bluuebunny/crossref_metadata_2025_split huggingface dataset:
Manipulating Charge‐Transfer Character with Electron‐Withdrawing Main‐Group Moieties for the Color Tuning of Iridium Electrophosphors
Authors: Zhou Guijiang , Ho Cheuk‐Lam , Wong Wai‐Yeung , Wang Qi , Ma Dongge , Wang Lixiang , Lin Zhenyang , Marder Todd B. , Beeby Andrew 
Published: February 2008

AbstractA new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2‐phenylpyridine) with various main‐group moieties in [Ir(ppy‐X)2(acac)] (X = B(Mes)2, SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO2Ph). This can be achieved by shifting the charge‐transfer character from the pyridyl groups in some traditional iridium ppy‐type complexes to the electron‐withdrawing main‐group moieties and these assignments were supported by theoretical calculations. This new color tuning strategy in IrIII‐based triplet emitters using electron‐withdrawing main‐group moieties provides access to IrIII phosphors with improved electron injection/electron transporting features essential for highly efficient, color‐switchable organic light‐emitting diodes (OLEDs). The present work furnished OLED colors spanning from bluish‐green to red (505–609 nm) with high electroluminescence efficiencies which have great potential for application in multicolor displays. The maximum external quantum efficiency of 9.4%, luminance efficiency of 10.3 cd A−1 and power efficiency of 5.0 lm W−1 for the red OLED (X = B(Mes)2), 11.1%, 35.0 cd A−1, and 26.8 lm W−1 for the bluish‐green device (X = OPh), 10.3%, 36.9 cd A−1, and 28.6 lm W−1 for the bright green device (X = NPh2) as well as 10.7%, 35.1 cd A−1, and 23.1 lm W−1 for the yellow‐emitting device (X = SO2Ph) can be obtained.
Spin‐Coated Highly Efficient Phosphorescent Organic Light‐Emitting Diodes Based on Bipolar Triphenylamine‐Benzimidazole Derivatives
Authors: Ge Ziyi , Hayakawa Teruaki , Ando Shinji , Ueda Mitsuru , Akiike Toshiyuki , Miyamoto Hidetoshi , Kajita Toru , Kakimoto Masa‐aki 
Published: February 2008

AbstractA new series of star‐shaped bipolar host molecules, tris(4′‐(1‐phenyl‐1H‐benzimidazol‐2‐yl)biphen‐yl‐4‐yl) amine (TIBN), tris(2′‐methyl‐4′‐(1‐phenyl‐1H‐benzimida zol‐2‐yl)biphenyl‐4‐yl)amine (Me‐TIBN), and tris(2,2′‐dimethyl‐4′‐(1‐phenyl‐1H‐benzimidazol‐2‐yl)biphenyl‐4‐yl)amine (DM‐TIBN), that contain hole‐transporting triphenylamine and electron‐transporting benzimidazole moieties are designed based on calculations using density functional theory and successfully prepared. The theoretical calculation of energy levels of TIBN derivatives affords helpful ideas to design molecules with a favorable localization of highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) levels and a predefined enhancement of the triplet energy gap. The TIBN derivatives are employed as hosts to fabricate phosphorescent organic light‐emitting diodes (OLEDs) by the two methods of spin‐coating and vacuum deposition. Notably, the spin‐coated Me‐TIBN and DM‐TIBN devices exhibit a much better performance than the vacuum‐deposited ones, in which the spin‐coated DM‐TIBN device (47 500 cd m−2, 27.3 cd A−1, 7.3 lm W−1) is outstanding with respect to other seminal work for solution‐processed OLEDs. More importantly, the new concept of localizing HOMO and LUMO levels for bipolar molecules is illustrated, and a facile strategy to tailor the energy levels by breaking the conjugation of hole‐ and electron‐transporting moieties is demonstrated.
Cover Picture: Tuning the Rate‐Dependent Stiffness of Materials by Exploiting Néel Relaxation of Magnetic Nanoparticles (Adv. Funct. Mater. 3/2008)
Authors: Singh Harpreet , Wang Mao , Rutledge Gregory C. , Hatton T. Alan 
Published: February 2008

