bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effectiveness of teaching an early parenting approach within a community‐based support service for adolescent mothers
Authors: Drummond Jane E. , Letourneau Nicole , Neufeld Susan M. , Stewart Miriam , Weir Angela 
Published: December 2007

AbstractA single blind, pre‐test, post‐test design was used to test the effectiveness of the Keys to Caregiving Program in enhancing adolescent mother–infant interactions. Participants were sequentially allocated to groups in order of referral. The outcome was the enhancement of maternal and infant behaviors that exhibited mutual responsiveness as measured by the Nursing Child Assessment Teaching Scale. Issues with recruitment and collaboration with the community agencies made achieving a desirable sample size difficult. Pre‐tests and post‐tests were completed for 13 participants. While the sample size was insufficient to confidently establish whether or not the Keys to Caregiving produced a between groups treatment effect, mothers within the treatment group evidenced significantly greater contingent responsiveness over time than those within the control group. © 2007 Wiley Periodicals, Inc. Res Nurs Health 31:12–22, 2008
Antibiotic use in five children's hospitals during 2002–2006: the impact of antibiotic guidelines issued by the Chinese Ministry of Health
Authors: Zhang Wenshuang , Shen Xuzhuang , Wang Yi , Chen Yuan , Huang Min , Zeng Qiyi , Wei Jinghai , Lu Quan , Wang Gang , Deng Li , Wang Xiaohong , Yao Kaihu , Yu Sangjie , Yang Yonghong 
Published: December 2007

AbstractPurposeTo investigate the pattern of antibiotic use in five Chinese children's hospitals from 2002 to 2006. To see if the Guidelines to encourage rational use of antibiotics issued by the Ministry of Health in October 2004 have any impact on the use.MethodsThe Anatomical Therapeutic Chemical Classification/Defined Daily Doses (ATC/DDD) methodology was used. Aggregate data on antibiotic use (ATC code‐J01) were expressed in numbers of DDD/100 bed‐days for inpatients.ResultsTotal 56 different substances of systemic antibiotics were used. The overall consumption of antibiotic drugs was 68.2, 58.4, 65.8, 65.6 and 49.9 DDD/100 bed‐days for the years 2002–2006, respectively. The top antibiotics used were third‐generation cephalosporins. There was considerable variation in both type and amount of antibiotics used in the five hospitals. In 2002, some hospitals had twice the antibiotic use compared to others. While the overall antibiotic use in 2005 was largely unchanged compared with previous years, by 2006 antibiotic use had decreased by 22.6% and the variation in use between hospitals was also reduced.ConclusionsThe ATC/DDD methodology proved useful for studying overall antibiotic usage in children's hospitals. The decline in antibiotic usage found in 2006 (and the reduced variation between hospitals) may be attributed to the impact of the Ministry of Health guidelines which took some time to be promulgated to individual staff members. Further research will focus on compliance of antibiotic use in these five hospitals with particular guideline recommendations for specific clinical problems such as bacterial resistance and surgical antibiotic prophylaxis. Copyright © 2007 John Wiley & Sons, Ltd.
Factors influencing the CON bond strength of the alkoxyamines in the styrene–acrylonitrile–TEMPO copolymerization system
Authors: Megiel E. , Kaim A. 
Published: December 2007

AbstractHomolytic bond dissociation energy (BDE) of the (CON) bond for several N‐alkoxyamines derived from 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and the corresponding (CH) bonds were determined from quantum‐mechanical calculations including the B3‐LYP6‐31G(d), B3‐LYP/6‐311++G(2df,p), UB3‐LYP/6‐311+G(3df,2p), and integrated IMOMO (G3:ROMP2/6‐31G(d)) method. The investigated N‐alkoxyamines were considered as models for dormant forms of propagating chains in the radical copolymerization process of styrene with acrylonitrile in the presence of TEMPO according to the terminal and penultimate model. The substituent effect on BDE was investigated. Radical stabilization energies (RSE) for radicals created from homolysis of the investigated N‐alkoxyamines were calculated according to Rüchardt's method. Polar, steric, and stabilization effects on CON alkoxyamine bond homolysis were studied. A dramatically weakened CON bond in the alkoxyamine‐containing two consecutive styrene units in the propagating chain was ascribed to geometric parameters characterizing energetically unfavorable conformation of the substituents. These phenomena can be regarded as the penultimate effect in the radical living/controlled copolymerization system of styrene with acrylonitrile. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1165–1177, 2008
Surface‐initiated ring‐opening polymerization of p‐dioxanone on Wang resin bead
Authors: Lee Hyo Jin , Ramaraj B. , Lee Soo Min , Yoon Kuk Ro 
Published: December 2007

