bluuebunny/crossref_metadata_2025_split huggingface dataset:
β‐Glucosidase and peroxidase stability in crude enzyme extracts from green beans of Vanilla planifolia Andrews
Authors: Dignum Mark J. W. , Kerler Josef , Verpoorte Rob 
Published: August 2002

AbstractThe extraction method for β‐glucosidase from green vanilla beans has been studied. The effect of storage of green beans and protein extracts on β‐glucosidase and peroxidase activity was investigated: the best method, resulting in the highest enzyme activities, particularly for glucosidase, was through extraction of very fresh green beans in the presence of BisTris propane buffer at pH 8. The best method for storage of the extracts was at −80°C after addition of 15% glycerol, when over 90% of initial activity was still present. Peroxidase activity did not change in frozen beans or in frozen extracts. Copyright © 2001 John Wiley & Sons, Ltd.
Efficient method for determining the glycyrrhizin content of fresh and dried roots, and root extracts, of Glycyrrhiza species
Authors: Lauren Denis R. , Jensen Dwayne J. , Douglas James A. , Follett John M. 
Published: August 2002

AbstractA reliable and efficient method suitable for the selective analysis of the glycyrrhizin content of fresh and dried roots of Glycyrrhiza species and of root extracts is described. The method was optimised for recovery and analysis of glycyrrhizin after conversion to its aglycone, 18β‐glycyrrhetinic acid. The reversed‐phase HPLC system was developed using a sterically protected C8 column that allowed UV detection of the aglycone at 254 mm without interference from co‐occurring components. The average recovery through the method was determined at 83%, with a range of 65–99%. Analysis of 150 dried root samples gave levels of glycyrrhizin consistent with earlier reported values. A comparison of post‐harvest treatment conditions showed that the drying of root samples at up to 65°C did not result in any measurable reduction in glycyrrhizin. Copyright © 2001 John Wiley & Sons, Ltd.
New 3‐deoxyanthocyanidins from leaves of Arrabidaea chica
Authors: Devia Beatriz , Llabres Gabriel , Wouters Jan , Dupont Leon , Escribano‐Bailon Maria Teresa , Pascual‐Teresa Sonia de , Angenot Luc , Tits Monique 
Published: August 2002

AbstractTwo new 3‐deoxyanthocyanidins, 6,7,3′,4′‐tetrahydroxy‐5‐methoxyflavylium and 6,7,4′‐trihydroxy‐5‐methoxyflavylium, and the pigment carajurin, which has been previously identified, were isolated from dried leaves of Arrabidaea chica, a creeper native to the American tropics. The structures of the components were elucidated by 1H‐ and 13C‐NMR spectroscopy and HPLC‐MS, including X‐ray crystallographic analysis for carajurin. Copyright © 2002 John Wiley & Sons, Ltd.
Increased fetal nuchal translucency at 11–14 weeks
Authors: Nicolaides Kypros H. , Heath Victoria , Cicero Simona 
Published: August 2002

AbstractNuchal translucency (NT) is the sonographic appearance of a subcutaneous collection of fluid behind the fetal neck. The measurement of fetal NT thickness at the 11–14‐week scan has been combined with maternal age to provide an effective method of screening for trisomy 21; for an invasive testing rate of 5%, about 75% of trisomic pregnancies can be identified. When maternal serum free‐β human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) at 11–14 weeks are also taken into account, the detection rate of chromosomal defects is about 90%. Increased NT can also identify a high proportion of other chromosomal abnormalities and is associated with major defects of the heart and great arteries, and a wide range of skeletal dysplasias and genetic syndromes. In monochorionic twins, discordancy for increased NT is an early marker of twin‐to‐twin transfusion syndrome (TTTS). As with the introduction of any new technology into routine clinical practice, it is essential that those undertaking the 11–14‐week scan are adequately trained and their results are subjected to rigorous audit. Copyright © 2002 John Wiley & Sons, Ltd.
Cadmium recovery and recycling from chemical bath deposition of CdS thin layers
Authors: Malinowska B. , Rakib M. , Durand G. 
Published: August 2002

