bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial filling technique in capillary electrophoresis for the separation of phenolic isomers with sulfonatocalix[4]arene as a selector
Authors: Xu Hui , Yu Xiao‐Dong , Chen Hong‐Yuan
Published: December 2003

p‐Sulfonatocalix[4]arene was used as a selector in capillary electrophoresis to separate phenolic positional isomers. To avoid the detection interference caused by the high UV absorption of calixarene, the partial filling technique was applied. The operation variables, including buffer, separation voltage, the concentration of the selector and the plug length of the selector zone, were systematically optimized. The detection limits of mass were in the range of 0.07–0.28 pg. Molecular modeling was used to explain the interaction between calixarene and phenolic isomers.
Chiral separation with ligand‐exchange micellar electrokinetic chromatography using a D‐penicillamine‐copper(II) ternary complex as chiral selector
Authors: Zheng Zhi‐Xia , Lin Jin‐Ming , Qu Feng , Hobo Toshiyuki
Published: December 2003

D‐Penicillamine is demonstrated for the first time as a chiral ligand for the enantioseparation of dansyl amino acids based on ligand‐exchange micellar electrokinetic chromatography (LE‐MEKC). Copper(II) was used as the central ion in the ternary complex. The effect of surfactant on the resolution was significant. A concentration of 20 mM sodium dodecyl sulfate (SDS) was shown to be necessary for the separation. Other important parameters, such as the concentration ratio of D‐penicillamine (D‐PEN) to Cu2+, the kind of metal central ion, the type and pH value of buffer, were also investigated. N‐Acetyl‐D‐penicillamine and L‐valine (Val), with similar structure to D‐penicillamine, were applied as their copper(II) complexes as chiral selector and the chiral recognition mechanism is briefly discussed. Under optimum experimental conditions, i.e., 20 mM NH4OAc, pH 6.5, a 2:1 concentration ratio of D‐penicillamine to Cu(II), 4 mM CuSO4 and 8 mM D‐penicillamine, the chiral separation of eight pairs of different dansyl amino acid enantiomers was accomplished with resolution ranging from 1.1 to 5.9. When L‐PEN was used instead of D‐PEN, reversal of the migration order was observed.
High‐throughput separation of DNA and proteins by three‐dimensional geometry gel electrophoresis: Feasibility studies
Authors: Ventzki Robert , Stegemann Josef
Published: December 2003

We report a novel separation method that is applicable to both DNA and protein samples, based on electrophoresis in a three‐dimensional (3‐D) geometry. In contrast to conventional electrophoresis, samples are applied in a two‐dimensional, planar array to one of the surfaces of a 3‐D geometry separation medium. Loading onto a plane results in a very high sample capacity. Sample migration and separation occur along the third spatial dimension, which is perpendicular to the loading plane. The key problem of electrophoresis in a 3‐D geometry separation setup is that temperature gradients are caused by Joule’s heat, affecting the electrical conductivity and viscosity of the separation medium. A means of achieving straight sample migration under these circumstances is to force heat flow through the separation medium parallel to the axis of sample migration. This can be done by dissipating the heat via the electrode sides of the gel and blocking any other heat transfer. The separation of DNA and proteins by this method has been tested using agarose gel electrophoresis, polyacrylamide gel electrophoresis, and sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. Data were acquired off‐line by conventional staining methods as well as on‐line by detection of laser‐induced fluorescence. We describe how to excise samples from the separation medium for preparative purposes. Possible unique applications of this 3‐D geometry electrophoresis separation method are also discussed.
Perfusive flow and intraparticle distribution of a neutral analyte in capillary electrochromatography
Authors: Tallarek Ulrich , Pačes Martin , Rapp Erdmann
Published: December 2003

The relevance and magnitude of an electroosmotic perfusion mechanism in electrochromatography is analyzed. To systemize our studies we first considered the transport of an electroneutral and nonadsorbing tracer. Based on the refractive index matching in a microfluidic setup containing fixed spherical porous particles, we conducted a quantitative analysis in real time of the spatio‐temporal distribution of fluorescent tracer molecules during their uptake by (and a release from) single particles using confocal laser scanning microscopy. Even under conditions of a significant electrical double layer overlap the intraparticle electroosmotic flow produces due to its unidirectional nature and in striking contrast to the symmetric (spherical) distributions typical for purely diffusive transport strongly asymmetric concentration profiles inside spherical particles as the locally charged pore liquid begins to respond to the externally applied electrical field. The profiles retain an axisymmetric nature, i.e., rotational symmetry with respect to the field direction. Results of our measurements could be successfully interpreted and further analyzed by a compact mathematical model. Intraparticle Peclet numbers of up to 150 have been realized and found to significantly enhance the mass transport on particle scale towards the convection‐dominated regime when compared to a conventional (diffusion‐limited) kinetics.
Capillary zone electrophoresis with a dynamic double coating for analysis of carbohydrate‐deficient transferrin in human serum: Impact of resolution between disialo‐ and trisialotransferrin on reference limits
Authors: Lanz Christian , Thormann Wolfgang
Published: December 2003

