Marina , Collins Craig , Orrei Veronica , Browne Helena , Pedone Carlo , Galdiero Massimiliano
Published: April 2007

We have identified a putative membrane‐interacting domain preceding the transmembrane domain of the Herpes simplex virus type 1 (HSV‐1) glycoprotein H (gH). Peptides derived from this region interact strongly with membranes and show a high tendency to partition at the interface. This region is predicted to bind at the membrane interface by adopting an α helical structure. Peptides representing either the HSV‐1 gH pretransmembrane region or a scrambled control with a different hydrophobic profile at the point of interface have been studied. The peptides derived from this domain of gH induce the fusion of liposomal membranes, adopt helical conformations in membrane mimetic environments and are able to inhibit HSV‐1 infectivity. The pretransmembrane region appears to be a common feature in viral fusion proteins of several virus families, and such a feature might be related to their fusogenic function. The identification of membrane‐interacting regions capable of modifying the biophysical properties of phospholipid membranes lends weight to the view that such domains might function directly in the fusion process and could facilitate the future development of HSV‐1 entry inhibitors.
Increased Single‐Nucleotide Discrimination in Allele‐Specific Polymerase Chain Reactions through Primer Probes Bearing Nucleobase and 2′‐Deoxyribose Modifications
Authors: Kranaster Ramon , Marx Andreas
Published: April 2007

The diagnosis of genetic dissimilarities between individuals is becoming increasingly important due to the discovery that these variations are related to complex phenotypes like the predisposition to certain diseases or compatibility with drugs. The most common among these sequence variations are single‐nucleotide polymorphisms (SNPs). The availability of reliable and efficient methods for the interrogation of the respective genotypes is the basis for any progress along these lines. Many methods for the detection of nucleotide variations in genes exist, in which amplification of the target gene is required before analysis can take place. The allele‐specific polymerase chain reaction (asPCR) combines target amplification and analysis in a single step. The principle of asPCR is based on the formation of matched or mismatched primer–target complexes. The most important parameter in asPCR is the discrimination of these matched or mismatched pairs. In recent publications we have shown that the reliability of SNP detection through asPCR is increased by employing chemically modified primer probes. In particular, primer probes that bear a polar 4′‐C‐methoxymethylene residue at the 3′ end have superior properties in discriminating single‐nucleotide variations by PCR. Here we describe the synthesis of several primer probes that bear nucleobase modifications in addition to the 4′‐C‐methoxymethylenated 2′‐deoxyriboses. We studied the effects of these alterations on single‐nucleotide discrimination in allele‐specific PCR promoted by a DNA polymerase and completed these results with single‐nucleotide‐incorporation kinetic studies. Moreover, we investigated thermal denaturing of the primer‐probe–template complexes and recorded circular dichroism (CD) spectra for inspecting the thermodynamic and photophysical duplex behaviour of the introduced modifications. In short, we found that primer probes bearing a 4′‐C‐methoxymethylene residue at the 2′‐deoxyribose moiety in combination with a thiolated thymidine moiety have synergistic effects and display significantly increased discrimination properties in asPCR.
Heat‐Induced Alterations in the Surface Population of Metal Sites in Bimetallic Nanoparticles
Authors: Hwang Bing‐Joe , Sarma Loka Subramanyam , Wang Guo‐Rung , Chen Ching‐Hsiang , Liu Din‐Goa , Sheu Hwo‐Shuenn , Lee Jyh‐Fu
Published: April 2007