AbstractCadmium sulfide thin layers for polycrystalline solar cells are produced by chemical bath deposition (CBD). This process generates wastes containing mainly ammonia and cadmium. We have implemented and described in a previous paper a process to recover 90% of ammonia and to confine cadmium as a cake which is a mixture of cadmium sulfide and cadmium cyanamide. The present paper concerns cadmium recycling to the CBD step. The cake is first dissolved in a moderate sulfuric acid solution 0.2–0.5 mol/l mixed with hydrogen peroxide (about 1 mol/l). This last component must be used in large excess (molar ratio H2O2/Cd ≥ 5) and must be completely removed from the solution before recycling or cadmium electrowinning. Hydrogen peroxide decomposition is electrochemically catalyzed by platinized platinum immersed into the solution. The resulting solution contains cadmium sulfate 0.2 mol/l, sodium and ammonium sulfate. One can either recycle it as a chemical bath, or recover the cadmium content by electrowinning; in this case the residual concentration of hydrogen peroxide is electrochemically reduced at the beginning of cadmium electrolysis. The raffinate solution is recycled into the stripping reactor. The pure cadmium metal recovered may be dissolved in a dilute sulfuric acid solution by means of internal electrolysis with two electrodes: a platinized platinum grid as cathode and the cadmium metal as anode. According to the mass of cadmium dissolved it is possible to obtain a concentrated solution of pure cadmium sulfate. The global process recovers at least 99.999% of cadmium and generates only solid sulfur and a liquid effluent containing traces of cadmium (< 10 μg/l). Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and miscibility studies of [60]fullerenated poly(2‐hydroxyethyl methacrylate)
Authors: Goh H. W. , Goh S. H. , Xu G. Q. 
Published: August 2002

Abstract[60]Fullerenated poly(2‐hydroxyethyl methacrylate)s containing 0.6–3.0 wt % C60 were synthesized. These polymers are soluble in methanol and N,N‐dimethylformamide (DMF). [60]Fullerenated poly(2‐hydroxyethyl methacrylate)s with higher C60 contents are only sparingly soluble in DMF and virtually insoluble in other organic solvents. A loading of 1.2 wt % C60 in poly(2‐hydroxyethyl methacrylate) does not greatly affect its miscibility with poly(N‐vinyl‐2‐pyrrolidone), poly(1‐vinylimidazole), and poly(4‐vinylpyridine). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1157–1166, 2002
Helical chirality of π‐conjugated main‐chain induced by polymerization of phenylacetylene with chiral bulky pinanyl groups: Effects of the flexible spacer and polymerization catalyst
Authors: Shinohara Ken‐ichi , Aoki Toshiki , Kaneko Takashi 
Published: August 2002

AbstractThree optically active phenylacetylene polymers with chiral bulky pinanyl groups, (−)‐poly[4‐(dimethylpinanylsilyl)phenylacetylene] [(−)‐poly(PSPA)], (+)‐poly{4‐[3‐(10‐pinanyl)tetramethyldisiloxy]phenylacethylene} [(+)‐poly(PDSPA)], and their copolymer [(−)‐copoly(PSPA/PDSPA)], were synthesized. We observed high chirality in the main‐chain chromophore of (−)‐poly(PSPA), due to the presence of a chiral helix, with circular dichroism spectroscopy. In contrast, (+)‐poly(PDSPA),with flexible SiOSi spacers between the chiral pinanyl group and the main chain, had lower chirality. (−)‐Poly(PSPA), with large circular dichroism signals, was prepared by polymerization with a rhodium catalyst and had a highly stereoregular main chain (high cis‐configuration percentage). However, (−)‐poly(PSPA) prepared with a tungsten catalyst had lower chirality and lower stereoregularity in the main chain. A membrane from (−)‐poly(PSPA) showed enantioselective permeability for tryptophan in an aqueous solution. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1689–1697, 2002
Controlled radical polymerization of 2‐hydroxyethyl methacrylate with a hydrophilic ruthenium complex and the synthesis of amphiphilic random and block copolymers with methyl methacrylate
Authors: Fuji Yusuke , Watanabe Kazuya , Baek Kyung‐Youl , Ando Tsuyoshi , Kamigaito Masami , Sawamoto Mitsuo 
Published: August 2002