Capillary electrophoresis with a dynamic double coating formed by charged polymeric reagents represents a very effective tool for the separation of iron‐saturated transferrin (Tf) isoforms and thus the determination of carbohydrate‐deficient transferrin (CDT) in human serum. The resolution between di‐ and trisialo‐Tf is dependent on the applied voltage and capillary temperature. With a 50 μm inside diameter (ID) capillary of about 60 cm total length mounted into the P/ACE MDQ, 28 kV and 40°C, the resolution of the two Tf isoforms is shown to be between 1.0 and 1.4, whereas with reduced voltage and/or temperature, increased resolution at the expense of elongated run times is observed. Best data with complete resolution (Rs ≥ 1.4) are obtained at 20 kV and 30°C. For the determination of CDT in serum, incomplete separation of di‐ and trisialo‐Tf is demonstrated to have an impact on the reference limits. Analysis of the sera of 54 healthy individuals with no or moderate alcohol consumption and using valley‐to‐valley peak integration, the upper (lower) reference limits for CDT in relation to total Tf at the two power levels are 1.33 (0.52) and 1.57 (0.81)%, respectively, representing intervals that are significantly different (P < 0.001). Furthermore, the reference intervals are shown to be strongly dependent on the peak integration approach used. Valley‐to‐valley peak integration should only be employed for conditions with complete resolution between disialo‐ and trisialo‐Tf.
Sparsely cross‐linked “nanogels” for microchannel DNA sequencing
Authors: Doherty Erin A. S. , Kan Cheuk Wai , Barron Annelise E.
Published: December 2003

We have developed sparsely cross‐linked “nanogels”, sub‐colloidal polymer structures composed of covalently linked, linear polyacrylamide chains, as novel DNA sequencing matrices for capillary electrophoresis. The presence of covalent cross‐links affords nanogel matrices with enhanced network stability relative to standard, linear polyacrylamide (LPA), improving the separation of large DNA fragments. Nanogels were synthesized via inverse emulsion (water‐in‐oil) copolymerization of acrylamide and N,N‐methylenebisacrylamide (Bis). In order to retain the fluidity necessary in a replaceable polymer matrix for capillary array electrophoresis (CAE), a low percentage of the Bis cross‐linker (< 10−4 mol%) was used. Nanogels were characterized by multiangle laser light scattering and rheometry, and were tested for DNA sequencing by CAE with four‐color laser‐induced fluorescence (LIF) detection. The properties and performance of nanogel matrices were compared to those of a commercially available LPA network, which was matched for both weight‐average molar mass (Mw) and extent of interchain entanglements (c/c*). Nanogels presented in this work have an average radius of gyration of 226 nm and a weight‐average molar mass of 8.8×106 g/mol. At concentrations above the overlap threshold, nanogels form a clear, viscous solution, similar to the LPA matrix (Mw ∼ 8.9×106 g/mol). The two matrices have similar flow and viscosity characteristics. However, because of the physical network stability provided by the internally cross‐linked structure of the nanogels, a substantially longer read length (∼ 63 bases, a 10.4% improvement) is obtained with the nanogel matrix at 98.5% accuracy of base‐calling. The nanogel network provides higher‐selectivity separation of ssDNA sequencing fragments longer than 375 bases. Moreover, nanogel matrices require 30% less polymer per unit volume than LPA. This is the first report of a sequencing matrix that provides better performance than LPA, in a side‐by‐side comparison of polymer matrices matched for Mw and extent of interchain entanglements.
Piperazine quaternary diammonium salts as additives to background electrolytes in capillary zone electrophoresis
Authors: Sebastiano Roberto , Lapadula Marta , Righetti Pier Giorgio , Gelfi Cecilia , Citterio Attilio
Published: December 2003

The differential behavior of five different quaternary mono‐ and diammonium salts, among the 18 investigated, in modulating the electroendoosmotic flow (EOF) and analyte separations in capillary zone electrophoresis is evaluated. It is found that quaternary diammonium salts with positive charges separated by more than four carbon atoms, while exhibiting a very strong affinity for chromatographic silica beads, to the point of exhibiting Rf values close to zero, display, on the contrary, a very poor affinity for the silica wall of capillaries. Compounds separated only by a C2 unit (i.e., 1,4‐dialkyl‐1,4‐diazoniabicyclo[2,2,2,]octane, salts 17 and 18) show high Rf values due to strong ion pair association. The unique behavior of quaternary monoammonium salts possessing an iodinated alkyl (butyl or octyl) tail (i.e., 1, 6, and 7) is attributed to their ability to be covalently affixed to the silica wall via alkylation of ionized silanols at alkaline pH values. They thus strongly modulate and typically invert the EOF, even when not present in the background electrolyte. On the contrary, all diammonium salts, devoid of such alkyl tails, are unable to modulate the EOF and to prevent analyte binding to the silica wall, since they are rapidly removed from the wall by the voltage gradient. However, if added in small amount to the background electrolyte, they offer excellent separations of mixtures of very similar organic acids and prevent any interaction with the capillary wall.
Appreciating appreciative inquiry
Authors: Rogers Patricia J. , Fraser Dugan
Published: December 2003

This chapter argues that Appreciative Inquiry has potential in some circumstances if evaluators can successfully implement the difficult group processes and sustained engagement that it requires.
Inquiry into appreciative evaluation
Authors: Patton Michael Quinn
Published: December 2003

