bluuebunny/crossref_metadata_2025 huggingface dataset:
Excitatory Muscarinic Modulation Strengthens Virtual Nicotinic Synapses on Sympathetic Neurons and Thereby Enhances Synaptic Gain
Authors: Kullmann Paul H. M. , Horn John P.
Published: September 2006

Acetylcholine excites many neuronal types by binding to postsynaptic m1-muscarinic receptors that signal to ion channels through the Gq/11 protein. To investigate the functional significance of this metabotropic pathway in sympathetic ganglia, we studied how muscarinic excitation modulated the integration of virtual nicotinic excitatory postsynaptic potentials (EPSPs) created in dissociated bullfrog B-type sympathetic neurons with the dynamic-clamp technique. Muscarine (1 μM) strengthened the impact of virtual synapses by reducing the artificial nicotinic conductance required to reach the postsynaptic firing threshold from 20.9 ± 5.4 to 13.1 ± 3.1 nS. Consequently, postganglionic action potential output increased by 4–215% when driven by different patterns of virtual presynaptic activity that were chosen to reflect the range of physiological firing rates and convergence levels seen in amphibian and mammalian sympathetic ganglia. In addition to inhibiting the M-type K+ conductance, muscarine activated a leak conductance in three of 37 cells. When this leak conductance was reproduced with the dynamic clamp, it also acted to strengthen virtual nicotinic synapses and enhance postganglionic spike output. Combining pharmacological M-conductance suppression with virtual leak activation, at resting potentials between −50 and −55 mV, produced synergistic strengthening of nicotinic synapses and an increase in the integrated postganglionic spike output. Together, these results reveal how muscarinic activation of a branched metabotropic pathway can enhance integration of fast EPSPs by modulating their effective strength. The results also support the hypothesis that muscarinic synapses permit faster and more accurate feedback control of autonomic behaviors by generating gain through synaptic amplification in sympathetic ganglia.
Delay of Movement Caused by Disruption of Cortical Preparatory Activity
Authors: Churchland Mark M. , Shenoy Krishna V.
Published: September 2006

We tested the hypothesis that delay-period activity in premotor cortex is essential to movement preparation. During a delayed-reach task, we used subthreshold intracortical microstimulation to disrupt putative “preparatory” activity. Microstimulation led to a highly specific increase in reach reaction time. Effects were largest when activity was disrupted around the time of the go cue. Earlier disruptions, which presumably allowed movement preparation time to recover, had only a weak impact. Furthermore, saccadic reaction time showed little or no increase. Finally, microstimulation of nearby primary motor cortex, even when slightly suprathreshold, had little effect on reach reaction time. These findings provide the first evidence, of a causal and temporally specific nature, that activity in premotor cortex is fundamental to movement preparation. Furthermore, although reaction times were increased, the movements themselves were essentially unperturbed. This supports the suggestion that movement preparation is an active and actively monitored process and that movement can be delayed until inaccuracies are repaired. These results are readily interpreted in the context of the recently developed optimal-subspace hypothesis.
Clinical and Morphologic Features of the Congenitally Unicuspid Acommissural Stenotic and Regurgitant Aortic Valve
Authors: Roberts William Clifford , Ko Jong Mi
Published: September 2006

Five adults, aged 30–75 years, are described with stenotic and regurgitant unicuspid acommissural aortic valves. Because none of these patients had clinical, echocardiographic or hemodynamic evidence of mitral valve disease, a case is made that these valves were congenitally malformed and not the result of an acquired condition.
Molecular Mechanisms of Neonatal Hyperinsulinism
Authors: Giurgea Irina , Bellanné-Chantelot Christine , Ribeiro Maria , Hubert Laurence , Sempoux Christine , Robert Jean-Jacques , Blankenstein Oliver , Hussain Kahlid , Brunelle Francis , Nihoul-Fékété Claire , Rahier Jacques , Jaubert Francis , de Lonlay Pascale
Published: September 2006

Congenital hyperinsulinism (CHI), characterized by profound hypoglycaemia related to inappropriate insulin secretion, may be associated histologically with either diffuse insulin hypersecretion or focal adenomatous hyperplasia, which share a similar clinical presentation, but result from different molecular mechanisms. Whereas diffuse CHI is of autosomal recessive, or less frequently of autosomal dominant, inheritance, focal CHI is sporadic. The most common mechanism underlying CHI is dysfunction of the pancreatic ATP-sensitive potassium channel (K+ATP). The two subunits of the K+ATP channel are encoded by the sulfonylurea receptor gene (SUR1 or ABCC8) and the inward-rectifying potassium channel gene (KIR6.2 or KCNJ11), both located in the 11p15.1 region. Germ-line, paternally inherited, mutations of the SUR1 or KIR6.2 genes, together with somatic maternal haplo-insufficiency for 11p15.5, were shown to result in focal CHI. Diffuse CHI results from germ-line mutations in the SUR1 or KIR6.2 genes, but also from mutations in several other genes, namely glutamate dehydrogenase (with associated hyperammonaemia), glucokinase, short-chain L-3-hydroxyacyl-CoA dehydrogenase, and insulin receptor gene. Hyperinsulinaemic hypoglycaemia may be observed in several overlapping syndromes, such as Beckwith-Wiedemann syndrome (BWS), Perlman syndrome, and, more rarely, Sotos syndrome. Mosaic genome-wide paternal isodisomy has recently been reported in patients with clinical signs of BWS and CHI. The primary causes of CHI are genetically heterogeneous and have not yet been completely unveiled. However, secondary causes of hyperinsulinism have to be considered such as fatty acid oxidation deficiency, congenital disorders of glycosylation and factitious hypoglycaemia secondary to Munchausen by proxy syndrome.
Parathyroid Development and the Role of Tubulin Chaperone E
Authors: Parvari Ruti , Diaz George A. , Hershkovitz Eli
Published: September 2006

