bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synthesis of α‐tert‐butyl‐ω‐[p‐vinylphenyl]‐terminated poly(2‐methylpropene) macromonomers
Authors: Nuyken Oskar , Gruber Freddy , Pask Stephen D. , Riederer Alexander , Walter Michael 
Published: April 2003

AbstractIn this communication a novel synthetic route to α‐tert‐butyl‐ω‐[p‐vinylphenyl]xy1terminated poly(2‐methylpropene) (PIB) macromonomers (P3 (VB); P5) is described:
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Attempts to synthesize such macromonomers in both one‐ and two‐step syntheses are described. The one‐step method using 4‐chloromethylstyrene/AlR3 as initiating system for the polymerization of 2‐methylpropene did not yield linear macromonomers but rather highly branched products. The alternative two‐step synthesis using 1‐(2‐bromoethyl)‐4‐chloromethylbenzene (BCB) or BCB/AgSbF, as initiator also failed to yield the desired products. Successful syntheticroutes, optimised on the basis of model experiments with low molar mass compounds, are also described for preparing the above macromonomers. Both of these routes involve isopropenylterminated PIB, which is easily assessible by Inifer technique followed by dehydrohalogenation. Friedel‐Crafts alkylation of phenol by the terminal olefin group of PIB, followed by subsequentesterification of the phenolic end‐groups with 4‐vinylbenzoyl chloride, affords the macromonomer P3(VB). Conversion of the terminal olefin group of PIB into a primary alcohol using 9‐bora[3,3, I]‐bicyclononane/H202, followed by esterification, yields the macromonomer P5.
Conversion of the polydiacetylene of bis(ethylurethane) of 5,7‐dodecadiyne‐1,12‐diol to a non‐thermochromic crystalline form by solvent extraction
Authors: Sandman Daniel J. , Downey Milton J. , Hankin Sandra H. W. 
Published: April 2003

AbstractExposure of crystals of the thermochromic polydiacetylene (PDA) of the bis(ethylurethane) of 5,7‐dodecadiyne‐1,12‐diol (ETCD) to the hot solvents chlorobenzene and N,N‐dimethylformamide results in the conversion of the material to a nonthermochromic form. The material resulting from chlorobenzene extraction retains its original shape and is crystalline. It was further characterized by differential scanning calorimetry, X‐ray powder diffraction, and Raman spectroscopy. Significant amounts of chlorobenzene are not retained in the extracted material. It is indicated that chlorobenzene extracts monomer and oligomer causing expansion of the lattice, some disordering of the polymer chains, and removal of the interactions which allow observation of thermochromism. The implications of these findings for the role of possible mechanical strains in the crystal structure‐thermochromism relationship in urethane‐substituted PDA crystals are discussed.
Cationic polymerization of α‐pinene with aluminium‐based binary catalysts, 2. Survey of catalyst systems
Authors: Higashimura Toshinobu , Lu Jiang , Kamigaito Masami , Sawamoto Mitsuo , Deng Yun‐Xiang 
Published: April 2003

AbstractA series of metal halides (AlCl3, AlBr3, AlEtCl2, BF3 · OEt2, SnCl4, TiCl4, and WCl6) were employed in conjunction with antimony trichloride (SbCl3) for the cationic polymerization of α‐pinene in toluene at −15°C. The combinations of aluminium halides (AlCl3, AlBr3, and AlEtCl2) with SbCl3 gave high molecular weight oligomers (M̄n ≥ 700) in good yield (>80 wt.‐%) with low dimer contents (5–17 wt.%). The other metal halides, both in the absence and presence of SbCl3, gave large amounts (20–40 wt.‐%) of dimers along with low molecular weight oligomers. 1H NMR analysis of the obtained oligomers showed that they consist of two isomerized repeating units, one (1) unsaturated (with a cyclohexene ring) and the other (2) saturated (with a bornyl structure). The oligomers obtained with aluminium halides/SbCl3 contained higher amounts of unsaturated units 1 than those with aluminium halides alone. The higher the molecular weight, the larger the content of 1. Isomerization of α‐pinene slightly occurred in the course of the polymerization, and the structure of the isomers depended on the catalyst systems. These results show that the aluminium halide/SbCl3 binary systems promote the ring‐opening of the cyclobutane unit in α‐pinene to give higher molecular weight oligomers.
Hydration of poly(pyridiniumsulfonatopropyl betaines)
Authors: Galin Monique , Galin Jean Claude 
Published: April 2003

