bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature‐dependent magneto‐photoluminescence spectroscopy of carbon nanotubes: evidence for dark excitons
Authors: Shaver J. , Kono J. 
Published: December 2007

AbstractWe review recent experimental and theoretical studies on the radiative properties of excitons in single‐walled carbon nanotubes (SWNTs) as a function of magnetic field and temperature. These studies not only provide new insight into the fundamental properties of excitons in the ultimate one‐dimensional (1D) limit but also reveal new phenomena associated with the unique crystal and electronic structure of SWNTs. During the past several years, SWNTs have emerged as one of the most ideal systems available for the systematic study of 1D excitons, which are predicted to possess a set of properties that are distinctly different from excitons in higher dimensions. In addition, their tubular nature allows them to exhibit non‐intuitive quantum phenomena when subjected to a parallel magnetic field, which breaks time reversal symmetry and adds an Aharonov‐Bohm phase to the electronic wavefunction. In particular, a series of recent experiments demonstrate that such a symmetry‐breaking magnetic field can dramatically “brighten” an optically‐inactive, or dark, exciton state at low temperature (see the title figure on the right). We show that this phenomenon, magnetic brightening, can be understood as a consequence of interplay between the strong intervalley Coulomb mixing and field‐induced lifting of valley degeneracy. Detailed temperature‐dependent photoluminescence studies of excitons in SWNTs in a varying magnetic field have thus provided one of the most critical tests for recently proposed theories of 1D excitons taking into account the strong 1D Coulomb interactions and unique band structure on an equal footing. Furthermore, results of these studies suggest the intriguing possibility of manipulating the optical properties of SWNTs by judicious symmetry control, which can lead to novel devices and applications in lasers and optoelectronics.
Composite Nano‐Titanium Oxide–Chitosan Artificial Skin Exhibits Strong Wound‐Healing Effect—An Approach with Anti‐Inflammatory and Bactericidal Kinetics
Authors: Peng Chiung‐Chi , Yang Ming‐Hua , Chiu Wen‐Ta , Chiu Chun‐Hung , Yang Chi‐Shen , Chen Yi‐Wen , Chen Kuan‐Chou , Peng Robert Y. 
Published: December 2007

AbstractA composite nano‐TiO2–chitosan with collagen artificial skin (NTCAS) showed promising characteristics of moderate water absorptivity (110 wt.‐%), fine thickness (0.34 mm), low density (0.33 mg · mm−3), moderate biodegradability (<3.0%), and favorable time‐dependent biodegradability (0.0521 mg · mL−1 · h−1 on Day 0; 0.0006 mg · mL−1 · h−1on Day 3 post covering). More importantly, it showed uniquely potent bactericidal (sterilization) property with relatively large values of pseudo first‐order kinetic coefficients (0.1736–0.0360 min−1) for TiO2 contents ranging from 2.63 × 10−5 to 2.11 × 10−4 mg · cm−2. In wounded subjects, NTCAS showed a steady level of TNF‐α, while the IL‐6 level reached a peak on Day 7, although significantly lower than in the control and Duoderm groups. In the animal model, NTCAS showed better and faster recovery than the other groups, which can be attributed to the unique bactericidal effect of nano‐TiO2 and immune‐enhancing effect of chitosan. NTCAS is a promising artificial skin substitute and is superior to any other market product currently in use.magnified image
Morphology and Phase Separation of Hydrophobic Clusters of Soy Globular Protein Polymers
Authors: Sun Xiuzhi Susan , Wang Donghai , Zhang Lu , Mo Xiaoqun , Zhu Li , Bolye Dan 
Published: December 2007