AbstractBiodegradable poly(p‐dioxanone) (PPDO) was formed on Wang resin surface by surface‐initiated ring‐opening polymerization (SI‐ROP). The SI‐ROP of p‐dioxanone (PDO) was achieved by heating a mixture of Tin(II) bis(2‐ethylhexanoate) [Sn(Oct)2], hydroxyl functionalized Wang resin, and PDO in anhydrous toluene at 80 °C. The resultant polymer‐grafted Wang resin (Wang‐g‐PPDO) was characterized by fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), optical microscopy (OM), and field‐emission scanning electron microscopy (FE‐SEM). The FTIR spectra of Wang‐g‐PPDO show peak characteristic of PPDO at 2943 cm−1 (CH stretch), at 1741 cm−1 (CO stretch), and 1136 cm−1 (COC stretch) indicating the formation of ester linkage between PPDO and hydroxyl terminated Wang resin. The DSC thermogram show melting peak corresponding to PPDO polymer on Wang resin surface. Thermogravimetric investigation shows increase in PPDO content on the Wang resin surface in terms of percentage of weight loss with increase in reaction time. The OM and SEM photographs clearly show the formation of PPDO polymer on the Wang resin surface without altering the spherical nature of Wang resin bead. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1178–1184, 2008
Vinyl addition polymerization of norbornene using cyclopentadienylzirconium trichloride activated by isobutyl‐modified methylaluminoxane
Authors: Nishizawa Osamu , Misaka Hideki , Kakuchi Toyoji , Satoh Toshifumi 
Published: December 2007

AbstractNorbornene polymerization using the commercially available and inexpensive catalyst system, cyclopentadienylzirconium trichloride (CpZrCl3) and isobutyl‐modified methylaluminoxane (MMAO), were carried out over a wide range of polymerization temperatures and monomer concentrations. For the CpZrCl3 catalyst system activated by aluminoxane with a 40 mol % methyl group and a 60 mol % isobutyl group (MMAO40/60), the polymerization temperature and monomer concentration significantly affected the molecular weight (Mn) of the obtained polymer and the catalytic activity. With an increase in the polymerization temperature from 0 to 27 °C, the catalytic activity and Mn increased, but these values dramatically decreased with the increasing polymerization temperature from 27 to 70 °C, meaning that the most suitable temperature was 27 °C. The CpZrCl3/MMAO40/60 ([Al]/[Zr] = 1000) catalyst system with the [NB] of 2.76 mol L−1 at 27 °C showed the highest activity of 145 kg molZr−1 h−1 and molecular weight of 211,000 g mol−1. The polymerization using the CpZrCl3/MMAO40/60 catalyst system proceeds through the vinyl addition mechanism to produce atactic polynorbornene, which was soluble in chloroform, toluene, and 1,2‐dichlorobenzene, but insoluble in methanol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1185–1191, 2008
One‐stage synthesis of narrowly dispersed polymeric core‐shell microspheres
Authors: Wen Fei , Zhang Wangqing , Zheng Peiwen , Zhang Xu , Yang Xinlin , Wang Yao , Jiang Xiaowei , Wei Guanwei , Shi Linqi 
Published: December 2007

AbstractA method of one‐stage soap‐free emulsion polymerization to synthesize narrowly dispersed core‐shell microspheres is proposed. Following this method, core‐shell microspheres of poly(styrene‐co‐4‐vinylpyridine), poly(styrene‐co‐methyl acrylic acid), and poly[styrene‐co‐2‐(acetoacetoxy)ethyl methacrylate‐co‐methyl acrylic acid] are synthesized by one‐stage soap‐free emulsion polymerization of a mixture of one or two hydrophobic monomers and a suitable hydrophilic monomer in water. The effect of the molar ratio of the hydrophobic monomer to the hydrophilic one on the size, the core thickness, and the shell thickness of the core‐shell microspheres is discussed. The molar ratio of the hydrophobic and hydrophilic monomers and the hydrophilicity of the resultant oligomers of the hydrophilic monomer are optimized to synthesize narrowly dispersed core‐shell microspheres. A possible mechanism of one‐stage soap‐free emulsion polymerization to synthesize core‐shell microspheres is suggested and coagglutination of the oligomers of the hydrophilic monomers on the hydrophobic core is considered to be the key to form core‐shell microspheres. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1192–1202, 2008
Styrene polymerization catalyzed by metal porphyrin complex/MAO for in situ synthesizing polystyrene containing air stable π cation radicals
Authors: Li Jianzhong , Li Min , Li Shiyun , Shi Liya , Ren Changyi , Cui Dongmei , Wang Yanhui , Tang Tao 
Published: December 2007

