bluuebunny/crossref_metadata_2025_split huggingface dataset:
NaDDC as a corrosion inhibitor of brass
Authors: Shah R. S. , Trivedi A. M. 
Published: May 2005

AbstractThe carbamate turns out to be a good inhibitor of the corrosion of brass (80/20 and 59/41) in 0.5 N sodium chloride, 1.0 n sodium hydroxide and buffer solutions (NaOH and citric acid, pH 4.4‐6.0). The inhibiting effect depends on inhibitor concentration, so that in some cases corrosion may even be stimulated. The inhibitor effect is attributed to the formation of insoluble complexes with the two alloy components.
Schutz von Materialien vor mikrobieller Zerstörung
Authors: Brill H. 
Published: May 2005

AbstractDer allgemeine Materialschutz hat zum Ziel, ein gegebenes Material über einen ausreichend langen Zeitraum unter den vorliegenden Bedingungen unverändert zu erhalten. Hierzu müssen möglichst alle schädigenden oder zerstörenden Einflüsse ausgeschaltet werden, da hierdurch hohe wirtschaftliche Verluste auftreten. Die produktschädigenden Einflüsse können physikalisch oder chemisch sowie biologisch bedingt sein. Zum Schutz der Materialien bieten sich verschiedene Maßnahmen an. Es sind dieses physikalische, chemische Verfahren und Schutzmaßnahmen durch Überzüge und Beschichtungen. Häufig werden Kombinationen verschiedener Schutzverfahren eingesetzt. Ziel der Forschungsaufgaben hinsichtlich des allgemeinen Materialschutzes ist es, die vorliegenden physikalischen und chemischen Verfahren zu verbessern und neue Methoden oder Technologien zu entwickeln, welche zu den bestehenden Vorteile bieten, insbesondere in Bezug auf die Wirksamkeit, Verträglichkeit und Toxizität.
Pitting of austenitic stainless steel clad metals
Authors: Krishnan K. N. , Prasad Rao K. 
Published: May 2005

AbstractAustenitic stainless steel welds with different ferrite contents (4 and 12 FN) were obtained by the Submerged Arc Welding (SAW) strip cladding process, and some clads were remelted by TIG. The welds were post weld heat treated (PWHT) at 600, 800, 1000°C for 1 h. Pitting potentials were measured in 1 N H2SO4 + 0.5 N NaCl. Etching at the pitting potentials was carried out in the same solution in order to locate the pit sites; pitting studies were also conducted in 10% FeCl3 solution.The results showed that an increase in ferrite content decreases pitting resistance. PWHT at 800°C decreases pitting resistance, too, whereas PWHT at 1000°C results in increased pitting resistance at austenite/ferrite interfaces. TIG samples showed less pits than their SAW counterparts.
The extraction of cholesterol from solid and liquid matrices using supercritical CO2
Authors: Ong Chye Peng , Ong Hui Ming , Li Sam Fong Yau , Lee Hian Kee 
Published: May 2005

AbstractThe design and construction of a relatively simple supercritical CO2 system capable of extracting compounds from solid and liquid matrices are described. The system consists of a conventional liquid chromatography pump, a cooler, a stainless steel extraction chamber, and a modified collection system. A preliminary evaluation of the extractor is carried out here by using it to extract cholesterol from egg yolk and blood serum. The extracts were analyzed by supercritical fluid chromatography, and the results compared with those obtained by Soxhlet extraction.
Determination of pyruvate, acetoacetate, lactate, and 3‐hydroxybutyrate in plasma of patients with diabetes mellitus by capillary isotachophoresis
Authors: Kr̆ivánková Ludmila , Boc̆ek Petr 
Published: May 2005

