bluuebunny/crossref_metadata_2025_split huggingface dataset:
Highly Sensitive, Photocontrolled, Organic Thin‐Film Transistors Using Soluble Star‐shaped Conjugated Molecules
Authors: Cho Mi Yeon , Kim Su Jin , Han Yoon Deok , Park Dong Hyuk , Kim Kyung Hwan , Choi Dong Hoon , Joo Jinsoo 
Published: September 2008

AbstractThe highly photosensitive characteristics of organic thin‐film transistors (OTFTs) made using soluble star‐shaped oligothiophenes with four‐armed π‐conjugation paths, 4(HPBT)‐benzene and 4(HP3T)‐benzene molecules having a relatively high quantum yield, are reported. 4(HPBT)‐benzene‐based organic phototransistors (OPTs) exhibited high photosensitivity (∼2500–4300 A W−1) even with low optical powers (∼6.8–30 µW cm−2) at zero gate bias. The measured photosensitivity of the devices was much higher than that of inorganic single‐crystal Si‐based phototransistors, as well as that of other OPTs reported earlier. With the highly photosensitive characteristics of the 4(HPBT)‐benzene‐based OPTs, a high ratio of the on and off current switching of ∼4 × 104 with low optical power and low gate bias was observed. The slow relaxation of the photoinduced charges and charge‐trapping phenomena at the interface could lead to a reproducible memory operation for 4(HPBT)‐benzene‐based OPTs.
Hydrothermal Reaction Mechanism and Pathway for the Formation of K2Ti6O13 Nanowires
Authors: Zhang Ting , Chen Qing , Peng Lian‐Mao 
Published: September 2008

AbstractCalculations and detailed first principle and thermodynamic analyses have been performed to understand the formation mechanism of K2Ti6O13 nanowires (NWs) by a hydrothermal reaction between bulk Na2Ti3O7 crystals and a KOH solution. It is found that direct ion exchange between K+ and Na+ plus H+ interactions with [TiO6] octahedra in Na2Ti3O7 promote the formation of an intermediate H2K2Ti6O14 phase. The large lattice mismatch between this intermediate phase and the bulk Na2Ti3O7 structure, and the large energy reduction associated with the formation of this intermediate phase, drive the splitting of the bulk crystal into H2K2Ti6O14 NWs. However, these NWs are not stable because of large [TiO6] octahedra distortion and are subject to a dehydration process, which results in uniform K2Ti6O13 NWs with narrowly distributed diameters of around 10 nm.
Synthesis and Optical Properties of KYF4/Yb, Er Nanocrystals, and their Surface Modification with Undoped KYF4
Authors: Schäfer Helmut , Ptacek Pavel , Zerzouf Otmane , Haase Markus 
Published: September 2008

AbstractKYF4/Yb3+, Er3+ nanocrystals with a mean diameter of approximately 13 nm were synthesized at 200 °C in the high boiling organic solvent N‐(2‐hydroxyethyl)ethylenediamine (HEEDA). The particles crystallize in the cubic phase known from α‐NaYF4 and form transparent colloidal solutions in tetraethylene glycol (TEG) or propanol. Solutions containing 1 wt % of the nanocrystals in TEG display visible upconversion emission upon continuous wave (CW) excitation at 978 nm. Growing undoped KYF4 on the surface of the KYF4/Yb3+, Er3+ nanocrystals increases the upconversion efficiency by more than a factor of 20. The XRD data of these particles, display a slight increase in the mean particle size from 13 to 15.5 nm, indicating that only a part of the subsequently added KYF4 shell material is deposited onto the particle surface. Nevertheless the performed surface modification obviously leads to core/shell structured particles.
An Air‐Supported Liquid Crystal System for Real‐Time and Label‐Free Characterization of Phospholipases and Their Inhibitors
Authors: Hartono Deny , Bi Xinyan , Yang Kun‐Lin , Yung Lin‐Yue Lanry 
Published: September 2008