Appreciative Inquiry evaluation offers an important new option in evaluation's increasingly vast repertoire of approaches. Its ultimate legitimacy and credibility will depend on how it is applied and used.
An overview of appreciative inquiry in evaluation
Authors: Coghlan Anne T. , Preskill Hallie , Tzavaras Catsambas Tessie
Published: December 2003

Appreciative inquiry is an approach to seeking what is right in an organization in order to create a better future for it. How and when it might be used in evaluation practice is explored in this chapter.
Using appreciative inquiry to evaluate project activities of a nongovernmental organization supporting victims of trauma in Sri Lanka
Authors: Jacobsgaard Mette
Published: December 2003

Appreciative Inquiry was used to highlight the successes of a donor‐supported project of working with victims of trauma in an environment of civil war and high security risk, and thereby also to honor the work of dedicated staff who often face extremely difficult situations.
Factors related to depression in rural and urban noncustodial, low‐income fathers
Authors: Hoard Laura R. , Anderson Elaine A.
Published: December 2003

Although the past 20 years have seen an increased focus on fatherhood, few studies have examined the relationship between a father's geographic location and his psychological well‐being. To address this gap, this study examined low‐income, noncustodial, predominantly African American fathers' depression in relation to locality, social support, and life stresses. Participants were 96 urban and 31 rural noncustodial fathers. Findings indicate depression is positively related to life stress and inversely related to social support. Locality, social support, and life stress accounted for a significant proportion of the variation in fathers' depression. Policy implications and direction for future research is discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 103–119, 2004.
Cultural and practical barriers to seeking mental health treatment for Chinese Americans
Authors: Kung Winnie W.
Published: December 2003

Based on a sample of 1747 from the Chinese American Psychiatric Epidemiological Study, this report examined perceived barriers to mental health treatment. Two factors emerged, namely practical barriers, which included cost of treatment, time, knowledge of access, and language, and cultural barriers consisting of credibility of treatment, recognition of need, and fear of loss of face. Average ratings of all practical barrier items were higher than cultural barrier items, demonstrating the importance of pragmatic considerations for this population. In a novel attempt, this study examined the empirical link between these perceived barriers and actual mental health service use. The practical barrier factor showed significance in predicting service use for both the whole sample and a subsample of individuals with at least one lifetime mental disorder. Cultural barriers, however, did not attain significance. Practice and research implications of the findings are discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 27–43, 2004.
Bystander education: Bringing a broader community perspective to sexual violence prevention
Authors: Banyard Victoria L. , Plante Elizabethe G. , Moynihan Mary M.
Published: December 2003

Recent research documents the problem of sexual violence across communities, often finding its causes to be embedded in community and cultural norms, thus demonstrating the need for community‐focused solutions. In this article we synthesize research from community psychology on community change and prevention with more individually focused studies of sexual violence prevention programs and bystander behavior in emergency and crime situations. The purpose of bringing together this research is to outline a new area of focus for sexual violence prevention: the mobilization of prosocial behavior on the part of potential bystanders. This approach has utility for increasing community receptivity to prevention messages, by decreasing resistance to them, and for increasing the likelihood of community members taking an active role in prevention and intervention. The specific case of sexual violence prevention on college campus communities illustrates this approach. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 61–79, 2004.
Involvement of brain lactate in neuronal metabolism
Authors: Serres Sébastien , Bouyer Jean‐Jacques , Bezancon Eric , Canioni Paul , Merle Michel
Published: December 2003

The involvement of brain lactate in neuronal metabolism was analyzed by ex vivo NMR spectroscopy with rats under the effects of pentobarbital, αchloralose or morphine, which were infused with a solution of either [1‐13C]glucose+lactate or glucose+[3‐13C]lactate for 20 min. Electroencephalogram recordings indicated different brain electrical activity levels under the three drugs with a clear distinction between pentobarbital, on the one hand, and αchloralose and morphine on the other. Labeling of metabolites in brain perchloric acid extracts and of blood glucose and lactate was determined by 13C‐ and/or 1H‐observed/13C‐edited‐NMR spectroscopy. The following were found: (i) the ratio between glutamate C3 and C4 13C‐enrichments increased from pentobarbital to αchloralose and morphine whatever the labeled precursor, indicating a link between metabolic and electrical activity; (ii) under glucose+[3‐13C]lactate infusion, alanine C3 and acetyl–CoA C2 enrichments were higher than that of lactate C3, revealing the occurrence of an isotopic dilution of the brain exogenous lactate (arising from blood) by lactate from brain (endogenous lactate); the latter was synthesized from glycolysis in a compartment other than the neurons; (iii) the contributions of labeled glucose and lactate to acetyl–CoA C2 enrichment indicated that the involvement of blood glucose relative to that of blood lactate to brain metabolism was correlated with brain activity. It can therefore be concluded that the brain electrical activity‐dependent increase in the contribution of blood glucose relative to that of blood lactate to brain metabolism occurred partly via the increase in the metabolism of lactate generated from astrocytic glycolysis. This conclusion supports the hypothesis of an astrocyte–neuron lactate shuttle component in the coupling mechanism between cerebral activity and energy metabolism. Copyright © 2003 John Wiley & Sons, Ltd.
Localized in vivo13C NMR spectroscopy of the brain
Authors: Gruetter Rolf , Adriany Gregor , Choi In‐Young , Henry Pierre‐Gilles , Lei Hongxia , Öz Gülin
Published: December 2003

