bluuebunny/crossref_metadata_2025_split huggingface dataset:
Density functional theory study of formaldehyde oligomers
Authors: Chaudhari Ajay , Sahu Prabhat K. , Lee Shyi‐Long 
Published: August 2004

AbstractHydrogen‐bonded formaldehyde oligomers (dimer to pentamer) are studied using density functional theory (DFT), the B3LYP method, and the 6‐311+G* basis set. Many‐body interaction energies are obtained to study the contribution of many‐body terms to binding energy. The basis set superposition error (BSSE)‐corrected total energies are −229.08170, −343.61410, −458.16660, and −572.70901 hartrees for dimer, trimer, tetramer, and pentamer, respectively, with corresponding binding energies −2.55, −4.86, −6.99, and −9.49 kcal/mol. Two‐body energies have been found to contribute significantly to the total binding energy in dimer to pentamer, whereas higher‐order interaction energies are negligible. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Conventional strain energy in the oxadiazetidines
Authors: Benton Christopher W. , Magers David H. 
Published: August 2004

AbstractThe conventional strain energies for all four isomers of oxadiazetidine are determined within the isodesmic, homodesmotic, and hyperhomodesmotic models. Optimum equilibrium geometries, harmonic vibrational frequencies, and corresponding electronic energies are computed for all pertinent molecular systems using self‐consistent field theory, second‐order perturbation theory, and density functional theory (DFT) and employing two basis sets of triple‐zeta valence quality: 6‐311G(d,p) and 6‐311+G(2df,2pd). The DFT functional employed is Becke's three‐parameter hybrid functional using the Lee, Yang, and Paar correlation functional. Single‐point fourth‐order perturbation theory and coupled‐cluster theory restricted to single and double excitations [CCSD(T)] calculations employing the larger basis set also are computed, at both the second‐order Møller–Plesset (MP2)/6‐311G(d,p) and the MP2/6‐311+G(2df,2pd) optimized geometries, to determine the effect of higher‐order correlation effects on strain energy computation and to gauge the effect of geometry on these effects. Using the same models and methods, the conventional strain energies for both isomers of oxazetidine also are computed, to determine the effect on the strain energy of replacing a nitrogen with a carbon in the ring. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
A computer program for automated data evaluation to support in vitro higher‐throughput screening for drug metabolism and pharmacokinetics attributes
Authors: Fung Eliza N. , Chu Inhou , Nomeir Amin A. 
Published: August 2004

AbstractWith the advances in analytical techniques, higher‐throughput screening for drug metabolism and pharmacokinetics (DMPK) attributes has become an integral part of drug discovery. However, as the number of compounds increases, the volume of data that needs to be processed and evaluated increases exponentially. As a result, a major challenge for the analytical chemist is how to quickly process the vast amount of data so as to keep up with the throughput of the screening assay. We have developed a customized computer program for automated evaluation of the liquid chromatography/tandem mass spectrometric (LC/MS/MS) data generated from the in vitro DMPK screening assays. This program performs automatic data processing and quality control. It identifies analytical anomalies, such as low internal standard intensity and poor reproducibility of replicates. All analytical anomalies for individual compounds are summarized into an ‘E‐Log’ in a color‐coded format for reviewing. With the use of this program and other supporting software, data processing and evaluation for up to 100 compounds are accomplished in several minutes. Copyright © 2004 John Wiley & Sons, Ltd.
Method for differential detection and identification of components in protein mixtures analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Ossipova Elena , Nord Lars I. , Kenne Lennart , Eriksson Jan 
Published: August 2004

