bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymerization of maleic anhydride–modified plant oils with polyols
Authors: Eren Tarik , Küsefoğlu Selim H. , Wool Richard 
Published: July 2003

AbstractIn this study soybean oil triglycerides were reacted with maleic anhydride in an ene reaction to introduce more than two maleate residues per triglycerides. The maleinized soybean oil (SOMA) was then polymerized with diols to the half‐ester stage only. Two different types of alcohols was used in this work: (1) short‐chain polyhydroxy linear or cyclic alcohols having 2, 3, 4, or 6 hydroxyl groups; and (2) long‐chain dihydroxy alcohols. The aim was to determine the effect of functionality and chain length by choosing alcohols with increasing number of hydroxyl groups and different chain lengths. The reaction of alcohols with anhydride functionalized soybean oil to give a polymeric half‐ester is a reaction that proceeds without the formation of byproducts and is different from complete polyesterification of maleinized oils, which are well known. To improve the reaction yields, different catalysts and different reaction conditions were examined. The structural analysis of the products was done with 1H‐NMR and IR spectroscopy. All of the new polymers obtained were resilient and soft rubbers at room temperature. Castor oil polymer mixed with 60% CaCO3 and 12% cork powder gave a resilient and nontacky linoleum composition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 197–202, 2003
Upgrading melamine–urea–formaldehyde polycondensation resins with buffering additives. I. The effect of hexamine sulfate and its limits
Authors: Kamoun C. , Pizzi A. , Zanetti M. 
Published: July 2003

AbstractIminoamino methylene base intermediates obtained by the decomposition of hexamethylenetetramine (hexamine) stabilized by the presence of strong anions such as SO and HSO, or hexamine sulfate, were shown to markedly improve the water and weather resistance of hardened melamine–urea–formaldehyde (MUF) resins used as wood adhesives and of the wet internal bond strength performance of wood boards bonded with them. The effect was shown to be induced by very small amounts, between 1 and 5 wt % of this material on resin solid content. This strong effect allowed the use of MUF resins of much lower melamine content and also provided good performance of the bonded joints. Because the main effect was also present at the smaller proportion of hexamine as hexamine sulfate, it was not due at all to any increase in the molar ratio of the resin as a consequence of hexamine sulfate addition. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 203–214, 2003
Upgrading of MUF polycondensation resins by buffering additives. II. Hexamine sulfate mechanisms and alternate buffers
Authors: Zanetti M. , Pizzi A. 
Published: July 2003

AbstractIminoamino methylene bases intermediates are obtained by the decomposition of hexamethylenetetramine (hexamine). These are stabilized by the presence of strong anions such as SO and HSO, that is, “hexamine sulfate.” The effect of hexamine sulfate was closely linked to the strong buffering action it has on MUF resins. Its role is mainly to induce regularity of the reaction and the stability of conditions during resin networking, due to the buffer. Shifting of the polycondensation ⇌ degradation equilibrium to the left appeared to be the determinant factor. This was a consequence of maintaining a higher, constant pH during curing, due to the buffer action. The modulus of elasticity (MOE) increases the curves of hexamine sulfate‐catalyzed MUF resins, confirming this trend. The resins are faster curing than when catalyzed by ammonium sulfate. The effect is valid within the narrow buffering range of pH's used for resin hardening. Polycondensation is far too slow to occur at a much higher pH, and degradation is, instead, more predominant at much lower pH's. The network formed is then more crosslinked and less tainted by degradation when curing occurs within the correct pH range. The result is a much better performance of the wood board after water attack. The effects induced by hexamine sulfate effects are of longer duration than those of other potential buffers. This is due to the hexamine sulfate heat stability under standard hot curing conditions of the resin. Alternate systems were found and shown to have a comparable effect. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 215–226, 2003
Synthesis of water‐soluble syndiotacticity‐rich low molecular weight poly(vinyl alcohol) by solution copolymerization of vinyl pivalate/vinyl acetate in tetrahydrofuran and saponification
Authors: Lyoo Won Seok , Yeum Jeong Hyun , Ghim Han Do , Lee Joon‐Seok , Ji Byung Chul , Yoon Nam Sik , Ha Jae Boo , Lee Jinwon 
Published: July 2003