AbstractA new air‐supported liquid crystal (LC) system for analyzing interfacial phenomena that occur based on the molecular interaction between LCs and adsorbed molecules of interest at the aqueous/LC interface is reported. Compared with existing LC‐based detection systems, the miniature system reported here requires less sample and involves simpler preparation. Using this system, the enzymatic hydrolysis of various phospholipases such as phospholipase A2 (PLA2), phospholipase C (PLC) and phospholipase D (PLD) are characterized. The hydrolysis of phospholipid monolayers self‐assembled at aqueous/LC interface induces an orientational response from the LCs. As a result, an optical signal that reflects the spatial and temporal distribution of phospholipids during the enzymatic reaction can be generated in a real‐time manner. When well‐known phospholipase inhibitors are introduced together with respective phospholipases, no orientational response of LCs is observed. In the case of inhibitors MJ33 and compound 48/80, cross‐inhibitions among phospholipases are also observed. This work demonstrates that the air‐supported LC system provides a facile label‐free assay for characterizing phospholipase activities and for screening enzyme inhibitors. It could potentially be useful for different high throughput and cost‐effective enzyme screening assays.
Optimization of Orange‐Emitting Electrophosphorescent Copolymers for Organic Light‐Emitting Diodes
Authors: Haldi Andreas , Kimyonok Alpay , Domercq Benoit , Hayden Lauren E. , Jones Simon C. , Marder Seth R. , Weck Marcus , Kippelen Bernard 
Published: September 2008

AbstractOrange‐emitting phosphorescent copolymers containing iridium complexes and bis(carbazolyl)fluorene groups in their side chains are employed as the emissive layer in multilayer organic light‐emitting diodes (OLEDs). The efficiency of the OLED devices is optimized by varying characteristics of the copolymers: the molecular weight, the iridium loading level, and the nature and length of the linker between the side chains and the polymer backbone. A maximum efficiency of 4.9 ± 0.4%, 8.8 ± 0.7 cd A−1 at 100 cd m−2 is achieved with an optimized copolymer.
A Ligand Exchange Route to Highly Luminescent Surface‐Functionalized ZnS Nanoparticles and Their Transparent Polymer Nanocomposites
Authors: Lü Changli , Gao Junfang , Fu Yuqin , Du Yaying , Shi Yongli , Su Zhongmin 
Published: September 2008

AbstractA facile ligand exchange approach for surface‐functionalized ZnS nanoparticles (NPs) with 5‐(2‐methacryloylethyloxymethyl)‐8‐quinolinol (MQ) is described. The MQ–ZnS NPs, with a cubic crystal structure, have the same diameter as ZnS NPs without MQ about 3.0 nm. The MQ–ZnS NPs exhibit strong fluorescence emission at about 500 nm and a high photoluminescence (PL) quantum yield (QY), up to 40%, with a decreasing ratio of MQ to ZnS NPs. The PL decay study reveals that the lifetimes of the different MQ–ZnS NPs with a single exponential decay are in the nanosecond time domain for emission at about 500 nm, which is obviously different from that of ZnS NPs with a biexponential decay for defect‐state emission at 420 nm. The functionalized MQ–ZnS NPs are successfully incorporated into the polymer matrix by in situ bulk polymerization to fabricate transparent bulk nanocomposites with good thermal stability and processability. Transmission electron microscopy results show that the NPs are uniformly dispersed in the polymer matrix without aggregation. The good PL properties of MQ–ZnS NPs are preserved in the bulk nanocomposites. It is observed that the nanocomposites have red‐shifted excitation and emission wavelengths compared with those of both the polymer matrix and MQ–ZnS NPs, possibly because of the cooperative interaction between MQ–ZnS NPs and the polymer matrix with blue emission.
Multifunctional Mesostructured Silica Microspheres from an Ultrasonic Aerosol Spray
Authors: Li Li , Tsung Chia‐Kuang , Ming Tian , Sun Zhenhua , Ni Weihai , Shi Qihui , Stucky Galen D. , Wang Jianfang 
Published: September 2008

AbstractMultifunctional mesostructured silica microspheres are prepared using ultrasonic aerosol spray in conjunction with solvent evaporation‐induced assembly. Rare earth ion–phenanthroline complexes, magnetite particles, photoacid generators, and pH‐sensitive dyes are chosen as luminescent, magnetic, and photosensitive components. The incorporation of these functional components into mesostructured silica microspheres can be readily realized by dispersing them in the precursor solution of the aerosol spray process. Luminescent microspheres that can emit at multiple wavelengths when excited at a single wavelength are produced by the addition of multiple rare earth complexes into the precursor solution. The addition of magnetite particles leads to the production of magnetic luminescent microspheres. Photoacid generators and pH‐sensitive dyes are further employed to produce magnetic photosensitive microspheres that can release acid and change color upon UV light illumination. Such multifunctional microspheres could have exciting potential for many optical and biotechnological applications, such as multiplexed labeling, diagnosis, simultaneous imaging and therapy, cell capture and separation, targeted delivery, and optical data storage.
Single Component Self‐Assembled Monolayers of Aromatic Azo‐Biphenyl: Influence of the Packing Tightness on the SAM Structure and Light‐Induced Molecular Movements
Authors: Elbing Mark , Błaszczyk Alfred , von Hänisch Carsten , Mayor Marcel , Ferri Violetta , Grave Christian , Rampi Maria Anita , Pace Giuseppina , Samorì Paolo , Shaporenko Andrei , Zharnikov Michael 
Published: September 2008

