bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micellar electrokinetic chromatography with laser‐induced fluorescence detection for rapid and sensitive analysis of two new bioactive reagents using dynamic covalent coating
Authors: Xie Jian Ping , Cui Feng Ling , Chen Xing Guo , Hu Zhi De 
Published: September 2004

AbstractA simple, rapid, selective, and sensitive micellar electrokinetic chromatography (MEKC) with laser‐induced fluorescence detection (LIF) method was developed, using hexamethyldisilazane (HMDS) as dynamic covalent coating (DCC), for the analysis of two new bioactive agents N‐n‐hexyl‐N ´‐(sodium p‐aminobenzenesulfonate) thiourea (HXPT) and N‐n‐undecyl‐N ´‐(sodium p‐aminobenzenesulfonate) thiourea (UPT) derivatized with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole. MEKC methods both not using DCC and using DCC were investigated. In a series of optimization steps, DCC and a running buffer of 20 mM Na2B4O7 + 16 mM SDS + 8% acetonitrile were applied for determination of the derivatives. Linear relationships for HXPT and UPT were obtained in the range of 5 to 100 μM (correlation coefficient: 0.9986 for HXPT, 0.9978 for UPT), and the detection limits for HXPT and UPT were 16.5 and 39.0 ng mL–1. The sensitivity was improved over that of fluorescence spectroscopy methods. The method was applied to the analysis of the two reagents in lab water waste with recoveries in the range of 95.6–107.5%.
Fast GC analysis with a 50 μm ID column: theory, practical aspects, and application to a highly complex sample
Authors: Mondello Luigi , Tranchida Peter Quinto , Casilli Alessandro , Favoino Olinda , Dugo Paola , Dugo Giovanni 
Published: September 2004

AbstractThis research focuses on the minimization of GC analysis times through the use of a 5 m×0.05 mm ID×0.05 μm (film thickness) column. Experimental minimum plate height (Hmin) and optimum linear velocity values were derived from standard compound applications, under various analytical conditions, and then related to classical chromatographic theory. Deviations from the latter are measured and discussed. Practical aspects linked to the use of such capillaries, such as column sample capacity and detector acquisition rates, are also considered. Furthermore, a fast, and what can be considered a very fast method, were applied to the separation of a fuel sample. Coefficients of variation of elution times and relative peak areas were calculated in the very fast application. All analytical results are compared with those obtained by conventional 0.25 mm ID column applications.
Large volume splitless injection with concurrent solvent recondensation: Keeping the sample in place in the hot vaporizing chamber
Authors: Biedermann Maurus , Fiscalini Alessandro , Grob Koni 
Published: September 2004

AbstractAn injector liner packed with a plug of glass wool is compared with a laminar and a mini laminar liner for large volume (20–50 μL) splitless injection with concurrent solvent recondensation (CSR‐LV splitless injection). Videos from experiments with perylene solutions injected into imitation injectors show that glass wool perfectly arrested the sample liquid and kept it in place until the solvent had evaporated. The sample must be transferred from the needle to the glass wool as a band, avoiding ‘thermospraying’ by partial solvent evaporation inside the needle. The liquid contacted the liner wall when the band was directed towards it, but from there it was largely diverted to the glass wool. In the laminar liners, part of the liquid remained and evaporated at the entrance of the obstacle, while the other proceeded to the center cavity. Vapors formed in the center cavity drove liquid from the entrance of the obstacle upwards, but the importance of such problems could not be verified in the real injector. Some liquid split into small droplets broke through the obstacle and entered the column. Breakthrough through the laminar liners was confirmed by a chromatographic experiment. An improved design of a laminar liner for large volume injection is discussed as a promising alternative if glass wool causes problems originating from insufficient inertness.
Der Einfluss von Oxidationsmitteln auf die Korrosionsbeständigkeit von Nicrofer 3127 hMo in niedrig‐ und mittelkonzentrierter Schwefelsäure
Authors: Werner H. , Klöwer J. , Alves H. 
Published: September 2004