AbstractAn isotachophoretic method was developed and optimized for simultaneous determination of pyruvate, acetoacetate, lactate, and 3‐hydroxybutyrate in 1–10 μL of untreated heparin plasma of patients with diabetes mellitus. A commercial instrument with a column switching system was used. The preseparation capillary was filled with the leading electrolyte of pH 4.2 and the analytical capillary was filled with leading electrolyte of pH 3.0. The concentrations of individual ketone bodies and lactate found in human plasma varied within 0.01–1.4 mmol/L and 0.8–11.8 mmol/L, respectively. Analysis time was about 30 min.
Application of capillary supercritical fluid chromatography–double focusing mass spectrometry under negative ion chemical ionization conditions
Authors: Huang Eric C. , Jackson Bruce J. , Markides Karin E. , Lee Milton L. 
Published: May 2005

AbstractThe application of mass spectrometry in the negative ion mode with capillary column supercritical fluid chromatography is described. The supercritical fluid chromatography mobile phase (CO2) was used as the primary reagent gas to generate thermalized electrons and reagent anions (such as O− and CO2−). When trace amounts of CH4 or NH3 gas were also introduced into the chemical ionization source, the mass spectrometer sensitivity was increased. Detection limits (S/N = 5) for heptachlor were determined to be 20 pg and 200 fg for full scan and selected ion monitoring modes, respectively. Mass spectra of a cyclic peptide, valinomycin, obtained with these mixed reagents (CH4 + CO2 and NH3 + CO2) gave the molecular anion at m/z 1110 as the most abundant ion and additional fragment ions that yielded peptide sequence information.
Evaluation of injection systems for open tubular liquid chromatography
Authors: Claessens Henk A. , Burcinova Andrea , Cramers Carel A. , Mussche Philippe , van Tilburg Chris C. E. 
Published: May 2005

AbstractThe main advantages of open tubular liquid chromatography (OTLC) over conventional packed‐column liquid chromatography are the gain in resolution and the increased permeability. At present the reproducible preparation of narrow‐bore columns and the lack of suitable commercial chromatographic equipment delay the development of OTLC. There are stringent requirements for injectors and detectors for OTLC with respect to their volumes, geometry, and contributions to the total band broadening. In this work some properties of two different sampling systems for OTLC were studied with respect to the accuracy and repeatability of the injected volumes. An approach is presented and discussed to determine the profile factors of these injection systems.
Detection limits of an ion mobility detector after capillary gas chromatography
Authors: St. Louis Robert H. , Siems William F. , Hill Herbert H. 
Published: May 2005

AbstractA method for setting gating parameters is presented that maximizes response in ion mobility detection following capillary gas chromatography. The method requires knowledge of the drift times of the product ion or ions of interest and the drift times of the reactant ions. These values are obtainable from ion mobility spectra captured after capillary gas chromatography.The capillary insertion distance into the ion source and the presence or absence of an aperture grid were also found to have considerable effect on chromatographic response. Under optimized conditions, minimum detectable limits of <1 fmol/s are reported for tributylamine, phenyl sulfide, and tributyl phosphate. These values demonstrate significant improvements over reported detection limits of organics by the flame ionization detector and sulfur‐containing species by the flame photometric detector. The values show slight improvement over those reported for detection of nitrogen and are comparable to those reported for detection of phosphorus‐containing species by the thermionization detector.
Metal‐element‐selective detection in packed microcolumn supercritical fluid chromatography combined with inductively coupled plasma atomic emission spectrometry
Authors: Fujimoto Chuzo , Yoshida Hiroyuki , Jinno Kiyokatsu 
Published: May 2005

AbstractAn interfacing technique between packed‐microcolumn (0.5‐mm i.d.) supercritical fluid chromatography and inductively coupled plasma atomic emission spectrometry was investigated. The loading limit of carbon dioxide gas into the plasma system was determined, and the results suggest that the detection system cannot be used for conventional 4.6‐mm i.d. columns. The potential of 0.5‐mm i.d. microcolumns was studied with respect to quantitation and use with unconventional elution modes such as modifier addition and step pressure programming. An analysis of ferrocenes and acetylacetonates was used to evaluate the total system performance.
Ion mobility detection following liquid chromatographic separation
Authors: McMinn Dennis G. , Kinzer Jeffery A. , Shumate Christopher B. , Siems William F. , Hill Herbert H. 
Published: May 2005

