bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive‐HALS I: Synthesis, characterization, copolymerization reactivity and photo‐stabilizing performance applied in UV‐curable coatings
Authors: Liu Xiaoxuan , Yang Jianwen , Chen Yonglie 
Published: January 2005

AbstractThe synthesis and characterization of four monomeric hindered piperidinol derivatives, 4‐methacryloyl‐1,2,2,6,6‐pentamethyl‐piperidinyl (MPMP), 4‐acryloyl‐1,2,2,6,6‐pentamethyl‐piperidinyl (APMP), 4‐methacryloyl‐2,2,6,6‐tetramethyl‐piperidinyl (MTMP) and 4‐acryloyl‐2,2,6,6‐tetramethyl‐piperidinyl (ATMP) as reactive‐hindered amine light stabilizers (r‐HALS) were reported. Their structures and compositions have been characterized by FT‐IR,1H‐NMR, GC/MS and elemental analysis. The aim of the present work is to examine the copolymerization reactivity of r‐HALS, and to investigate the photostabilizing performance applied in UV‐curable coatings. The results have shown that r‐HALS (MPMP, APMP, MTMP and ATMP) can be readily copolymerized with commonly used oligomer or reactive diluent. The photostabilizing effect of these r‐HALS applied in UV‐curable coatings of an epoxy acrylate (CN124A80) was better than that of commercial HALS (Tinuvin 770 and Tinuvin 292). Copyright © 2002 John Wiley & Sons, Ltd.
Inorganic–organic hybrid materials­from poly(methylmethacrylate) ­crosslinked by an organically modified ­oxozirconium cluster. Synthesis and ­characterization
Authors: Gross Silvia , Trimmel Gregor , Schubert Ulrich , Noto Vito Di 
Published: January 2005

AbstractThe presence of inorganic moieties in polymers greatly expands the range of their properties and applications and at the same time overcomes some of the disadvantages of conventional polymer chemistry, such as low temperature hardness and brittleness, photochemical instability, or low electric conductivity. In this framework, the cluster Zr4O2(OMc)12 (OMc = methacrylate) (Zr4), was prepared starting from zirconium butoxide and an excess of methacrylic acid. Inorganic–organic hybrid materials were then synthesized by radical‐initiated copolymerization of Zr4 and methylmethacrylate in benzene with different molar ratios. Glassy, highly transparent hybrid polymers were obtained. The thermal behavior, the composition and the structure of the polymers were investigated by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (IR), 13C MAS NMR, X‐ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectrometry (ICP‐AES). The spectroscopic data show that­the clusters crosslink the poly(methylmethacrylate) (PMMA) chains and that the oxometallate complexes are completely incorporated into the hybrid materials. Compared with the undoped polymer, the hybrid polymers have enhanced thermal properties and a characteristic dielectric behavior. Copyright © 2002 John Wiley & Sons, Ltd.
Effect of functional groups on the ­thermal degradation of copolymers
Authors: Shibasaki Yoshio , Yang Min , Sun Ling 
Published: January 2005

AbstractThermal degradation mechanisms of the copolymers of styrene (St) with methacrylonitrile (MAN) and α‐methylstyrene (αMSt) were studied by pyrolysis gas chromatography (Py‐GC) and thermogravimetry (TG). Thermal degradation of vinyl polymers in flash pyrolysis proceeded mainly in the competition between depolymerization and back biting reaction caused by abstraction of H atom at α‐position in pen‐penultimate unit. Monomer molecules were regenerated by depolymerization, and dimer, trimer and ologomers were produced by back biting reaction. Methyl groups at α‐position of monomer unit strictly hindered the back biting reaction. The role of functional groups on the thermal degradation was elucidated on the basis of bond dissociation energies­of main chain (QCC), apparent activation energies­(ΔEa) obtained by Ozawa's method from the TG­curves at various heating rates. Effect of chemical reactivity of C≡N group in MAN unit on the thermal degradation was clarified by the controlled rate thermogravimetry (CRTG). Copyright © 2002 John Wiley & Sons, Ltd.
Organometallic polymers: synthesis and electro‐optical properties
Authors: Fratoddi Ilaria , Altamura Patrizia , Sterzo Claudio Lo , Furlani Anita , Galassi Emiliano , D'Amico Arnaldo , Russo Maria V. 
Published: January 2005

