bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pain Reduction on Insertion of a Feeding Tube in Preterm Infants: A Randomized Controlled Trial
Authors: Kristoffersen Laila , Skogvoll Eirik , Hafström Mia 
Published: May 2011

BACKGROUND:
Gavage feeding is required in preterm infants who cannot feed by themselves. Insertion of the feeding tube is painful, and reducing the discomfort in these patients is desirable.

OBJECTIVE:
The aim of this study was to assess pain and discomfort during nasal insertion of a feeding tube, and to evaluate different measures for pain relief.

METHODS:
We included 24 preterm infants with postmenstrual age 28 to 32 weeks' who were in stable condition. Each infant acted as his or her own control over a 3-week period during which the tube was changed 6 times. On these occasions, 6 different treatment combinations were given in randomized order: pacifier or no pacifier, combined with no fluid, sterile water, or 30% sucrose. Pain and discomfort were assessed by at least 2 independent and experienced observers using a pain assessment tool, the Premature Infant Pain Profile; score range: 0 to 21. In general, scores of 4 to 6 are interpreted as normal or no discomfort; ≥12 usually signals significant pain and distress.

RESULTS:
The median Premature Infant Pain Profile score during the procedure was 9 and decreased gradually toward 4 after 5 minutes. The lowest pain score was achieved by combining a pacifier with oral sucrose. Sterile water without a pacifier gave the highest score.

CONCLUSIONS:
Insertion of a feeding tube in preterm infants leads to a measurable degree of pain and discomfort, according to the Premature Infant Pain Profile assessment tool. Pain relief was best achieved by combining a pacifier with 30% sucrose.
Fabrication and Transport Properties of Te-Doped Bi Nanowire Arrays
Authors: Lin Y. M. , Sun X. , Cronin S. B. , Zhang Z. , Ying J. Y. , Dresselhaus M. S. 
Published: May 2011

ABSTRACTTe-doped Bi nanowires with a 40 nm wire diameter have been successfully synthesized in anodic alumina templates by the pressure injection technique. Due to the unique semimetal-semiconductor transition that occurs in Bi nanowires, these systems exhibit a rather different temperature dependence in transport properties from their bulk counterparts. An improved theoretical model of this unique 1D nanowire system is developed based on the band structure of bulk bismuth. The temperature dependence of resistance for Bi nanowire arrays have been studied experimentally for various Te dopant concentrations and the results are compared with theoretical predictions.
A New Alternative for the Low-Workfunction Electrode in Organic Devices
Authors: Koch Norbert , Zojer Egbert , Rajagopal Aparna , Ghijsen Jacques , Johnson Robert L. , Leising Günther , Pireaux Jean-Jacques 
Published: May 2011

ABSTRACTThe application of ele ctroactive organic materials in devices (light emitting diodes, photovoltaic cells) often requires electrodes with a low workfunction. Commonly, aluminum or alkaline earth metals are used, which usually exhibit strong interaction with the organic material, such as the formation of new covalent bonds or doping. This results in a strong modification of the electronic structure of the organic/metal interface, and in most cases does not yield the energy level alignment expected for the unreacted interface. As a n alternative to the above-mentioned metals we propose the use of samarium, with a workfunction of 2.7 eV, for the following reason: we have studied the interface formation between Sm and p -sexiphenyl (6P, which exhibits intense blue electroluminescence), with ultraviolet photoelectron spectroscopy. Sm was deposited stepwise onto thin films of 6P in ultrahigh vacuum, and the photoelectron spectra were recorded after each step. We did not find any indication for a strong interaction between the two materials. Metallic Sm is formed instantaneously and the valence electronic structure of 6P remains unchanged upon the metal deposition. The weak interaction at this interface allows one to determine the energy level alignment between a metal and an organic material in a direct manner from the photoelectron spectra, without the need for making any assumptions on the workfunction or ionization potential.
1/f Noise Behavior in Pentacene Organic Thin Film Transistors
Authors: Necliudov P. V. , Gundlach D. J. , Jackson T. N. , Rumyantsev S. L. , Shur M. S. 
Published: May 2011