AbstractThe hydration of poly(2‐vinyl‐ and 4‐vinylpyridinium‐3‐sulfonatopropyl betaines) (P2VP‐SB (1) and P4VP‐SB (2)) was studied by sorption isothermal analysis (activity of water a = 0,14–0,98) and by differential scanning calorimetry (DSC, weight fraction of water <0,5). The sorption isotherms at 296 K are typical of a multilayer sorption process (Guggenheim‐Anderson‐De Boer equation): the number of site‐bound water molecules per monomeric unit is 1,33 and 1,59 for 1 and 2, respectively; polymer‐water mixing for indirectly bound solvation layers corresponds to a thermodynamically unfavourable process characterized by Flory's interaction parameter χ of 0,85 and 0,75 for 1 and 2, respectively (Takizawa approach); however, clustering of water molecules (Zimm‐Lundberg theory) is never observed. For 1, DSC allows to quantify three types of water: non‐freezable bound water (type I), 5,0 mol per monomeric unit; freezable bound water (type II), 5,5 mol per monomeric unit, showing a two‐peak melting endotherm at 267 ± 1 K and 271 ± 1 K; bulk free water (type III, melting temperature Tm = 274 K), emerging far before the saturation of all the binding sites for type II water. The poly(pyridinium zwitterions) display slightly decreased hydrophilicity with respect to their aliphatic quaternary ammonium homologues.
The ring‐opening metathesis polymerization of (±)‐5‐endo‐methoxynorborn‐2‐ene. Microstructure of the polymers
Authors: Ivin Kenneth J. , Lam Luk‐Mui , Rooney John J. 
Published: April 2003

AbstractThe title monomer (±)‐5‐endo‐methoxynorborn‐2‐ene ((±)‐5‐endo‐methoxybicyclo[2.2.1]‐hept‐2‐ene, 1) was polymerized by Ru‐, W‐, Ir‐, Re‐ and Mo‐based metathesis catalysts to yield polymers with cis contents ranging from 10% to 48%. An assignment of the 13C NMR spectra was made. No significant head‐tail bias was observed and no splitting due to tacticity could be positively identified.
Electron microscopy investigations of polyester‐polyurethane elastomers stained with ruthenium tetroxide
Authors: Schrader Sigurd , Li Xuan , Guo Fanxiu , Liu Yong , Luo Jijiang , Xu Duanfu 
Published: April 2003

AbstractMicrophase separation of as‐reacted polyester‐polyurethane samples based on α‐hydro‐ω‐hydroxypoly(oxyethyleneoxyadipoyl)/4,4′‐methylenedi(phenyl isocyanate)/1,4‐butanediol/2‐ethyl‐2‐hydroxymethyl‐1,3‐propanediol (mole ratio 1:3,2:1,9:0,1) was studied using transmission electron microscopy. A new staining technique was applied which uses ruthenium tetroxide vapour for the treatment of the polymer. Ruthenium tetroxide reacts preferably with the hard‐segment‐rich microdomains of the polyester‐polyurethane. Therefore, a well‐contrasted pattern is formed by staining which reflects the microdomain structure of the polymer. The hard‐segment‐rich microdomains have irregular, mostly globular shape, and their sizes range from about 2 to 8 nm.
Protein phosphatase 1cγ is required in germ cells in murine testis
Authors: Oppedisano‐Wells Leandra , Varmuza Susannah 
Published: April 2003

AbstractThe protein phosphatase 1cγ (PP1cγ) gene is required for spermatogenesis. Males homozygous for a null mutation are sterile, and display both germ cell and Sertoli cell defects. As these two cell types are physically and functionally intimately connected in the testis, the question arises as to whether the primary site of PP1cγ action is in Sertoli cells, germ cells, or both. We generated chimeric males by embryo aggregation to test whether wild type Sertoli cells are capable of rescuing mutant germ cells. To distinguish between the desired XY‐XY chimeras and uninformative XX‐XY chimeras, we designed an adaptation of the single nucleotide primer extension (SNuPE) assay. None of the XY‐XY chimeras sired pups derived from mutant germ cells, indicating that the protein is required in germ cells for production of functional sperm. Analysis of a chimeric testis revealed intermediate phenotypes when compared with PP1cγ−/− testes, suggestive of cell nonautonomous effects. We conclude that PP1cγ is required in a cell autonomous fashion in germ cells. There may be an additional cell nonautonomous role played by this gene in testes, possibly mediated by defective signaling between germ cells and Sertoli cells. Mol. Reprod. Dev. 65: 157–166, 2003. © 2003 Wiley‐Liss, Inc.
Expression of vascular endothelial growth factor and its receptors in the rhesus monkey (Macaca mulatta) endometrium and placenta during early pregnancy
Authors: Wang Hongmei , Li Qinglei , Lin Haiyan , Yu Xiaodong , Qian Dong , Dai Jiejie , Duan Enkui , Zhu Cheng 
Published: April 2003