AbstractA hydrophilic ruthenium complex with ionic phosphine ligands {1: RuCl2[P(3‐C6H4SO3Na)(C6H5)2]2} induced controlled radical polymerization of 2‐hydroxyethyl methacrylate (HEMA) in methanol under homogeneous conditions; the initiator was a chloride (R‐Cl) such as CHCl2COPh. The number‐average molecular weights of poly(HEMA) increased in direct proportion to monomer conversion, and the molecular weight distributions were relatively narrow (Mw/Mn = 1.4–1.7). A similar living radical polymerization was possible with (MMA)2‐Cl [(CH3)2C(CO2CH3)CH2C(CH3)(CO2CH3)Cl] as an initiator coupled with amine additives such as n‐Bu3N. In a similar homogeneous system in methanol, methyl methacrylate (MMA) could also be polymerized in living fashion with the R‐Cl/1 initiating system. Especially for such hydrophobic polymers, the water‐soluble ruthenium catalyst was readily removed from the polymers by simple washing with an aqueous dilute acid. This system can be applied to the direct synthesis of amphiphilic random and block copolymers of HEMA and MMA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2055–2065, 2002
Hollow‐particle latexes: Preparation and properties
Authors: Pavlyuchenko V. N. , Sorochinskaya O. V. , Ivanchev S. S. , Klubin V. V. , Kreichman G. S. , Budtov V. P. , Skrifvars M. , Halme E. , Koskinen J. 
Published: August 2002

AbstractHollow‐particle latexes were prepared according to the following stages: (1) the preparation of the methyl methacrylate–methacrylic acid (MAA)–ethylene glycol dimethacrylate copolymer (I) latex, (2) the preparation of a shell (II) based on polystyrene or styrene–acrylonitrile–divinyl benzene copolymer polymerized onto copolymer (I) particles, and (3) the neutralization of the core (I) carboxyl groups with a base (NH4OH or NaOH) at temperatures close to the glass‐transition temperature of the polymer (II). The neutralization resulted in the expansion of the particles and formed water‐filled hollow particles. The microspheres had an overall diameter of 460–650 nm and a hollow diameter of 300–450 nm. Rheological studies and particle size measurements by transmission electron microscopy and dynamic light scattering of the copolymer (I) latex indicate that the maximum particle swelling occurred at an approximately equimolar MAA/base ratio. It was found that even without the neutralization of the MAA units, a small hollow formation in the latex particles occurred during stage 2 because one volume of the copolymer (I) retained about 8 volume parts of water. It was also discovered that the final hollow‐particle geometry after neutralization depends on the shell copolymer thickness and type as well as on the conditions during stage 3, that is, the time, temperature, base type, and concentration. The opacifying ability of the synthesized hollow particles was investigated in latex coatings. The opacifying ability values were generally in agreement with the hollow‐particle geometry. The only exception was related to the copolymer (I)/copolymer (II) ratio. The maximum hollow volume was obtained at this value equal to 1/8, whereas the highest opacifying ability was observed at 1/10. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1435–1449, 2001
Regioselective and stereoselective alternating copolymerization of carbon monoxide with functional olefins
Authors: Yuan Jian Chao , Chen Min Dong , Zhang Yu Hua , Lu Shi Jie 
Published: August 2002

AbstractEnantioselective, alternating copolymerizations of carbon monoxide with ω‐undecylenic acid, ethyl acrylate, and butyl acrylate were carried out for the first time with a palladium catalyst modified by 1,4:3,6‐dianhydro‐2,5‐dideoxy‐2,5‐bis(diphenylphosphino)‐L‐iditol. Optical rotation, elemental analysis, and 1H NMR,13C NMR, and IR spectra showed that the copolymers were optically active, isotactic, alternating poly(1,4‐ketone) or poly(spiroketal) structures. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2027–2036, 2001
Synthesis of high molar mass poly(alkylene phosphate)s by polyaddition of diepoxides to difunctional phosphoric acids: Unusual elimination of the side reactions
Authors: Biedron T. , Kaluzynski K. , Pretula J. , Kubisa P. , Penczek S. , Loontjens T. 
Published: August 2002

AbstractThe reaction between diepoxides and difunctional acids of phosphorus was studied as a potential route to linear polyesters of phosphoric acid. The reaction between diepoxide and POH groups in H3PO4 and related acids leads to linear phosphates, but cyclic phosphates are also formed as side products. The formation of such unreactive groups terminates polyaddition. However, cyclization is practically eliminated when the epoxide ring is fused to another ring, such as in cyclohexene oxide. A commercially available diepoxide containing two cyclohexene oxide moieties, 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexanecarboxylate (ERL), was, therefore, used for polyaddition studies. Indeed, in the polyaddition of ERL with ethylphosphoric acid, high molecular weight (number‐average molecular weight up to 104) linear polyphosphates were obtained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3024–3033, 2001
Early cure behavior of a liquid dicyanate ester resin
Authors: Lin King‐Fu , Shyu Jing‐Yau 
Published: August 2002