ABSTRACTWe studied the low frequency noise in top-contact pentacene Thin Film Transistors (TFTs). The relative spectral noise density of the drain current fluctuations SI/I2 had a form of 1/f noise in the measured frequency range 1Hz - 3.5kHz.Our studies of the noise dependencies on the gate-source VGS and drain-source VDS voltages showed that the dependencies differed from those observed for conducting polymers and resembled those reported for crystalline Si n-MOSFETs.To compare the device noise level with those of other devices and materials, we extracted the Hooge parameter α. In order to calculate the total number of carriers we used a model simulating the device DC characteristics, similar to that for amorphous Si TFTs. The extracted Hooge parameter was 0.04. For an organic material this is an extremely small value, which is three orders of magnitude smaller that the Hooge parameter values reported for conducting polymers and only several times higher than the values for amorphous Si TFTs.
The Agreement of Poly-5,5'-(4,4'-Dinonyl-2,2'Bithiazole) Spectral Signatures to those of Corresponding Oligomers
Authors: Blanda Wendy M. , Francis Anthony H. , Curtis M. David 
Published: May 2011

ABSTRACTStudy of the electronic spectra of conjugated oligomers can provide a useful approach to obtain an analysis of the often complicated spectra of their corresponding polymers. One advantage of studying oligomers is that there is often a well defined conformational morphology and one may eliminate or reduce the spectral consequences of a distribution of conjugation lengths. In the present work, electronic spectra of some oligomers of poly-5,5'-(4,4'-dinonyl-2,2'bithiazole) were studied, both in solution and in the solid state, and the results compared with spectra of the polymer. For solution data, the plot of molar extinction coefficient vs. the number of double bonds is found to be linear, as is the Kuhn plot. This is consistent with quantum-chemical molecular modeling calculations, and closely resembles the behavior of other conjugated oligomers, such as polythiophenes and polyenes. However, the solid state spectra exhibit a large red shift in both absorption and emission. These and other results suggest the presence of strong intermolecular interactions in the solid state that significantly modify the magnitude of the homo-lumo gap of the oligothiazoles and their polymers. By comparing oligothiazoles in solution to thin film results, polymer behavior is explored.
Poly(Binaphthalenevinylene-alt-Phenylenevinylene) Derivatives: Novel Luminescent Polymers for Light-Emitting Devices
Authors: Zheng Lixin , Jiang Xuezhong , Liu Michelle S. , Jen Alex K-Y. 
Published: May 2011

ABSTRACTNovel conjugated light-emitting polymers were synthesized via a Wittig-Horner condensation reaction between a binaphthyl dicarbaldehyde and a series of electron-rich or electron-deficient aryl diphosphonates. After comparing these materials with the model compound, 4c, it was revealed that the introduction of a twisted, non-coplanar binaphthyl structure provided an effective approach for tailoring the spectral characteristics of the polymers and improving their solubility and thermal stability (glass transition temperature, Tg, 200°C). Furthermore, the band structures of the polymers could be fine-tuned by changing the electronic properties of the bridging aromatic units. The electroluninescence (EL) and device characteristics were also reported in this paper.
Synthesis and Optical Properties of Phthalonitrile Oligomers
Authors: Tsai ZoHong , Sandman Daniel J. 
Published: May 2011

ABSTRACTPhthalonitrile and its derivatives react with Tin(II) reagents to give intensely colored linear oligomers. Structures are proposed for the oligomers based on elemental analysis, infrared, 1H and 13C spectra, and mass spectra. Stannous chloride has two kinds of properties, reducing reagent and Lewis acid. Tin(II) alkoxide initiates phthalonitrile oligomeriaztion when excess alkoxide is present. The mass spectrum indicates a chain length of at least a hexamer. In semi-empirical AM1 calculations, the helical conformation of a pentamer is indicated to be more stable than a linear conformation. The position of the electronic spectral maximum can be controlled by different kinds of reaction conditions and solution absorption and emission spectra were recorded.
Side Chain Influence on Main Chain Orientation of PPV-Type Oligomers
Authors: Müllner Ruth , Noirez Laurence , Zojer Egbert , Stelzer Franz , Leising Günther 
Published: May 2011

ABSTRACTOligo (p-phenylene vinylene)s OPV were synthesized having cyanobiphenyloxy-groups bonded to the vinylene double bonds via alkylene spacers. A Pd(0)-reaction was used to synthesize the oligomers starting with the dibromo-substituted benzene and the alkenyloxy-biphenyl-nitrile. The orientation of the mesogens by a magnetic field and their influence on the orientation of the main chain was investigated by means of neutron diffraction ND. Data on the photophysics of the oligomers were gained using several spectroscopic methods such as UV/VIS, polarized optical microscopy POM, SEC, 1H-NMR, FT-IR.
Frequency Dependent Dielectric Permittivity Studies in Emeraldine Base and Weakly Doped Polyaniline and its Deriviatives
Authors: Pintoa Nicholas J. , Sinha Ghanshyam P. , Aliev Fouad M. 
Published: May 2011