AbstractSyndiotacticity‐rich low molecular weight poly(vinyl alcohol) (PVA) was synthesized by solution copolymerization of vinyl pivalate (VPi) and vinyl acetate (VAc) in tetrahydrofuran (THF) at low temperature using 2,2′‐azobis(2,4‐dimethylvaleronitrile) (ADMVN) as an initiator and successive saponification of copoly(VPi/VAc). Effects of initiator and monomer concentrations and polymerization temperature on the polymerization behavior and molecular structure of PVA prepared were investigated. The polymerization rate of VPi and VAc in THF was proportional to the 0.96 power of ADMVN concentration, indicating the heterogeneous nature of THF polymerization. Low‐temperature solution copolymerization of VPi and VAc in THF by adopting ADMVN proved to be successful in obtaining water‐soluble PVA with number‐average degree of polymerization of 180–360, syndiotactic diad content of 56–58%, and ultimate conversion of VPi and VAc into copoly(VPi/VAc) of over 80%, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 227–232, 2003
Thermal and mechanical properties of microwave‐ and heat‐cured poly(methyl methacrylate) used as dental base material
Authors: Usanmaz Ali , Ateş Julide , Doğan Arife 
Published: July 2003

AbstractThe thermal and mechanical properties of dental base materials cured by microwave and conventional heat methods were studied. The commercial dental base poly(methyl metacrylate) (PMMA) powder and liquid were mixed in a 3/1 ratio. They were polymerized by a peroxy catalyst at 65°C, then cured with a boiling water temperature and microwave radiation for periods of 5, 10, 15, 20, 25, 30, and 35 min for heat curing and 1, 2, 3, 5, and 7 min for microwave radiation. The microwave radiation outputs used were 500 and 700 W. The products of 5‐min heat curing and 1‐, 2‐, and 7‐min microwave curing were soluble in chloroform. All the others were partially soluble. The viscosity‐average molecular weights of the soluble samples were about 1 × 106. The thermal properties of the polymer samples were studied by differential scanning calorimetry (DSC). For the samples that were not cured completely, broad exothermic peaks at around 125°C were obtained in the DSC thermograms. The glass‐transition temperatures for completely cured samples were 110–120°C. The mechanical properties of the samples were determined from tensile and three‐point bending tests. The elastic modulus was highest for samples obtained by the conventional method with a 30‐min curing period. However, the bending modulus was highest for 7‐min cured samples in a 700‐W microwave. The mechanical strengths of the 700‐W output were higher than those at 500 W. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 251–256, 2003
In situ epoxidized natural rubber: Improved oil resistance of natural rubber
Authors: Tanrattanakul Varaporn , Wattanathai Boonsit , Tiangjunya Adul , Muhamud Putsadee 
Published: July 2003

AbstractThis study sought to synthesize an in situ epoxidized natural rubber (NR) from 20% dry rubber content latex stabilized by nonionic surfactant, 5 phr of Terric 16A16, in the presence of hydrogen peroxide and formic acid at the temperature of 50°C. The molar ratios of H2O2 and HCOOH to isoprene unit were equal, 0.75 : 0.75. Reaction was carried out for 3 to 8 h. This reaction yielded products of various epoxide contents depending on reaction time. Based on DSC characterization, epoxide contents of the in situ epoxidized natural rubbers (ENRs) were about 22–39 mol %. Tensile properties and tear resistance of the in situ ENRs were equal to, or better than, those of NR and commercial ENRs. The in situ epoxidation improved resistance to petroleum ether, but not to toluene. Changes in volume and weight of specimens immersed in ASTM no. 3 oil and automobile oils (various trade names: Shell engine oil, Shell gear oil, and Toyota motor oil) exhibited significant decrease after epoxidation, except in Shell brake fluid. Similar results were obtained from tensile testing of the oil‐immersed specimens. Tensile strength and elongation at break of the in situ ENRs were much higher than those of NR after immersion in those oils at room temperature for 7 days, except the immersion in brake fluid. Improved oil resistance of the in situ ENRs under severe condition was obtained in gear oil. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 261–269, 2003
UV‐curable powder coatings based on dendritic poly(ether‐amide)
Authors: Wei Huanyu , Liang Hongbo , Zou Jianhua , Shi Wenfang 
Published: July 2003