Localized 13C NMR spectroscopy provides a new investigative tool for studying cerebral metabolism. The application of 13C NMR spectroscopy to living intact humans and animals presents the investigator with a number of unique challenges. This review provides in the first part a tutorial insight into the ingredients required for achieving a successful implementation of localized 13C NMR spectroscopy. The difficulties in establishing 13C NMR are the need for decoupling of the one‐bond 13C–1H heteronuclear J coupling, the large chemical shift range, the low sensitivity and the need for localization of the signals. The methodological consequences of these technical problems are discussed, particularly with respect to (a) RF front‐end considerations, (b) localization methods, (c) the low sensitivity, and (d) quantification methods. Lastly, some achievements of in vivo localized 13C NMR spectroscopy of the brain are reviewed, such as: (a) the measurement of brain glutamine synthesis and the feasibility of quantifying glutamatergic action in the brain; (b) the demonstration of significant anaplerotic fluxes in the brain; (c) the demonstration of a highly regulated malate‐aspartate shuttle in brain energy metabolism and isotope flux; (d) quantification of neuronal and glial energy metabolism; and (e) brain glycogen metabolism in hypoglycemia in rats and humans. We conclude that the unique and novel insights provided by 13C NMR spectroscopy have opened many new research areas that are likely to improve the understanding of brain carbohydrate metabolism in health and disease. Copyright © 2003 John Wiley & Sons, Ltd.
Role of glial metabolism in diabetic encephalopathy as detected by high resolution 13C NMR
Authors: García‐Espinosa María A. , García‐Martín María L. , Cerdán Sebastián
Published: December 2003

The roles of glial energetics and of the glutamine cycle in diabetic encephalopathy have been investigated ex vivo by 13C NMR in extracts of adult rat brain. Streptozotocin‐induced diabetic or euglycemic animals received intravenous infusions of (1‐13C) glucose in the absence and presence of trifluoroacetic acid or methionine sulfoximine, two selective inhibitors of the glial tricarboxylic acid cycle or of glutamine synthase, respectively. (1‐13C) glucose infusions resulted in smaller 13C incorporation in all carbons of cerebral glutamate, glutamine and GABA in the diabetic animals. Co‐infusion of trifluoroacetic acid with (1‐13C) glucose further reduced the 13C enrichments in cerebral glutamate and glutamine, the decrease being larger in the diabetic animals than in the corresponding euglycemic controls. Methionine sulfoximine decreased to undetectable levels the fractional 13C enrichment in the carbons of cerebral glutamine in both groups and had no significant effect on 13C incorporation in glutamate and GABA, suggesting that glutamine is not the main precursor of glutamate and GABA. Additional animals were infused with (1,2‐13C2) acetate, a major substrate of glial metabolism. In this case, (1,2‐13C2) acetate infusions resulted in increased 13C incorporation in all carbons of glutamate, glutamine and GABA in the diabetic animals. Together, these results reveal that diabetic encephalopathy has an important effect in astroglial metabolism, decreasing glucose transport and metabolism and increasing the relative contribution of glial oxidative metabolism to the support of glutamatergic and GABAergic neurotransmissions. Copyright © 2003 John Wiley & Sons, Ltd.
Feeding versus infusion: a novel approach to study the NAA metabolism in rat brain
Authors: Karelson Gunnar , Ziegler André , Künnecke Basil , Seelig Joachim
Published: December 2003

Using in vivo 13C‐NMR spectroscopy, the energy metabolism in rat brain has commonly been studied via infusion of 13C‐labeled substrates on a minute to hour time scale. In the present study, as a novel approach, 13C‐enriched animal chow was administered over several days and compared with a 2 h infusion of [U‐13C6]‐glucose. Rats received chow containing either [U‐13C6]‐glucose or [U‐13C]‐biomass (a mixture of proteins, lipids, DNA, and carbohydrates) during 3 to 5 days. During feeding with 13C‐labeled glucose and biomass, in vivo 13C‐NMR spectroscopy was carried out daily and revealed slow but successive label incorporation into a large number of metabolites. Lipids and proteins were not significantly 13C‐enriched during a 2 h infusion of 13C‐labeled glucose, but became the most prominent resonances in the 13C feeding experiment. Likewise, feeding with 13C‐enriched biomass led to additional 13C‐label incorporation into creatine, urea carbons and glycogen. Finally, only the acetyl moiety of N‐acetyl‐aspartate (NAA) became significantly enriched during the 2 h infusion experiment, whereas the aspartyl moiety remained at natural abundance levels. In the feeding experiments, however, label incorporation into all carbons of NAA could be observed. Moreover, isotopomer analysis of brain extracts revealed that the acetyl moiety of NAA in feeding experiments was always more strongly 13C‐enriched than its aspartyl moiety, suggesting that the turnover of the acetyl moiety is faster than that of the aspartyl moiety. The different enrichment kinetics of acetyl and aspartyl moiety could be explained by the existence of two different metabolic pathways reflecting the compartmentalised synthesis of NAA. Copyright © 2003 John Wiley & Sons, Ltd.
In vivo1H‐[13C]‐NMR spectroscopy of cerebral metabolism
Authors: de Graaf Robin A. , Mason Graeme F. , Patel Anant B. , Behar Kevin L. , Rothman Douglas L.
Published: December 2003

