bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrospray mass spectrometric studies of the complexational behavior of maleonitrile thiacrown ethers with various metals
Authors: Starke Ines , Fürstenberg Sylvia , Müller Holger , Holdt Hans‐Jürgen , Kleinpeter Erich 
Published: February 2006

AbstractElectrospray ionization was employed to study the mass spectrometric behavior of the maleonitrile tetrathiacrown ethers mn12S4 (1) and mn13S4 (2) and maleonitrile pentathiacrown ether mn15S5 (3) and of their complexes with various metal salts (MX2, M = Pd, Pt, Ni, Co, Fe; X = Cl, CrCl3, Ni(BF4)2, TlPF6 or Cd(NO3)2) and Cu(SO3CF3)2. Both singly charged, [MXL]+ and [MXL2]+, and doubly charged complexes, [MLn]2+ (n = 2–5), were observed. The formation of the different complexes consisting of the transition metal ion, the counterion and the various crown ethers and their subsequent dissociation was also studied by collision‐induced dissociation measurements which were also used to evaluate the relative stabilities of the complexes. It was found that the collisional voltages for the dissociation of the complexes were generally greater in the [MXL]+ complexes than in the corresponding [MXL2]+ complexes. Copyright © 2006 John Wiley & Sons, Ltd.
Stability studies of testosterone and epitestosterone glucuronides in urine
Authors: Jiménez C. , Torre R. de la , Segura J. , Ventura R. 
Published: February 2006

AbstractThe stability of testosterone glucuronide (TG), epitestosterone glucuronide (EG) and the T/E ratio in urine has been studied. Samples were analyzed by gas chromatography coupled to mass spectrometry (GC/MS). Urine samples were submitted to a solid‐liquid cleanup followed by extraction of unconjugated testosterone (T) and epitestosterone (E) with tert‐butyl methyl ether (free fraction). The remaining aqueous phase was hydrolyzed with β‐glucuronidase and extracted at alkaline pH with n‐pentane. Analytes were analyzed by GC/MS as their enol‐trimethylsilyl (TMS) derivatives. The urine for stability testing was obtained from an excretion study after the administration of T to healthy volunteers. The homogeneity of the sample was verified before starting the stability study. The stability of TG and EG was evaluated at different storage conditions. For long‐term stability testing, analyte concentration in urine stored at 4°C and −20°C was determined at different time intervals for 22 months. For short‐term stability testing, analyte concentration was evaluated in urine stored at 37°C for 3 and 7 days. The effect of repeated freezing (at −20°C) and thawing (at room temperature) was studied for up to three cycles. Data obtained in this work demonstrated the stability of TG, EG and the T/E ratio in sterilized urine samples stored at 4 and −20°C for 22 months and after going through repeated freeze/thaw cycles. Decreases in concentration were observed after 7 days of storage at 37°C due to the partial cleavage of the glucuronide conjugates; however, the T/E ratio was not affected. These results show the feasibility of preparing reference materials containing TG and EG to be used for quality control purposes. Copyright © 2006 John Wiley & Sons, Ltd.
Rapid characterization of edible oils by direct matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis using triacylglycerols
Authors: Lay Jackson O. , Liyanage Rohana , Durham Bill , Brooks John 
Published: February 2006

AbstractDirect matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometric (MALDI‐TOFMS) analysis of solutions of edible fats/oils yielded spectra useful for their rapid differentiation and classification. Results also reflected the individual fatty acid components and their degree of unsaturation. After dissolution in hexane, MALDI‐MS analysis revealed spectra showing characteristic triacylglycerols (TAGs), the main fat/oil components, as sodium adduct ions. The Euclidean distances calculated using the mass and intensity values for 20 TAGs were used to evaluate and compare spectra. With cluster analysis, animal fats grouped together differently than vegetable oils and the individual oils grouped together by type. The ion abundances for the individual TAGs and their presumed compositions were used to approximate the overall fatty acid composition of canola, soybean, corn, olive and peanut oil, as well as lard. Using this approach the calculated fatty acid compositions and degree of unsaturation generally fell within about 4% of literature values. When the degree of saturation was compared with values calculated from the package labeling the differences were about 7%. Copyright © 2006 John Wiley & Sons, Ltd.
A novel discharge source of hydronium ions for proton transfer reaction ionization: design, characterization, and performance
Authors: Inomata Satoshi , Tanimoto Hiroshi , Aoki Nobuyuki , Hirokawa Jun , Sadanaga Yasuhiro 
Published: February 2006