AbstractSemi‐crystalline dendritic poly(ether‐amide)s were synthesized by modifying hydroxyl end‐groups of dendritic poly(ether‐amide) with aromatic urethane acrylate and octadetyl isocyanate. The ratio of these modifiers can adjust the final properties of products to fulfill the requirements of UV‐curable powder coatings. These UV‐curable semi‐crystalline dendritic poly(ether‐amide)s have a Tg in the range of 41–45°C and a Tm of around 120°C. Their thermal behavior and semi‐crystalline properties were studied by DSC and XRD. The photopolymerization kinetics was investigated by Photo‐DSC. The residual unsaturation, thermal stability, and hardness of the UV‐cured films were also studied. The obtained results show that these semi‐crystalline dentritic poly(ether‐amide)s may be used as prepolymers in UV‐curable powder coating systems. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 287–291, 2003
Studies on phase separation rate in porous polyimide membrane formation by immersion precipitation
Authors: Matsuyama Hideto , Nakagawa Keizo , Maki Taisuke , Teramoto Masaaki 
Published: July 2003

AbstractPhase separation rate during porous membrane formation by immersion precipitation was investigated by light scattering in a polyimide/N‐Methylpyrrolidone (NMP)/water system. In the light scattering measurement, plots of scattered intensity against scattered angle showed maxima in all cases, which indicated that phase separation occurred by a spinodal decomposition (SD). Characteristic properties of the early stage of SD, such as an apparent diffusion coefficient Dapp and an interphase periodic distance Λ, were obtained. The growth process of Λ was also followed by light scattering. The growth rate had the same tendency as Dapp when water content in the nonsolvent bath and the polymer concentration in the cast solution were changed. The pore size of the final membrane increased with decreasing water content, which was opposite to the tendency of Λ growth rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 292–296, 2003
Controlled degradation of cured natural rubber by encapsulated benzophenone as a photosensitizer
Authors: Riyajan Sa‐Ad , Sakdapipanich Jitladda Tangpakdee , Tanaka Yasuyuki 
Published: July 2003

AbstractThe photodegradation of raw natural rubber and natural rubber compound film were studied using an artificial solar energy simulator. The properties of degraded rubber sheets containing benzophenone (BP) were determined by solution viscosity, 1H‐NMR, and FTIR analyses. In the case of rubber compounds containing BP, the changes of tensile strength and crosslinking density were determined. It was found that BP could amply accelerate the photodegradation of rubber. To control the release rate of BP, it was necessary to encapsulate BP with urea–formaldehyde as a matrix. The encapsulated BP or capsule was formed by an interfacial polycondensation reaction between formaldehyde and urea. The kinetic of release rate of BP from urea–formaldehyde capsule was markedly observed within 15 days of release time; after that the rate of BP released from urea–formaldehyde microcapsule was very slow. At the same concentration of BP, the degradation rate of rubber compound by adding BP directly was faster than that of the rubber containing encapsulated BP. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 297–305, 2003
A pheromonotropic peptide of Helicoverpa zea, with melanizing activity, interaction with PBAN, and distribution of immunoreactivity
Authors: Raina Ashok K. , Kingan Timothy G. , Kochansky Jan P. 
Published: July 2003