AbstractFür Nicrofer 3127 hMo wurden aus 24 h‐Versuchen mit gravimetrischer Auswertung die Isokorrosionslinien für eine Abtragungsgeschwindigkeit < 0,1 mm/a in belüfteter technischer und p.a. Schwefelsäure jeweils ohne und mit 1 g/l Chlorid im Konzentrationsbereich bis 90% ermittelt. Messungen des Freien Korrosionspotentials belegen, dass die höhere Beständigkeit von Nicrofer 3127 hMo in der technischen Säure auf deren Oxidationsmittelgehalt zurückzuführen ist.Dieser wirkt ab einer Schwefelsäurekonzentration von 20% passivitätserhaltend bei Temperaturen, die in Abhängigkeit von der Säurekonzentration 10–50 K über der Isokorrosionslinie von p.a. Schwefelsäure liegen. Bei Schwefelsäurekonzentrationen bis 10% ist der Oxidationsmittelgehalt der technischen Schwefelsäure zu gering, um die Korrosionsbeständigkeit von Nicrofer 3127 hMo gegenüber der in p.a. Säure zu verbessern.In den chloridhaltigen Schwefelsäuren verhält sich Nicrofer 3127 hMo analog. Infolge der aktivierenden Wirkung des Chlorides wird der Einsatzbereich im Vergleich zu den chloridfreien Schwefelsäuren durch niedrigere Temperaturen begrenzt.
Protective organic‐inorganic hybrid coatings on mild steel derived from Ti(OC4H9)4‐modified precursors
Authors: Nguyen V. , Perrin F. X. , Vernet J. L. 
Published: September 2004

AbstractTitania‐poly(methyl methacrylate‐co‐butyl methacrylate‐co‐methacrylic acid) hybrids prepared by a sol‐gel method were deposited by dip coating on mild steel. Transparent and defect free coatings with titania content ranging between 0 and 12.7 wt.% have been prepared. Barrier properties and dry adherence have been tested by electrochemical impedance spectroscopy (EIS) and the vertical pull‐off test, respectively. The pull‐off test results suggest that the titanium alkoxide precursor must intercede on the substrate/coating interphase during film formation to create specific adhesive bondings with the substrate.In this paper, two capacitance models are used to estimate the water uptake, one based on a uniform and one on a heterogeneous distribution of sorbed water. Water uptake determined from these two models is compared to the gravimetry results. It is suggested that a reliable determination of the actual water uptake in coatings from capacitance measurements require an extensive experimental work. The variations in the state of sorbed water with the specimen type or immersion time, the leaching of organics during immersion or the slow diffusion of ions are fundamental factors that must be considered when comparing the water uptake determined from gravimetry and capacitance models.
Effect of Thermal Degradation on Glass Transition Temperature of PMMA
Authors: Wondraczek Katrin , Adams Jörg , Fuhrmann Jürgen 
Published: September 2004

AbstractSummary: For industrial polymer applications, the structure‐property relation during thermal treatment is of high interest. If a polymer is degraded, its molecular structure will alter, and its mechanical properties are affected as well; thus limiting the usability. The objective of this paper is to highlight the effect of thermal degradation on the glass transition temperature of the remaining polymer. We used commercial atactic poly(methyl methacrylate) (PMMA) as an example. The residue of an oxidatively degraded PMMA was analyzed in terms of its structure‐property relation. A characteristic evolution of the glass transition temperature as a function of degradation time was observed. The glass transition temperature of the degradation product correlates with the molecular weight, monomer content, and tacticity of the remaining polymer. Based on the Tg data, four different degradation domains are discussed in detail. Each period is characterized by a certain trend in Tg due to specialities of the superimposing rate processes.Glass transition temperature versus normalized weight loss as determined by DDSC measurements.magnified imageGlass transition temperature versus normalized weight loss as determined by DDSC measurements.
Preparation of Polymeric Nanoparticles by Photo‐Crosslinking of an Acryloylated Polyaspartamide in w/o Microemulsion
Authors: Craparo Emanuela Fabiola , Cavallaro Gennara , Bondì Maria Luisa , Giammona Gaetano 
Published: September 2004