AbstractThe synthesis of organometallic polymers, namely ­Pt‐DOB ([Pt(PPh3)2(CCp C6H4(2,5OC16H33)2CC)]
n and Pt‐TRI ([Pt(PBu
3)
2(CCC
4H
2SCCC
4H
2SCCC
4H
2SCC)]
n) has been carried out. The platinum polyynes with a rigid rod structure have been obtained by two synthetic routes: dehydrohalogenation and Stille coupling in the version “extended one pot” (EOP). Pt‐DOB and Pt‐TRI have been fully characterized by means of FT‐IR, UV‐vis,
1H‐ and
31P‐NMR, gel permeation chromatography (GPC) and photoluminescence spectra. Different organic spacers have been employed in order to study and compare the response of new materials as mass sensors, using a quartz crystal microbalance sensor (QCMB) technique. The materials were exposed to ethanol and isopropanol vapors and showed a different response depending on the nature of the organic spacer. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of branched polymers by means of living anionic polymerization — Part 6. Synthesis of well‐defined comb‐like branched polystyrenes and graft copolymers with highly branched architecture
Authors: Hirao Akira , Kawano Hiroki , Ryu Sang Woog 
Published: January 2005

AbstractThe synthesis of well‐defined comb‐like branched polymers and graft copolymers with one branch chain per repeating unit by the methodology based on “grafting‐onto” method is described. The methodology involves three reaction steps. The first reaction step is to prepare poly(m‐tert‐butyldimethylsilyloxymethylstyrene)s with predictable molecular weights and narrow molecular weight distributions by living anionic polymerization of m‐tert‐butyldimethylsilyloxymethylstyrene in tetrahydrofuran (THF) at −78 °C. In the second reaction step, the resulting polymers are quantitatively transformed into poly(m‐chloromethylstyrene)s by treatment with BCl
3. Finally, by the reaction of the poly(m‐chloromethylstyrene)s thus prepared with living anionic polymers of styrene, isoprene, and 2‐vinylpyridine, comb‐like branched polymers and graft copolymers are synthesized. Each of all linking reactions proceeded quantitatively to afford the branched polymers with one branch chain per repeating unit. Attempts to synthesize highly branched polystyrenes having more than one branch chain per repeating unit were made by reacting poly(m‐bromomethylstyrene)s with the polymer anions prepared from polystyryllithium with end‐functionalized polystyrenes with 1,1‐diphenylethylene moiety. For the same purpose, we prepared a new polystyrene derivative having two bromomethylphenyl groups in each styrene unit to react with polystyryllithium. Copyright © 2002 John Wiley & Sons, Ltd.
On the study of polyurethane Ionomer—Part I
Authors: Chwang C. P. , Wang C. L. , Kuo Y. M. , Lee S. N. , Chao A. , Chao D. Y. 
Published: January 2005

AbstractThe reaction of toluene diisocyanate (TDI) with dimethylol propionic acid (DMPA) or diaminopentane sulphonic acid sodium salt (ES‐200) and other additives to form the structure of anionic polyurethane (PU) ionomer molecule has been proven by FT‐IR spectroscopy.In aqueous solution, the surface tension of anionic PU ionomer molecule is seen to slightly increase with increasing concentration of ES‐200. This is because the adsorption of hydrophobic groups of ionomer molecules at the surface of aqueous solution becomes even more ordered. Under the same experimental conditions, the surface tension of anionic PU ionomer molecule appears to slightly decrease with increasing concentration of DMPA, as a result of increased hydrophobic groups of ionomer molecule adsorbed at the surface of aqueous solution. The number average particle size of anionic PU ionomer molecule in aqueous solution appears to steadily increase with an increase in the concentration of DMPA or ES‐200. This is because the intermolecular interaction between ionomer–ionomer molecules themselves and between ionomer–water molecules may increase the free volume of anionic PU ionomer molecule, thus causing their number average particle size to increase.Experimental results indicate that both the tensile strength and the modulus of self‐cured film of anionic PU ionomer molecule appear to decrease with increasing concentration of DMPA or ES‐200, as a result of intramolecular interaction. However, the elongation of self‐cured film of anionic PU ionomer molecule is seen to increase with increasing concentration of DMPA or ES‐200. This may be the result of weakening crosslinking due to strong intramolecular interaction of ionomer molecule. For the peel strength of self‐cured film of anionic PU ionomer coated on the fabric (30% polyester/70% cotton), it has been found that the peel strength increases with increasing concentration of DMPA or ES‐200, as a result of increased hydrophilic interaction between ionomer molecules themselves. Copyright © 2002 John Wiley & Sons, Ltd.
On the study of polyurethane ionomer — Part II
Authors: Chwang C. P. , Lee S. N. , Kuo Y. M. , Chao S. , Chao D. Y. 
Published: January 2005