AbstractThe sequence of an 18–amino acid residue peptide was deduced from the gene encoding PBAN and other peptides with common C‐termini in Helicoverpa zea. The peptide caused melanization in larvae and pheromone production in females of H. zea, and was designated pheromonotropic melanizing peptide (Hez‐PMP). The peptide has a 83% sequence homology with a pheromonotropic peptide isolated from Pseudaletia separata. PMP caused melanization and mortality when injected into larvae just before molting. Whereas intense melanization was caused with a dose of 1,000 pmol, peak mortality occurred at 100 pmol, with 50% of larvae dying within 48 h after injection. Pheromonotropic activity of PMP was dose dependent. Co‐injection of Hez‐PMP and Hez‐PBAN into a female resulted in suppression of the pheromonotropic effect of PBAN. Whole‐mount immunocytochemical studies revealed PMP‐like immunoreactivity in frontal ganglion, subesophageal, thoracic, and abdominal ganglia as well as the esophageal nerve. Arch. Insect Biochem. Physiol. 53:147–157, 2003. Published 2003 Wiley‐Liss, Inc.
Kinases, intracellular calcium, and apolipophorin‐III influence the adhesion of larval hemocytes of the lepidopterous insect, Galleria mellonella
Authors: Zakarian Robert J. , Dunphy Gary B. , Rau Manfred E. , Albert Paul J. 
Published: July 2003

AbstractBased on the results from the use of selective inhibitors and activators, active protein kinase A, protein tyrosine kinase, and protein kinase C (PKC) isoforms decreased the adhesion of larval Galleria mellonella hemocytes to glass slides. The protein kinase A inhibitor at all concentrations increased granular cell adhesion only whereas protein tyrosine kinase elevated both granular and plasmatocyte attachment at the lowest concentration. Active, Ca2+‐ and lipid‐dependent PKC isoforms limited plasmatocyte and granular cell adhesion whereas PKC that was inhibited by selected compounds (with differed modes of PKC inhibition) enhanced hemocyte attachment. The granular cells were more sensitive to the PKC inhibitors than were plasmatocytes. Phospholipase C and its diacylglyceride product were necessary to reduce hemocyte adhesion and maintain PKC activity. Extracellular Ca2+, possibly transported through L‐channels, was required for plasmatocyte attachment. In contrast, lowering the levels of cytosolic Ca2+ was associated with decreased PKC activity and was required for hemocyte adhesion. Arch. Insect Biochem. Physiol. 53:158–171, 2003. © 2003 Wiley‐Liss, Inc.
Antisense inhibition of neuronal nicotinic receptors in the tobacco‐feeding insect, Manduca sexta
Authors: Fickbohm David , Trimmer Barry Andrew 
Published: July 2003

AbstractAcetylcholine is the predominant excitatory transmitter in the insect central nervous system with many of its effects mediated by nicotinic acetylcholine receptors. These receptors are present at very high density and are structurally heterogeneous, although little is known about functional distinctions between them. An interesting system for examining these receptors is the larval stage of Manduca sexta, a nicotine‐resistant tobacco‐feeding insect. The nicotinic responses of cultured neurons were found to be blocked by mecamylamine and curare but highly resistant to α‐bungarotoxin. The responses were also unaffected by the reducing agent dithiothreitol and the alkylating agent bromoacetylcholine suggesting that the α‐subunit dicysteine agonist binding site is protected. To begin determining the functional roles of different subunits in these receptors, cultured neurons were treated with oligonucleotides based on the gene sequence of the alpha subunit, MARA1. Antisense DNA caused a significant downward shift in the amplitude distribution of nicotinic responses compared to sense or reverse antisense treatments. These treatments did not affect currents mediated by the application of GABA. The reduction in the nicotinic depolarization and inward currents did not affect the rate of current onset or recovery, suggesting that antisense MARA1 causes a partial block of all nicotinic responses in these neurons. These results demonstrate that receptor gene expression in insect neurons can be manipulated in a sequence‐specific manner by antisense treatment and they provide evidence that MARA1 is important for normal nicotinic responses in Manduca. Arch. Insect Biochem. Physiol. 53:172–185, 2003. © 2003 Wiley‐Liss, Inc.
Effect of silkworm hemolymph on N‐linked glycosylation in two Trichoplusia ni insect cell lines
Authors: Joosten Christoph E. , Park Tai Hyun , Shuler Michael L. 
Published: July 2003