AbstractProtein hydrophobic interaction has been considered the most important factor dominating protein folding, aggregation, gelling, self‐assembly, adhesion, and cohesion properties. In this paper, morphology and phase separation of hydrophobic clusters, networks, and aggregates of soy globular protein polymers, induced by using a reducing agent (NaHSO3), are studied using microscopic instruments. The morphology and phase separation of these hydrophobic clusters are sensitive to protein structure and composition, pH, and ionic‐strength (Im). Most of the clusters are in spherical‐shape architecture and mainly consist of hydrophobic polypeptides. Rod‐shape clusters were also observed at higher ionic strength, and mainly consist of hydrophilic polypeptides. The ratio of hydrophobic/hydrophilic (HB/HL) polypeptides is important to facilitate the formation of clusters in an environment with a certain pH value and ionic strength. At HB/HL 0.8, uniform spherical clusters were observed and diameters ranged from 30 to 70 nm. At HB/HL <0.8, large spherical clusters were formed with diameters ranging from 100 to 1 000 nm, and at HB/HL ≥1.8, large hydrophobic aggregates formed, and size of aggregates can be up to 2 500 nm. When solid content increased from 3% to 38%, at Im ≤ 0.058 mol · L−1, pH = 4.8, HB/HL ratio <0.8, the networks turned into a continuous substance that has strong adhesion to various surfaces; at Im ≥ 0.115 mol · L−1, HB/HL ratio ≥1.8, the large aggregates became very cohesive and viscoelastic. Clear phase separation was observed during curing between hydrophobic and hydrophilic protein polymers. Phase‐separation degree increased as HB/HL ratio increased.magnified image
Are quantitative measurements by electrochemical diagnostic procedures possible?
Authors: Finke M. 
Published: December 2007

AbstractIn order to guarantee the demanded run‐time of chemical and petrochemical production plants and to keep them in up most technical conditions, an alignment between maintenance strategy, inspection intervals, and diagnostic methods is necessary. For the determination of the useful life of an equipment, it is necessary to select testing methods, which possess high sensitivity and long PF intervals (lead time to failure). This approach supports an optimal condition‐based maintenance program to avoid unplanned shutdown. In order to monitor corrosion processes, electrochemical methods can be successfully employed. In this paper, contributions of some online diagnostic methods are described, especially concerning their quantitative presentation.
Listen to corrosion at work — A newly developed versatile corrosion monitoring tool ready for plant application
Authors: Schmitt G. 
Published: December 2007

AbstractThe basic principle of a new approach of electrochemical noise (ECN) diagnostics, the Coulombs counting method, is outlined, and the wide range of application as an online‐monitoring tool in technical corrosion systems is exemplified. It is shown that corrosion monitoring can be achieved with ECN sensors as simple as monitoring temperatures. A special feature of this method is that corrosion in crevices or under deposits can be investigated under real‐time conditions. This allows to monitor the efficiency of mitigation measures, e.g. application of corrosion inhibitors, under crevice corrosion conditions. The new ECN diagnostic approach listens to the message of corroding systems and translates it into technically relevant information.
Using electrochemical noise for corrosion testing: Determination of critical pitting temperatures
Authors: Heyn A. , Goellner J. 
Published: December 2007

AbstractThe phenomenon of the electrochemical noise is already known for some decades. With the growing technical possibilities in the fields of electronic measuring devices and recording techniques, a new window of observation has been opened to observe and record smallest charge fluctuations from dynamic corrosion processes. The main advantage compared to other electrochemical techniques is the contemporary and sensible way of getting information from the beginning of and the tendency to corrosion. This is also the basis for applications for corrosion testing and examination. In this paper, it is shown in the example of the determination of critical pitting temperatures (CPTs), how a conventional testing method can be improved by these advantages. The prerequisites concerning the measuring technique, the experimental procedure and the assessment of the measured data are shown as well as some fundamental and technical restrictions, which have to be taken into account.
An attempt to detect SCC by combined measurements of electrochemical noise and acoustic emission
Authors: Kovač J. , Leban M. , Legat A. 
Published: December 2007

AbstractElectrochemical voltage and current noise (EN) were measured simultaneously with acoustic emission (AE) during intergranular stress‐corrosion cracking (IGSCC) on tensile specimens under a constant load. The elongation of the test specimens was also measured continuously during the tests, as an additional measuring technique. The test specimens were made from sensitized stainless steel of type 304, and immersed in an aqueous solution of sodium thiosulphate. The main aim of our work was to find out how successfully IGSCC processes could be detected by the simultaneous use of all three measurement methods. The results of the tests indicated that the accumulation of cracking and dissolution events could be satisfactorily monitored, whereas it was not possible to detect individual IGSCC events with the existing measuring set‐up. It is not clear whether this inability to detect single IGSCC events was a consequence of the continuous nature of the IGSCC processes, or whether it was due to the insufficient resolution of the measurement system set‐up.
Corrosion and corrosion testing of magnesium alloys
Authors: Bender S. , Goellner J. , Heyn A. , Boese E. 
Published: December 2007