AbstractVascular endothelial growth factor (VEGF) is fundamental for development and maintenance of endometrial and placental vascular function during pregnancy. While there are a number of studies on VEGF in the human placenta, they are mostly restricted to late pregnancy. To further understand the role of VEGF in mediating angiogenesis during human early pregnancy, we employed a rhesus monkey early pregnancy model to study the temporal and spatial expression of VEGF and its receptors, fms‐like tyrosine kinase (Flt)‐1, and kinase‐insert domain‐containing receptor (KDR) mRNAs and proteins in the uteri on day 12, 18, and 26 of pregnancy using in situ hybridization, RT‐PCR, and immunohistochemistry. VEGF mRNA had been identified in the luminal epithelium on day 12, in the glandular epithelium on day 12 and 18, and the highest expression was detected in the walls of some spiral arterioles adjacent to the implantation site on day 18, in the placental villi and in the fetal‐maternal border on day 18 and 26. Besides, immunostaining of VEGF was detected in the placental villi and endometrial compartments including spiral arteries walls and the glandular epithelium. The localization of VEGF in the endothelium correlates with the presence of Flt‐1 and KDR receptors on vascular structure. All the results above suggest that VEGF‐VEGFR pairs were involved in the process of trophoblast invasion, maternal vascular transformation, and fetoplacental vascular differentiation and development during the rhesus monkey early pregnancy. Expression of VEGF, Flt‐1, and KDR in the epithelial cells also hints some additionally functional roles of VEGF during early pregnancy. Mol Reprod. Dev. 65: 123–131, 2003. © 2003 Wiley‐Liss, Inc.
Imaging single mammalian cells with a 1.5 T clinical MRI scanner
Authors: Foster‐Gareau Paula , Heyn Chris , Alejski Andrew , Rutt Brian K. 
Published: April 2003

AbstractIn the present work, we demonstrate that the steady‐state free precession (SSFP) imaging pulse sequence FIESTA (fast imaging employing steady state acquisition) used in conjunction with a custom‐built insertable gradient coil and customized RF coils can be used to detect individual SPIO‐labeled cells using a commonly available 1.5 T clinical MRI scanner. This work provides the first evidence that single‐cell tracking will be possible using clinical MRI scanners, opening up new possibilities for cell tracking and monitoring of cellular therapeutics in vivo in humans. Magn Reson Med 49:968–971, 2003. © 2003 Wiley‐Liss, Inc.
Method for quantitative imaging of the macromolecular 1H fraction in tissues
Authors: Ropele Stefan , Seifert Thomas , Enzinger Christian , Fazekas Franz 
Published: April 2003

AbstractA new method was developed for mapping the relative density of the macromolecular protons involved in magnetization transfer (MT). This method employs a stimulated echo preparation scheme in order to modulate the phase distribution within a spin ensemble. This labeled spin ensemble is then used as an intrinsic indicator, which is diluted due to magnetization exchange with macromolecular protons. A pulse sequence is presented which compensates for longitudinal relaxation, allows observation of the dilution effect only, and provides for calculation of parameter maps using indicator dilution theory. Compared to other quantitative MT techniques, neither additional relaxation time measurements nor knowledge regarding the lineshape of the macromolecular proton pool are required. Moreover, the inherent low specific absorption rate and the low sensitivity for B1 errors make this method favorable in a clinical setting. This sequence was used to measure the macromolecular proton density in cross‐linked bovine serum albumin. Using a navigated echo planar readout, the sequence was also employed to visualize the macromolecular content of human brain in vivo. Magn Reson Med 49:864–871, 2003. © 2003 Wiley‐Liss, Inc.
Comparison of inversion recovery preparation schemes for lipid suppression in 1H MRSI of human brain
Authors: Ebel Andreas , Govindaraju Varanavasi , Maudsley Andrew A. 
Published: April 2003