AbstractAiming at modulating the packing density within functional self‐assembled monolayers (SAMs), two azo‐biphenyl derivatives AZO1 and AZO2 comprising a terminal sulfur anchor group have been designed and synthesized. While AZO1 allows for a coplanar arrangement of both biphenyl subunits, additional steric repulsion due to two methyl side groups attached to the footing biphenyl of AZO2 results in an increased intermolecular distance within the SAM, providing additional free volume. SAMs of both derivatives on gold and platinum substrates have been formed and thoroughly investigated by photoelectron (XPS) and near‐edge absorption fine structure (NEXAFS) spectroscopy as well as cyclic voltammetry and scanning tunneling microscopy. These measurements confirmed the formation of tightly packed SAMs for AZO1, while AZO2 formed SAMs consisting of less organized and more loosely packed molecules. Optical investigations of both azo derivatives in solution as well as their SAMs displayed efficient photoisomerization in solution and in SAMs. Comparable maximal cis/trans ratios of ca. 0.9 have been observed in all cases upon irradiation at λ = 370 and 360 nm for AZO1 and AZO2, respectively. The thermally induced cis → trans back reaction on AZO1 was found to be slower by a factor of 3 in SAMs as compared to solution, while AZO2 displayed comparable rates of the back reaction in both environments. This behavior can be explained by the different nature of molecular isomerization in the two SAM systems: whereas the isomerization in AZO1 SAMs takes place in a highly coordinated, collective way and involves many adjacent molecules, AZO2 species behave rather individually even packed in SAMs, such that their isomerization process is similar in SAMs and in solutions.
Solution‐Processible Phosphorescent Blue Dendrimers Based on Biphenyl‐Dendrons and Fac‐tris(phenyltriazolyl)iridium(III) Cores
Authors: Lo Shih‐Chun , Bera Raghu N. , Harding Ruth E. , Burn Paul L. , Samuel Ifor D. W. 
Published: September 2008

AbstractSolution‐processible saturated blue phosphorescence is an important goal for organic light‐emitting diodes (OLEDs). Fac‐tris(5‐aryltriazolyl)iridium(III) complexes can emit blue phosphorescence at room temperature. Mono‐ and doubly dendronized fac‐tris(1‐methyl‐5‐phenyl‐3‐n‐propyl‐1H‐[1,2,4]triazolyl)iridium(III) 1 and fac‐tris{1‐methyl‐5‐(4‐fluorophenyl)‐3‐n‐propyl‐1H‐[1,2,4]triazolyl}iridium(III) 4 with first generation biphenyl‐based dendrons were prepared. The dendrimers emitted blue light at room temperature and could be solution processed to form thin films. The doubly dendronized 3 had a film photoluminescence quantum yield of 67% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.33). OLEDs comprised of a neat film of dendrimer 3 and an electron transport layer achieved a brightness of 142 cd m−2 at 3.8 V with an external quantum efficiency of 7.9%, and CIE coordinates of (0.18, 0.35). Attachment of the fluorine atom to the emissive core had the effect of moving the luminescence to shorter wavelengths but also quenched the luminescence of the mono‐ and doubly dendronized dendrimers.
Flow distribution property of the constructal distributor and heat transfer intensification in a mini heat exchanger
Authors: Fan Yilin , Boichot Raphaël , Goldin Thierry , Luo Lingai 
Published: September 2008

AbstractThis article reports a numerical and experimental study on flow maldistribution and heat transfer intensification in a mini heat exchanger with constructal distributor/collector integrated. The flow distribution characteristics of the constructal component functioning as a fluid distributor or as a fluid collector have been investigated and compared using computational fluid dynamics simulations. An experimental setup is designed and constructed for thermal and hydraulic performances tests. The effects of various assembly configurations on heat transfer characteristics and pressure drops are discussed. The results indicate that the integration of one constructal collector at the outlet of the heat exchanger can achieve almost uniform flow distribution and consequently better intensify the heat transfer. It is also the most advantageous configuration based on a balanced consideration of heat transfer intensification and pump power consumption under the investigation conditions. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Spitzenverstärkte optische Nahfeldmikroskopie
Authors: Hartschuh Achim 
Published: September 2008