AbstractThe effective stiffness of materials impregnated with magnetic nanoparticles can be modulated by magnetic fields if the nanoparticle Néel relaxation rates are slower than the characteristic deformation rates, report T. Alan Hatton and co‐workers on p 462. Analysis indicates that the deflection of magnetic dipoles against the applied magnetic field on deformation of the material provides the energy absorption necessary for the enhanced stiffness observed in drop ball impact tests. The penetration depth, fraction of the impact energy that is absorbed by the rotating dipoles, and the effective increase in stiffness depend on the ratio of the characteristic magnetic energy density relative to the elastic energy density, and on the shape of the impacting object.Magnetic NanoparticlesHybrid nanostructures with two or more nanoscale components have attracted much attention recently owing to the synergistic properties induced by interactions between the different components. Hao Zeng and Shouheng Sun give an overview on p. 391 of efforts to synthesize multicomponent nanoparticles with at least one magnetic component, and focus on our recent developments. Such nanoparticles show interesting magnetic, magneto‐optical, plasmonic, and semiconducting properties, which can be modulated by interfacial interactions between different components, opening a new avenue to advanced multifunctional nanomaterials for device concepts and applications.SensorsImprinted polymer films for the selective analysis of D‐glucose and D‐mannose can be prepared by co‐electropolymerization of phenol with a 3‐hydroxyphenyl boronic acid‐monosaccharide complex containing D‐glucose or D‐mannose on a gold support. Itamar Willner and co‐workers report on p. 478 that the analysis of the monosaccharides is based on a competitive electrochemical assay that employs the ferrocene‐modified‐monosaccharides as the redox label. Similarly, enantioselectivity is demonstrated by the imprint of D‐glucose recognition sites on the polymer and the application of the redox‐active indicator.Light‐Emitting DiodesColor tuning of cyclometalated iridium phosphors can be achieved by simple tailoring of the phenyl ring of ppy (Hppy = 2‐phenylpyridine) with various main‐group moieties in [Ir(ppy‐X)2(acac)]. This can be achieved by shifting the charge‐transfer character from the pyridyl groups in traditional iridium ppy‐type complexes to the electron‐withdrawing main‐group moieties, as shown by Wai‐Yeung Wong, Dongge Ma, Todd Marder, and co‐workers on p. 499. This new color tuning strategy provides access to IrIII phosphors with improved electron injection/electron transporting features essential for highly efficient, color‐switchable organic light‐emitting diodes (OLEDs).
Worldwide genetic variation in dopamine and serotonin pathway genes: Implications for association studies
Authors: Gardner Michelle , Bertranpetit Jaume , Comas David 
Published: February 2008

AbstractThe dopamine and serotonin systems are two of the most important neurotransmitter pathways in the human nervous system and their roles in controlling behavior and mental status are well accepted. Genes from both systems have been widely implicated in psychiatric and behavioral disorders, with numerous reports of associations and almost equally as numerous reports of the failure to replicate a previous finding of association. We investigate a set of 21 dopamine and serotonin genes commonly tested for association with psychiatric disease in a set of 39 worldwide populations representing global genetic diversity to see whether the failure to replicate findings of association may be explained by population based differences in allele frequencies and linkage disequilibrium (LD) in this gene set. We present results demonstrating a surprising homogeneity of the allele frequencies across worldwide populations in these genes. LD both for populations within continent groupings and across continental regions also showed a remarkable similarity. These findings taken together suggest that ethnic differences in these parameters are not major generators of artifacts in genetic association studies of psychiatric disorders with genes from this set. Therefore, factors other than ethnic differences in genetic variation may explain the discrepancies reported among genetic association studies with this set of genes to date. The transferability of tagSNPs defined in the HapMap populations to other worldwide populations was also investigated and found to be high. A list of tagSNPs per gene and continental region is proposed providing a guide for future association studies with these genes. © 2008 Wiley‐Liss, Inc.
A family‐ and population‐based study of the UFD1L gene for schizophrenia
Authors: Xie Lin , Ye Lin , Ju Guizhi , Xu Qi , Zhang Xuan , Liu Shuzheng , Shi Jieping , Yu Yaqin , Wang Zhenqi , Shen Yan , Wei Jun 
Published: February 2008