AbstractSummary: Biodegradable polymeric nanoparticles have been prepared by UV irradiation of an acryloylated water soluble polymer by an inverse microemulsion. The starting polymer was a α,β‐poly(N‐2‐hydroxyethyl)‐D,L‐aspartamide (PHEA) partially functionalized with glycidyl methacrylate (GMA) in order to introduce reactive vinyl groups in the side chain. The PHEA‐GMA copolymer obtained (PHG) was crosslinked by UV irradiation of the inverse microemulsion prepared by mixing an aqueous solution of PHG with propylene carbonate (PC)/ethyl acetate (EtOAc) in the presence of sorbitan trioleate (SPAN 85) as surfactant. Nanoparticles obtained were characterized by FTIR spectrophotometry, transmission electron microscopy, size distribution analysis and zeta potential measurements. Nanoparticles investigated revealed spherical and homogeneous shading, the particle size having a mean diameter of 88 ± 13 nm (PDI = 0.21) and a negative surface charge in several aqueous media. Moreover, in vitro chemical and enzymatic hydrolysis studies evidenced the partial biodegradability of PHG nanoparticles, which is more evident after incubation with enzymes such as esterases. PHG nanoparticles were loaded during UV irradiation process with Cytarabine, chosen as a model drug, and Cyt‐loaded PHG nanoparticles were able to release it in a simulated physiological fluid (phosphate buffer at pH 7.4) and in blood plasma.Transmission electron micrograph of photo‐crosslinked PHG.magnified imageTransmission electron micrograph of photo‐crosslinked PHG.
Synthesis of Laser‐Alignable Liquid Crystalline Conducting Polymers
Authors: Brown John W. , Foot Peter J. S. , Gabaston Laurence I. , Ibison Paul , Prevost Adeline 
Published: September 2004

AbstractSummary: The synthetic routes to three series of liquid crystal conducting polymers (based on pyrrole, thiophene, and aniline monomers) are reported and the optimum conditions for polymer preparation are described. These polymers show increased conductivity when laser‐aligned, the greatest effect being shown by the N‐substituted pyrrole‐based system. Information on their liquid crystal and spectroscopic properties and other characteristics are also included.Structure of the monomers M1, M2, and M3.magnified imageStructure of the monomers M1, M2, and M3.
Polycarbonate/Montmorillonite Nanocomposites Prepared by Microwave‐Aided Solid State Polymerization
Authors: Yoo Youngjae , Choi Kil‐Yeong , Lee Jae Heung 
Published: September 2004

AbstractSummary: Polycarbonate/montmorillonite (MMT) nanocomposites were prepared by microwave solid‐state polymerization. The MMTs were modified with alkyl ammonium salt. Pre‐intercalated polycarbonate nanocomposite was prepared using two conventional methods; a melt process and a solution process. Melt processing was accomplished in a Haake internal mixer for 30 mins at 180 °C. Solution processing was accomplished in a homogenizer using chloroform. The wide‐angle X‐ray diffraction (WAXD) peak indicating the gallery size of MMTs was shifted to lower levels after the pre‐intercalation process. Subsequently, microwave solid‐state polymerization converted the pre‐intercalated nanocomposite into the exfoliated nanocomposite. WAXD revealed that exfoliation and/or further intercalated structures were obtained when comparing the results from the microwave solid‐state polymerization with results from conventional solid‐state polymerization using oil heating. This means that microwave solid‐state polymerization is more effective than conventional solid‐state polymerization using oil heating. It was shown that conventional melt and solution processing of MMT and polycarbonate prepolymer yielded intercalated nanocomposites with interlayer spacing of 2.5 and 2.7 nm respectively. Microwave solid‐state polymerized nanocomposite showed the exfoliated and/or intercalated structure, whereas conventional solid‐state polymerization using oil heating only increased the gallery size of MMT. The thermal decomposition behavior and morphologies were investigated by thermogravimetric analysis (TGA) and transmission electron microscopy (TEM).Schematic diagram of microwave solid‐state polymerization.magnified imageSchematic diagram of microwave solid‐state polymerization.
The Kodaira dimension of certain moduli spaces of Abelian surfaces
Authors: Erdenberger C. 
Published: September 2004

AbstractThe moduli space of (1, p)‐polarized abelian surfaces is a quasi‐projective variety. In the case when p is a prime, we want to study its Kodaira dimension. We will show that it is of general type for p > 71 and some smaller values of p. This improves an earlier result of G. K. Sankaran. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonautonomous abstract Cauchy problems for strongly measurable families
Authors: Tanaka Naoki 
Published: September 2004

AbstractThis paper is devoted to the study of the inhomogeneous abstract Cauchy problem for time‐dependent linear evolution equation u′(t) = A(t)u(t) + f(t) for t ∈ [0, T], under the strong measurability of A and a new type of quasi‐stability condition from the viewpoint of the theory of finite difference approximations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of Polyaniline Nanobelts
Authors: Li Guicun , Peng Hongrui , Wang Yi , Qin Yong , Cui Zuolin , Zhang Zhikun 
Published: September 2004