AbstractA novel ion source based on direct current (d.c.) discharge has been developed for proton transfer reaction ionization operated at relatively high ion drift tube pressure. The shape and geometry of the ion source are designed to maximize overall ion intensity and to minimize interference from sample air. The initial performance of the technique, including speciation and intensity of reagent ions, their stability, and the impact of artifact signals, is evaluated by means of a proton transfer reaction time‐of‐flight mass spectrometer (PTR‐TOFMS) newly built in our laboratory. Intensities of the hydronium (H3O+) ions are typically (5–7) × 105 counts for a 1‐min integration time with a duty cycle of ∼1%. The fluctuations of the ion signals over a period of hours are within 4%. Although the formation of artifact ions from sample air (NO+ and O), which react with volatile organic compounds (VOCs) and subsequently cause fragmentation, is observed as background signals in addition to hydronium and mono‐ and di‐hydrate H3O+ ions, intensities of both NO+ and O ions are only ∼0.5% of those of H3O+ ions. Using our PTR‐TOFMS system at a drift tube pressure of ∼5 Torr, the detection sensitivities are significantly improved and the detection limits for propene, acetaldehyde, acetone, isoprene, benzene, toluene, and p‐xylene are estimated to be at the sub‐ppbv level for 1‐min integration. Copyright © 2006 John Wiley & Sons, Ltd.
Determination of aerobic‐anaerobic metabolism‐related compounds in a Chaoborus flavicans population by infusion ion trap mass spectrometry of extracts of individual larvae
Authors: da Graça Gama Melão Maria , Simó‐Alfonso Ernesto , Ramis‐Ramos Guillermo , Vicente Eduardo 
Published: February 2006

AbstractIn a daily migration, the aquatic larvae of Chaoborus flavicans (a phantom midge) alternate oxygen‐saturated and anoxic lake strata. To investigate this cycle, larvae were collected at a natural environment, and acetate, propionate, pyruvate, lactate, glycerol, phosphate, maleate, succinate, glucose and citrate were determined. Each larva was homogenized with 200 µL water and deproteinized with a spin‐filter; 50 µL aliquots were mixed with 50 µL of a buffer containing 80 mM propylamine, 20 mM HCl and 0.06 mM 2,4‐dihydroxybenzoic acid (internal standard) in methanol. The extracts were infused in an electrospray ionization ion‐trap mass spectrometer. The limits of detection for the [M–H]− peaks ranged from 2 µM for pyruvate and lactate to 200 µM for acetate and glycerol. The MS2 ion‐trap spectra obtained at pH 7 (ammonium acetate buffer) were used to distinguish maleate (cis‐2‐butenedioic), which gave [M–CO2–H]− (m/z 71), from fumarate (trans‐2‐butenedioic), which showed first a loss of water yielding an instable peak at m/z 97. The compounds involved in the aerobic‐anaerobic adjustment of the metabolism were revealed by linear discriminant analysis. Acetate, citrate, glucose, maleate (which decreased during the daytime), and particularly succinate (which increased), showed the maximal discrimination power between the day‐ and night‐time samples. Copyright © 2006 John Wiley & Sons, Ltd.
Science students' critical examination of scientific information related to socioscientific issues
Authors: Kolstø Stein Dankert , Bungum Berit , Arnesen Erik , Isnes Anders , Kristensen Terje , Mathiassen Ketil , Mestad Idar , Quale Andreas , Tonning Anne Sissel Vedvik , Ulvik Marit 
Published: February 2006

AbstractIt is widely accepted that to be scientifically literate one needs to have the ability to make thoughtful decisions about socioscientific issues (SSI). This includes critical assessment of scientific claims and arguments involved. In this study we asked 89 science education students with substantial academic qualifications in science, working in groups of two and three, to assess the reliability of scientific claims in an article of their own choice, but related to a socioscientific issue, and to present their evaluation in a short text. In analyzing the students' texts, we focused on the criteria they had explicitly and implicitly used in their evaluations. Through a qualitative analysis, we identified 13 different criteria focusing on empirical and theoretical adequacy, completeness of presented information, social aspects, and manipulative strategies. An inspection of the students' evaluations revealed that they drew upon knowledge of possible institutional interests, different signs of competence and an appreciation of concurrent expert views, but also methodological norms in science, specialized content knowledge, and an appreciation of evidence and disclosure of sources. The number of criteria used and the quality of their application varied, indicating that critical examination of texts with a science dimension needs to be emphasized in science teacher education. © 2006 Wiley Periodicals, Inc. Sci Ed 90:632–655, 2006
Metal enolates of α‐CF3 ketones: theoretical guideline, direct generation, and synthetic use
Authors: Mikami Koichi , Itoh Yoshimitsu 
Published: February 2006