13C NMR spectroscopy in combination with the infusion of13C‐labeled precursors is currently the only technique that is capable of quantitatively studying energy metabolism, neurotransmission and other metabolic pathways non‐invasivelyin vivo.1H‐[13C]‐NMR spectroscopy is a high‐sensitivity alternative to direct13C NMR spectroscopy. The development of improved NMR methods for water suppression, spatial localization, broadband decoupling, shimming and signal quantification, together with the availability of high magnetic field strengths, has made1H‐[13C]‐NMR spectroscopy the method of choice for the detection of metabolism at a high spatial and/or temporal resolution.1H‐[13C]‐NMR spectroscopy can now be used to discriminate glutamatergic (excitatory) and GABAergic (inhibitory) neuronal activity. The improved sensitivity allows the detection of metabolism in different tissues (e.g. gray and white matter) and potentially even in smaller structures, like cortical layers. Finally,1H‐[13C]‐NMR spectroscopy allows the detection of energy metabolism and neurotransmission during functional activation, thereby further strengthening our understanding of the neurochemical basis of brain function. Copyright © 2003 John Wiley & Sons, Ltd.
Regulation of glial metabolism studied by 13C‐NMR
Authors: Zwingmann Claudia , Leibfritz Dieter
Published: December 2003

Glial metabolism and their metabolic trafficking with neurons are essential parts of neuronal function, as they modulate, by this means, neuronal activity. Ex vivo and in vitro 13C‐NMR spectroscopy have been used to monitor neural cellular and tissue metabolism. Special emphasis has been given to the metabolic specialization of astrocytes and its enzymatic regulation. For this purpose primary cell cultures are useful tools to study neuronal–glial metabolic relationships as the extracellular fluid can be investigated and manipulated by various stimuli. In astrocytes, glucose is utilized predominantly anaerobically. Glycolysis is interrelated to the astrocytic TCA cycle via bi‐directional signals and metabolic exchange processes between astrocytes and neurons. Besides glucose oxidation, neuronally released glutamate is metabolized through the glial TCA cycle. The flexibility of glutamate metabolism, depending on ammonia and energy homeostasis, and the discovered pyruvate recycling pathway in astrocytes, modulates the glutamine–glutamate cycle. 13C‐NMR studies have extended the concept of the ‘non‐stoichiometric’ glutamate–glutamine cycle between neurons and astrocytes. An alanine–lactate shuttle between neurons and astrocytes contributes to nitrogen transfer from neurons to astrocytes, recycles energy substrates for neurons, and in return promotes intercellular glutamine–glutamate cycling. The conversion of alanine to lactate in astrocytes is regulated by intracytosolic pyruvate compartmentation. In essence, the metabolic flexibility and compartmentalized enzymatic specialization of astrocytes buffers the brain tissue against metabolic impairments and excitotoxicity in response to extracellular stimuli, some of them being released by neurons. These in vitro studies using 13C‐NMR spectroscopy provide important knowledge regarding physiological and pathophysiological regulation of neural metabolism to improve our understanding of general brain function. Copyright © 2003 John Wiley & Sons, Ltd.
Iterative solution of large linear systems with non‐smooth submatrices using partial wavelet transforms and split‐matrix matrix–vector multiplication
Authors: González Patricia , Cabaleiro José C. , Pena Tomás F.
Published: December 2003

The iterative solution of large linear systems with highly irregular matrices cannot be accelerated by wavelet transformation and subsequent sparsification if the transformed matrix is still highly irregular. In this paper we show that if the irregularity of the original matrix is limited to a relatively small known set of rows or columns (as is the case in significant applications), then acceleration can be achieved by a mixed approach in which only the ‘smooth’ submatrix is transformed and iterative solution is implemented using a novel ‘split‐matrix’ form of matrix–vector multiplication. Copyright © 2003 John Wiley & Sons, Ltd.
Stabilized finite element methods with reduced integration techniques for miscible displacements in porous media
Authors: Dias C. M. , Coutinho A. L. G. A.
Published: December 2003

The objective of this work is to study some techniques to increase computational performance of stabilized finite element simulations of miscible displacements. We propose the use of a reduced integration technique for bilinear quadrilateral elements in the determination of the pressure and concentration fields. We also study the evaluation of pressure gradient (Darcy's velocity) by differentiation at super‐convergent points. Numerical examples are shown to validate our approach, accessing its efficiency and accuracy. Copyright © 2003 John Wiley & Sons, Ltd.
An unconditionally stable three level finite difference scheme for solving parabolic two‐step micro heat transport equations in a three‐dimensional double‐layered thin film
Authors: Dai Weizhong , Li Quang , Nassar Raja , Shen Lixin
Published: December 2003

Heat transport at the microscale is of vital importance in microtechnology applications. The heat transport equations are parabolic two‐step equations, which are different from the traditional heat diffusion equation. In this study, we develop a three‐level finite difference scheme for solving the micro heat transport equations in a three‐dimensional double‐layered thin film. It is shown by the discrete energy method that the scheme is unconditionally stable. Numerical results for thermal analysis of a gold layer on a chromium padding layer are obtained. Copyright © 2003 John Wiley & Sons, Ltd.
Numerical modelling of void inclusions in porous media
Authors: Rodríguez‐Ferran Antonio , Sarrate Josep , Huerta Antonio
Published: December 2003