The development of the parathyroid glands involves complex embryonic processes of cell-specific differentiation and migration of the glands from their sites of origin in the pharynx and pharyngeal pouches to their final positions along the ventral midline of the pharyngeal and upper thoracic region. The recognition of several distinct genetic forms of isolated and syndromic hypoparathyroidism led us to review the recent findings on the molecular mechanisms of the development of the parathyroid glands. Although far from being understood, a special emphasis was given to the possible role of tubulin chaperone E (TBCE), which was implicated in the pathogenesis of the hypopathyroidism, retardation and dysmorphism (HRD) syndrome. The novel finding that TBCE plays a critical role in the formation of the parathyroid opens a novel domain of research, not anticipated previously, into the complex process of parathyroid development.
Insulin-Like Growth Factor Delivery Across the Blood-Brain Barrier
Authors: Riikonen Raili
Published: September 2006

Background: Recent data indicate that insulin-like growth factor-1 (IGF-1) can cross the blood-brain barrier when bound to binding proteins. IGF-1 is very important for early brain development, myelination and survival of cerebellar neurons. It is antiapoptotic and is important for synaptic development. The aim of this study was to identify neurological conditions with low CNS IGF-1. Methods: Levels of CSF IGF-1 were determined by radio-immunoassay (Mediagnost, Tübingen, Germany). Results: Levels of CSF IGF-1 were low in some progressive diseases of white matter and the cerebellum. In some other diseases not involving cerebellum or white matter, CSF IGF-1 was normal. Conclusions: Our findings might pave the way for rational therapy in patients with neurodegeneration. Patients with low CNS IGF-1 might be candidates for IGF-1 therapy.
Autoimmune Cholangitis Presented as Fever of Unknown Origin
Authors: Petrogiannopoulos Constantinos , Papamichael Konstantinos , Karachalios Georgios , Karachaliou Iris , Kostakos Nikolaos , Barbati Kalypso , Zacharof Antonios
Published: September 2006

Autoimmune cholangitis is a rare chronic cholestatic liver disease. Fever of unknown origin is defined as a temperature higher than 38.3°C that lasts for more than 3 weeks with no obvious source despite appropriate investigation. We describe the case of a 62-year-old woman who presented with fever, fatigue and weight loss. The serum biochemical study showed an increase in alkaline phosphatase and γ-glutamyl transpeptidase levels. Antinuclear, antimitochondrial, anti-smooth-muscle antibodies and antibodies against the cytoplasm of neutrophils were negative. Liver biopsy was compatible with autoimmune cholangitis. The patient was successfully treated with methylprednisolone and ursodeoxycholic acid. We describe here a rare case of fever as preceding and leading symptom of autoimmune cholangitis.
Synergism of CAY-1 with Amphotericin B and Itraconazole
Authors: De Lucca A.J. , Bland J.M. , Boue S. , Vigo C.B. , Cleveland T.E. , Walsh T.J.
Published: September 2006

Background: CAY-1 is a fungicidal saponin from cayenne pepper whose mode of action differs from amphotericin B (AB) and itraconazole (IT). This work determined CAY-1 synergism with AB or IT. Methods: CAY-1 was purified and used in checkerboard microdilution studies where CAY-1 and AB or IT were mixed with nongerminated (NG) and germinating (G) conidia of three Aspergillus species and Candida albicans. Inhibition was visually determined at 24 and 48 h. Results: CAY-1 had predominantly additive-synergistic interaction with AB or IT against the Aspergillus NG and G conidia. Excellent synergy between CAY-1 and AB occurred at 24 and 48 h against C. albicans. Results suggest CAY-1 enhances AB and IT efficacy.
In vitro and in vivo Antiplasmodial Activity of Momordica balsamina Alone or in a Traditional Mixture
Authors: Benoit-Vical F. , Grellier P. , Abdoulaye A. , Moussa I. , Ousmane A. , Berry A. , Ikhiri K. , Poupat C.
Published: September 2006

Background: Because of the dramatic situation of malaria in Africa, there is an urgent need to find new and cheap drugs, such as herbal medicines. Here we report the study of the in vitro and in vivo antimalarial activity of Momordica balsamina alone or in a traditional mixture used in Niger. Methods: Extracts were obtained with different solvents and tested in vitro on Plasmodium falciparum and in vivo on Plasmodium vinckei. Results: The best extracts are methanolic and present promising results in vivo by intraperitoneal and oral administration. Conclusion: The antimalarial activity of M. balsamina, traditionally used in Niger, is confirmed in vitro and in vivo without any toxicity in healthy mice.
Pharmacology and Statistics: Recommendations to Strengthen a Productive Partnership
Authors: Spector Reynold , Vesell Elliot S.
Published: September 2006