The ability to alter the surface population of metal sites in bimetallic nanoparticles (NPs) is of great interest in the context of heterogeneous catalysis. Here, we report findings of surface alterations of Pt and Ru metallic sites in bimetallic carbon‐supported (PtRu/C) NPs that were induced by employing a controlled thermal‐treatment strategy. The thermal‐treatment procedure was designed in such a way that the particle size of the initial NPs was not altered and only the surface population of Pt and Ru was changed, thus allowing us to deduce structural information independent of particle‐size effects. X‐ray absorption spectroscopy (XAS) was utilized to deduce the structural parameters that can provide information on atomic distribution and/or extent of alloying as well as the surface population of Pt and Ru in PtRu/C NPs. The PtRu/C catalyst sample was obtained from Johnson Matthey, and first the as‐received catalyst was reduced in 2 % H2 and 98 % Ar gas mixture at 300 °C for 4 h (PtRu/C as‐reduced). Later this sample was subjected to thermal treatment in either oxygen (PtRu/C‐O2‐300) or hydrogen (PtRu/C‐H2‐350). The XAS results reveal that when the as‐reduced PtRu/C catalyst was exposed to the O2 thermal‐treatment strategy, a considerable amount of Ru was moved to the catalyst surface. In contrast, the H2 thermal‐treatment strategy led to a higher population of Pt on the PtRu/C surface. Characterization of the heat‐treated PtRu/C samples by X‐ray diffraction and transmission electron microscopy reveals that there is no significant change in the particle size of thermally treated samples when compared to the as‐received PtRu/C sample. The electrochemical properties of the as‐reduced and heat‐treated PtRu/C catalyst samples were confirmed by cyclic voltammetry, CO‐adsorption stripping voltammetry, and linear sweep voltammetry. Both XAS and electrochemical investigations concluded that the PtRu/C‐H2‐350 sample exhibits significant enhancement in reactivity toward methanol oxidation as a result of the increased surface population of the Pt when compared to the PtRu/C‐O2‐300 and PtRu/C as‐reduced samples.
Antiestrogenic effect of 20S‐protopanaxadiol and its synergy with tamoxifen on breast cancer cells
Authors: Yu Yan , Zhou Qun , Hang Yan , Bu Xuexian , Jia William
Published: April 2007

BACKGROUND.

20S‐protopanaxadiol (aPPD) is a major gastrointestinal metabolic product of ginsenosides. The latter share structural similarity with steroids and are the main pharmacologically active component in ginseng.

METHODS.

The authors investigated the interaction between aPPD and estrogen receptors (ER) in human breast adenocarcinoma MCF‐7 cells through receptor binding assay, ER‐induced gene expression, and cell proliferation both in vitro and in vivo.

RESULTS.

aPPD, but not its close analog ginsenosides, competed with the [3H]‐17‐β estradiol (E2) for ER with IC50 at 26.3 μM. aPPD alone weakly induced luciferase reporter‐gene expression controlled by an estrogen‐regulated element, which was completely blocked by tamoxifen. aPPD alone, or in synergy with tamoxifen, blocked E2‐induced transcriptional activation. aPPD also inhibited colony formation of endometrial cancer cells. aPPD potently inhibited estrogen‐stimulated MCF‐7 cell proliferation and synergistically enhanced the cytotoxicity of tamoxifen on both ER+ MCF‐7 and ER− MDA‐MB231 cells. Furthermore, aPPD, but not tamoxifen, inhibited Akt phosphorylation. Growth of MCF‐7 xenograft tumor supplemented with E2 was completely inhibited in animals treated with aPPD, tamoxifen, or aPPD plus tamoxifen.

CONCLUSIONS.

These results suggested that aPPD inhibits estrogen‐stimulated gene expression and cell proliferation in ER‐positive breast cancer cells. In addition, aPPD synergistically enhances cytotoxicity of tamoxifen in an ER‐independent fashion, probably by down‐regulating Akt activity. Cancer 2007. © 2007 American Cancer Society.
High‐throughput enhancer trap by remobilization of transposonMinosinCiona intestinalis
Authors: Awazu Satoko , Matsuoka Terumi , Inaba Kazuo , Satoh Nori , Sasakura Yasunori
Published: April 2007

The enhancer trap approach utilizing transposons yields us information about gene functions and gene expression patterns. In the ascidianCiona intestinalis, transposon‐based transgenesis and insertional mutagenesis were achieved with a Tc1/marinertransposonMinos. We report development of a novel technique for enhancer trap inC. intestinalis. This technique uses remobilization ofMinosin theCionagenome. AMinosvector for enhancer trap was constructed and a tandem array insertion of the vector was introduced into theCionagenome to create a mutator line.Minoswas remobilized inCionachromosomes to create new insertions by providing transposases. These transposase‐introduced animals were crossed with wild‐type animals. Nearly 80% of F1 families showed novel GFP expression patterns. This high‐throughput enhancer trap screen will be useful to create new marker transgenic lines showing reporter gene expression in specific tissues and to identify novel patterns of gene expression. genesis 45:307–317, 2007. © 2007 Wiley‐Liss, Inc.