AbstractThe difficulty as well as the significance of the direct generation of metal enolates of α‐CF3 ketones cannot be easily understood by chemists unfamiliar with F. In sharp contrast to the sunny side of non‐F, hydrocarbon chemistry, F chemistry has long been overshadowed. Metal enolates of carbonyl compounds are synthetically important in CC bond‐forming reactions. However, the metal enolates of fluorinated carbonyl compounds have been severely limited to α‐F metal enolates. α‐CF3 metal enolates have generally been recognized as unstable and difficult to prepare because of the facile β‐M–F elimination. However, we have developed a direct generation and synthetic application of α‐CF3 metal enolates. Therefore, the present results regarding the direct generation and synthetic use of metal enolates of α‐CF3 ketones might be recognized as a real breakthrough for the general use of metal enolates in F chemistry. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 1–11; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20066
Controlling the regiochemistry of radical cyclizations
Authors: Ishibashi Hiroyuki 
Published: February 2006

AbstractThis review describes the results of our recent studies on the control of the regiochemistry of radical cyclizations. N‐vinylic α‐chloroacetamides generally cyclized in a 5‐endo‐trig manner to give five‐membered lactams, whereas 4‐exo‐trig cyclization occurred when the cyclized radical intermediates were highly stabilized by an adjacent phenyl or phenylthio group to afford β‐lactams. The 5‐exo or 6‐exo cyclization of aryl radicals onto the alkenic bond of enamides could be shifted to the corresponding 6‐endo or 7‐endo mode of cyclization by a positional change of the carbonyl group of enamides. The 6‐endo‐ and 7‐endo‐selective aryl radical cyclizations were applied to radical cascades for the synthesis of alkaloids such as phenanthroindolizidine, cephalotaxine skeleton, and lennoxamine. The 5‐exo‐trig cyclization of an alkyl radical onto the alkenyl bond of enamides could also be shifted to the 6‐endo mode by a positional change of the carbonyl group of enamides. The 6‐endo‐ selective cyclization was applied to the radical cascade to afford a cylindricine skeleton. Other examples of controlling the regiochemistry of radical cyclizations and their applications to the synthesis of natural products are also discussed. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 23–31; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20069
Organic–inorganic hybrid mesoporous silicas: functionalization, pore size, and morphology control
Authors: Park Sung Soo , Ha Chang‐Sik 
Published: February 2006

AbstractTopological design of mesoporous silica materials, pore architecture, pore size, and morphology are currently major issues in areas such as catalytic conversion of bulky molecules, adsorption, host–guest chemistry, etc. In this sense, we discuss the pore size‐controlled mesostructure, framework functionalization, and morphology control of organic–inorganic hybrid mesoporous silicas by which we can improve the applicability of mesoporous materials. First, we explain that the sizes of hexagonal‐ and cubic‐type pores in organic–inorganic hybrid mesoporous silicas are well controlled from 24.3 to 98.0 Å by the direct micelle‐control method using an organosilica precursor and surfactants with different alkyl chain lengths or triblock copolymers as templates and swelling agents incorporated in the formed micelles. Second, we describe that organic–inorganic hybrid mesoporous materials with various functional groups form various external morphologies such as rod, cauliflower, film, rope, spheroid, monolith, and fiber shapes. Third, we discuss that transition metals (Ti and Ru) and rare‐earth ions (Eu3+ and Tb3+) are used to modify organic–inorganic hybrid mesoporous silica materials. Such hybrid mesoporous silica materials are expected to be applied as excellent catalysts for organic reactions, photocatalysis, optical devices, etc. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 32–42; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20070
The impacts of network relationships on SMEs' internationalization process
Authors: Zain Mohamed , Ng Siew Imm 
Published: February 2006

AbstractIn today's globalization era, more and more firms are striving to have an international presence, even though they face many challenges. Based on a multisite case study method, this article examines how indigenous Malaysian small and medium‐sized enterprises (SMEs) use their network relationships to facilitate their internationalization process. The evidence from the case of three software firms and one control firm in this study support the firms' internationalization process in the ways that network relationships trigger and motivate them to internationalize, influence their marketselection decision and mode‐of‐entry decision, help them gain initial credibility, allow access to additional relationships and established channels, help in lowering cost and reducing risk, and influence their internationalization pace and pattern. © 2006 Wiley Periodicals, Inc.
Auslegung und Gestaltung von hochtourigen Kleinstverdichtern
Authors: Surek D. , Stempin S. , Goldner A. 
Published: February 2006