Critical to the discovery, development and rational use of drugs and vaccines are the foundational principles and proper application of statistics. However, in too many cases, there has been misuse of statistics and/or overemphasis on statistical significance (p < 0.05), as though this criterion possessed truth-guaranteeing properties. To clarify confusion about the proper use of statistics in pharmacology, we summarize briefly the foundational principles of probability; the role of statistics in assessment of causality; the three basic uses of statistical methods, especially those employed in hypothesis testing; and current statistical issues in pharmacological research. We then review and provide examples of the meaning of statistical significance, the consequences of lack of randomization in epidemiology/observation studies, the criteria for measurement instrument validation, the problems with subgroup analyses, the need for multiple comparison statistical methods, and how to handle dropouts and missing data. Finally, based on sound experimental and statistical principles, we make a series of recommendations to both experimentalists and journal editors to improve published pharmacological experiments. These include widespread use of blinding and randomization and/or random selection of subjects in both basic and clinical pharmacology, mandatory use of rigorous evidentiary criteria in epidemiology/observation studies claiming causal associations, proper interpretation of statistical versus clinical/ pharmacological significance, appropriate interpretation of meta-analyses, meaningful validation of methods, and a more rational statistical approach to subgroup analyses and genetic association studies.
Extracellular Signal-Regulated Kinase (ERK1/2) Contributes to Endotoxin-Induced Hyporeactivity via Nitric Oxide and Prostacyclin Production in Rat Aorta
Authors: Korkmaz Belma , Ozveren Elif , Buharalioglu Cuneyt Kemal , Tunctan Bahar
Published: September 2006

This study was conducted to determine if mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK1/2) contribute to endotoxin-induced vascular hyporeactivity via nitric oxide (NO) and/or prostacyclin (PGI2) production in the rat isolated thoracic aorta. Incubation of endothelium-intact rings with endotoxin (100 µg/ml) for 4 h decreased the Emax value and increased the EC50 value of norepinephrine. The endotoxin-induced increase in the EC50 value of norepinephrine was decreased by phenylene-1,3-bis[ethane-2-isothiourea] dihydrobromide (1,3-PBIT), a selective inducible NO synthase inhibitor, and U0126, a selective inhibitor of ERK1/2 phosphorylation by MAPK kinase. The endotoxin-induced decrease in the Emax value of norepinephrine was reversed by 1,3-PBIT and further decreased by U0126. 1,3-PBIT and U0126 decreased the endotoxin-induced increase in the tissue nitrite and 6-keto-PGF1α levels. These data suggest that events related to the activation of ERK1/2 contribute to the endotoxin-induced hyporeactivity by increasing NO and PGI2 production.
Urinary Bactericidal Activity of Oral Antibiotics against Common Urinary Tract Pathogens in an ex vivo Model
Authors: Bedenic Branka , Topic Marijana , Budimir Ana , Bubonja Marina
Published: September 2006

Background: In this investigation, the urine samples obtained in a single oral-dose pharmacokinetic study were examined for their bactericidal activity against a range of relevant urinary tract pathogens. Methods: Six healthy volunteers received a single oral dose of ten oral antibiotics available in Croatia. Urine samples were taken every 2 h during the whole dosing interval of the particular antibiotic. The urinary bactericidal activity was tested by determination of urinary bactericidal titers. Results: All antibiotics showed a significant urinary bactericidal activity against non-extended spectrum β-lactamase Escherichia coli and Proteus mirabilis. Fluoroquinolones displayed high and persisting levels of urinary bactericidal activity against all gram-negative bacteria and Staphylococcus saprophyticus. Conclusions: Average urinary bactericidal activity can be predicted from in vitro susceptibility testing, but we expect that there will be patients with a low level of urinary bactericidal activity.
Combination Therapy with the Single Inhaler Salmeterol/Fluticasone Propionate versus Increased Doses of Inhaled Corticosteroids in Patients with Asthma
Authors: Li Hong-tao , Zhang Tian-tuo , Zhou Hong , Qu Xiu-juan , Wu Wei-ming , Huang Jin
Published: September 2006

Background: Although results from a few meta-analyses were most uniformly supportive of the beneficial effect of combination therapy on lung function, there were inconsistent results on other endpoints such as asthma exacerbation. Single inhalers of salmeterol and fluticasone propionate have been available, and some studies compared the effect of combination products with increased doses of inhaled corticosteroids (ICSs) on several outcome variables. Objectives: We reviewed the studies systematically, providing a quantitative summary estimate on the efficacy and safety measures of the combination products. Methods: We searched databases (Medline and Embase) from January 1997 to December 2005 using ‘fluticasone and salmerterol’ or ‘Seretide’ or ‘Advair’, in combination with ‘randomized controlled trial’. The databases of GlaxoSmithKline Clinical Trial Register and Cochrane Controlled Trials Register, or relevant articles were searched for additional studies. Results: Combination products had a comparatively low, but significant improvement in pulmonary function, with morning peak expiratory flow (PEF), evening PEF and FEV1 increasing by 17.86 liters/min, 15.57 liters/min and 0.09 liter, respectively, compared with increased doses of inhaled corticosteroid (ICSs) over 12 weeks’ treatment. But there were no statistically significant differences in other endpoints such as asthma exacerbation, overall withdrawal and drug-related adverse events, with the exception of overall adverse events and symptom free 24 h, which favored combination products. Conclusions: Thecombination products provided a statistically significant improvement in lung function and in symptoms but provided no significantly increased protection against exacerbation. Unless high doses of ICSs are required, there is insufficient evidence at present to recommend the use of combination products rather than increased moderate doses of ICSs as a first-line treatment for patients uncontrolled on their current doses of ICSs.
Strength of Unidirectional Short Fiber Structures as a Function of Fiber Length
Authors: Vas László Mihály
Published: September 2006