AbstractA novel catalyst system based on nickel(II) tetraphenylporphyrin (Ni(II)TPP) and methylaluminoxane for styrene polymerization was developed. This catalyst system has a high thermal stability and show fairly good activity. The obtained polystyrene (PS) was isotactic‐rich atactic polymer by 13C NMR analysis, and its molecular weight distribution was rather narrow (Mw/Mn ≈ 1.6, by GPC analysis). ESR revealed that Ni(II)TPP π cation radicals were formed in the polymerization and could remain in the resulting PS stably. The mechanism of the polymerization was discussed and a special coordination mechanism was proposed. The PS product containing Ni(II)TPP π cation radicals can be used as a potential functional material. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1240–1248, 2008
Precision synthesis of microstructures in star‐shaped copolymers of ϵ‐caprolactone, L‐lactide, and 1,5‐dioxepan‐2‐one
Authors: Odelius Karin , Albertsson Ann‐Christine 
Published: December 2007

AbstractStar‐shaped homo‐ and copolymers were synthesized in a controlled fashion using two different initiating systems. Homopolymers of ε‐caprolactone, L‐lactide, and 1,5‐dioxepan‐2‐one were firstly polymerized using (I) a spirocyclic tin initiator and (II) stannous octoate (cocatalyst) together with pentaerythritol ethoxylate 15/4 EO/OH (coinitiator), to give polymers with identical core moieties. Our gained understanding of the versatile and controllable initiator systems kinetics, the transesterification reactions occurring, and the role which the reaction conditions play on the material outcome, made it possible to tailor the copolymer microstructure. Two strategies were used to successfully synthesize copolymers of different microstructures with the two initiator systems, i.e., a more multiblock‐ or a block‐structure. The correct choice of the monomer addition order enabled two distinct blocks to be created for the copolymers of poly(DXO‐co‐LLA) and poly(CL‐co‐LLA). In the case of poly(CL‐co‐DXO), multiblock copolymers were created using both systems whereas longer blocks were created with the spirocyclic tin initiator. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 1249–1264, 2008
Synthesis and characterization of novel photoisomerizable liquid crystalline polymers containing cinnamoyl groups
Authors: Yang Po‐Chih , Liu Jui‐Hsiang 
Published: December 2007

AbstractA series of novel liquid crystalline monomers and polymers incorporating phenylbenzoate or phenylcinnamate segments as mesogenic cores have been synthesized to investigate the sensitivity of the photochromic cinnamoyl derivatives and to overcome the defects of the thermal instability of azobenzene. Their liquid crystalline, thermal, and photoinduced properties of all monomers and polymers were characterized. The polymers showed excellent solubility in common organic solvents such as CHCl3, toluene, and DMF and exhibited good thermal stability with decomposition temperatures (Td) at 5% weight loss greater than 340 °C and about 50% weight loss occurred beyond 430 °C under nitrogen atmosphere. The pitch length (about 574 nm) of the synthesized cholesteric polymeric film (CP2) was estimated using scanning electron microscopy. These photochromic polymers exhibited strong UV–vis absorption maxima at about 264 or 320 nm. Moreover, photo induced configurational E/Z isomerization further changed the π‐electron conjugation systems leading to a decrease at the π‐π* transition and an increase in the range of 300 nm to 400 nm for photochromic copolymers. The thermal stability of the Z‐structural segment was confirmed by heating the polymer at 50 °C for over 5 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1289–1304, 2008
Synthesis of conjugated polymers with pendant ruthenium terpyridine trithiocyanato complexes and their applications in heterojunction photovoltaic cells
Authors: Cheng Kai Wing , Mak Chris S. C. , Chan Wai Kin , Ching Ng Alan Man , Djurišić Aleksandra B. 
Published: December 2007