AbstractIn der Medizintechnik und im Bereich der physikalischen Technik werden oft sehr geringe Luft‐ und Gasvolumenströme bei geringen Drücken von Δp = 10 kPa bis 20 kPa z. B. für die Luftversorgung, für Heiz‐ oder Kühlgeräte benötigt. Dafür eignen sich Seitenkanalverdichter in besonderer Weise, da sie für kleine Volumenströme und große Druckzahlen, d. h. für kleine Durchmesserzahlen und geringe Schnelllaufzahlen geeignet sind. Bei Kleinstverdichtern werden auch strenge Anforderungen an die Größe der Abmessungen, die Masse und die abgestrahlte Lautstärke gestellt. Diese Forderungen führen zu hohen Drehzahlen und zu hohen Schaufeldrehfrequenzen bei den üblichen Umfangsgeschwindigkeiten des Laufrades von ua= 70 m/s bis 80 m/s. Bei diesen mäßigen Umfangsgeschwindigkeiten entstehen auch keine nennenswert hohen Schalldruckpegel, aber höhere Schaufeldrehfrequenzen als bei großen Seitenkanalverdichtern. Da sich die hochfrequenten Geräusche durch sekundäre Schallschutzmaßnahmen leichter eindämmen lassen als niederfrequente Geräusche, sind damit Vorteile verbunden.
Druckmessung im 10–3 mbar Bereich mit Wärmeleitungs‐ und Membran‐Vakuummeter
Authors: Jitschin Wolfgang 
Published: February 2006

AbstractZur zuverlässigen und einfachen Druckmessung im 10–3 mbar Bereich bieten sich das Wärmeleitungs‐ und das kapazitive Membran‐Vakuummeter an. Geräte beider Typen wurden eingesetzt, um an einem Kolbenmanometer den Glockendruck zu erfassen. Die Messeigenschaften der Geräte wurden durch regelmäßige Kalibrierungen überwacht und erwiesen sich als stabil. Wie sich aus den Kalibrierdaten ergibt, scheint das Wärmeleitungsvakuummeter wegen seiner besseren Nullpunktstabilität vorteilhaft zu sein. Im praktischen Einsatz treten jedoch erhebliche Unterschiede der Druckanzeigen der beiden Geräte auf. In der vorliegenden Arbeit werden daher ihre Messeigenschaften beim Einsatz untersucht, bei dem der Druck eines unbekannten Gases innerhalb kurzer Zeit zuverlässig gemessen werden soll. Die Untersuchungen zeigen, dass das Wärmeleitungs‐Vakuummeter wegen seiner langsamen Reaktion bei kleinen Drücken und seiner Abhängigkeit von der Gasart unzuverlässige Werte liefert. Bei der vorliegenden praktischen Anwendung erweist sich das Membran‐Vakuummeter sehr deutlich als überlegenes Messgerät.
Permanente plasmapolymere Trennschichten
Authors: Vissing Klaus‐D. , Klyszcz‐Nasko Holger 
Published: February 2006

AbstractBeschichtungen mit Trennaktivität zeichnen sich dadurch aus, dass das O/Si‐Verhältnis ca. 1:1 und das Kohlenstoff‐Siliziumverhältnis ca. 2:1 beträgt. Hieraus lässt sich folgern, dass für die Trennwirkung eine Struktur verantwortlich ist, die dem PDMS ähnlich ist und für die dreidimensionale Vernetzung ein erhöhter Anteil an Si‐O‐Bindungen notwendig ist.Das entwickelte Trennschichtsystem (EP 1 301 286 B1) wird derzeit vielfältig eingesetzt und getestet, um seine Leistungsfähigkeit zu beweisen. In Einzelfällen sind bis zu 1250 Entformungen ohne Verschlechterung der Trennwirkung durchgeführt worden. In anderen Fällen erfolgt bereits eine Qualifizierung.
Kontrollierte Abscheidung und Alterung von Plasmapolymerschichten
Authors: Unger Wolfgang 
Published: February 2006