AbstractThe corrosion behaviour of magnesium alloys is not substantially comparable to other metals, such as iron, nickel and copper. It is always accompanied by hydrogen evolution. More hydrogen is evolved at a more positive potential or a higher anodic current density. The ‘strange’ hydrogen evolution behaviour is a common phenomenon for magnesium alloys and it is called negative difference effect (NDE). The NDE continues to receive considerable discussion.Furthermore, the corrosion behaviour of magnesium alloys depends mainly on the pH value of the surrounding electrolyte. Voluminous reaction products, formed in neutral electrolytes, lead to a diffusion‐controlled dissolution on the surface of the underlying magnesium alloy. Therefore, influences from structure and alloying are suppressed very strongly. In alkaline environments, passivation occurs as a result of the formation of a hydroxide layer on the magnesium surface. Therefore, differences in the corrosion behaviour between the alloys are hardly detectable. Measurable effects can only be detected using very ‘aggressive’ corrosion conditions. Present methods do not adequately take into account the specific character of the corrosion of magnesium alloys. It can be better characterized using a rotating disc electrode for electrochemical measurements, which enables model defined flow conditions on the surface. Furthermore, the application of electrochemical noise offers the possibility of a simple and sensitive assessment of the corrosion susceptibility of magnesium alloys. Due to the high sensitivity of this measurement procedure, it is also possible to carry out examinations under more practical conditions.
Investigation of the initial stage of crevice corrosion on Al99.5 by electrochemical noise analysis
Authors: Schneider M. , Galle K. 
Published: December 2007

AbstractThe electrochemical noise analysis (ENA) is a powerful tool to investigate the initial state of local corrosion processes as pitting corrosion or crevice corrosion on aluminium alloys. The focus of this work lays on Al99.5 (AA1050). In spite of the good corrosion protection and the very low passive current density the noise activity in the early state of corrosion can be very well observed. ENA was performed by using current noise measurement under potentiostatic control. The effect of chromate inhibitors on the noise activity of the initial state of corrosion on Al99.5 is surprisingly negligible. This phenomenon is discussed in this paper.
Modeling of electrochemical noise transients
Authors: Bierwirth M. , Goellner J. 
Published: December 2007

AbstractStarting from the elementary corrosion reactions on a passive metal surface a model is developed for the origin of electrochemical noise. The ion currents flowing at the electrochemical reactions are described by the electrons remaining in the metal and then interpreted as a measuring signal. The measurable sum current is composed of the superimposition of the electron currents of the partial reactions. Due to the inhomogeneity of the metal surface, local metal dissolutions take place in preferential areas until the area is consumed or repassivated after short times. The short‐time surplus of free electrons leads for every metal dissolution event to a current transient, which itself consists of the partial currents of the elementary anodic and cathodic reactions. Due to the different reaction speeds, there are temporary charge disequilibria and thus measurable noise transients. In model calculations the influence of the diffusion of the oxygen on the sum signal as well as the variation of the anodic current is shown. Furthermore, the results show that a measurable noise signal can only arise under certain conditions. This signal arisen directly at the metal surface is not, however, ascertainable without further amplification. In the measurement amplifiers filter stages play an important role for signal conditioning. The influence of the measuring technique is shown at the filtration of a simulated test signal in different frequency domains. It is discussed how the signal distortion affects the detectability of the partial reactions described at the beginning and in which way the noise signal is estimated. Indications for the layout of suitable measuring parameters are given.
Copolymers of Thiophene and Cyano‐Substituted Phenylene: Facile Tuning of Electronic Energy Levels and their Photovoltaic Application
Authors: Zou Yingping , Sang Guangyi , Zhou Erjun , Li Yongfang 
Published: December 2007