ABSTRACTWe report on a study of the complex dielectric permittivity in polyaniline (PAN), poly-o-toluidine (POT) and poly-o-ethylaniline (OPEA) in the undoped and weakly doped state in the frequency range 1 mHz upto 1 MHz. The doping concentration defined as y=[C1-]/[N] was chosen so that 0 ≤ y ≤ 0.07. OPEA with y=0.50 was also investigated. The objective of this work was to investigate the contribution of the mobile charge defects (polarons and bipolarons) on the conductivity and dielectric relaxation at such low doping levels. The three samples were chosen so as to compare the effects of introducing larger interchain disorder while maintaining a similar conduction mechanism. In all samples studied we observe the presence of a dielectric relaxation mechanism and the relaxation times depend on the doping level and disorder. The presence of a larger number of polarons as the doping level is increased leads to multiple paths for the system to relax leading to progressively non Debye like relaxation process. The results are interpreted in terms of creation and annihilation of polarons and bipolarons and their subsequent diffusion.
Luminescence Properties and Energy Transfer Processes in Fluorescent and Phosphorescent Tris(Phenylquinoxaline)
Authors: Blumstengel Sylke , Colabella Elio , Tubino Riccardo , Jandke M. , Strohriegl P. 
Published: May 2011

ABSTRACTWe have studied the photophysical properties and energy transfer processes in tris(phenylquinoxalines ) (TPQ). TPQs emit blue fluorescence with a maximum at 2.9 eV as well as green phosphorescence at 2.2 eV. When doped with a phosphorescent dye efficient energy transfer takes place from the excited singlet and triplet state of the TPQ host to the guest molecules. The mechanism of energy transfer can be understood in the frame of Förster's theory of dipole-dipole interaction. Besides the interesting photophysical properties, TPQs are also very efficient electron transport materials. Red light-emitting diodes utilizing doped TPQ as emitter and electron transport layer have been prepared and electroluminescence properties investigated.
The Internal Field Distribution in Light Emitting Electrochemical Cells and Light Emitting Diodes: A Comparative Study
Authors: Moderegger Erik , Wenzl Franz P. , Tasch Stefan , Leising Günther 
Published: May 2011

ABSTRACTWe determined the internal electric field distribution in light emitting electro-chemical cells (LECs) and light emitting diodes (LEDs) based on methyl substituted poly(paraphenylen) (mLPPP) by performing electroabsorption measurements as a function of an external bias voltage. Based on these results we outline the working principle of both types of devices. In the case of the LEC we observed an abrupt increase in the EA signal above a threshold voltage of about 2V which we attributed to junction formation due to in-situ electrochemical doping. For single layer LEDs we found the behavior expected for metal/insulator/metal/structures, i.e. the electric field drops linearly over the bulk polymer and no space-charge regions were observed.These findings are important for improving the performance of organic electroluminescent devices.
Excited State Electronic Interactions in Oligothiophenes with Novel Supramolecular Structure
Authors: Tubino R. , Borghesi A. , Sassella A. , Botta C. , Porzio W. , Sala F. Della , Carlo A. Di , Lugli P. 
Published: May 2011

ABSTRACTMolecular beam deposition of quaterthiophene oligomer on a single crystal of potassium acid phtalate yields thin films exhibiting a novel supramolecular organisation which has been determined by a combined study of X-ray diffraction and polarized optical transmission measurements. In this structure consisting of stacks of tilted H aggregates, a commensurate ratio between the KAP substrate and the overgrown oligothiophene layer (quasi-epitaxial growth) is attained. The samples are optically extremely anisotropic, with the projection of the molecular axis on the substrate surface perfectly aligned along the b crystallographic axis. Using these novel structural data, the optical properties are interpreted within the framework of the transition density approach.
New Aspects of Organic Electric Materials in Calamitic Liquid Crystalline Photoconductors
Authors: Maeda Hiroki , Funahashi Masahiro , Hanna Jun-Ichi 
Published: May 2011