AbstractCoronaspray ion mobility spectrometry was used in sample detection following reversed‐phase liquid chromatographic separation. Samples were introduced by coronaspray using a fused silica transfer line that was inserted through a stainless steel needle. Ion mobility spectra and chromatographic responses via monitoring of reactant‐ion depletion in the software second gate mode were shown for esters of para‐hydroxy benzoic acid, isomers of nitroaniline, and a mixture of acetaminophen, caffeine, and phenacetin.
COLOC‐S: A modified COLOC sequence for selective long‐range X‐H correlation 2D NMR spectroscopy
Authors: Krishnamurthy V. V. , Casida John E. 
Published: May 2005

AbstractThe COLOC‐S pulse sequence (a modification of COLOC) provides rapid and selective long‐range correlation 2D NMR spectra. It combines the advantages of the COLOC and Freeman sequences. This modification is analysed in terms of the Product Operator Formalism, and its application is illustrated by spectral peak assignments of two insecticides, ryanodine and 1R, cis‐phenothrin.
Application of two‐dimensional dipolar exchange spectroscopy with multiple mixing periods
Authors: Meyerhoff Dieter J. , Nunlist Rudi , O'Connell John F. 
Published: May 2005

AbstractA NOESY‐type experiment with multiple mixing periods and acquisitions within a single pulse sequence was used to obtain a complete NOE correlation map of a small organic molecule. Incorporating multiple mixing periods and acquisitions into a single sequence can eliminate the need for repeating NOESY experiments with different mixing periods to observe dipolar exchange of considerably different rates or to determine exchange rates. The sequence has been applied to the molecular structure elucidation of cis‐8a‐vinyloctahydro‐3H‐2‐benzopyran‐3,7‐dione, a small organic molecule where the use of a single mixing period does not reveal all protons undergoing dipolar exchange.
Time‐resolved EPR studies of covalently linked porphyrin—crown ether—quinones, dissolved in liquid crystals
Authors: Batchelor Stephen N. , Sun Licheng , Möbius Klaus , Kurreck Harry 
Published: May 2005

AbstractTime‐resolved EPR spectra are reported for photoexcited porphyrin—quinones with butylene and cis‐ or trans‐ cyclohexylene spacers between porphyrin donors and crown ether—quinone acceptors. In the nematic phases of liquid crystals, polarized triplet EPR spectra of the porphyrin moiety could be observed at early delay times (0.1–0.6 μs) after laser flash irradiation. At later delay times (1–2 μs) the triplet EPR spectra of the charge‐separated radical pair state, created by intramolecular electron transfer from the porphyrin donor to the crown ether quinone acceptor, could be detected. The similarity of the zero‐field splitting parameters D of the cyclohexylene‐ and butylene‐linked compounds shows that the radical pair of the flexible butylene‐linked compound is in a stretched conformation. However, longer laser irradiation of the species with the flexible bridge results in the formation of a novel triplet radical pair species with a shorter porphyrin—quinone separation indicating a photoinduced backfolding of the quinone over the porphyrin plane. Comparison of the cis‐ and trans‐cyclohexylene‐linked compounds reveals a distortion of the cyclohexylene spacer in the cis compound.
Magnetic characterization of the geometry and chemistry of small metal clusters
Authors: Mile Brynmor , Sillman Philip D. 
Published: May 2005