Numerical modelling of porous flow in a low‐permeability matrix with high‐permeability inclusions is a challenging task because the large ratio of permeabilities ill‐conditions the finite element system of equations. We propose a coupled model where Darcy flow is used for the porous matrix and potential flow is used for the inclusions. We discuss appropriate interface conditions in detail and show that the head drop in the inclusions can be prescribed in a very simple way. Algorithmic aspects are treated in full detail. Numerical examples show that this coupled approach precludes ill‐conditioning and is more efficient than heterogeneous Darcy flow. Copyright © 2003 John Wiley & Sons, Ltd.
Effects of watchdog organizations on the social capital market
Authors: Silvergleid Jordan E.
Published: December 2003

This chapter examines the effects that watchdog agency evaluations of nonprofit organizations have on private donations.
Charitable fundraising for fun and profit: A satire
Authors: Levis Bill
Published: December 2003

Want to know how to milk the charitable sector of its lifeblood? Read on! This story tells you all you need to know to divert millions of dollars in contributions from America's charities.
Cost‐effectiveness of nonprofit telemarketing campaigns
Authors: Keating Elizabeth K. , Parsons Linda M. , Alston Roberts Andrea
Published: December 2003

Professional fundraisers get a lot of bad press. This chapter documents the expenses, yields, and other characteristics of charitable telemarketing campaigns.
Development of novel flame‐retardant thermosets based on benzoxazine–phenolic resins and a glycidyl phosphinate
Authors: Espinosa M. A. , Cádiz V. , Galiá M.
Published: December 2003

Modified novolac resins with benzoxazine rings were prepared and copolymerized with a glycidyl phosphinate. Their curing behavior and the thermal properties of the curing resins were studied. Copolymerization was studied with model compounds considering the functionality of the benzoxazine‐based phenolic resins and the easy isomerization of the glycidyl phosphinate. Phenolic novolac resin acts as an initiator but p‐toluensulfonic acid had to be used to decrease the curing temperature and to prevent glycidyl phosphinate from isomerizing. The materials obtained exhibited high glass‐transition temperatures and retardation on thermal degradation rates. V‐0 materials were obtained when the materials were tested for ignition resistance with the UL‐94 test. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 279–289, 2004
Chain‐growth limiting reactions in the cationic polymerization of 3‐ethyl‐3‐hydroxymethyloxetane
Authors: Bednarek Melania , Kubisa Przemysław
Published: December 2003

3‐Ethyl‐3‐hydroxymethyloxetane (EOX) polymerizes readily to branched multihydroxyl polyethers. Molecular weights of the polymers are, however, limited, and macromolecules are predominantly cyclic. This indicates that intramolecular chain transfer to polymer (back‐biting) proceeds in the system. Repeating units in poly‐EOX contain two nucleophilic sites that may participate in back‐biting, namely ether groups and hydroxyl groups. Analysis of matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of poly‐EOX prepared in the presence of analogous polyether that does not contain HO groups (poly(3,3‐dimethyloxetane)‐poly‐DMOX) shows that the ether group in the repeating unit of poly‐DMOX does not participate in chain transfer to the polymer. However, when DMOX was polymerized in the presence of poly‐EOX, clear evidence of participation of HOgroups in intramolecular chain transfer was obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 245–252, 2004
Effect of phenol and derivatives on atom transfer radical polymerization in the presence of air
Authors: Gnanou Yves , Hizal Gürkan
Published: December 2003

The various phenolic compounds in conjunction with Cu(II) or Cu(I)‐N,N,N′,N″,N″‐pentamethyl diethylenetriamine (PMDETA) complexes are used to initiate atom transfer radical polymerization (ATRP) of methyl methacrylate, styrene, and methyl acrylate in the presence of a limited amount of air at temperatures in the range of 80–110 °C. Meanwhile, an effort is directed toward the elucidation of the role of phenol and derivatives in ATRP catalyzed by Cu(II)/PMDETA. The catalytic sequence involves the formation of Cu(I) by electron transfer from phenol to Cu(II); Cu(I) so formed can then react in two distinctly different ways: with organic halide to form a propagating radical or with oxygen to form copper salt in its higher oxidation state; and regeneration of Cu(I) by excess phenol. Such regeneration of Cu(I) would be expected to lead to polymerization as a result of the consumption of oxygen and phenol as well. The phenols with electron releasing groups tended to increase the conversion of the polymerization. In this respect, sodium phenoxide, a more effective additive was found, whereas p‐nitro phenol was the least effective. The obtained polymers displayed the common features of a controlled polymerization such as molecular weight control and low polydispersity index value (Mw/Mn < 1.5). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 351–359, 2004
UV grafting of methacrylic acid and acrylic acid on high‐density polyethylene in different solvents and the wettability of grafted high‐density polyethylene. II. Wettability
Authors: Wang Huiliang , Brown Hugh R.
Published: December 2003