AbstractA series of copolymers of thiophene and different molar ratios of DOCNP have been synthesized and characterized. The copolymers exhibit interesting tunable electronic energy levels and optoelectronic properties. The LUMO energy levels of the copolymers decreased with increasing DOCNP content, while the HOMO levels changed only a little. The copolymer films show broad absorption and high absorption coefficients in the visible region, which could be beneficial to the application as photovoltaic materials in solar cells. The results show that the introduction of a proper amount of electron‐acceptor groups in the polymer main chains induces an extension of the absorption spectra and improves the photovoltaic properties of the copolymers.magnified image
Solid‐State Electrochromic Devices via Ionic Self‐Assembled Multilayers (ISAM) of a Polyviologen
Authors: Jain Vaibhav , Yochum Hank , Wang Hong , Montazami Reza , Hurtado Mónica A. Vidales , Mendoza‐Galván Arturo , Gibson Harry W. , Heflin James R. 
Published: December 2007

AbstractA PV was synthesized by polymerization of N,N′‐bis(δ‐aminopropyl)‐4,4′‐bipyridinium bromide hydrobromide (APD) and isophthaloyl chloride (ISP). The PV was completely soluble in water as well as in organic solvents. The spectroelectrochemical and EC properties of the resulting ionic self‐assembled multilayers of PV/poly‐(2‐acrylamido‐2‐methylpropanesulfonic acid) (PAMPs) were examined by cyclic voltammetry, FT‐IR spectroscopy, UV‐vis spectroscopy, optical switching and current density measurements. Solid state devices made of PV films sandwiched with PANI as a counter electrode have switching times of 100–250 ms. 40 Bilayer films of PV/PAMPs show high contrast (ΔT = 61%) in 0.1 M NaClO4 liquid electrolyte solution and CE as high as 57 cm2 · C−1, one of the highest reported so far for any bipyridinium salt system.magnified image
Influence of a Melt Flow on Generation of Functionally Graded Structure in Bulk Polymeric Materials under Uniaxial Thermal Gradient
Authors: Koide Satoshi , Asakawa Naoki , Inoue Yoshio , Yazawa Koji 
Published: December 2007

AbstractA mechanism for the generation of the compositional gradient along the long axis for poly(ε‐caprolactone) (PCL)/poly(ethylene oxide) (PEO) blend under uniaxial thermal gradient was proposed by observations of the convection of polymer using graphite powder as a visual probe. The convection under the thermal gradient promoted the transfer of PCL into the liquid phase from the interface of PEO crystallites. The convex downward shape of the solid–liquid interface indicates the generation of the compositional gradient along the radial direction. By dissolution of PEO, a porous scaffold with a porosity gradient structure along the longitudinal direction was fabricated.magnified image
Synthesis of Poly(N‐aryl‐2,7‐carbazole)s for Efficient Blue Electroluminescence Materials
Authors: Koguchi Ryohei , Kobayashi Norifumi , Shinnai Toshinobu , Oikawa Kazuma , Tsuchiya Kazuhiko , Kijima Masashi 
Published: December 2007

AbstractSeveral poly(N‐phenyl‐2,7‐carbazole)s that have dialkoxy groups at the m‐ and p‐positions (PmpCzDC, PmpPhDC, PmpCBiDC, PmpEHC), a silyl group at the p‐position (PpPhDSiC), and a diphenylamino group (PmPhDAC, PmEHAC) at the m‐position of the N‐phenyl portion are synthesized, and their optical properties are characterized. These polymers have been used as emitting layer materials of organic light‐emitting diode (OLED) devices that have a configuration of ITO/PEDOT(PSS)/polymer/CsF/Al. The OLED devices embedded with PmpCzDC, PmpPhDC, and PmpEHC show intense luminance of about 15 000 cd · m−2 with efficiencies of about 1 cd · A−1, while the devices embedded with PpPhDSiC, PmPhDAC, and PmEHAC show less luminance but retain the color purity of blue emission under a wide range of applied voltages.magnified image
A New Concept for an Alkaline Developable Positive‐Tone Resist: Molecular Resist Utilizing Acid Catalyzed Isomerization from Oxabenzonorbornadiene to Naphthol
Authors: Mori Hajime , Nomura Eisaku , Hosoda Asao , Miyake Yasuhito , Taniguchi Hisaji 
Published: December 2007

AbstractA novel positive‐tone molecular resist possessing oxabenzonorbornadiene moiety was developed for electron‐beam (EB) lithography. The synthesized resist material showed relatively high glass transition temperature and readily formed uniform amorphous films on a silicon wafer. The sensitivity of an EB resist was ca. 8 µC · cm−2 and line and space patterns of 200 nm could be fabricated. The promising feature of the resist materials is that no outgassed products from base matrixes are theoretically produced under the exposure and post‐exposure bake procedure.magnified image
Decision making in Parkinson's disease: Analysis of behavioral and physiological patterns in the Iowa gambling task
Authors: Kobayakawa Mutsutaka , Koyama Shinichi , Mimura Masaru , Kawamura Mitsuru 
Published: December 2007