AbstractThe application of electron paramagnetic resonance (EPR) spectroscopy in determining the geometric and electronic structures of small naked clusters, Mn, of the alkali and coinage metals (n < 9) is assessed. The EPR spectra and the paramagnetic parameters derived therefrom provide stringent tests of quantitative molecular orbital calculations. Perturbations of the cluster shape by interaction with substrate molecules are readily detected and have a bearing on the dynamic nature of the active sites of heterogeneous catalysts. Previous studies of the metal trimers in hydrocarbon matrices are extended to the preparation of an unusual acute Na3 cluster associated with water and the heteronuclear clusters Na2Li and Au2Ag. Both adopt static obtuse 2B2 geometries and show no fluxionality, in contrast to the homonuclear pseudo‐rotating Jahn—Teller clusters Li3 and Na3. There is a reversal in paramagnetic parameters in the series Cu3, Ag3, Au3 which is due in part to the emergence of relativistic effects because of the high charge on the gold nucleus. The first ENDOR spectrum is reported of a metal cluster Li3, the parameters fitting exactly those determined from the more complex EPR spectrum of Li3. A new heteronuclear septameric species, Na2K5, has been examined which has the pentagonal bipyramidal structure seen for homonuclear septamer clusters. There is an unpaired spin density of 0.41 on the apical sodium nuclei with only 0.004 at the basal potassium nuclei.
EPR and ENDOR characterization of semiquinone anion radicals related to photosynthesis
Authors: MacMillan Fraser , Lendzian Friedhelm , Lubitz Wolfgang 
Published: May 2005

AbstractEPR and ENDOR experiments were performed on the radical anions of 1,4‐benzoquinone, 2,3‐dimethyl‐1,4‐benzoquinone, 2,3,5,6‐tetramethyl‐1,4‐benzoquinone, 2,3‐dimethyl‐5‐ethyl‐1,4‐benzoquinone, plastoquinone‐1, plastoquinone‐9 and ubiquinone‐10. In liquid solutions the isotropic hyperfine coupling constants could be determined. In the frozen state hyperfine tensors for α‐protons and the freely rotating methyl groups were measured whereas other β‐protons (CH2) were broadened beyond detection probably caused by several superimposed chain conformations. In the immobilized radicals proton hyperfine couplings of hydrogen bonds formed between the alcoholic solvent and the CO groups of the quinones could be determined by experiments in protonated and deuterated solvents. Two different types of strong hydrogen bonds exist in these systems: in‐plane with aiso > 0 and out‐of‐plane with aiso ≈︁ 0. The latter type is observed if substituents at both carbons adjacent to the CO groups force the hydrogen bond out of the molecular plane. By use of the point‐dipole model and oxygen spin densities obtained from 17O hyperfine couplings, hydrogen bond lengths could be determined from the measured dipolar proton hyperfine tensors. These findings are very important for the binding and function of quinones in biological systems such as the photosynthetic reaction centres of plants and bacteria.
Electron paramagnetic resonance and Mössbauer studies of metal chelation by adriamycin
Authors: Zweier Jay L. , Levy Abraham 
Published: May 2005