AbstractThe early cure behavior of 4,4‐dicyanato 1,1‐diphenolethane resin with and without incorporating Cr(acac)3, Co(acac)3, and Cu(acac)2, respectively, as catalysts was investigated by gel permeation chromatography. The curing intermediates were separated by the column elution method and characterized by Fourier transform infrared, 1H, and 3C NMR spectroscopies. The results indicated that the formed dimer in the early cure stage is a straight chain containing a primary amino group. The formed triazine ring in the trimer has a strong catalytic effect on the remaining cyanate groups so that the reactivity of the trimers was significantly increased. The reactivities of the curing intermediates decreased with molecular size until 7‐mer was reached. The initial monomer consumption is described by second‐order‐rate kinetics. In the presence of metal acetylacetonates, the curing reactions may be accelerated, but they did not change the reaction path and preceding sequence of reactivities. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3085–3092, 2001
Morphology of micron‐sized, monomer‐adsorbed, crosslinked polymer particles having snowmanlike shapes prepared by the dynamic swelling method
Authors: Okubo Masayoshi , Wang Zhaoqun , Yamashita Tsuyoshi , Ise Eriko , Minami Hideto 
Published: August 2002

AbstractA series of monomer‐adsorbed, crosslinked polystyrene/polydivinylbenzene composite particles having snowmanlike shapes were prepared by the dynamic swelling method that the authors had proposed in 1991. The morphology of the snowman‐shaped particles was estimated with the contact angle of the monomer phase on the polymer particle. Influences of the kind of monomers and polyvinyl alcohol colloidal stabilizer on the morphology were obviously observed and discussed from the viewpoint of thermodynamic stability. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3106–3111, 2001
Hydrogen‐bonding interaction and miscibility between poly(ε‐caprolactone) and enzymatically polymerized novel polyphenols
Authors: He Yong , Li Jianchun , Uyama Hiroshi , Kobayashi Shiro , Inoue Yoshio 
Published: August 2002

AbstractThe intermolecular hydrogen‐bonding interaction and miscibility between enzymatically prepared novel polyphenols [poly(bisphenol A) and poly(p‐tert‐butyl phenol)] and poly(ε‐caprolactone) (PCL) were investigated as a function of composition by Fourier transform infrared spectroscopy (FTIR) and DSC. The blend films of PCL and polyphenols were prepared by casting polymer solution. The FTIR spectra clearly indicated that PCL and polyphenols interact through strong intermolecular hydrogen bonds formed between the PCL carbonyls and the polyphenol hydroxyl groups. The melting point and degree of crystallinity of the PCL component decreased with an increased polyphenol content. A single glass‐transition temperature was observed for the blend, and its value increased with the content of polyphenol, indicating that PCL and polyphenols are miscible in the amorphous state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2898–2905, 2001
Crystallization kinetics and melting behavior of metallocene short‐chain branched polyethylene fractions
Authors: Chiu Fang‐Chyou , Fu Qiang , Peng Ya , Shih Hsi‐Hsin 
Published: August 2002

AbstractMetallocene polyethylene (mPE) fractions are recognized as being more homogeneous with respect to short‐chain branch (SCB) distribution as compared with unfractionated mPEs. Differential scanning calorimetry and polarized optical microscopy (POM) were used to study the influences of SCB content on the crystallization kinetics, melting behavior, and crystal morphology of four butyl‐branched mPE fractions. The parent mPE of the studied fractions was also investigated for comparative purposes. mPE fractions showed a much simpler crystallization behavior as compared with their parent mPE during the cooling experiments. The Ozawa equation was successfully used to analyze the nonisothermal crystallization kinetics of the fractions. The Ozawa exponent n decreased from about 3.5 to 2 as the temperature declined for each fraction, indicating the crystal‐growth geometry changed from three‐dimensional to two‐dimensional. For isothermal crystallization, the fraction with a lesser SCB content exhibited a higher crystallization temperature (Tc) window. The results from the Avrami equation analysis showed the exponent n values were around 3 (with minor variation), which implied that the crystal‐growth geometry is pseudo‐three‐dimensional. Both of the activation energies for nonisothermal and isothermal crystallization were determined for each fraction with Kissinger and Arrhenius‐type equations, respectively. Double melting peaks were observed for both nonisothermally or isothermally crystallized specimens. The high‐melting peak was confirmed induced via the annealing effect during heating scans. The Hoffman–Weeks plot was inapplicable in obtaining the equilibrium melting temperature (Tm°) for each fraction. The relationship between Tc and Tm for the fractions is approximately Tm = Tc (°C) + 8.3. The POM results indicated that the crystals of parent or fractions formed under cooling conditions did not exhibit the typical spherulitic morphology as a result of the high SCB content. © 2002 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 325–337, 2002
Exchange equilibria on nonconventional pyridine strong base anion exchangers by surface‐complexation theory
Authors: Neagu Violeta , Luca Cornelia 
Published: August 2002