The strength of super-oriented polymer fibers or unidirectional short fiber composites strongly depends on the length of the molecule chains or the reinforcing fibers, respectively. A simple statistical model is developed based on the theory of fiber flows and the strength of the structure and its dependence on fiber length are determined in case of fibers broken or damaged owing to parting rigidly from the environment simultaneously. Later, two new special and modified versions of the so-called ES-bundle and one of the idealized statistical fiber-bundle-cells developed earlier, are introduced and applied to model the breaking process of the fibrous structure at different damage modes and its dependence on the fiber length is analyzed. In case of constant fiber length, a simple analytical relationship between the mean tensile strength and the fiber length is obtained which is valid for all the cases discussed. On the basis of the results, formulas are developed to estimate the strength of short fiber composites as a function of fiber length and fiber content, as well as to model the effect of the reduction in the fiber adhesion in case of a very small matrix content. The practical applicability of the results is demonstrated by identifying the relationship between tensile strength and molecule mass of PP fibers.
Strength Modeling of Two-component Hybrid Fiber Composites in case of Simultaneous Fiber Failures
Authors: Vas Laszlo Mihaly , Czigány Tibor
Published: September 2006

The strength of unidirectional short fiber hybrid structures and composites is strongly influenced by the length of the constituent and reinforcing elementary fibers. Based on our earlier fiber bundle-theoretical results, we have developed a simple statistical model and determined the strength of hybrid structures for elementary fibers, which simultaneously fail or debond from the environment in a brittle manner, and the dependence of the strength on the length of the elementary fibers. In the case of constant elementary fiber length, a simple analytical relation is obtained between the average tensile strength and the length of the elementary fiber. Based on these results, formulae have been developed to estimate the strength of unidirectional short hybrid fiber reinforced composites as a function of fiber length and fiber content. Practical applicability of the results has been demonstrated for basalt fiber hybrid composites taking into account fiber fragmentation, imperfect interfacial adhesion, and fiber orientation by using suitable correction factors.
Comparing German and Danish Employee Representatives on European Works Councils: Do Differences in National Background Matter?
Authors: Bicknell Helen , Knudsen Herman
Published: September 2006

This article aims to analyse the links and possible‘fit’ between German and Danish representation structures and trade union policies on the one hand, and the views and activities of European Works Council (EWC) representatives from the two countries on the other. Which similarities or differences can be observed in the way German and Danish EWC representatives act on and view EWCs? Can differences be explained by cross-national variations in representation structures and associated trade union policies? The article describes the national representation structures in the two countries, their linkage to EWCs and trade unions, and identifies the typical profile of German and Danish EWC representatives respectively. Data on how the representatives view the EWC and its activities and the extent to which they have been involved in negotiations with management are presented and analysed. It is concluded that the views and practices of German and Danish EWC representatives largely converge. Those divergent views that are found are explained by differences in national representation structures, union policies and labour market situation.
The Differential Effects of Regulatory Reform: Evidence from the Australian Luxury Hotel Industry
Authors: Knox Angela
Published: September 2006

Australia's industrial relations framework has undergone substantial change since the 1980s. This has involved a series of distinct phases including: award restructuring, the introduction of enterprise and individual bargaining, and award simplification. Notably, the federal award for the hotel industry formed the Test Case for award simplification, forming the first simplified award in Australia. Exploratory research analysing the Test Case processes suggested that the simplified award favours employers and leads to disadvantageous outcomes for employees. This study builds on the extant evidence by analysing the implications of award simplification in the context of actual hotel workplaces. Its purpose is to examine the effects of award simplification and compare them with the outcomes associated with enterprise bargaining, focusing in particular on working time arrangements in the Australian hotel industry. The study adopts a qualitative approach, involving multiple case studies. Overall, the findings suggest that hotel employers are adopting bifurcated employment strategies, reflecting their respective bargaining arrangements. At a more subtle level, the effects of regulatory reform differed both within and between workplaces, highlighting rather distinctive and varied implications for many different employees. Importantly, this revealed the diverse needs and preferences of the parties involved and illustrated the complex outcomes associated with regulatory reform. These outcomes appear to be substantially more nuanced than indicated previously.
Enterprise Bargaining Under the Workplace RelationsAct 1996 in Construction and Hospitality Small Businesses: A Comparative Study
Authors: Cairncross Grant , Buultjens Jeremy
Published: September 2006

A major change in Australian industrial relations system since the early 1990s has been the shift from conciliation and arbitration to formalized enterprise and individual bargaining. These changes occurred at the federal and state levels. At the federal level, the introduction of individual bargaining through Australian Workplace Agreements (AWAs) and award simplification has resulted in substantially reduced reliance on awards. However, the small business sector has been viewed as reluctant participants in formalized bargaining for various reasons. Despite this reluctance, during the late 1990s there have been increasing numbers of small businesses negotiating collective agreements at the federal level. This article examines 102 certified agreements involving small firms from the construction and hospitality industries in order to identify the outcomes from these agreements. The study found that the increasing incidence of small businesses adopting enterprise agreements are largely due to the fact that state awards have disappeared in Victoria thereby necessitating a move to certified agreements under the federal Workplace Relations Act 1996. The study shows that in small to medium enterprises employees who are highly organized, and represented by unions, can obtain improvements to conditions of employment under enterprise bargaining. These conditions are often obtained through the use of sustained pattern bargaining campaigns, particularly in the construction industry, and especially in Victoria. Conversely, where union coverage is weak employers are capable of using enterprise bargaining to obtain changes in working conditions that, with regard to pay rates, penalty rates and flexible hours of work in particular, are of benefit to the employers and are in some cases a major change to those existing under the award.
Vibration Estimation of Flexible Space Structures using Range Imaging Sensors
Authors: Lichter Matthew D. , Ueno Hiroshi , Dubowsky Steven
Published: September 2006