AbstractWe demonstrate that the semi‐quantitative information in matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of tryptically digested protein mixtures can, via a systematic statistical approach, be utilized for the identification of a protein present in different concentrations in two samples. Multiple mass spectra were acquired from a series of tryptically digested test samples in which the concentration of one protein was varied and the concentrations of three other proteins were held constant. The mass spectra were subjected to soft independent modeling of class analogy (SIMCA) analysis assuming that spectra originating from two different samples belonged to different data classes. The SIMCA analysis yielded information on which individual m/z values discriminate between two classes. Protein identification by proteolytic peptide mass fingerprinting was performed with different numbers of mass values in the fingerprint according to the discriminatory information, beginning with the mass corresponding to the best discrimination, followed by the best together with the second best, etc. By using the Probity algorithm, which computes the statistical significance of each identification result, we demonstrate that the first protein identified at a desired significance level (0.001) is the protein that was present in a different concentration in the two samples. Differential analysis of expression is often performed by comparing 2D‐gel‐spot intensities followed by mass spectrometric identification of the respective protein in each spot that differs. The method presented here has the potential to allow identification of the protein component that differs in cases where a gel‐spot is poorly resolved and contains several proteins. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of sodium dodecyl sulfate micelles on peptide mass fingerprinting by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Tummala Rama , Limbach Patrick A. 
Published: August 2004

AbstractHere we have examined the effect of sodium dodecyl sulfate (SDS) at various concentrations on matrix‐assisted laser desorption/ionization (MALDI) peptide mass fingerprinting experiments. Several model proteins were digested with trypsin and then various amounts of SDS were added prior to MALDI mass spectrometry. Evaluation of the data was made by calculating the amino acid sequence coverage within each analysis. It was found that addition of 0.1–0.3% w/v SDS prior to MALDI analysis results in an increase in the number of tryptic peptides detected thereby improving the total sequence coverage of the analysis. The use of SDS at concentrations near its critical micelle concentration can improve sequence coverage from MALDI peptide mass fingerprinting analyses allowing for increased confidence in protein identification or additional opportunities to identify putative regions of posttranslational modification. Copyright © 2004 John Wiley & Sons, Ltd.
On‐line laser desorption/ionization mass spectrometry of matrix‐coated aerosols
Authors: Jackson Shelley N. , Mishra Sushama , Murray Kermit K. 
Published: August 2004

AbstractMatrix‐assisted laser desorption/ionization (MALDI) was used for the on‐line analysis of single particles. An aerosol was generated at atmospheric pressure and particles were introduced into a time‐of‐flight (TOF) mass spectrometer through a single‐stage differentially pumped capillary inlet. Prior to entering the mass spectrometer, a matrix was added to the particles using a heated saturator and condenser. A liquid matrix, 3‐nitrobenzyl alcohol (NBA), and a solid matrix, picolinic acid (PA), were used. Particles were ablated with a 351 nm excimer laser and the resulting ions were mass‐separated in a two‐stage reflectron TOF mass spectrometer. Aerosol particles containing the biomolecules erythromycin and gramicidin S were analyzed with and without the matrix addition step. The addition of NBA to the particles resulted in mass spectra that contained an intact molecular ion mass peak. In contrast, PA‐coated particles did not yield molecular ion peaks from matrix‐coated particles. Copyright © 2004 John Wiley & Sons, Ltd.
Single‐drop microextraction and gas chromatography/mass spectrometric determination of anisaldehyde isomers in human urine and blood serum
Authors: Liu Bo‐Min , Malik Pridap , Wu Hui‐Fen 
Published: August 2004

AbstractThe application of single‐drop microextraction (SDME) followed by gas chromatography/chemical ionization mass spectrometry (GC/CI‐MS) was investigated for the determination of anisaldehyde isomers in human urine and blood serum. The effects of extraction solvent, sample agitation rate, salt addition, sampling time and temperature on the extraction efficiency were examined and optimized. Analytical parameters such as linearity, reproducibility, detection limit and relative recovery were evaluated under the optimized experimental conditions. Good reproducibilities of replicate extractions (n = 5) were obtained, with relative standard deviation (RSD) values below 6%. The limits of detection (LOD) using an extraction time of 5 min were found to be in the range 2–5 ng/mL under the selected ion monitoring (SIM) mode of GC/MS. Recoveries of 82–98% were achieved after 5 min extraction. Copyright © 2004 John Wiley & Sons, Ltd.
Stability of porphyrin–calix[4]arene complexes analyzed by electrospray ionization mass spectrometry
Authors: Arai Satoshi , Ishihara Shinsuke , Takeoka Shinji , Ohkawa Haruki , Shibue Toshimichi , Nishide Hiroyuki 
Published: August 2004