AbstractThe surface‐complexation theory was applied for the description of ion‐exchange equilibria on nonconventional strong base anion exchangers with pyridine structures. Binary equilibria are described by a logarithm equilibrium parameter that is a linear function of the composition of the resin phase for chloride/nitrate, chloride/bicarbonate, and chloride/sulfate ion exchanges. Evaluation of date demonstrates that there are similar predictions from ion‐exchange isotherms and the surface‐complexation theory for the studied ion exchanges. We assume that ion‐exchange equilibrium, regardless of its approach model, depends on the relationship between the chemical structure of the functional sites of the ion exchanger and the counterions that partake to the ion‐exchange process. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 488–494, 2002; DOI 10.1002/polb.10097
Friction and damage in the scratching of poly(n‐butyl acrylate) films
Authors: Zhang S. L. , Tsou A. H. , Li J. C. M. 
Published: August 2002

AbstractScratch testing was performed on poly(n‐butyl acrylate) (PnBA) films with a sapphire indenter with a spherical tip (76 μm in radius). For uncrosslinked PnBA film, the surface of which is sticky, the horizontal or scratching force decreases with decreasing normal load and has a residual value (∼ 6 mN) as the normal load approaches zero. The relation between the scratching force and normal load can be understood by finite element computation based on the Johnson–Kendall–Roberts theory under the assumption that the scratching force is proportional to the contact area, which depends on the normal load. With increasing driving speed, the scratching force shows a power relation with speed indicating a rate process. For crosslinked PnBA film, which behaves as an elastomer, the horizontal force approaches zero at zero normal load. Below a critical normal load, which depends on the thickness of the film, the crosslinked film recovers elastically after being scratched. Above the critical load, the film is damaged and, depending on its thickness, shows two distinct damage mechanisms. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 585–592, 2002; DOI 10.1002/polb.10117
Modeling of tensile moduli in polystyrene/ polybutadiene blends
Authors: Joseph Susan , Thomas Sabu 
Published: August 2002

AbstractThe tensile moduli of polystyrene/polybutadiene blends were studied with reference to the effect of the blend ratio. A comparison between the experimental results and the theoretical predictions of the tensile properties was also made. The models selected were the parallel, series, Halpin–Tsai, Takayanagi, Kerner, and Kunori models. Various theoretical models were applied to predict the location of the phase inversion region in these blends. Different equations were also applied for the prediction of the tensile modulus of cocontinuous structures for comparison. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 755–764, 2002
Solid‐state NMR analyses of the crystalline–noncrystalline structure and its thermal changes for ethylene ionomers
Authors: Kuwabara Kazuhiro , Horii Fumitaka 
Published: August 2002

AbstractThe crystalline–noncrystalline structure and its structural changes from thermal treatments for ethylene ionomers have been investigated with solid‐state 13C and 23Na NMR spectroscopy. 13C spin–lattice relaxation time (T1C) measurements reveal that as‐received ethylene ionomers have much enhanced molecular mobility in the crystalline region in comparison with conventional polyethylene samples. By appropriate annealing, however, polyethylene‐like morphological features reflecting T1C behavior can also be observed. 13C spin–spin relaxation time (T2C) measurements for the noncrystalline region reveal the existence of two components with different T2C values, and these two components have been assigned to the crystalline–amorphous interfacial and rubbery–amorphous components. These results indicate that the structure of the major part of the noncrystalline region in the ethylene ionomers is similar to that of bulk‐crystallized polyethylene samples, regardless of possible ionic aggregates. The origin of the lower temperature endothermic peak in the heating process of the differential scanning calorimetry curve observed for the as‐received sample has also been examined somewhat in detail. As a result, it is proposed that the melting of smaller crystallites produced during storage at room temperature is the origin of the lower temperature peak. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1142–1153, 2002