AbstractEs wird gezeigt, dass mit einer Kombination der Oberflächenanalyseverfahren ESCA, ToF‐ SIMS und XAS eine erfolgreiche chemische Charakterisierung von Plasmapolymerfilmen erreicht werden kann. Es werden Elemente und Bindungstypen identifiziert und (semi‐)quantitativ bestimmt. Eine Korrelation zwischen Abscheidebedingungen und chemischen Eigenschaften der Plasmapolymerschichten kann hergestellt werden; eine kontrollierte Abscheidung wird damit möglich. Alterungsprozesse, die als Folge einer Atmosphärenexposition auftreten, können beobachtet werden. Die direkte Verbindung der Analysetechniken mit einem Plasmareaktor ermöglicht es, die Alterungsphänomene der Schichten systematisch mit Bezug auf eine frisch abgeschiedene und keinerlei Atomsphäre ausgesetzte Plasmapolymerschicht zu studieren.Die Verfahrensweise wird exemplarisch am Beispiel von Ethylen‐, Allylamin‐ und Allylalkohol‐Plasmapolymerschichten demonstriert.
Der Natur auf der Spur: einzigartige Farbanmutungen auf Basis Photonischer Kristalle mit Opalstruktur
Authors: Winkler Holger , Bauer Josef , Schneider René , Heckmeier Michael 
Published: February 2006

AbstractSeit ihrer theoretischen Beschreibung Ende der Achtziger Jahre sind Photonische Kristalle im Fokus von Wissenschaft und Technik: Diese dem Edelstein Opal ähnlichen Beugungsgitterstrukturen ermöglichen neuartige Farbeffekte und eine Vielzahl interessanter optischer Anwendungen. Im vorliegenden Artikel wird ein Prozess beschrieben, der es erstmals ermöglicht, großflächig Photonische Kristalle herzustellen.
Studies on the pathway from ornithine to proline in cultured skin fibroblasts with reference to the defect in hyperornithinaemia with hyperammonaemia and homocitrullinuria
Authors: Gray R. G. F. , Hill S. E. , Pollitt R. J. 
Published: February 2006

AbstractThe reduction in the conversion of ornithine to proline by fibroblasts from a patient with hyperornithinaemia with hyperammonaemia and homocitrullinuria cannot be explained by a reduced uptake of exogenous ornithine, an altered total intracellular ornithine content, or reduced conversion of γ‐glutamate semialdehyde to proline. However, neither could the postulated defect in mitochondrial ornithine uptake be demonstrated using the digitonin method. Increasing the ornithine concentration in the medium increased the incorporation of14C label from ornithine into protein in both the patient's and control cells. In the patient's cells the apparentKm for ornithine was ten times that of the controls although theVmax values were comparable. this result parallels the clinical response to ornithine supplementation.
Biochemical variability of arylsulphatases‐A,‐B and‐C in cultured fibroblasts from patients with multiple sulphatase deficiency
Authors: Chang P. L. , Rosa N. E. , Ballantyne S. R. , Davidson R. G. 
Published: February 2006

AbstractMultiple sulphatase deficiency (MSD) in man is inherited as an autosomal recessive trait and associated with deficient activities of various sulphohydrolases. Cultured fibroblasts from seven different patients were assayed for arylsulphatases‐A,‐B and‐C activities. On the basis of the results, they may be classified into three groups: I, deficient in all three arylsulphatases: II, deficient only in arylsulphatases‐A and‐C with half or near‐normal arylsulphatase‐B; electrophoretically, arylsulphatase‐A activity bands are undetectable as in metachromatic leukodystrophy; III, same as in II except electrophoretically, the residual arylsulphatase‐A is detectable as faint activity bands similar to those in pseudo arylsulphatase‐A deficiency. In addition to the variability among different strains, within the same strain of MSD or normal cells, each enzyme activity increased several fold with increasing time in culture. These sources of biochemical variability among and within different cell strains have not been recognized before in the study of this apparently monogenic trait with multiple enzyme deficiencies. They may account for some of the discrepancies reported in the literature on arylsulphatase activities among cultured cells from different multiple sulphatase deficient patients.
Chemical studies on postmortem tissues from an infant with a sphingomyelin storage disorder
Authors: Donaghey S. F. O'B. , Raine D. Noel , Crossley J. E. 
Published: February 2006

AbstractInvestigations of formalin‐stored tissues from a female child 3 weeks old showed that the concentrations of sphingomyelin, cholesterol and other lipids were increased in spleen and other tissues. Although the disorder could not be confirmed enzymatically, the findings are most consistent with the patient having a sphingomyelin storage disorder. Tissue lipid data for a series of subjects without storage disorders are presented and may provide useful information for interpretation of results from autopsy samples.
Ascorbic acid: An unstable ninhydrin‐positive urinary constituent running with valine in a commonly used screening system
Authors: Pollitt R. J. , Sandhu B. 
Published: February 2006

AbstractLarge amounts of ascorbic acid occur occasionally in the urine of children being investigated for possible inherited metabolic disease and may give a positive ninhydrin reaction after thin‐layer chromatography. As this compound is unstable in urine and runs with valine in a solvent system commonly used for preliminary screening, it is a possible source of confusion.