AbstractTo reduce contamination from subcutaneous lipid regions in MR spectroscopic imaging (MRSI) of whole brain, lipid signals are often suppressed using T1 nulling methods. If a range of lipid T1 values is present, the suppression efficiency will be improved using multiple inversion recovery (MIR) preparation. This study compared single IR (SIR) and double IR (DIR) applied with a volumetric MRSI sequence at 1.5 T based on experimental measurement of lipid T1 and T2 relaxation rates. At short and medium echo times (TEs), an approximately 28–47% improvement in lipid suppression was achieved with DIR compared to SIR. However, it also led to a loss of 37–43% in signal‐to‐noise ratio (SNR) for metabolites. Thus, SIR appears to be the better choice for suppressing lipid signals and maintaining metabolite sensitivity. Magn Reson Med 49:903–908, 2003. © 2003 Wiley‐Liss, Inc.
Proton echo‐planar spectroscopic imaging with highly effective outer volume suppression using combined presaturation and spatially selective echo dephasing
Authors: Chu Archie , Alger Jeffry R. , Moore Gregory J. , Posse Stefan 
Published: April 2003

AbstractA highly effective outer volume suppression (OVS) technique, termed spatially selective echo dephasing (SSED), which employs gradient dephasing of spatially selective spin echoes, is introduced. SSED, which is relatively insensitive to T1 dispersion among lipid signals and B1 inhomogeneity, was integrated with very high spatial resolution 2D proton echo‐planar spectroscopic imaging (PEPSI) to assess residual lipid bleeding into cortical regions in the human brain. The method was optimized to minimize signal refocusing of secondary spin‐echoes in areas of overlapping suppression slices. A comparison of spatial presaturation with single or double SSED, and with combined presaturation and SSED shows that the latter method has superior performance with spatially uniform lipid suppression factors in excess of 70. Metabolite mapping (choline, creatine, and NAA) with a 64 × 64 spatial matrix and 0.3 cm3 voxels in close proximity to peripheral lipid regions was demonstrated at 1.5 T with a scan time of 32 min using the standard head coil. Magn Reson Med 49:817–821, 2003. © 2003 Wiley‐Liss, Inc.
PUBS: Pulsatility‐based segmentation of lumens conducting non‐steady flow
Authors: Alperin Noam , Lee Sang Hoon 
Published: April 2003

AbstractDynamic velocity‐encoded phase‐contrast MRI (PC‐MRI) techniques are being used increasingly to quantify pulsatile flows for a variety of clinical applications. Studies suggest that the reliability of flow quantitation with PC‐MRI appears to be dominated by the consistency in the delineation of the lumen boundary. An automated method that utilizes both spatial and temporal information has been developed for improved accuracy and reproducibility. The method's accuracy was evaluated using a flow phantom with 8‐ and 5‐mm‐diameter lumens at two different flow rates. The reproducibility of the method was further evaluated with arterial, venous, and cerebrospinal fluid flow data from human subjects. The results were compared with measurements obtained manually by observers of different skill levels. Measurement values obtained manually were consistently smaller than those obtained with the pulsatility‐based segmentation (PUBS) method. For the 8‐mm lumen, significant improvements in measurement accuracy were obtained. Average lumen area measurement errors of about 18% for the high and low flows, obtained manually by a skilled observer, were reduced to 2.9% and 4.8%, respectively. For the 5‐mm lumen, the skilled observer underestimated the lumen area by 13%, while the PUBS method overestimated the lumen area by 28%. Overestimated lumen area measurements for the smaller lumen are attributed to the partial‐volume effect. There was significantly less measurement variability with the PUBS method. An average fourfold reduction in interobserver measurement variability was obtained with the new method. Magn Reson Med 49:934–944, 2003. © 2003 Wiley‐Liss, Inc.
Managing the impersonal in a personalized public service
Authors: Gretchen Kay 
Published: April 2003

AbstractWhat happens when an apparently personalized small public service enters the information highway? How does it integrate the new frame of mind implied in the impersonal, open approach to information? The practical implications of implementing information technology as a means to use information strategically in the Maltese public service, with its apparently paradoxical administrative style, prompted the pilot study in early 2000 upon which this article is based. Using a simplified empirical approach, the study tested the hypothesis that small scale could affect the way leaders deal with the impersonal, such as information resource management. Although limited in scope, the results of the study support a qualified conclusion that small scale, through its link with personalization and associated informal mechanisms, does affect the way top managers in the public service deal with the impersonal, at least in the short and medium term. To what extent it does so, or the space for change, are subjects for further research. The article concludes with suggestions for further investigation into this topic, both in its narrow and wider applications. Copyright © 2002 John Wiley & Sons, Ltd.
Savings from integrating administrative systems for social assistance programmes in Russia
Authors: Jerome Gallagher L. , Struyk Raymond J. , Nikonova Ludmila 
Published: April 2003