AbstractRecent studies suggest that social recognition processes are affected by Parkinson's disease (PD). However, whether PD patients exhibit behavioral changes is still controversial. The purpose of the present study was to examine the decision making of PD patients performing the Iowa Gambling Task (IGT). We recruited a large number of early, nondemented PD patients for the IGT. We also recorded the skin conductance responses (SCRs) during the task as a measure of emotional arousal. Compared with the normal control (NC) subjects, PD patients selected more disadvantageous decks in the IGT, and their SCRs were lower than those of NC subjects before making decisions and after receiving reward or punishment. The tendency toward risky choices was not correlated with age, education, global cognitive function, or the severity of the disease. These results confirmed that the decision making of PD patients was affected by the disease, rather than by other cognitive functions; moreover, such behavior was related to lower emotional responses. Behavioral and SCR patterns of PD patients were similar to those of amygdala‐damaged patients. The response bias toward risky choices in PD may be explained by the dysfunction of the amygdala, which is known to be involved in risk evaluation. © 2007 Movement Disorder Society
Electrophysiological signs and the prevalence of adverse effects of acetylcholinesterase inhibitors in patients with myasthenia gravis
Authors: Punga Anna Rostedt , Sawada Mikio , Stålberg Erik V. 
Published: December 2007

AbstractThe aim of this prospective study was to assess whether extra discharges (EDs), sometimes following the compound muscle action potential, could be used as a neurophysiological indicator of overdose of acetylcholinesterase inhibitors (AChEIs) in patients with myasthenia gravis (MG). The characteristics and frequency of EDs were explored and the correlation of EDs with cholinergic side effects was also determined. Twenty‐two MG patients (14 women, 8 men; 61 ± 16 years of age) with daily AChEI treatment were examined. The mean disease duration was 10 years (range 2–62 years) and all patients had been treated with AChEI since MG onset. Both single and repetitive stimulation of the ulnar and accessory nerves were performed before and 60 min after oral pyridostigmine bromide (PB) administration and after additional edrophonium injection. Fatigue, side effects, and AChE activity in blood were assessed before and 60 min after PB intake. The daily dose of PB ranged from 150 to 900 mg/day. Fourteen patients (64%) experienced daily cholinergic adverse effects, and muscarinic side effects correlated with AChE activity. Eleven patients (50%) developed EDs after oral PB. Among the eight patients with daily nicotinic side effects, EDs were significantly (P < 0.05) more common. Additionally, older patients were more prone to develop cholinergic side effects and EDs. Thus, when EDs are found, patients should be asked about daily muscular symptoms, which may be related to AChEI treatment and not solely to MG. Muscle Nerve, 2007
Optimal timing of switches between product sales for sports and entertainment tickets
Authors: Drake Matthew J. , Duran Serhan , Griffin Paul M. , Swann Julie L. 
Published: December 2007

AbstractLike airlines and hotels, sports teams and entertainment venues can benefit from revenue management efforts for their ticket sales. Teams and entertainment venues usually offer bundles of tickets early in their selling horizon and put single‐event tickets on sale at a later date; these organizations must determine the best time to offer individual tickets because both types of ticket sales consume the same fixed inventory. We model the optimal a priori timing decision for a seller with a fixed number of identical tickets to switch from selling the tickets as fixed bundles to individual tickets to maximize the revenue realized before the start of the performance season. We assume that bundle and single‐ticket customers each arrive according to independent, nonhomogeneous Markovian death processes with a linear death rate that can vary over time and that the benefit from selling a ticket in a package is higher than from selling the ticket individually. We characterize the circumstances in which it is optimal for the seller to practice mixed bundling and when the seller should only sell bundles or individual tickets, and we establish comparative statics for the optimal timing decision for the special case of constant customer arrival rates. We extend our analytical results to find the optimal time for offering two groups of tickets with high and low demand. Finally, we apply the timing model to a data set obtained from the sports industry. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2008