Future space applications will require robotic systems to assemble, inspect, and maintain large space structures in orbit. For effective planning and control, robots will need to know the deformation and vibration of the structures with which they interact. This paper presents a method for estimating the shape, motion, and dynamic model parameters of a vibrating space structure using range imaging sensors. The method assumes that the mode shapes are approximately known a priori. An unscented Kalman filter exploits a mechanics-based dynamic model to extract the modal frequencies and damping as well as the modal coefficients and their time rate of change. Both asynchronous-capture (raster-scanning) and synchronous-capture sensors are treated. Theoretical development and experimental results using emulated space hardware are presented.
Time-optimal Trajectories for an Omni-directional Vehicle
Authors: Balkcom Devin J. , Kavathekar Paritosh A. , Mason Matthew T.
Published: September 2006

A common mobile robot design consists of three ‘omniwheels’ arranged at the vertices of an equilateral triangle, with wheel axles aligned with the rays from the center of the triangle to each wheel. Omniwheels, like standard wheels, are driven by the motors in a direction perpendicular to the wheel axle, but unlike standard wheels, can slip in a direction parallel to the axle. Unlike a steered car, a vehicle with this design can move in any direction without needing to rotate first, and can spin as it does so.

The shortest paths for this vehicle are straight lines. However, the vehicle can move more quickly in some directions than in others. What are the fastest trajectories? We consider a kinematic model of the vehicle and place independent bounds on the speeds of the wheels, but do not consider dynamics or bound accelerations. We derive the analytical fastest trajectories between configurations. The time-optimal trajectories contain only spins in place, circular arcs, and straight lines parallel to the wheel axles. We classify optimal trajectories by the order and type of the segments; there are four such classes, and there are no more than 18 control switches in any optimal trajectory.
The PVT, an Elastic Conservative Transmission
Authors: Ingvast Johan , Wikander Jan , Ridderström Christian
Published: September 2006

This paper presents an innovative transmission called the passively variable transmission (PVT) that has a high torque ratio for large loads and a low velocity ratio for small loads. The change in these ratios depends passively on the load, in contrast to the continuous variable transmission (CVT), where the transmission ratio is controlled explicitly. Another difference from the CVT is that the PVT is elastic and the term transmission ratio is therefore not applicable. A theory section formulates alternative ways of describing the torque and velocity relations for elastic conservative transmisions as well as other important properties.

This theory is used to analyze and illustrate the characteristics of a PVT. The theory is also used to compare the PVT with another novel elastic conservative transmission, called load sensitive CVT.

The nonlinearities and elasticity of the PVT make it difficult to control using linear control theory. Feedback linearization was therefore used to design a torque controller, and experimental results show low impedance at small loads. Further, the controller tracks a reference torque well as long as the reference rate does not cause motor saturation. The abilities of the PVT are also illustrated by comparing it with an actuator having a traditional transmission. The load case is recorded joint torques and angles from the carpus joint of a walking horse. Simulation show that the required peak power is reduced by more than 20% and the product of the maximum torque and the maximum angular velocity is reduced by approximately 30%.
Preparation of Poly(phenylene oxide-gstyrenesulfonic acid) and their Characterization for DMFC Membrane
Authors: Cho Chang Gi , Jang Hye Young , You Young Gyu , Li Guang Hua , An Sung Guk
Published: September 2006

Well-defined poly(2,6-dimethyl-4,4′-phenylene oxide)-g-poly(styrenesulfonic acid) (PPO-g-PSSA) graft copolymer was synthesized via living radical polymerization. For the graft copolymer, poly(2,6-dimethylphenylene oxide) (PPO) was brominated first, and the brominated PPO (PPO-Br) was used as a macroinitiator in the atom transfer radical polymerization (ATRP) of styrenesulfonic acid sodium salt. The number of grafts per PPO chain and the molecular weight of the graft were controlled by adjusting the degree of bromination, and conversion in ATRP, respectively. The graft copolymers obtained were transformed into proton exchange membranes for direct methanol fuel cell (DMFC) application. The performance of the membranes was measured in terms of water uptake, proton conductivity, methanol permeability, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with PSSA block content. Very low methanol permeability and good proton conductivity were observed by adjusting grafting frequency and PSSA block content.
Gas Transport Properties of ODPA-TAPOB Hyperbranched Polyimide-Silica Hybrid Membranes
Authors: Suzuki Tomoyuki , Yamada Yasuharu , Sakai Jun
Published: September 2006