AbstractEPR and Mössbauer studies demonstrate that iron chelation by adriamycin is complex, with several different chelation structures. At physiological pH in aqueous solution, three different EPR spectra are observed: a spectrum at g = 4.2 of Fe3+ in a rhombic crystal field (type 1); a spectrum at g = 2.01 with symmetric Gaussian lineshape linewidth 225 G (1 G = 10−4 T), suggestive of Fe3+ bound in an octahedral crystal field (type 2); and a broad spectrum centered at g = 2.0 suggestive of ferromagnetically coupled Fe3+ (type 3). The type 1 and 2 spectra are observed at adriamycin/Fe3+ ratios >4, the type 3 spectrum is observed at ratios <4 and at ratios <2 an increasing amount of Fe3+ gives rise to EPR silent iron(III) hydroxide polymers. At 4 K the type 1 and 2 complexes exhibit a broad doublet Mössbauer signal with an isomer shift δ = 0.56 (1) mm s−1 and quadrupole splitting δEQ = 0.74 (1) mm s−1. The type 3 complex gives rise to a sextet signal with isomer shift ΔEq = 0.47 (1) mm s−1 and hyperfine splitting HF = 476 (1) kG with exhibits superparamagnetic relaxation behavior with a blocking temperature of 23 K, consistent with a microcrystal size of 25 Å. Cu2+ binds to adriamycin at adriamycin/Cu2+ ratios >4:1 giving rise to an EPR spectrum with axial symmetry g∥ = 2.26, g⟂ = 2.066, A∥ = 188 G, while 2:1 complexes exhibit a single Gaussian line at g = 2.09 indicative of exchange‐coupled Cu2+. The exchange‐coupled Cu2+ and ferromagnetically coupled Fe3+ complexes can be explained by the formation of stacked 2:1 adriamycin‐metal polymers. On titration of adriamycin with Fe3+‐nitrilotriacetate a different spectrum is observed at g = 4.3 and its intensity plateaus at an adriamycin/iron ratio of 2. The iron adriamycin complexes cycle to reduce molecular oxygen and this cycle has been hypothesized to be a mechanism mediating the therapeutic and toxic effects of the drug. Both EPR and Mössbauer experiments demonstrate that the type 1 and 2 chelates reduce their Fe3+ to Fe2+ while the type 3 chelate does not. Therefore, the stoichiometry and method of complex preparation can profoundly effect the properties of these complexes.
Pharmacological compartment viscosity and polarity measured with very low‐frequency EPR in tumors of living animals
Authors: Halpern Howard J. , Chandramouli G. V. R. , Yu Cheng , Peric Miroslav , Barth Eugene D. , Teicher Beverly A. , Grdina David 
Published: May 2005

AbstractQuantitative measurements of the viscosity of a non‐vascular pharmacological compartment in a living animal are presented. Using novel, very low‐frequency electron paramagnetic resonance spectroscopy, capable of measurements in humans, novel analytical techniques and partially deuterated spin probes, the viscosity of the body water of murine fibrosarcomas implanted in the leg of a living animal were measured. The average viscosity was 1.9 ± 0.2 cP. Variation of the viscosity with tumor size and histology did not appear to be significant.
Rotational isomerism—XII Rotamer energies and 3JHF and 4JHH couplings in 1‐chloro‐2‐bromo‐2‐fluoropropane (1)
Authors: Abraham R. J. , Oliver W. L. 
Published: May 2005

AbstractThe complete analysis of the NMR spectrum of CH2Cl.CFBr.CH3 in CCl4 and acetone is given. The long range 4JHH couplings in this molecule differ considerably and surprisingly are both positive. An analysis of the solvent dependence of the couplings enables the rotamer couplings and energies to be obtained. The rotamer energies and their variation with solvent are in accord with quantitative predictions and results from similar halogenated ethanes. The values of the 4JHH couplings can be rationalised in terms of substituent electronegativity effects.
Nuclear magnetic resonance studies of hydrazyl radicals
Authors: Sagdeev R. Z. , Molin Yu. N. , Koryakov V. I. , Cheerkov A. K. , Matevosyan R. O. 
Published: May 2005

AbstractA study of the nuclear magnetic resonance spectra of six hydrazyl radicals in solution, including α,α′‐diphenyl‐β‐picryl‐hydrazyl (DPPH), has been carried out. From the values of the paramagnetic shifts the constants (αH) of hyperfine coupling with the protons were found. For DPPH these have the following values:
equation image
On the basis of the analysis of the hyperfine constants a conclusion is drawn concerning the substantial role of σ‐electron spin density delocalization in aromatic rings. The geometric structure of radicals investigated is also discussed in the paper.
NMR‐untersuchungen an piperidinen—III. 1H‐messungen an alkylpiperidinen
Authors: Wendisch Detlef , Reiff Helmut , Schubart Rüdiger 
Published: May 2005

AbstractEs werden die 1H‐220 MHz‐Spektren von verschiedenen Alkylpiperidinen beschrieben. Alle Protonen des Ringes Können weitgehend zugeordnet werden. Die Effekte von N‐Methyl‐ und C‐Methylgruppen auf benachbarte Ringprotonen werden eingehend diskutiert.
Der Einfluss des anomer verknüpften Adeninrestes auf die 13C‐chemischen Verschiebungen von Pyranosen
Authors: Voelter Wolfgang , Breitmaier Eberhard 
Published: May 2005