AbstractSummary: Polyaniline nanobelts have been synthesized by a self‐assembly process using the chemical oxidative polymerization of aniline in a surfactant gel. The morphologies of polyaniline nanostructures were characterized by field‐emission scanning electron microscopy and transmission electron microscopy. The effects of the concentrations of cetyltrimethylammonium bromide on the morphologies of polyaniline nanostructures have also been investigated.A scanning electron microscopy image of polyaniline nanobelts synthesized with 0.12 M cetyltrimethylammonium bromide at −7 °C.magnified imageA scanning electron microscopy image of polyaniline nanobelts synthesized with 0.12 M cetyltrimethylammonium bromide at −7 °C.
Preparation of Antimicrobial Ultrafine Cellulose Acetate Fibers with Silver Nanoparticles
Authors: Son Won Keun , Youk Ji Ho , Lee Taek Seung , Park Won Ho 
Published: September 2004

AbstractSummary: A feasible method for the preparation of antimicrobial ultrafine fibers with silver nanoparticles was developed by direct electrospinning of a cellulose acetate (CA) solution with small amounts of silver nitrate followed by photoreduction. Silver nanoparticles in ultrafine CA fibers were stabilized by interactions with carbonyl oxygen atoms in CA. Ultrafine CA fibers with silver nanoparticles showed very strong antimicrobial activity.TEM image of an ultrafine CA fiber electrospun from 10 wt.‐% CA solution with 0.5 wt.‐% AgNO3.magnified imageTEM image of an ultrafine CA fiber electrospun from 10 wt.‐% CA solution with 0.5 wt.‐% AgNO3.
Crazing and Fracture in Polymers: Micro‐Mechanisms and Effect of Molecular Variables
Authors: Kausch H.H. , Halary J.‐L. , Plummer C.J.G. 
Published: September 2004

AbstractThe influence of the primary molecular parameters chain configuration, architecture and molecular weight (MW) on the mode of mechanical breakdown is discussed for two series of (amorphous) thermoplastic polymers, methyl methacrylate glutarimide copolymers and amorphous semi‐aromatic polyamides. Structural and dynamic analyses and fracture mechanical methods applied to such adequately chemically modified (glassy) polymers permit us to show and to explain the effect of intrinsic variables on local molecular motions and on the competition between chain scission, disentanglement and segmental slip, which in turn determine the dominant mode of instability and plastic behaviour. Above a critical molecular weight, toughness depends most strongly on the entanglement density; a positive effect of the intensity of sub‐Tg relaxations and in‐chain cooperative motions on the toughness of these materials is clearly evident.
Linear Viscoelasticity and Non‐Linear Elasticity of Block Copolymer Blends Used as Soft Adhesives
Authors: Roos Alexandra , Creton Costantino 
Published: September 2004

AbstractThe debonding of pressure‐sensitive‐adhesives from a rigid surface often occurs with the formation of a fibrillar structure bridging the surface and the adhesive. This fibrillar structure is responsible for the large (of the order of 1 kJ/m2) adhesion energy, which is measured, for this type of adhesive despite the very low level of applied stress. One way to account for this dissipated energy is viscous flow in the elongation process of the fibrils. However, for certain types of adhesives, the extension of the fibrils is essentially a quasi reversible elastic process and the energy is only dissipated rather rapidly when the fibrils are detached from the surface. It is therefore essential to characterize the elastic properties of theses adhesives not only in the linear viscoelastic regime but also in the large strain non‐linear elastic domain. We have therefore performed tensile tests of model adhesive films based on block copolymers. The respective roles played by the linear viscoelasticity and non‐linear elasticity in controlling the properties will be discussed.
Micromechanical Mechanisms for Toughness Enhancement in β‐Modified Polypropylene
Authors: Henning Sven , Adhikari Rameshwar , Michler Georg H. , Calleja Francisco J. Baltá , Karger‐Kocsis József 
Published: September 2004