The wettability of high‐density polyethylene grafted with methacrylic acid is strongly influenced by the nature of the grafting solvent. Here, the wettability is expressed by the water contact angle and absorbency. The initial (10‐s) contact angle of polyethylene (PE) grafted in acetone/water solution decreased rapidly with the extent of grafting at low grafting levels and then remained independent of the grafting level at about 50°. When a water droplet was left on the surface for a longer time, its contact angle decreased to a very low value in the period of about 10 min. For the PE samples grafted in dichloromethane, petroleum ether, cyclohexane, and chloroform, there was only a small decrease (10°) in the contact angle of water from that observed on pure PE, even when the extent of grafting was very large. The PE films grafted in these organic solvents also took a much longer time than PE films grafted in acetone/ water solution to obtain equilibrium water absorbency. The water absorbency of PE films grafted in 30% acetone/water solution was about twice that of PE films grafted in the other solvents at the same extent of grafting. These results suggested that for the solvents other than acetone/water, the grafted layer is partially buried below the surface of PE. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 263–270, 2004
Synthesis and properties of organosoluble polyimides based on 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone
Authors: Yang Chin‐Ping , Su Yu‐Yang
Published: December 2003

A novel, fluorinated diamine monomer with the ether–ketone group, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone (2), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 4,4′‐dihydroxybenzophenone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Flourinated polyimides (PIs) 5a–f and copolyimides (co‐PIs) 5c/a–f were synthesized from 2 and various commercial aromatic dianhydrides via thermal or chemical imidization. PIs 5a–f had inherent viscosities ranging from 0.72 to 1.22 dL/g. Besides the chemical imidization of 5c(C), the 5(C) series were soluble in amide‐type solvents and even in less polar solvents, but PIs 5a–f prepared via thermal imidization were insoluble. PI films 5a–f exhibited tensile strengths ranging from 92 to 112 MPa, elongations at break from 8 to 15%, and initial moduli from 2.0 to 2.1 GPa. The glass‐transition temperatures of the 5 series were in the range of 232–278 °C, and the 10% weight‐loss temperatures were above 535 °C, with more than a 50% char yield at 800 °C in nitrogen. In comparison of the PI 5 series with the analogous non‐fluorinated PIs 6 series based on 4,4′‐bis(4‐aminophenoxy)benzophenone, the 5 series revealed better solubility, lower color intensity, dielectric constant, and moisture absorption. Their PI films had cutoff wavelengths between 370 and 410 nm, b* values ranging from 9.6 to 58.3, dielectric constants of 3.05–3.64 (1 MHz), with moisture absorption in the range of 0.08–0.38 wt %. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 222–236, 2004
Self‐organized liquid‐crystalline polyethers obtained by grafting tapered mesogenic groups onto poly(epichlorohydrin): Toward biomimetic ion channels 2
Authors: Ronda Joan Carles , Reina José Antonio , Giamberini Marta
Published: December 2003

A set of high‐molecular‐weight, new, side‐chain liquid‐crystalline polyethers was obtained by chemical modification of poly(epichlorohydrin) with potassium 3,4,5‐tris[4‐(n‐dodecan‐1‐yloxy)benzyloxy]benzoate. The degree of modification depended on the reaction conditions and ranged from 39 to 58%. The highest value was an apparent modification plateau. NMR characterization indicated no side reactions of any kind (e.g., deshydrohalogenation). All random‐grafted copolymers had hexagonal columnar mesophases with the exception of the least modified copolymer, which had a nematic columnar mesophase. X‐ray diffraction experiments performed on mechanically oriented samples showed that tapered groups were tilted with respect to the column axes. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 326–340, 2004
Ultraviolet grafting of methacrylic acid and acrylic acid on high‐density polyethylene in different solvents and the wettability of grafted high‐density polyethylene. I. Grafting
Authors: Wang Huiliang , Brown Hugh R.
Published: December 2003

Methacrylic acid (MAA) and acrylic acid (AA) were grafted onto high‐density polyethylene (PE) with UV initiation and a range of solvents. With acetone as the solvent, MAA was more easily grafted onto PE when the photoinitiator benzophenone was precoated on PE than when it was dissolved in the monomer solution. The grafting was faster in aliphatic solvents than in polar solvents or a UV‐adsorbing aromatic solvent (toluene). Acetone itself could initiate the photografting of both MAA and AA onto PE when it was mixed with water. The extent of grafting of MAA onto PE showed a maximum when there was about 40% acetone in the mixture. For AA, when the acetone/water concentration was 10%, the extent of grafting increased rapidly with the irradiation time. At higher acetone concentrations, the extent of grafting was low. Atomic force microscopy images showed that the surface topography of PE grafted with MAA in acetone/water was quite different from that obtained when the grafting was performed in other organic solvents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 253–262, 2004
Polymeric ruthenium bipyridine complexes: New potential materials for polymer solar cells
Authors: Marin Veronica , Holder Elisabeth , Schubert Ulrich S.
Published: December 2003