AbstractDer Einfluß des anomer verknüpften Adeninrestes auf die 13C‐chemischen Verschiebungen von Aldopyranosen wird für eine Reihe von Pyranosyladeninen diskutiert. Anomere Kohlenstoffatome mit axial verknüpftem Heterocyclus absorbieren stets bei höherem Feld als entsprechende mit äquatorial orientiertem Adenin. Diese Regel kann zur Bestimmung der Pyranosekonformation verwendet werden. Wird die anomere Hydroxylgruppe durch einen Adeninrest ersetzt, dann verschiebt sich die Resonanz von C‐5 des Pyranoserestes nach tieferem Feld.
Sexually dimorphic mechanosensitive swimmeret sensilla affect abdominal posture in the lobster
Authors: Kotak Vibhakar C. , Page Charles H. 
Published: May 2005

AbstractThe sensilla on the male and female second swimmerets are sexually dimorphic. Female swimmerets contain many long “smooth hairs” (long simple setae) on the coxa and rami. The endopodite of the male swimmeret has an accessory lobe covered with short “bristly spines” (serrate setae). In both sexes the swimmeret rami are lined by “feathered hairs” (plumose setae). The influence of mechanosensory stimulation of these sensilla upon abdominal tonic motor activity was analyzed in an in vitro swimmeret‐nerve cord preparation. Movement of several clusters of smooth hairs produced an abdominal extension program by exciting the flexor inhibitor f5, inhibiting the flexor excitors, and activating several extensors. Stimulation of the male bristly spines excited the medium‐sized flexor excitors f3 and f4. In both sexes the feathered hairs did not generate any response to mechanical stimulation. We infer that in nongravid females the smooth hairs are involved in receiving mechanosensitive cues to support abdominal extension. Bristly spines may contribute to postural adjustments that assist mating. The long latencies of these responses and their propagation to adjacent ganglia suggest that they are mediated by postural interneurons rather than by direct afferent terminations on postural motoneurons.
Differential Pavlovian conditioning in the mollusc Pleurobranchaea
Authors: Mpitsos George J. , Cohan Christopher S. 
Published: May 2005

AbstractThe present differential Pavlovian conditioning experiments on the sea slug Pleurobranchaea californica extend conditioning described in a preceding paper and provide the conditioning foundation for studies reported in another accompanying paper comparing learned behavior in whole animals with the behavior and motor patterns of electrophysiological preparations. All animals received two appetitive‐conditioned stimuli (CSs), one derived from beer (Sbr) and the other derived from squid muscle (Ssq), in different temporal relationships to an electric shock unconditioned stimulus (UCS). Two groups of animals were run concurrently. One group (n = 19) received Sbr as the CS+ in close temporal pairing with the UCS, and Ssq as the CS− explicitly unpaired with the UCS (Sbr+/Ssq−). The second group (n = 20) received the opposite contingencies (Sbr−/Ssq+). All animals received only one day of conditioning involving 5 trials with an intertrial interval of 2 h. There were two replicate experiments, each involving about half of the total n, and each yielding similar results as the sum we report here. Before conditioning, animals exhibited feeding behavior (extension of the proboscis and bite‐strike responses) to both stimuli at similar low thresholds. Conditioning produced long‐term behavioral changes in all animals throughout the 4.5‐day postconditioning observation period. However, only the Sbr+/Ssq− animals consistently exhibited the appropriate differentially conditioned food‐aversion behavior which consisted of strong withdrawal and high‐threshold feeding responses to Sbr, and low‐threshold feeding responses to Ssq. We discuss the possibility that such differences between Sbr+/Ssq − and Sbr−/Ssq+ conditioning may arise either from inherent differences in the responses of the animals to Sbr and Ssq, or, as seems more likely to us, from training and testing effects produced by differences in the compositions of the two stimuli.