AbstractThe present work was undertaken to investigate the association of the UFD1L locus with schizophrenia among 304 Chinese family trios of Han descent. We detected four single nucleotide polymorphisms (SNPs) in the 5′‐end region of the UFD1L gene. The transmission disequilibrium test (TDT) revealed allelic associations for rs5746744 (χ2 = 8.02, P = 0.005) and rs1547931 (χ2 = 7.18, P = 0.007), but failed to replicate disease association for rs5992403 present in the promoter region, which was initially found in Italian and Canadian samples. The allelic association for rs5746744 and rs1547931 was replicated with independently recruited case–control samples. The 2‐SNP haplotype analysis showed an association for the rs5992403‐rs5746744 haplotypes (χ2 = 18.92, df = 3, P = 0.0003), the rs5746744‐rs1547931 haplotypes (χ2 = 11.06, df = 3, P = 0.011) and the rs1547931‐rs2238769 haplotypes (χ2 = 18.88, df = 3, P = 0.0003). The 4‐SNP haplotype analysis also showed strong association with illness (χ2 = 29.54, df = 9, P = 0.0005) but there were more than one individual haplotypes with a low frequency excessively non‐transmitted. The four SNPs tested were not located in the same LD block among the Chinese population. This study raises the possibility that a disease‐resistant variant may be carried by two or more haplotypes at the UFD1L locus due to frequent recombination during meiosis. © 2008 Wiley‐Liss, Inc.
Synthesis, characterization, and thermal degradation kinetics of poly(decamethylene 2‐oxoglutarate)
Authors: Doğan Fatih , Akat Hakan , Balcan Mehmet , Kaya İsmet , Yürekli Mehmet 
Published: February 2008

AbstractPoly(decamethylene 2‐oxoglutarate) [poly (DMOG)] was synthesized by a melt polycondensation reaction. The structure of poly(DMOG) was confirmed by means of Fourier transform infrared, 1H‐NMR, and 13C NMR spectroscopies. The molecular weight distribution values of poly(DMOG) were determined with size exclusion chromatography. The number‐average molecular weight, weight‐average molecular weight, and polydispersity index values of poly(DMOG) were found to be 13,200, 19,000, and 1.439, respectively. Also, characterization was made by thermogravimetry (TG)–dynamic thermal analysis. The kinetics of the thermal degradation of poly (DMOG) was investigated by thermogravimetric analysis at different heating rates. TG curves showed that the thermal decomposition of poly(DMOG) occurred in one stage. The apparent activation energies of thermal decomposition for poly(DMOG), as determined by the Tang method, the Flynn–Wall–Ozawa method, the Kissinger–Akahira–Sunose method, and the Coats–Redfern method were 122.5, 126.8, 121.4, and 122.9 kJ/mol, respectively. The mechanism function and pre‐exponential factor were also determined by the master plots method. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
High‐flow nylon 6 by in situ polymerization: Synthesis and characterization
Authors: Zhang Fan , Zhou Li , Liu Yaochi , Xu Weijian , Xiong Yuanqin 
Published: February 2008

AbstractA new synthetic strategy for high‐flow nylon 6 was developed in this article. Generation 1, 2, 3 (G1, G2, G3) polyamidoamine (PAMAM) dendrimers reacted with p‐phthalic acid by equimolar terminal groups in water solution, respectively, and mother salt solution was then prepared. The high‐flow nylon 6 was prepared with suitable quantity of mother salt solution, end‐capping agent, and ϵ‐caprolactam by in situ polymerization. Blue shifts are found for the peaks of NH (γNH and 2δNH) of the high‐flow nylon 6 compared with pure nylon 6 in the IR spectra. Comparing with the pure nylon 6, the high‐flow nylon 6 containing low content of PAMAM units, has high‐flow property and almost the same mechanical property. The high‐flow nylon 6 with low content of PAMAM units has greater melt‐flow index (MFI) (the value of MFI increased by 70–90%). Hardly any decrease in the tensile strength is observed with the elongation at break decreasing by 20–35%. But the izod impact strength of the high‐flow nylon 6 increases. The SEM images show that the high‐flow nylon 6 presents brittle fracture with conglomeration‐like structure, while pure nylon 6 exhibits plastic fracture with island‐like structure. DSC thermograms of nonisothermal crystallization exhibit that the peak of high‐flow nylon 6 broadens compared with pure nylon 6, and the broader peak means the wider processing temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis of fluorine‐containing acrylate copolymer and application as resins on dyed polyester microfiber fabric
Authors: Xie Kongliang , Hou Aiqin , Shi Yaqi 
Published: February 2008

AbstractThe two resins of fluorine‐containing acrylate are synthesized by atom transfer radical polymerization. The raw materials used are hexafluorobutyl mathacrylate and dodecafluoroheptyl methacrylate. The FTIR, 1HNMR, and 19FNMR are used to characterize copolymer structures. The application as resins on dyed polyester microfiber fabric is investigated. Shade darkening effect of the resins is discussed by color yield (K/S), rates of the color yield increase (I%), and the color differences (ΔE). The polymers containing perfluorine groups have excellent shade darkening effect on dyed polyester microfiber fabric. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synergistic effects of carbon fillers on tensile and flexural properties in liquid‐crystal polymer based resins
Authors: King Julia A. , Keith Jason M. , Glenn Odell L. , Miskioglu Ibrahim , Cole Andrew J. , McLaughlin Scott R. , Pagel Rachel M. 
Published: February 2008