AbstractRussian local governments now have primary responsibility for the administration of social assistance programmes thanks to a combination of decentralization of some responsibilities from higher levels of government and the transfer of certain administrative functions from state enterprises to municipalities. Over the past few years, there has also been a distinct shift to means‐testing of social assistance. This article reports on the results of a pilot project undertaken to improve the efficiency of programme administration conducted in the city of Arzamas (pop. 110,000). The municipal administration promotes it as a programme to ease client burden and improve access to benefits. Specifically, the pilot introduced a unified application form for all the major social assistance programmes in the city and required, regardless of how many programmes are applied for, that applicants visit only one office and supply one set of documents verifying their eligibility for assistance. Benefit processing is also consolidated. Staff efficiency improvements are substantial: under the one‐window system, 127 benefits are processed per month per staff member, while 85 benefits were processed per month per staff member under the old administrative system. Impressive time savings for clients were also observed: the statistically average client saves between 1.3 and 2.4 hours, depending on the degree to which a client was able to coordinate documentation collection and trips to the benefit agencies under the old system. The total potential time saved by clients as a result of the one‐window reforms is between 4100 and 7600 person hours per month. Copyright © 2002 John Wiley & Sons, Ltd.
Nurturing knowledge: the UK Higher Education Links scheme
Authors: Eldridge Derek A. , Wilson Elisabeth M. 
Published: April 2003

AbstractThis article examines the development of academic networks and expertise through the UK Higher Education Links scheme, which is funded by the UK Department for International Development, managed by the British Council and supported by the principals of UK higher education institutions. The links are established between UK and overseas universities primarily to enhance research and/or teaching capacity, with the ultimate aim of alleviating poverty and promoting sustainable development. This article draws on data gathered for a large‐scale, multiple‐method evaluation which endorsed the scheme's continuation. It is argued that a crucial factor helping to make individual links a success was good relationships between respective co‐ordinators, although the nature of these relationships varied. The article discusses the extent to which the formation of fruitful academic networks and partnerships enabling knowledge transfer were encouraged. Copyright © 2003 John Wiley & Sons, Ltd.
Governance conditions, roles and capacity‐building needs in the rebel‐held areas of Southern Sudan
Authors: Blunt Peter 
Published: April 2003

AbstractAn assessment is made of the state of sustainable human development (SHD) and the institutions of governance that are in the process of being established in the rebel‐held areas of Southern Sudan. The development roles of the main governance actors—government, civil society and the private sector—are examined and capacity‐building needs are described. The importance of good leadership, institutionalised partnerships between government and national and international NGOs, and capacity building for transparency and accountability is stressed. Most pointedly, the risks of allowing governance practices, suited to the management of a liberation struggle, to spill over into the civil administration of a peaceful state are emphasised. The conditions necessary for the institutionalisation of sound governance practices are discussed. Of particular importance are a genuine desire on the part of the leadership to establish such conditions and a willingness on the part of external donors to address issues of accountability and transparency openly in collaboration with the leadership. The data are also suggestive of broad development strategies that address the bases of SHD and empowerment. These broad strategies are designed to improve the very low levels of health and education that exist in the Southern Sudan, and thereby empower people to engage in economic activity and in governance decision‐making. Rehabilitation and maintenance of the physical infrastructure underlies all development activity. The findings highlight the governance difficulties faced by war‐torn societies, the challenges facing post‐crisis administrations and (confirming Caplan 2002) the need for such administrations to possess sufficient executive authority to be able to perform effectively in situations of ‘pre‐state, post‐imperial chaos’. Most critical of all, however, is the genuine interest of the major powers in doing more than—when it suits them—extinguishing the flames of conflict or establishing acquiescent political regimes following the military pacification of ‘rogue’ or anarchic states. Effective post‐crisis administration and development calls for much greater commitment of resources from the major powers than has been forthcoming to date, reflecting a belief among them that equitable and sustainable global development is the preferred route to the prevention of such crises. Copyright © 2003 John Wiley & Sons, Ltd.