AbstractSpektroskopiemethoden mit höchster Ortsauflösung sind von grundlegender Bedeutung für die Untersuchung der physikalischen und chemischen Eigenschaften von nanostrukturierten Materialien einschließlich Quantenstrukturen und biologischen Oberflächen. Wir stellen ein optisches Verfahren vor, das auf den stark überhöhten elektrischen Feldern in der Nähe einer laserbeleuchteten Metallspitze basiert. Diese Felder ermöglichen die Messung verschiedener optischer Signale in räumlich stark begrenzten Bereichen und ermöglichen so eine detaillierte Probencharakterisierung weit jenseits der Beugungsgrenze. Darüber hinaus liefern die verstärkten Felder auch die notwendige Nachweisempfindlichkeit für die Messung kleinster Probenvolumina. Zunächst werden die Grundlagen der Nahfeldoptik erläutert, im Anschluss behandeln wir die verschiedenen Mechanismen, die zur lokalen Feldverstärkung beitragen, und zeigen, wie sich damit optische Signale verstärken lassen. Verschiedene experimentelle Umsetzungen und einige aktuelle Ergebnisse zu Raman‐ und Fluoreszenzmikroskopie mit bis zu 10 nm Ortsauflösung an einzelnen Molekülen werden vorgestellt.
Semiconductor Quantum Dots for Bioanalysis
Authors: Gill Ron , Zayats Maya , Willner Itamar 
Published: September 2008

AbstractSemiconductor nanoparticles, or quantum dots (QDs), have unique photophysical properties, such as size‐controlled fluorescence, have high fluorescence quantum yields, and stability against photobleaching. These properties enable the use of QDs as optical labels for the multiplexed analysis of immunocomplexes or DNA hybridization processes. Semiconductor QDs are also used to probe biocatalytic transformations. The time‐dependent replication or telomerization of nucleic acids, the oxidation of phenol derivatives by tyrosinase, or the hydrolytic cleavage of peptides by proteases are probed by using fluorescence resonance energy transfer or photoinduced electron transfer. The photoexcitation of QD–biomolecule hybrids associated with electrodes enables the photoelectrochemical transduction of biorecognition events or biocatalytic transformations. Examples are the generation of photocurrents by duplex DNA assemblies bridging CdS NPs to electrodes, and by the formation of photocurrents as a result of biocatalyzed transformations. Semiconductor nanoparticles are also used as labels for the electrochemical detection of DNA or proteins: Semiconductor NPs functionalized with nucleic acids or proteins bind to biorecognition complexes, and the subsequent dissolution of the NPs allows the voltammetric detection of the related ions, and the tracing of the recognition events.
It All Began with an Error: The Nomofungin/Communesin Story
Authors: Siengalewicz Peter , Gaich Tanja , Mulzer Johann 
Published: September 2008

AbstractThe communesin/nomofungin/perophoramidine story is an impressive example of how biogenetic considerations can lead to the correction of structural misassignments and inspire synthetic chemists with new, fruitful ideas. Intensive studies by a number of research groups culminated in the total synthesis of perophoramidine by the Funk research group in 2004. In 2007, Qin and co‐workers completed the first total synthesis of a communesin.
Postsynthetic DNA Modification through the Copper‐Catalyzed Azide–Alkyne Cycloaddition Reaction
Authors: Gramlich Philipp M. E. , Wirges Christian T. , Manetto Antonio , Carell Thomas 
Published: September 2008

AbstractThe attachment of labels onto DNA is of utmost importance in many areas of biomedical research and is valuable in the construction of DNA‐based functional nanomaterials. The copper(I)‐catalyzed Huisgen cycloaddition of azides and alkynes (CuAAC) has recently been added to the repertoire of DNA labeling methods, thus allowing the virtually unlimited functionalization of both small synthetic oligonucleotides and large gene fragments with unprecedented efficiency. The CuAAC reaction yields the labeled polynucleotides in very high purity after a simple precipitation step. The reviewed technology is currently changing the way in which functionalized DNA strands are generated cost‐efficiently in high quality for their application in molecular diagnostics systems and nanotechnological research.
AACVD of WO3 thin films from W(O)(OPri)3[O(CH2)nNMe2] (n = 2, 3)
Authors: Molloy K. C. , Williams P. A. 
Published: September 2008