AbstractOne emerging market for thermally and electrically conductive resins is bipolar plates for use in fuel cells. Adding carbon fillers to thermoplastic resins increases the composite thermal and electrical conductivity. These fillers have an effect on the composite tensile and flexural properties, which are also important for bipolar plates. In this study, various amounts of three different types of carbon (carbon black, synthetic graphite particles, and carbon fibers) were added to Vectra A950RX liquid‐crystal polymer. In addition, composites containing combinations of fillers were also investigated via a factorial design. The tensile and flexural properties of the resulting composites were then measured. The objective of this study was to determine the effects and interactions of each filler with respect to the tensile and flexural properties. The addition of carbon black caused the tensile and flexural properties to decrease. Adding synthetic graphite particles caused the tensile and flexural modulus to increase. The addition of carbon fiber caused the tensile and flexural modulus and ultimate flexural strength to increase. In many cases, combining two different fillers caused a statistically significant effect on composite tensile and flexural properties at the 95% confidence level. For example, when 40 wt % synthetic graphite particles and 4 wt % carbon black were combined, the composite ultimate tensile and flexural strength increased more than what would be expected from the individual additive effect of each single filler. It is possible that linkages were formed between the carbon black and synthetic graphite particles that resulted in improved ultimate tensile and flexural strength. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of carbon fillers on the rheology of highly filled liquid‐crystal polymer based resins
Authors: King Julia A. , Tambling Troy M. , Morrison Faith A. , Keith Jason M. , Cole Andrew J. , Pagel Rachel M. 
Published: February 2008

AbstractAdding conductive carbon fillers to insulating resins increases the composite electrical and thermal conductivity. Often, enough of a single type of carbon filler is added to achieve the desired conductivity while still allowing the material to be molded into a bipolar plate for a fuel cell. In this study, various amounts of three different carbons (carbon black, synthetic graphite particles, and carbon fiber) were added to Vectra A950RX liquid‐crystal polymer. The rheological properties of the resulting single‐filler composites were measured. In addition, the rheological properties of composites containing combinations of different carbon fillers were studied via a factorial design. In all cases, the viscosity increased with increasing filler volume fraction and followed a shear‐thinning power‐law model. The factorial design results indicated that each of the single fillers and all the filler combinations caused a statistically significant increase in the composite viscosity when compared at a shear rate of 500 s−1 or at a stress of 105 Pa. For composites containing synthetic graphite particles and/or carbon fiber, the viscosity variation with the volume fraction of carbon followed a modified Maron–Pierce equation. When compared at a constant volume fraction of carbon, composites containing carbon black showed viscosity enhancement above and beyond that shown by the other composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and cure kinetics of liquefied wood/phenol/formaldehyde resins
Authors: Pan Hui , Shupe Todd F. , Hse Chung‐Yun 
Published: February 2008

AbstractWood liquefaction was conducted at a 2/1 phenol/wood ratio in two different reactors: (1) an atmospheric three‐necked flask reactor and (2) a sealed Parr reactor. The liquefied wood mixture (liquefied wood, unreacted phenol, and wood residue) was further condensed with formaldehyde under acidic conditions to synthesize two novolac‐type liquefied wood/phenol/formaldehyde (LWPF) resins: LWPF1 (the atmospheric reactor) and LWPF2 (the sealed reactor). The LWPF1 resin had a higher solid content and higher molecular weight than the LWPF2 resin. The cure kinetic mechanisms of the LWPF resins were investigated with dynamic and isothermal differential scanning calorimetry (DSC). The isothermal DSC data indicated that the cure reactions of both resins followed an autocatalytic mechanism. The activation energies of the liquefied wood resins were close to that of a reported lignin–phenol–formaldehyde resin but were higher than that of a typical phenol formaldehyde resin. The two liquefied wood resins followed similar cure kinetics; however, the LWPF1 resin had a higher activation energy for rate constant k1 and a lower activation energy for rate constant k2 than LWPF2. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Antioxidant Versus Cytotoxic Properties of Hydroxycinnamic Acid Derivatives – A New Paradigm in Phenolic Research
Authors: Esteves Mário , Siquet Christophe , Gaspar Alexandra , Rio Vitor , Sousa Joana B. , Reis Salette , Marques Maria P. M. , Borges Fernanda 
Published: February 2008