Physical and gas transport properties of novel hyperbranched polyimide-silica hybrid membranes were investigated. Hyperbranched polyamic acid as a precursor was prepared by polycondensation of a triamine monomer, 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), and a dianhydride monomer, 4,4′-oxidiphthalic anhydride (ODPA), and subsequently modified the end groups by 3-aminopropyltrimethoxy-silane (APTrMOS). Hyperbranched polyimide-silica hybrid membranes were prepared using the polyamic acid, water, and tetramethoxysilane (TMOS) by the sol-gel method and thermal imidization. The 5% weight-loss temperature and glass transition temperature of the hybrid membranes determined by TGDTA measurements considerably increased with increasing silica content, indicating effective cross-linking at polymer-silica interface mediated by APTrMOS. CO2, O2, N2, and CH4 permeability coefficients of the hybrid membranes increased with increasing silica content. In addition to the increased permeability, CO2/CH4 selectivity of the hybrid membranes increased with increasing silica content. It was concluded that the ODPA-TAPOB hyperbranched polyimide-silica hybrid membranes have high thermal stability and good gas selectivity, and are expected to apply to a high-performance gas separation membrane.
Syntheses and Characterization of Polyimide containing Metal Phthalocyanine for Organic Electroluminescent Devices
Authors: Jung Sin Hye , Ha Chang-Sik
Published: September 2006

We synthesized two soluble copolyimides (PI) containing Co, Cu-phthalocyanine from 2,2-bis(3,4-dicarboxy-phenyl)hexafluoroisopropane dianhydride-2,4,5,6-tetramethyl-1,4-phenylene-diamine (6FDA-4MPDA) PI and 2,2-bis(3,4-dicarboxy-phenyl)hexafluoroisopropane dianhydride-4,4′-oxy dianiline (6FDA-ODA) PI for organic electroluminescent devices (OELD). The new copolyimides were characterized by Fourier Transform in frared (FT-IR)and ultra-violet (UV) spectroscopy. Some of fundamental OELD performances including current density-applied voltage characteristics were also investigated. It was found that the copolyimides containing Co and Cu-phthalocanine exhibited better hole-transporting properties for OELD than either of the 6FDA-4MPDA PI and 6FDA-ODA PI doped with N, N-diphenyl- N, N′-di(m-toly)benzidine (TPD) or Co-, or Cu-phthalocyanine did..
Poly(ester imide)s Possessing Low Coef-cient of Thermal Expansion and Low Water Absorption
Authors: Hasegawa Masatoshi , Koseki Kazunori
Published: September 2006

The film properties of polyimides (PIs) containing para-ester linkages in the main chains, poly(ester imide)s (PEsI) are reported in this paper. An ester-containing dianhydride monomer (TAHQ) was synthesized from hydroquinone and trimellitic anhydride chloride. PEsIs derived from TAHQ and various diamines with stiff/linear structures, p-phenylenediamine (PDA), trans-1,4-cyclohexanediamine (CHDA), 2,2′-bis(trifluoromethyl)benzidine (TFMB), 4-aminophenyl-4′-aminophenylbenzoate (APAB), and 4,4′-daminobenzanilide (DABA), exhibited extremely low linear coefficient of thermal expansion (CTE) values, for example, CTE = 3.2 ppm K-1 for TAHQ/PDA and 3.3 ppm K-1 for TAHQ/APAB. The results revealed that the para-ester linkages behave as a rod-like segment favorable for thermal imidization-induced in-plane orientation. Copolymerization with flexible 4,4′-oxydianiline made precise CTE matching possible between PEsI/copper substrate and the significant improvement of film toughness at the same time. Wide-angle X-ray diffraction measurements showed that some of the PEsIs examined are semi-crystalline. The present work proposes novel high temperature insulation materials suitable for the substrates for flexible printed circuit, possessing not only a copper-level low CTE but also high film toughness, high dimensional stability, and low water absorption. PEsIs were compared with the corresponding amide-containing PIs. Highly transparent PEsIs are also reported.
Alicyclic Polyimides based on bicyclo[2.2.1]heptane- 2,3,5,6-tetracarboxylic 2,3-5,6-dianhydrides
Authors: Matsumoto Toshihiko , Kawabata Shuichi , Takahashi Risa
Published: September 2006

The alicyclic polyimides were prepared by reacting bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic-2,3-5,6-dianhydride (BHDA) with aliphatic or aromatic diamines in hexamethylphosphoramide. The poly(amic acid)s possessed inherent viscosities (νinh)in the range from 0.13 to 0.38, and they formed free-standing and flexible films after being cast then cured. The fully alicyclic polyimide films exhibited a cutoff around 230 nm, and are transparent even in the near infrared region. The optically estimated ε of the fully alicyclic polyimides was about 2.6. All the alicyclic polyimide possessed negligibly small birefringence below 10-4. Semi-aromatic polyimide PI(BHDA + 1,3-BAB) had good thermal stability with no significant weight loss up to 350°C, and the T5 was around 450°C, although the Tg was as low as 197°C. All polyimides exhibited broad dispersive peaks of diffraction around 16° (2τ). The PI(BHDA + BBH) film possessed a tensile modulus of 2.05 GPa and a tensile strength of 52 MPa, and these values can compete in terms of strength with those of a commercial polycarbonate.
Development of Highly Soluble Addition-type Imide Oligomers for Matrix of Carbon Fiber Composite (I): Imide Oligomers Based on Asymmetric Biphenyltetracarboxylic Dianhydride and 9,9-Bis(4-aminophenyl) fluorene
Authors: Ishida Yuichi , Ogasawara Toshio , Yokota Rikio
Published: September 2006