AbstractPhotosensitive‐fluorescein polyurethane (PU) ionomer was successfully synthesized at our laboratory. The reaction of toluene diisocyanate with polyester, fluorescein, hydroxypropyl acrylate and other major additives to form the structures of these ionomers has been proven by FT‐IR spectroscopy. For a dilute concentration of photosensitive‐fluorescein PU ionomer molecule in aqueous solution, the fluorescence studied exhibits fluorescence at around 508 nm. In aqueous solution, the number average particle size appears to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate used to prepare the photosensitive‐fluorescein PU ionomer molecules. The reason for the free volume of photosensitive‐fluorescein PU ionomer molecules is due to strong intermolecular interactions between hydrophilic groups of these ionomer molecules increasing. Therefore, the number average particle sizes of these ionomer molecules increases. Furthermore, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomer molecule results in an increase is the average particle size of this ionomer molecule. This is due to increased free volume resulting from strong intermolecular interaction between hydrophilic groups of ionomer molecules. For self‐cured films made by photosensitive‐fluorescein PU ionomer, the tensile strength is seen to increase with increasing concentration of epoxy, fluorescein and hydroxypropyl acrylate, respectively. This may be attributed to increased crosslinking due to strong intermolecular interaction between photosensitive‐fluorescein PU ionomer molecules themselves. However, the addition of benzoin as a photoinitiator to photosensitive‐fluorescein PU ionomers results in an increase in the tensile strength of these ionomers as well. Copyright © 2002 John Wiley & Sons, Ltd.
Preparation of benzyl alcohol by hydrogenation of benzoic acid catalyzed by a magnesium Oxide‐supported poly‐γ‐aminopropylsiloxane–Ru–Pd–Sn complex
Authors: Mao Bao‐Wei , Wu Jin‐Fei , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: January 2005

AbstractBenzyl alcohol in higher than 90% yield was achieved from the hydrogenation of benzoic acid catalyzed by using a magnesium oxide‐supported poly‐γ‐aminopropylsiloxane–ruthenium–palladium–stannum trimetallic complex catalyst (MgO–NH2–Ru–Pd–Sn) in 1,4‐dioxane. The Ru/Pd/Sn mole ratio, reaction temperature, hydrogen gas pressure and reaction time greatly influenced the reaction. The catalyst was stable and could be used repeatedly without any remarkable changes in catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
Asymmetric hydration of allyl alcohol catalyzed by polysulfostyrene– gelatin–Co complex
Authors: Zhang Xi , Li Yan‐Jie , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: January 2005

AbstractA new chiral polymer–metal complex, polysulfostyrene–gelatin–cobalt complex (PSS–GE–Co) has been prepared and found to be able to catalyze the asymmetric hydration of allyl alcohol to give (S)‐(−)‐1,2‐propanediol in 98% yield with 98.9% optical yield. The catalyst is very stable and can be reused without any remarkable effect in catalytic activity and optical selectivity. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis and characterization of liquid crystalline copolyesters containing horizontal and lateral rods in main chain
Authors: Li Chenguang , Xie Xuming , Cao Shaokui 
Published: January 2005

AbstractA series of liquid crystalline copolyesters containing both horizontal and lateral rods in main chain were synthesized through solution polymerization of 2,5‐bis(4‐alkoxy benzoyloxy)hydroquinone, 4,4′‐dihydroxy‐α,ω‐diphenoxydecane and 4,4′‐dichloroformyl‐α,ω‐diphenoxydecane. These copolyesters were soluble in common organic solvents, showed thermotropic nematic liquid crystallinity that can be easily obtained at room temperature, thereby making them processable at relatively low temperatures in their high‐ordered liquid crystalline states where they are thermally stable. Their thermal transitions can be well adjusted by judiciously controlling the attachment content of lateral rods, and their thermal behaviors were well examined. All synthesized polymers were characterized by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide angle X‐ray diffraction (WAXD). Copyright © 2002 John Wiley & Sons, Ltd.
Preparation and catalytic behaviors of silica‐supported casein–Fe complex in hydrogenation of cyclohexanone
Authors: Shen Lin , Ye Jiang‐Li , Huang Mei‐Yu , Jiang Ying‐Yan 
Published: January 2005