AbstractTwo conjugated polymers based on poly(phenylenethiophene) and poly (fluorenethiophene) main chain functionalized with pendant trithiocyanato ruthenium terpyridine complexes were synthesized by the Suzuki coupling reaction. The ruthenium complexes can extend the absorption band to longer wavelength and enhance the photosensitivity in this region. The polymers exhibit very broad absorption band spanning from 400 to 750 nm due to the presence of π‐conjugated system and the ruthenium complexes. Such enhancement in optical absorption enables the utilization of solar light in the near IR region. By space charge limited current modeling, the hole carrier mobilities of the polymers were calculated to be in the order of 10−4 cm2 V−1 s−1, which greatly facilitate the transport of charges after the separation of excitons. Heterojunction photovoltaic cells with simple structure ITO/polymer/C60/Al were fabricated. Under simulated AM1.5 solar light illumination, the short circuit currents, open circuit voltages, and power conversion efficiencies of the photovoltaic cells were measured to be 1.53–2.58 mA cm−2, 0.12–0.24 V, and 0.084–0.12%, respectively. Deposition of PEDOT:PSS on ITO surface did not show significant difference in device performance. Plot of incident photon to charge efficiency as the function of wavelength suggests that absorption by both conjugated main chain and ruthenium complex are essential to the photocurrent generation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1305–1317, 2008
A new strategy to characterize the extent of reaction of thermoset elastomers
Authors: Webb Antonio R. , Yang Jian , Ameer Guillermo A. 
Published: December 2007

AbstractA new method for determining the extent of reaction of thermoset elastomers was developed based on equilibrium swelling and dynamic mechanical analysis (DMA). The extent of reaction was defined based on the molecular weight between crosslinks (Mc) of a polymer sample in relation toMcat the onset of gelation and at complete reaction. The molecular weight between crosslinks was measured using equilibrium swelling, whereas rheology and DMA were used to determine the exact point of gelation and reaction completion, respectively. The extent of reaction of poly(1,8‐octanediol‐co‐citrate) at various polymerization conditions was investigated and this method was used to study the relationship between mechanical properties, molecular weight between crosslinks, and extent of reaction. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1318–1328, 2008
Synthesis and thiol–ene photopolymerization of allyl‐ether functionalized dendrimers
Authors: Nilsson Camilla , Simpson Neil , Malkoch Michael , Johansson Mats , Malmström Eva 
Published: December 2007

AbstractWell‐defined, allyl‐ether functional, first‐generation dendrimers have been synthesized. The convergent growth approach was utilized, using the anhydride of the allyl‐ether terminated building block. Three different core moieties were used: trimethylolpropane, trisphenol, and ditrimethylolpropane. The coupling reactions proceeded in good yields and all compounds were characterized by NMR, MALDI‐TOF, and SEC. The allyl‐terminated dendrimers were crosslinked by thiol–ene chemistry, using a multifunctional thiol, TriThiol, to give clear and smooth films. The photopolymerization was conducted in the presence of a photoinitiator, Irgacure 651, and no traces of either allyl‐ether groups or thiols were observed by FT‐Raman after cure. All crosslinked films were characterized with respect to mechanical (DMA) and thermal (DSC) properties. It was found that homogeneous networks were formed and that the core functionality and structure had little effect on the network properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1339–1348, 2008
Conjugated polymers containing electron‐transporting, hole‐transporting, and light‐emitting units in the polymer main chain
Authors: Fu Yaqin , Sun Minghao , Wu Yonggang , Bo Zhishan , Ma Dongge 
Published: December 2007

AbstractConjugated polymers containing electron‐transporting, hole‐transporting, and blue light‐emitting units were synthesized by Suzuki polycondensation. These copolymers exhibited excellent thermal and optical stability. Optical investigation indicated that the incorporation of the spirobifluorene units in the polymer main chain could markedly increase the effective conjugation length of polymers. Electrochemical studies showed that the incorporation of spirobifluorene unit could raise the electrochemical stability and improve the electron‐ and hole‐injecting abilities. The electroluminescent results also showed that the introducing of spirobifluorene units could significantly improve the device performance. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1349–1356, 2008
Alkyl side chain driven tunable red–yellow–green emission: Investigation on the new π‐conjugated polymers comprising of 2,7‐carbazole unit and 2,1,3‐benzo‐thiadiazole units with different side chains
Authors: Du Junping , Xu Erjian , Zhong Hongliang , Yu Feng , Liu Chang , Wu Huanrong , Zeng Danli , Ren Shijie , Sun Jing , Liu Yingchun , Cao Amin , Fang Qiang 
Published: December 2007