ABSTRACTCalamitic liquid crystalline photoconductors such as 2-(4'-octylphenyl)-6-butyloxynaphthalene (8-PNP-O4) and 2-(4'-octylphenyl)-6-dodecyloxynaphthalene (8-PNP-O12) exhibit fast ambipolar carrier transport in all the smectic mesophases up to 1.0 × 10−2 cm2/Vs. The structural defects of liquid crystals, i.e. domain boundaries and disclinations in domains, are electrically inactive and cause neither shallow nor deep defect states due to their fluid nature. It is illustrated that the carrier transport does not suffer from these structural defects in polydomain, by examining transient photo-currents in very thick liquid crystalline layers over 100μm. With an insight that this allowance of the polydomain structure and the fluidity of liquid crystalline photoconductors provides us new aspects in terms of electric property and application, e.g. multi-gap processing, the position detect sensor is demonstrated in a wedge cell filled of 8-PNP-O12, referring the position sensitive transit time of photo-induced transient current.The present result indicates that the photoconductive liquid crystalline material is available for multi-gap structured devices.
Electrical and Electrochemical Properties of Nanocomposite Thin Films Formed by Exchange-Precipitation Route from Nanocrystals and Organic Cross-Linkers
Authors: Leibowitz Frank L. , Zheng Wenxia , Maye Mathew M. , Ly Nam K. , Zhong Chuan-Jian 
Published: May 2011

ABSTRACTThe structural, electrical and electrochemical properties of nanoparticle thin films derived by a one-step exchange-crosslinking-precipitation route were characterized by microscopic, spectroscopic and electrochemical techniques. Thiolate-encapsulated gold nanocrystals of 2-nm and 5-nm core sizes and alkyldithiol crosslinkers were studied as a model system. The mixing of the two components in solutions allowed sequential exchanging, crosslinking and precipitation of dithiol-crosslinked nanocrystal thin films. The films were specularly reflecting and electronically continuous, and have potential applications in catalysis and molecular recognition.
Photoemission Study of Metal-Deposited p-Sexiphenyl Film
Authors: Ito E. , Koch N. , Oji H. , Ishii H. , Leising G. , Seki K. 
Published: May 2011

ABSTRACTMetal deposition on a p-sexiphenyl (6P) film was studied by ultraviolet photoelectron spectroscopy (UPS), metastable atom electron spectroscopy (MAES), and X-ray photoelectron spectroscopy (XPS). The deposited metals were Au, Mg, and several alkali metals (K, Na, Rb, and Cs). No chemical reaction between 6P and Au or Mg was observed in the measured spectra, while additional gap states appeared in the UPS and MAES spectra by deposition of the alkali metals. The diffusion of Au and Mg atoms into the 6P film was observed in the MAES spectra. We found the trend of the vacuum level shift is different between the systems of the 6P on the Au and its reversed systems (Au on the 6P film), suggesting the different formation of the interface depending on the deposition sequence.
In Situ Attenuated Total Reflection FTIR Spectroelectrochemistry Of Polybenzimidazobenzophenanthroline (BBL)
Authors: Yohannes Teketel , Neugebauer H. , Sariciftci Niyazi S. , Yi S. , Jenekhe Samson A. 
Published: May 2011

ABSTRACTFourier transform infrared (FTIR) spectroscopy is a powerful method to determine the doping induced structural changes and electronic band structure modifications of conjugated polymer films. Here, we report in situ attenuated total reflection (ATR) FTIR spectroelectrochemical results of reduction reactions (n-doping) of the conjugated ladder polymer polybenzimidazophenanthroline, BBL. The ATR-FTIR spectra are recorded in situ during continuous potential cycling of a BBL coated germanium reflection element in a three electrode spectroelectrochemical cell. The spectra and the structural changes during the reduction (n-doping) of the polymer film at different electrode potentials are presented. In contrast to most of the other conjugated polymers, this polymer shows four reversible redox reactions during n-doping, corresponding to various forms of BBL with different conductivities.
Realization of Polymeric Electro-Optic Modulators with Less Than One Volt Drive Voltage Requirement
Authors: Zhang Cheng , Lee Michael , Winklemann Adam , Northcroft Heidi , Lindsey Christopher , Jen Alex K. Y. , Londergan Timothy , Steier William H. , Dalton Larry R. 
Published: May 2011