Methyl methacrylate‐containing bipyridine monomers were synthesized with a hydoxy‐functionalized bipyridine. The 4′‐methyl group of the 2,2′‐bipyridine was used to introduce hydoxy‐functionalized alkyl spacers of two different lengths. Two, different synthetic routes were applied for the preparation of the hydoxy‐functionalized bipyridineviaa bromo‐(C7spacer) or a silylated‐(C3spacer) intermediate. A copolymer of poly(methyl methacrylate) with bipyridine units in the side chains was prepared by free‐radical copolymerization and characterized with1H NMR, ultraviolet–visible, and IR spectroscopy as well as gel permeation chromatography. The bipyridine units of the copolymer were reacted with ruthenium bipyridine precursors. The resulting graft copolymers displayed promising photophysical and electrochemical properties, opening interesting perspectives for applications in the field of solar‐cell devices. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 374–385, 2004
Asymmetric polymerization using C1 resources
Authors: Nozaki Kyoko
Published: December 2003

Two examples of asymmetric alternating copolymerization, (1) the alternating copolymerization of α‐olefins (monosubstituted ethenes) with carbon monoxide and (2) the alternating copolymerization of meso‐epoxide with carbon dioxide, are described, and the meaning of chirality in polymer synthesis is emphasized. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 215–221, 2004
Anisotropic elastic moduli and Poisson's ratios of a poly(ethylene terephthalate) film
Authors: Zhang S. L. , Li J. C. M.
Published: December 2003

Expressions for the directional dependence of Young's modulus and Poisson's ratio were derived for a general material under plane‐stress conditions. Experiments with a laser extensometer to measure the Young's modulus and Poisson's ratio directly by a tension test are described, and the results are compared with the theoretical expressions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 260–266, 2004
Effect of supercritical carbon dioxide on the crystallization and melting behavior of linear bisphenol A polycarbonate
Authors: Liao Xia , Wang Jin , Li Gang , He Jiasong
Published: December 2003

The crystallization and melting behavior of bisphenol A polycarbonate treated with supercritical carbon dioxide (CO2) has been investigated with differential scanning calorimetry. Supercritical CO2 depresses the crystallization temperature (Tc) of polycarbonate (PC). The lower melting point of PC crystals increase nonlinearly with increasing treatment temperature. This indicates that the depression of Tc is not a constant at the same pressure. Tc decreases faster at a higher treatment temperature than at a lower temperature. The leveling off of the depression in Tc at higher pressures is due to the antiplasticization effect of the hydrostatic pressure of CO2. The melting curves of PC show two melting endotherms. The lower melting peak moves to a higher temperature with increasing treatment temperature, pressure, and time. The higher temperature peak moves toward a higher temperature as the treatment temperature is increased, whereas this peak is independent of the treatment pressure, time, and heating rate. The double melting peaks observed for PC can be attributed to the melting of crystals with different stability mechanisms. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 280–285, 2004
Optical and electroluminescent properties of novel poly(aryl ether)s with isolated carbazole and p‐quaterphenyl fluorophores
Authors: Chen Yun , Hwang Shiao‐Wen , Chen Shinn‐Horng
Published: December 2003

We report the optical and electroluminescent properties of four novel poly(aryl ether)s (P1–P4) consisting of alternate isolated hole‐transporting [carbazole or 3,6‐bis(styryl)carbazole] and electron‐transporting [dicyano‐p‐quaterphenyl or bis(trifluoromethyl)‐p‐quaterphenyl] fluorophores. The photoluminescence (PL) spectra of the four polymeric films show maximum peaks around 407–413 nm for P1, P2 and 442–447 nm for P3, P4. The PL spectra of P1∼P4 are dependent on the composition of the two isolated fluorophores. According to the observation of relative quantum yield in poor solvent (cyclohexane), P2 containing more bulky trifluoromethyl groups in p‐quaterphenyl segments prevented aggregate quenching processes more than P1. Compared with P1 and P2 with carbazole segments, P3 and P4 with 3,6‐bis(styryl)carbazole segments exhibited less interchain interaction and a low threshold electric field in a single‐layer device. The p‐quaterphenyl and carbazole [or 3,6‐bis(styryl)carbazole] segments were regarded as electron‐transporting and hole‐transporting units, respectively, in the single‐layer light‐emitting diodes (Al/P1–P4/ITO). In the double‐layer device (ITO/MEH‐PPV/P2/Al), the maximum luminance was doubled, and the threshold electric fields diminished because P2 functioned as an electron‐transporting and hole‐blocking layer. Furthermore, the voltage‐tunable multicolor emission from orange to green was observed. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 333–340, 2004
Characterization of photoresists for ArF‐excimer laser lithography using monoenergetic positron beams
Authors: Uedono A. , Ohdaira T. , Suzuki R. , Mikado T. , Fukui S. , Kimura S. , Miyamoto H. , Nemoto H.
Published: December 2003

The volume and depth distributions of open spaces in photoresist films designed for ArF‐excimer laser light exposure were studied with monoenergetic positron beams. We measured the Doppler broadening spectra of the annihilation radiation and lifetime spectra of positrons for acrylate and cyclic olefin‐co‐maleic anhydride (COMA) polymers spin‐coated onto Si wafers with methyl amyl ketone, cyclohexanone, and propylene glycol methyl ether acetate solvents. The volume of open spaces in both prebaked acrylate and COMA films was estimated to be 0.12 nm3. The volume of open spaces in acrylate films decreased up to 20% by postexposure baking, but no large change was observed for COMA films. The decrease in the open volume was attributed to the removal of large molecules (adamantyl) from flexible main chains after the chemically amplified reaction of acrylate. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 341–346, 2004