AbstractA silica‐supported casein–Fe complex (SiO
2‐CA‐Fe
III) has been prepared and used as catalysts for the hydrogenation of various organic compounds under mild conditions, especially to catalyze the hydrogenation of cyclohexanone to cyclohexanol effectively at room temperature and 1 atmH
2. The experimental results indicate that Fe content in SiO
2‐CA‐Fe complex, reaction temperature and time greatly influence the yield of cyclohexanol. When proper reaction conditions were selected, the yield of cyclohexanol could amount to 100%. This complex was very stable and could be reused without any change in catalytic activity. Copyright © 2002 John Wiley & Sons, Ltd.
A rapid TLC bioautographic method for the detection of acetylcholinesterase and butyrylcholinesterase inhibitors in plants
Authors: Marston A. , Kissling J. , Hostettmann K. 
Published: January 2005

AbstractA simple and rapid bioautographic enzyme assay on TLC plates has been developed for the screening of acetylcholinesterase and butyrylcholinesterase inhibition by plant extracts. Enzyme activity was detected by the conversion of naphthyl acetate into naphthol and the formation of the corresponding purple‐coloured diazonium dye with Fast Blue B salt. Inhibitors of cholinesterases produced white spots on the dye‐coloured background of the TLC plates. The alkaloids galanthamine and physostigmine, which are known inhibitors of acetylcholinesterase, were used to determine the sensitivity of the assay. Various plant extracts were tested using the bioassay. Copyright © 2001 John Wiley & Sons, Ltd.
Congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation
Authors: Souka A. P. , Krampl E. , Geerts L. , Nicolaides K. H. 
Published: January 2005

AbstractCongenital lymphedema is an autosomal dominant condition characterized by chronic tissue swelling caused by deficient lymphatic drainage due to hypoplastic/aplastic lymphatic vessels and usually affecting the lower limbs. The locus of the gene has been identified in the long arm of chromosome 15. We report one case of congenital lymphedema presenting with increased nuchal translucency at 13 weeks of gestation. Copyright © 2002 John Wiley & Sons, Ltd.
Correlation of ultrasound findings and biochemical markers in the second trimester of pregnancy in fetuses with trisomy 21
Authors: Souter Vivienne L. , Nyberg David A. , El‐Bastawissi Amira , Zebelman Arthur , Luthhardt Fred , Luthy David A. 
Published: January 2005

AbstractObjectiveThe aim of the present study was to assess possible correlations between ultrasound findings and maternal serum biochemical (‘triple test’) markers among fetuses with trisomy 21 in the second trimester of pregnancy.MethodsThe study was a retrospective cohort study of 72 pregnancies affected by trisomy 21 who had a second trimester ultrasound and biochemical screen performed at a single center between 1990 and 1999. The biochemical screen consisted of alpha‐fetoprotein (AFP), total beta human chorionic gonadotrophin (hCG) and estriol (uE3). Marker levels were expressed in multiples of the median (MoM). The ultrasound findings assessed were major structural anomalies, short humerus length, short femur length, increased nuchal fold thickness (NF), hyperechoic bowel, echogenic intracardiac focus (EIF), ventriculomegaly, choroid plexus cysts and renal pyelectasis.ResultsSecond trimester maternal serum biochemical markers and ultrasound findings appeared to be largely independent of each other. However, some significant correlations were observed. Estriol was significantly lower when a fetal cystic hygroma was detected on ultrasound compared to those with no cystic hygroma (0.40 vs 0.70 MoM, p<0.05). The median hCG level was significantly lower in those pregnancies with a normal second trimester fetal ultrasound compared to those with positive ultrasound findings (2.07 vs 2.87 MoM, p<0.05). Median hCG levels were also significantly higher in those cases with NF⩾5 mm as compared to those with NF<5 mm (2.99 vs 2.49 MoM, p<0.05). This difference persisted after exclusion of the five cases with cystic hygromas (2.99 vs 2.49 MoM, p<0.05). A significant positive correlation was observed between log10 hCG and log10 NF MoM (Spearman's ρ=0.252, p<0.05).NF was significantly greater among fetuses with an identifiable cardiac defect compared with those without a detectable cardiac defect (median of 7.0 mm vs 3.8 mm, p<0.01). This difference persisted when expressed as multiples of the median (2.8 vs 1.3 MoM, p<0.01).ConclusionSecond trimester ultrasound and biochemical markers are largely independent in fetuses with trisomy 21, however significant correlations between the two were observed in the present series. These may be important in screening protocols that combine second trimester ultrasound and biochemical markers. Copyright © 2002 John Wiley & Sons, Ltd.
The importance of investigating for uniparental disomy in prenatally identified balanced acrocentric rearrangements
Authors: McGowan Kathryn D. , Weiser Joseph J. , Horwitz Juli , Ann Berend Sue , McCaskill Christopher , Reid Sutton V. , Shaffer Lisa G. 
Published: January 2005