AbstractTrihydroxycinnamic derivatives were synthesized and evaluated for their antioxidant and cytotoxic activities. The ester derivatives exhibited a higher radical‐scavenging activity, when liposomes were used as target systems, a fact which may be related to their lipophilicity and conformational preferences. These compounds were found to display significant growth inhibition and cytotoxic effects towards a human cervix adenocarcinoma cell line (HeLa). The partition coefficients presently obtained for the trihydroxycinnamic derivatives correlate well both with their structural characteristics and with their antioxidant/cytotoxic activities. A positive structure‐activity‐property relationship between cytotoxic and antioxidant activities, which is intrinsically related with physico‐chemical and conformational properties, is anticipated, as a noteworthy study that must be done for phenolic systems. As damage events are frequently correlated with oxidative stress, the prevalence of both properties in a single compound could be beneficial in terms of rationale preventive or therapeutic purposes.
Synthesis and Anti‐HIV Activity Evaluation of Novel 2,4‐Disubstituted 7‐Methyl‐1,1,3‐trioxo‐2,4‐dihydro‐pyrazolo‐[4,5‐e][1,2]thiadiazines
Authors: Liu Xin‐yong , Yan Ren‐zhang , Wang Yan , Zhan Peng , De Clercq Erik , Pannecouque Christophe , Witvrouw Myriam , Molina Maria Teresa , Vega Salvador 
Published: February 2008

AbstractA series of novel 2,4‐disubstituted 7‐methyl‐1,1,3‐trioxo‐2,4‐dihydro‐pyrazolo[4,5‐e] [1,2,4]thiadiazines (PTDs) was synthesized, structurally confirmed by spectral analysis, and evaluated for their anti‐HIV activities by inhibition of HIV‐induced cytopathogenicity in MT‐4 cell culture. The results showed that some compounds exhibited inhibitory activity specifically against HIV‐2 replication. The most active HIV‐2 inhibitor was compound 7i (R1 = benzyl, R2 = 4‐t‐butyl‐benzyl) with an EC50 value of 18.7 μM and SI=15, which may provide a useful lead for further molecular optimization.
Combining Light Harvesting and Electron Transfer in Silica–Titania‐Based Organic–Inorganic Hybrid Materials
Authors: Lin Cheng‐Lan , Chen Chih‐Hsien , Lim Tsong‐Shin , Fann Wunshain , Luh Tien‐Yau 
Published: February 2008

AbstractA convenient protocol to fabricate an organic–inorganic hybrid system with covalently bound light‐harvesting chromophores (stilbene and terphenylene–divinylene) and an electron acceptor (titanium oxide) is described. Efficient energy‐ and electron‐transfer processes may take place in these systems. Covalent bonding between the acceptor chromophores and the titania/silica matrix would be important for electron transfer, whereas fluorescence resonant energy transfer (FRET) would strongly depend on the ratio of donor to acceptor chromophores. Time‐resolved spectroscopy was employed to elucidate the detailed photophysical processes. The coupling of FRET and electron transfer was shown to work coherently to lead to photocurrent enhancement. The photocurrent responses reached a maximum when the hybrid‐material thin film contained 60 % acceptor and 40 % donor.
A photobioreactor system for precision cultivation of photoautotrophic microorganisms and for high‐content analysis of suspension dynamics
Authors: Nedbal Ladislav , Trtílek Martin , Červený Jan , Komárek Ondřej , Pakrasi Himadri B. 
Published: February 2008

AbstractSmall‐scale photobioreactors for cultivation of photoautotrophic microbes are required for precise characterization of the growth parameters of wild‐type and engineered strains of these organisms, for their screening, and for optimization of culture conditions. Here, we describe the design and use of a flat‐cuvette photobioreactor that allows accurate control of culture irradiance, temperature, pH, and gas composition combined with real‐time monitoring by a built‐in fluorometer and densitometer. The high‐power LED light source generates precise irradiance levels that are programmed by user‐designed protocols. The irradiance, temperature, and gas composition may be static or dynamically modulated, while optical density and pH may be stabilized in turbidostat and pH‐stat modes, respectively. We demonstrate that the instrument is able to detect minute variations of growth caused, for example, by sudden dilution or by circadian rhythms. The sensitivity of the instrument is sufficient to monitor suspension optical density as low as 10−2. This newly designed photobioreactor can significantly contribute to the study and use of photoautotrophic microbes in systems biology and biotechnology. Biotechnol. Bioeng. 2008;100: 902–910. © 2008 Wiley Periodicals, Inc.