AbstractMonomeric tungsten oxo‐aminoalkoxides W(O)(OPri)3(L) [L = O(CH2)nNMe2; n = 2 (dmae, 1) and 3 (dmap, 2)] were synthesized by alcohol exchange with [W(O)(OPri)4]2 and characterized spectroscopically. 1, 2 and [W(O)(OPri)4]2 were used as precursors for the aerosol‐assisted chemical vapour deposition of WO3 thin films, which were characterized by glancing angle X‐ray diffraction, SEM and transmission‐reflectance measurements. Copyright © 2008 John Wiley & Sons, Ltd.
Enhancement of PEMFC performance by using carbon nanotubes supported PtCo alloy catalysts
Authors: Saha Madhu Sudan , Chen Yougui , Li Ruying , Sun Xueliang 
Published: September 2008

AbstractCarbon nanotube‐based PtCo (PtCo/CNT) alloy electrocatalysts for the oxygen reduction reaction were prepared by the silane‐assisted deposition method. The transmission electron microscopy (TEM) reveals that the prepared PtCo alloy nanoparticles are uniformly dispersed on the surface of the CNTs support with narrow particle size distribution. As compared to Pt/CNTs catalyst, the bimetallic PtCo/CNTs catalyst exhibits an improved performance as cathode material in a H2/O2fuel cell. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Manufacture of solvent‐free polylactic‐glycolic acid (PLGA) scaffolds for tissue engineering
Authors: Liu Shih‐Jung , Hsueh Chun‐Lien , Wen‐Neng Ueng Steve , Lin Song‐Su , Chen Jan‐Kan 
Published: September 2008

AbstractConventional methods for fabricating polymeric scaffolds often use organic solvents which might be harmful to cells or tissues. The purpose of this report was to develop a solvent‐free method for the fabrication of three‐dimensional scaffolds for tissue engineering. To manufacture a scaffold, polylactide‐polyglycolide (PLGA) copolymers were premixed with sodium chloride particulates. The mixture was then compression molded and sintered to form a cylinder. After sintering, the cylinder was submerged in water for 48 h to leach out the particulates. The scaffold, with approximately 2 × 107 mesenchymal stem cells (MSCs) of the New Zealand rabbit, was then cultured in an osteogenic culture medium for 14 days. The alkaline phosphatase activity, calcium level, and the mineral deposition of cultured cells in the PLGA scaffolds were determined. The results showed that an increase of alkaline phosphatase activity and calcium levels, as well as abundant mineral deposition, was observed in the cultured mesenchymal stem cells. In addition, scaffolds with pore sizes of 88–125 µm showed the most number of cells during the period of culture. Developing solvent‐free biodegradable scaffolds for bone cells may provide a potential method for the treatment of infected bone defects. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Crystalline study of amorphous poly(ethylene terephthalate) sheets through annealing
Authors: Tsai Ruey‐Shi , Lee Da‐Kong , Fang Han‐Yu , Tsai Hong‐Bing 
Published: September 2008

AbstractPoly(ethylene terephthalate) (PET) sheets of different crystallinity were obtained by annealing. The annealed PET sheets were characterized by the density measurement, differential scanning calorimetry (DSC), ultraviolet (UV)‐visible spectrometry, X‐ray diffraction, and infrared (IR) spectrometry. The density data can be used as a basic measurement of the degree of crystallinity. The total transition heat data obtained from the first run DSC heating curves can correlate with the crystallinity, although it may underestimate the crystallinity for those samples with higher crystallinity. The visible light transmittance data can be related to the crystallinity, and are very sensitive to the change of the crystallinity for the PET sheets of low crystallinity. The X‐ray diffraction data and IR transmittance data do not show strong linear relationship to the crystallinity in a quantitative way. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Ethanol‐tolerant Pt‐alloy cathodes for direct ethanol fuel cell (DEFC) applications
Authors: Rodríguez Varela F. J. , Savadogo O. 
Published: September 2008

AbstractThe electroactivity of Pt1Co1(a/o)/C and Pt3Cr1(a/o)/C for the oxygen reduction reaction (ORR) in ethanol‐containing medium was studied. It was found that these cathodes present a high tolerance to this alcohol. The onset potential of the ORR decreased at 14 and 12 mV in the presence of 0.5 M ethanol on Pt1Co1/C and Pt3Cr1/C, respectively. The tolerance of the Pt alloys is one order of magnitude higher than that shown by Pt‐alone catalysts in previous works. Exceptionally, the Pt1Co1/C alloy maintained a very important electrocatalytic activity, i.e. a very small variation in current density at 400 mV in electrochemical cell measurements and improved performances in a direct ethanol fuel cell (DEFC). The current densities obtained from the DEFC equipped with a 10% Pt1Co1/C cathode were similar to those obtained when 20% Pt3Cr1/C was used. However, a higher performance in terms of Pt content was shown by PtCo/C. These electrochemical characteristics indicate the advantage of using PtCo alloys as cathodes in DEFCs. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.