AbstractWe report the finding of paternal isodisomy for chromosome 14 in a fetus found to have a der(14;14)(q10;q10) by amniocentesis. The pregnancy was complicated by severe polyhydramnios and elevated amniotic fluid alpha‐fetoprotein (AFP). The infant showed features consistent with paternal uniparental disomy (UPD) including postnatal growth retardation, poor respiratory function, feeding difficulties, and evidence of hypertrophic cardiomyopathy. The present case, in addition to other reported cases of UPD involving balanced acrocentric rearrangements, supports testing for UPD in prenatally detected Robertsonian translocations and isochromosomes. Copyright © 2002 John Wiley & Sons, Ltd.
Maternal serum human chorionic gonadotrophin and pregnancy‐associated plasma protein A in twin pregnancies in the first trimester
Authors: Niemimaa Marko , Suonpää Mikko , Heinonen Seppo , Seppälä Maija , Bloigu Risto , Ryynänen Markku 
Published: January 2005

AbstractObjectivesTo determine the levels of free β‐human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein A (PAPP‐A) in twin pregnancies in the first trimester.MethodsSerum samples were obtained from 67 pregnant women with twin pregnancies and maternal serum free β‐hCG and PAPP‐A concentrations were compared with those of 4279 singleton controls between the 8th and 13th weeks of gestation.ResultsThe geometric means of chromosomally normal twin pregnancies were 1.85 MoM for free β‐hCG and 2.36 MoM for PAPP‐A. There were no cases affected by Down syndrome in either group.ConclusionTwin pregnancies secrete more PAPP‐A than expected on the basis of singleton controls whereas free β‐hCG production is not increased. The results of the present study can be used to establish normal reference values when introducing first trimester Down syndrome screening in prenatal care. Copyright © 2002 John Wiley & Sons, Ltd.
Transcervical chorionic villus sampling in multiple pregnancies using a biopsy forceps
Authors: Casals Gemma , Borrell Antoni , Martínez Josep M. , Soler Anna , Cararach Vicenç , Fortuny Albert 
Published: January 2005

AbstractObjectiveThe aim of this study was to assess the effectiveness and safety of chorionic villus sampling (CVS) performed in multiple pregnancies by means of a transcervical biopsy forceps.MethodsThe study included CVS performed from January 1990 to March 2000 in our Unit. The results were analysed in two consecutive periods, period A (1990–1994) and period B (1995–2000), in an attempt to assess the effect of increasing experience.ResultsSeventy‐five samplings were performed in 39 multiple pregnancies, 38 twin sets and one triplet. A cytogenetic report was obtained in 73% of cases in period A and in 98% in period B. An abnormal karyotype was observed in 11 samples. The need for subsequent amniocentesis decreased from 38% in period A to 10% in period B. The spontaneous fetal loss rate in chromosomally and structurally normal fetuses before the 20th week decreased from 8.7% in period A to 3.3% in period B. The fetal loss rate after the 20th week was 3.3% in period B and none in period A. It must be noted that in three out of the four cases of fetal loss an amniocentesis was needed after CVS.ConclusionOur results suggest that effectiveness and safety improved with increasing experience. Transcervical chorionic villus sampling allows an earlier prenatal genetic diagnosis in multiple pregnancies and this may be particularly relevant for a safer selective termination when chosen by parents if one of the fetuses has an abnormal karyotype. Copyright © 2002 John Wiley & Sons, Ltd.