Novel highly soluble addition-type imide oligomers were synthesized from 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), 9,9-bis(4-aminophenyl)fluorene (BAFL), 4,4′-diaminodiphenyl ether (4,4′-ODA), and 4-phenylethynylphthalic anhydride (PEPA) to fabricate carbon fiber-reinforced plastics (CFRP) by routing imide solution prepreg. The imide oligomers were soluble in aprotic polar solvents of more than 35 wt.%. Imide oligomers consisting of less than 50mol% BAFL per total diamine had good processability when using a hot press. The glass transition temperature ( Tg)values of the cured resins were higher than 340°C. The Tg values increased when the BAFL component increased. The 5% weight loss temperatures ( Td5) were higher than 550°C. The elongations-at-break of the BAFL copolymers were less than that of the polymer without BAFL. An imide solution prepreg was prepared from the imide oligomer solution and carbon fibers. Polyimide/carbon fiber composite without voids was fabricated from the imide solution prepreg.
Effect of Curing Conditions on the Fabrication of Zn-oxide Nanoparticles Dispersed in a Polyimide Film
Authors: Roh Hyung-Gu , Kim Gun-Hong , Kim Young-Ho
Published: September 2006

Zinc oxide nanoparticles were formed by reacting polyamic acid (PAA) with Zn during curing. In this paper, we investigated the effect of curing conditions on the zinc oxide nanoparticle formation. The polyimide (PI) precursors used in this study were biphenyltetracarboxylic dianhydride- p-phenylene diamine (BPDA-PDA) type and oxydiphthalic dianhydride 3-sulful dianhydride (ODPA-3SDA) type PAAs. Zn thin films were deposited on silicon substrates by DC magnetron sputter. PAA was then spin-coated onto Zn thin films and the PAA/metal films were cured at various conditions. The characterization using transmission electron microscope observation was carried out to investigate the size and distribution of zinc oxide particles. Zinc oxide nanoparticles were formed in the PI film regardless of the curing conditions. The size, distribution and density of zinc oxide particles were strongly dependent on the curing conditions..
Synthesis and Characterization of Self-Assembling Amphiphilic Aromatic Amide Dendrons
Authors: Hayakawa Teruaki , Nakasugi Shigemasa , Kakimoto Masa-Aki , Tokita Masatoshi , Watanabe Junji
Published: September 2006

The sub-micrometer and micrometer-scale self-assembled structures of a series of amphiphilic dendrons constructed from the building blocks of aromatic amide, triethylene glycol, and octadecyl groups were evaluated. The dendrons from the first to the third generations were prepared by a straightforward synthesis. Self-assembling study of the dendrons was carried out by the characterization of the films prepared by casting from the solutions using scanning electron microscopy and atomic force microscopy. The solution of the first generation amphiphilic dendron provided the dot-like or fibrous structures with a diameter of several hundred nanometers. The hexagonally arranged open pores of approximately 1.1- 1.4 μm were formed by casting the solution of the second and the third generation amphiphilic dendrons under a moist air flow.
Structure-Properties Correlation in Polyimide/Silica Hybrids
Authors: Musto Pellegrino , Ragosta Giuseppe , Scarinzi Gennaro , Mascia Leno
Published: September 2006

Polyimide/silica hybrids were prepared by a sol-gel process and were evaluated in terms of curing behavior, morphology, water sorption properties and mechanical performances at ambient and at higher temperatures. The spectroscopic examination showed that the presence of the inorganic phase catalyzes the imidization reaction of the polyamic acid pre-polymer. Two types of morphology were obtained by tailoring the composition of the precursor solution mixture, i.e. phase-separated or co-continuous systems. Water sorption was found to be strongly influenced by the system morphology. The presence of the inorganic phase increased considerably the amount of absorbed water and phase-separated hybrids absorbed more than co-continuous hybrids. Also the mechanical properties were found to depend on the system morphology. The largest increase in rigidity both at ambient and attemperatures up to 250°C was achieved when the two phases were co-continuous. Conventional two-phase systems, on the other hand, exhibited improved fracture toughness.
Control of Glass Transition, Solubility, and Thermo-Optic Coef-cients of a Siloxane-Containing Polyimide by Silica Hybridization
Authors: Terui Yoshiharu , Ando Shinji
Published: September 2006

In order to utilize significant enhancement of thermo-optic coefficients (i.e. temperature dependence of refractive index, d n-d T) of polymers above glass transition temperatures ( Tg values) for dynamic control of refractive index, the Tg of siloxane-containing polyimide (PI), derived from bis(3,4- dicarboxyphenyl)ether dianhydride and bis(3-aminopropyldimethylsilyl)ether, was controlled by hybridization with silica (amorphous SiO2) particles generated by the in situ sol-gel reaction. The Tg values for the hybrid films were increased from 55 to 105°C with increasing the silica content. In addition, resistance to the organic solvents was significantly improved by the hybridization. These results indicate that the PI chains were physically or chemically bonded to the silica particles in the hybrids. The characteristic high transparency of the matrix PI in the visible light region was retained in the hybrid films without causing light scattering, which demonstrates that the precipitated silica particles were nano-sized and uniformly dispersed in the hybrid films. The refractive indices of the hybrids decreased from that of the matrix (1.552) to 1.543 as the silica content increased due to low refractive index of silica. The d n-d T values below Tg were decreased from -158 to -127 ppm K-1 as the silica contents increased due to the deceases in thermal volume expansion. On the other hand, the hybrid films exhibited an abrupt increase in d n-d T at Tg and quite large d n-d T values (in a range -330 to -350 ppm K-1)above Tg. The refractive indices and the d n-d T values were stable after annealing at 300°C for 1 h under N2 flow.
Fractional Formula Description of Angle-interlock Woven Fabric Construction
Authors: Nie Jianbin , Lu Shiyan , Gu Bohong
Published: September 2006