AbstractFour new soluble polymers containing a 2,7‐carbazole unit and a 2,1,3‐benzothiadiazole unit in the main chain were synthesized by Suzuki polycondensation. Variation of the substituent groups (R) at 5‐position of 2,1,3‐benzothiadiazole unit resulted in different color emission of the copolymers. Thus, when R was CH3 (or H), the polymer showed yellow–green (or red) emission; whereas the polymers showed the emission from green to yellow–green, when R was CH2(CH2)5CH3 or CH2OCH(CH3)2. To investigate the nature of the color change, a Gaussian 03 program was used for estimation of the dihedral angles between a 5‐R‐2,1,3‐benzothiadiazole unit and a 2,7‐carbazole unit. The results showed that the different substituents at 5‐position of 2,1,3‐benzothiadiazole brought about different the dihedral angles, which gave the different conjugation levels to the polymers. Hence, the tunablity of emission color may be attributed to the different conjugation levels between 2,7‐carbazole units and 5‐R‐2,1,3‐benzothiadiazole units induced by simply changing substituent groups at 5‐position of benzothiadiazole unit. Electrochemically, the copolymers exhibited a higher oxidation potential as well as the reversible reduction behavior bearing from 2,1,3‐benzothiadiazole unit. To investigate the electroluminescent properties of the polymers, the nonoptimized devices were fabricated and the results showed that the electroluminescent emission wavelength was basically similar to that of the photoluminescent. All polymers showed good thermal stability with 5 wt % loss temperature of more than 296 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1376–1387, 2008
Synthesis and micellization of star‐like hyperbranched polymer with poly(ethylene oxide) and poly(ε‐caprolactone) arms
Authors: Wang Huan‐Bing , Chen Xue‐Si , Pan Cai‐Yuan 
Published: December 2007

AbstractNovel star‐like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3‐amino‐1,2‐propanediol (APD) with feed molar ratio of 1:2. 1H, 13C, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A‐MPEO) and carboxylic acid‐terminated poly(ε‐caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core–shell structures with poly(1TT‐2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star‐like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and 1H NMR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1388–1401, 2008
The effect of γ‐cyclodextrin addition in the self‐assembly behavior of pyrene labeled poly(acrylic) acid with different chain sizes
Authors: Costa Telma , Seixas de Melo J. S. 
Published: December 2007

AbstractThe interaction between poly(acrylic acid) polymers (PAA) of low‐ (2000 g/mol) and high‐ (450,000 g/mol) molecular weight (Mw) hydrophobically modified with pyrene (PAAMePy) and β‐ and γ‐cyclodextrins (β‐CD, γ‐CD) was investigated with fluorescent techniques. The interaction with β‐CD promotes little variation in the spectral and photophysical behavior of the polymer, whereas significant changes are observed upon addition of γ‐CD. The degree of inclusion (between the pyrene groups of the polymer and the cyclodextrins) is followed through the observation of the changes in the absorption, excitation (collected in the monomer and excimer emission regions) and emission (IE/IM ratio) spectra and from time‐resolved data. Within the studied range of γ‐CD concentration, the fluorescence decays of the long chain (high Mw) PAAMePy polymers were found tri‐exponential in the monomer and excimer emission regions in agreement with previous studies. In the case of the low Mw PAAMePy polymers, tri‐exponential decays were observed at the monomer and excimer emission wavelengths. However, when a γ‐CD concentration of 0.01 and 0.03 M is reached for, respectively, the low‐ and high‐labeled pyrene short chain (low Mw) polymers, the fluorescence decays in the excimer region become biexponential (two excimers) with no rising component, thus showing that all pyrene groups are encapsulated (and preassociated) into the γ‐CD cavity. In the case of the high Mw polymers, the addition of γ‐CD has been found to change the level of polymer interaction from pure intramolecular (water in the absence of cyclodextrin) to a coexistence of intra‐ with intermolecular interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1402–1415, 2008