AbstractTwo samples of isotactic polypropylene (iPP) representing the crystalline α‐ and β‐modifications are compared with regard to their semicrystalline morphology and the resulting micromechanical mechanisms. Processes at room temperature (23°C) and at −40°C have been investigated by means of different microscopic techniques. Good results can be achieved by the application of a chemical etching technique to the deformed samples prior to scanning electron microscopy inspection. The toughness enhancement that is measured for the β‐iPP is attributed to micromechanical mechanisms initiated within the intercrystalline, amorphous phase. It is shown that the specific nanostructure (lamellar arrangement) causes significant changes in the mechanical behaviour of the materials.
Thermal Oxidation and Its Relation to Chemiluminescence from Polyolefins and Polyamides
Authors: Matisová‐Rychlá Lyda , Rychlý Jozef , Tiemblo P. , Gómez‐Elvira J.M. , Elvira M. 
Published: September 2004

AbstractChemiluminescence (CL) from oxidation of polypropylene, polyethylene and polyamide has been compared and kinetic parameters based on the simplified kinetic scheme involving both bimolecular decomposition of hydroperoxides as an initiating event and correction for the oxidation spreading were determined. Induction times of oxidation determined from the autocatalytic shape of chemiluminescence intensity‐time runs increase with an increasing initial molar mass of polypropylene within low molar masses up to 180 kDa regardless of the route of the polypropylene synthesis. The more complex chemiluminescence patterns in case of polyamides may be related with an increase of initially present defect structures including the terminal amino groups.
Salivary production in Parkinson's disease
Authors: Proulx Melisa , De Courval François P. , Wiseman Michael A. , Panisset Michel 
Published: September 2004

AbstractHypersialorrhea is a common phenomenon in Parkinson disease (PD). The objective of this study was to determine whether patients with PD had an abnormally increased production of saliva and whether the production of saliva could be associated to factors related to either the disease characteristics or to its treatment. A total of 83 patients with PD and 55 control subjects participated in this study. Because of the age difference between the two groups, comparisons were made on a ±2‐year age‐matched sample of 44 PD patients and 44 control subjects. PD patients produced significantly less saliva than control subjects. Correlations were obtained with the 83 PD patients between unstimulated salivary flow and patients characteristics. When controlling for age, sex, and Hoehn and Yahr scale, decreased production of saliva correlated significantly with the dose of levodopa and the symptoms of xerostomia. When controlling for medications, there was no relationship between the production of saliva and the evolution of the disease. This study shows that patients with PD produce less saliva than normal. Factors influencing the production of saliva include the use of levodopa and female gender. Our results may have implications for the treatment of drooling in PD. © 2004 Movement Disorder Society
Continuous subcutaneous apomorphine therapy improves dyskinesias in Parkinson's disease: A prospective study using single‐dose challenges
Authors: Katzenschlager Regina , Hughes Andrew , Evans Andrew , Manson Alice J. , Hoffman Marion , Swinn Lesley , Watt Hilary , Bhatia Kailash , Quinn Niall , Lees Andrew J. 
Published: September 2004

AbstractContinuous subcutaneous (SC) infusion of the dopamine agonist apomorphine was shown in retrospective studies to improve drug‐induced dyskinesias in Parkinson's disease (PD). We prospectively assessed the antidyskinetic effect of continuous SC apomorphine therapy using subjective and objective measures, and sought to determine whether any observed dyskinesia reduction could be corroborated using single‐dose dopaminergic challenges. Twelve PD patients with on–off fluctuations and disabling dyskinesias who were scheduled to start apomorphine pump treatment underwent acute levodopa and apomorphine challenges at baseline and 6 months later. Video recordings involving motor tasks were rated blindly by two independent raters using modified AIMS and Goetz dyskinesia scales. At 6 months, mean apomorphine dose was 75.2 mg per day and the mean l‐dopa dose had been reduced by 55%. Daily off time in patients' diaries was reduced by 38% (2.4 hours). The l‐dopa challenges showed a reduction of 44% in AIMS and 40% in Goetz scores (both P < 0.01). Apomorphine challenges showed a reduction of 39% in AIMS and 36% in Goetz scores (both P < 0.01). Patients' self‐assessment scores reflected these significant changes. Dyskinesia improvement correlated with reduction in oral medication and with the final apomorphine dose (P < 0.05). This prospective study confirms marked dyskinesia reduction on continuous subcutaneous apomorphine therapy, paralleled by reduced dyskinesias during dopaminergic challenge tests. Our findings support the concept that replacement of short‐acting oral antiparkinsonian medication with continuous dopamine receptor stimulation may reverse, at least partially, the sensitization process believed to mediate the development of drug‐induced dyskinesias in PD. © 2004 Movement Disorder Society