ABSTRACTThe roles played by spatially anisotropic intermolecular electrostatic interactions, chromophore shape, host dielectric constant, and poling field strength in defining maximum achievable electro-optic activity for electrically poled chromophore/polymer materials are investigated by equilibrium and Monte-Carlo quantum statistical mechanical calculations. Even simple Hamiltonians reproduce critical qualitative features such as the existence of a maximum in plots of electro-optic activity versus chromophore number density in a polymer matrix. Comparison of theoretical results for various methods provides a useful check on the validity of approximations employed with individual methods. The most significant conclusion to derive from a comparison of experimental and theoretical results is the dependence of maximum achievable electro-optic activity upon chromophore shape. Theoretical calculations suggest a new paradigm for the design of optimum electro-optic chromophores; realization of the desired shapes may be facilitated by dendritic synthetic approaches. In the presence of intermolecular electrostatic interactions, the dependence of electro-optic activity upon material dielectric permittivity and electric poling field strength is more complex than in the absence of such interactions. Of particularly, interest are conditions that lead to second order phase transitions to lattices containing centrically (antiferroelectricallly) ordered chromophore domains. Such phase transitions can lead to further complications in the attempted preparation of device quality materials but can be effectively avoided by utilization of theoretically derived phase diagrams.
High Performance Side-Chain Polyquinolines and Perfluorocyclobutane-Containing Thermoset Polymers for Electro-Optic Applications
Authors: Ma Hong , Wu Jianyao , Herguth Petra , Chen Baoquan , Purohit Ajay , Jen Alex K.-Y. 
Published: May 2011

ABSTRACTA modular approach for making second-order nonlinear optical (NLO) side-chain aromatic polyquinolines has been developed. The synthesis provides a method for readily incorporating NLO chromophores into the pendent phenyl moieties of parent polyquinolines at the final stage via the Mitsunobu reaction. The method produces polyquinolines with a wide range of polymer backbones and offers great flexibility in the selection of NLO chromophores. These side-chain NLO polyquinolines demonstrate high electro-optic (E-O) activities (up to 35 pm/V at 830 nm and 22 pm/V at 1300 nm) and excellent tradeoffs among thermal, optical, and electrical properties.Most recently, a series of novel second-order NLO thermoset polymers containing silicon-perfluorocyclobutane (PFCB) has also been synthesized. This was accomplished via the crosslinking reaction between the di(trifluorovinylether)-containing NLO chromophores and the tris(trifluorovinylether) monomer in solid state at 180-250 °C. The radical-mediated, stepwise cycloaddition reaction offers great tolerance to very sensitive functional groups such as tricyanovinyl acceptor. A variety of NLO chromophores could be easily incorporated into these thermoset polymers compared to the modular approach. Preliminary results have indicated these polymers to possess excellent processability, low optical loss, and a combination of highly desirable thermal, nonlinear optical, and mechanical properties.
Tuning of Redox Behavior and Fluorescence of Cyano-containing Oligophenylenevinylenes
Authors: Liu Michelle S. , Jiang Xuezhong , Jen Alex K-Y. 
Published: May 2011

ABSTRACTA series of cyano-containing distyrylbenzenes which have the electron-withdrawing groups functionalized on the central phenylene ring were synthesized via the Wittig-Horner reaction. Electrochemical study showed that the electron-affinity of these molecules increased with the increasing strength of electron-accepting groups. 1,4-Bis(4'- t-Butylstyryl)-2,5-bis(dicyanovinyl)benzene (6) possessed a low LUMO energy level at -4.01 eV, which provided a better match to the work function of Al cathode. Compared to the cyano-terephthalylidene (2), introducing cyano groups on the aromatic ring (3) instead of on the vinylene linkage provided better stabilization to the radical anions. The emission colors spanning green, yellow, orange, red could be achieved by changing the electron-accepting strength of oligophenylenevinylenes (3-6). Energy gap reductions were caused by a stronger decrease of the LUMO energies than the HOMO energies. These results provided new insights for the design of suitable polymers with much improved electron affinities facilitating electron injection from higher work function metal electrodes.
A Polyaniline Coating Material for Inhibiting Corrosion in Marine Environment
Authors: Lin Yuan , Yang Sze C. , Clark Robert , Brown Richard 
Published: May 2011

ABSTRACTThe conventional molecular ion doped polyaniline undergoes dedoping in sea water because the sea water, with pH = 8, induces deprotontation of polyaniline. In this article we report polyaniline complexes that remain conductive in sea water. These complexes are useful for corrosion protection of metals in marine environment and for chromate replacement coatings. The reason for the pH stability of these polyaniline complexes was discussed. The polymeric complexes of polyaniline were used as an additive in an epoxy primer coating on AL7075-T6 without surface pre-treatment of the metal. Corrosion tests show that these polymeric complexes of polyaniline are effective for improving the corrosion inhibition in seawater for aluminum alloys.