This article presents a simplified method, known as a fractional formula description, to describe the angle-interlock woven fabric construction. According to the interweaving between warp and weft yarns in multi-layered angle-interlock fabric, the construction of the angle-interlock fabric is represented by a fractional formula to illustrate the interweave rule of a warp yarn in a unit cell. Furthermore, this article also gives an extended method to apply the fractional formula to the multilayered angle-interlock fabric design. From the discussion of the fractional formula description method, it is proven that the description method is more efficient and valid for the representation and design of angle-interlock woven fabric construction and fabric design, especially for the computer-aided design (CAD) of multilayered angle-interlock woven fabric.
Enhancing Flame-resistance and Antibacterial Properties of Cotton Fabric
Authors: Gouda M.
Published: September 2006

The main purpose of this work is to enhance the flame resistance and antibacterial properties of cotton fabric via treatment with carbamoylguanidine phosphate using the pad-dry technique followed by after treatment with some transition metal chlorides. The effects of pH, curing conditions, and carbamoylguanidine phosphate on the extent of modification are evaluated. Analyses of the data reveal that:

I. the limiting oxygen index of the treated fabric samples follows a decreasing order:

carbamoylguanidine phosphate-Al complex4carbamoylguanidine phosphate4carbamoylguanidine phosphate-Ni complex4carbamoylguanidine phosphate-Cu complex,

II. antibacterial properties of the treated cotton fabric samples follow a decreasing order:

carbamoylguanidine phosphate-Cu complex4carbamoylguanidine phosphate-Ni complex4carbamoylguanidine phosphate-Al complex4carbamoylguanidine phosphate, and

III. such finished fabrics show high durability to washing.
Early FDG-PET assessment in combination with clinical risk scores determines prognosis in recurring lymphoma
Authors: Schot Bart W. , Zijlstra Josée M. , Sluiter Wim J. , van Imhoff Gustaaf W. , Pruim Jan , Vaalburg Willem , Vellenga Edo
Published: September 2006

This study was set up to demonstrate whether prognostic classification based on the secondary age-adjusted International Prognostic Index (sAA-IPI) for recurring aggressive non-Hodgkin lymphoma (NHL) or the prognostic score for recurring Hodgkin lymphoma (HL) can be improved by including the midtreatment results of fluorine-18-fluorodeoxy-glucose–positron emission tomography (FDG-PET). Clinical data on patients with recurring lymphoma who were treated with second-line chemotherapy (DHAP-VIM-DHAP) followed by autologous stem cell transplantation (ASCT) were collected and combined with the results of FDG-PET performed before and after 2 cycles of reinduction chemotherapy. PET responses after 2 courses were scored as complete remission (CR), partial remission (PR), or no response (NR). A multivariate analysis was performed to design a predictive model. The number of patients (101 of 117) included those (78 patients with aggressive NHL and 23 patients with HL) that could be analyzed according to protocol. Of these, 80 patients were chemosensitive and 77 received transplants. Both secondary clinical risk score (P < .001) and FDG-PET response (P < .001) were independent predictive factors for the total evaluable group of patients with lymphoma and for patients with NHL alone. The combined use of the clinical risk score and FDG-PET response after 2 chemotherapy courses identified at least 4 categories of patients with a failure-free survival varying between 5% to 100% after transplantation (P < .001). These data indicate that the secondary clinical risk score in conjunction with FDG-PET response provides a more accurate prognostic instrument for the outcome of second-line treatment at least in patients with recurring NHL.
The THAP–zinc finger protein THAP1 regulates endothelial cell proliferation through modulation of pRB/E2F cell-cycle target genes
Authors: Cayrol Corinne , Lacroix Chrystelle , Mathe Catherine , Ecochard Vincent , Ceribelli Michele , Loreau Emilie , Lazar Vladimir , Dessen Philippe , Mantovani Roberto , Aguilar Luc , Girard Jean-Philippe
Published: September 2006

We recently cloned a novel human nuclear factor (designated THAP1) from postcapillary venule endothelial cells (ECs) that contains a DNA-binding THAP domain, shared with zebrafish E2F6 and several Caenorhabditis elegans proteins interacting genetically with retinoblastoma gene product (pRB). Here, we show that THAP1 is a physiologic regulator of EC proliferation and cell-cycle progression, 2 essential processes for angiogenesis. Retroviral-mediated gene transfer of THAP1 into primary human ECs inhibited proliferation, and large-scale expression profiling with microarrays revealed that THAP1-mediated growth inhibition is due to coordinated repression of pRB/E2F cell-cycle target genes. Silencing of endogenous THAP1 through RNA interference similarly inhibited EC proliferation and G1/S cell-cycle progression, and resulted in down-regulation of several pRB/E2F cell-cycle target genes, including RRM1, a gene required for S-phase DNA synthesis. Chromatin immunoprecipitation assays in proliferating ECs showed that endogenous THAP1 associates in vivo with a consensus THAP1-binding site found in the RRM1 promoter, indicating that RRM1 is a direct transcriptional target of THAP1. The similar phenotypes observed after THAP1 overexpression and silencing suggest that an optimal range of THAP1 expression is essential for EC proliferation. Together, these data provide the first links in mammals among THAP proteins, cell proliferation, and pRB/E2F cell-cycle pathways.