AbstractA recombinant N‐linked glycoprotein, secreted human placental alkaline phosphatase (SEAP), was produced in two Trichoplusia ni insect cell lines using the baculovirus expression vector. Silkworm hemolymph (SH) was added to TNMFH + 10% fetal bovine serum (FBS) medium to a concentration of 2.5% or 5%, and SEAP production and glycosylation in the presence of SH were compared with controls devoid of hemolymph. Growing Tn‐4s cells in 5% SH‐supplemented medium required progressive adaptation of the cells to SH, and adapted cells had a SEAP specific yield decreased by 2.5‐fold compared with control cells not exposed to SH. Although SEAP produced in the control possessed little complex glycosylation (<1%), SEAP produced by SH‐adapted cells in the presence of 5% SH possessed 8.7% sialylated structures, as well as unusual, asialylated, agalactosylated structures with a high degree of polymerization (DP). On the basis of enzymatic and mass‐spectrometric analyses, we propose that these structures are glucosylated, high‐mannose oligosaccharides. SEAP was also produced by Tn‐4s cells without adaptation to SH when SH was added just prior to baculovirus infection, but SEAP specific yield was adversely affected (approximately fourfold reduction compared with control devoid of hemolymph), and glycosylation of SEAP produced under these conditions was characterized by large amounts of high‐mannose and high‐DP structures and an absence of complex structures. Similarly, Tn5B1‐4 cells that were not adapted to SH had a SEAP specific yield reduced by approximately fivefold in SH‐containing medium; however, these cells were able to produce 13.5% sialylated SEAP in the presence of 2.5% SH, whereas complex structures were not produced in the absence of SH. We propose that SH improves glycosylation either directly or indirectly by decreasing SEAP specific yield. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 695–705, 2003.
On‐line monitoring of Phaffia rhodozyma fed‐batch process with in situ dispersive raman spectroscopy
Authors: Cannizzaro Christopher , Rhiel Martin , Marison Ian , von Stockar Urs 
Published: July 2003

AbstractSince the yeast Phaffia rhodozyma was first described some 35 years ago, there has been significant interest in the development of commercial processes to exploit its ability to produce carotenoids (∼80% astaxanthin). However, the optimal conditions for carotenoid production are not well understood. A key limitation has been the lack of an appropriate sensor for on‐line carotenoid quantification. In this study, an in situ Raman spectroscopy probe was used to monitor intracellular carotenoid production for three consecutive P. rhodozyma fed‐batch experiments. Raman spectroscopy is particularly well suited to the study of carotenoids due to a resonance effect, which greatly enhances the intensity of the three fundamental carotenoid bands, ν1 (1513 cm−1, CC stretch), ν2 (1154 cm−1, C—C stretch), and ν3 (1003 cm−1, CH3 rock). For all three cultures, the peak height of these bands was linearly correlated with intracellular carotenoid content (1 to 45 mg/L) to a precision of better than 5%, and the correlation from one experiment was directly applicable to others. ©2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 668–680, 2003.
Scalable inoculation strategies for microcarrier‐based animal cell bioprocesses
Authors: Dürrschmid M. , Landauer K. , Simic G. , Blüml G. , Doblhoff‐Dier O. 
Published: July 2003

AbstractScalability is a major demand for high‐yield, stable bioprocess systems in animal cell culture–based biopharmaceutical production. Increased yields can be achieved through high‐density cell culture, such as in the combination of microcarrier and fluidized bed bioreactor technology. To minimize inocula volume in industrial applications of fluidized bed fermentation systems, it is crucial to increase the bed volume in the reactor during the fermentation process. We tested scale‐up strategy for the production of recombinant human arylsulfatase B (ASB) enzyme used in enzyme replacement therapy in patients afflicted with mucopolysaccharidosis type VI (MPS VI). This enzyme was derived from Chinese hamster ovary (CHO) cells cultivated as adherent cell culture on Cytoline macroporous microcarriers (Amersham Biosciences, Uppsala, Sweden) using a Cytopilot Mini fluidized bed bioreactor (FBR; Amersham Biosciences, Vogelbusch, Austria). Both 1:2 expansion (herein referred to as the addition of fresh, not‐yet‐colonized microcarriers) and 1:6 expansion of the carrier bed were performed successfully; the cells restarted to proliferate for colonizing these newly added carriers; and the stability of the culture was not negatively affected. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 681–686, 2003.