AbstractThe stability of some porphyrin–calix[4]arene sodium‐ion complexes were determined by a collision‐activated decomposition (CAD) method utilizing electrospray ionization mass spectrometry (ESI‐MS). Comparing the values of E1/2, the collision energy at which the relative intensity of the complex ion is 0.5, we found that the porphyrin‐calix[4]arene complex with the higher value of E1/2 corresponded to that with the larger association constant (Kass), as measured by 1H‐NMR in CDCl3. Both our ESI‐MS and NMR studies proved that the number of hydrogen bonds and the rigidity of the calix[4]arene stabilized the complex. The ESI‐MS technique could be successful in screening the binding affinity in host–guest systems with a small amount of sample. Copyright © 2004 John Wiley & Sons, Ltd.
Mass spectral study of meso‐alkyl and meso‐cycloalkyl calix(4)pyrroles under electron impact conditions
Authors: Prabhakar S. , Radha Kishan M. , Mirza S. P. , Raghavan K. V. , Vairamani M. 
Published: August 2004

AbstractA series of meso‐cycloalkyl calix(4)pyrroles (I) and meso‐dialkyl calix(4)pyrroles (II) has been studied under electron ionization (EI) mass spectral conditions. All the calix(4)pyrroles showed prominent molecular ions. The cleavage of the CC bond linked at position 2 of the pyrrole ring (β‐cleavage) is the foremost and dominant fragmentation process. The β‐cleavage process, either through ring opening or directly, results in the loss of an alkyl radical from the molecular ion. The collision‐induced dissociation (CID) spectra of I showed specific sequential expulsion of pyrrole and/or cycloalkyl rings from the molecular ion with or without hydrogen migrations, revealing more information on the structure of individual compounds than was available from the EI spectra. The isomeric cycloalkyl calix(4)pyrroles showed distinguishable CID spectra, indicating structure specificity in initial ring opening whereas, in the case of II, the EI mass spectrum contains all the structure‐indicative fragment ions. The CID spectra of II resulted in a dominant [M–R]+ ion, with other characteristic ions being less abundant. Copyright © 2004 John Wiley & Sons, Ltd.
Isolation and Partial Characterization of Mexican Oxalis tuberosa Starch
Authors: Hernández‐Lauzardo Ana Niurka , Méndez‐Montealvo Guadalupe , Velázquez del Valle Miguel Gerardo , Solorza‐Feria Javier , Bello‐Pérez Luis Arturo 
Published: August 2004

AbstractThe chemical, physicochemical and rheological characteristics of Oxalis tuberosa starch were investigated. Oxalis starch presented an apparent amylose content of 33%, similar to maize starch used as control, with a granule size between 25–50 μm with oval and elliptical shapes and A‐type X‐ray diffraction pattern. The gelatinization temperature of oxalis starch was 64.0°C, that was lower than the one determined in maize starch (73.0°C), with an enthalpy value of 12.2 J/g, which was similar to that of maize starch.Both oxalis and maize starch pastes behaved as weak viscoelastic systems with the elastic character (G′) predominating over the viscous character (G′′). An increase in the level of solids in the pastes increased the values of the moduli. The results suggest that heating the systems (gelatinization), causes a more pronounced enhancement in the structure of the maize starch pastes than in that of oxalis starch pastes.Overall, it was concluded that due to its physicochemical, functional and rheological properties, Oxalis starch could be suitable for testing its use in the cosmetic and in the food industry.
Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches
Authors: Xie Xueju (Sherry) , Liu Qiang 
Published: August 2004

AbstractResistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.
Effect of Protease Addition on Starch Recovery from Steeped Sorghum and Maize
Authors: Mezo‐Villanueva Martha , Serna‐Saldívar Sergio O. 
Published: August 2004

AbstractThe effect of protease addition on starch recovery from steeped white regular sorghum (RSOR) compared to yellow maize (YMZ) was determined. An in vitro wet milling method standardized to test dosages from 0 to 1.5 Anson units (AU/100 g grain) indicated that starch yields increased proportionally as enzyme concentration increased. The yields were significantly lower for RSOR. A factorial experiment with a level of confidence of P < 0.05 was performed to study the effect of protease addition (1.25 AU/100 g grain) to coarsely ground kernels for 4 h after 20 h or 44 h SO2 steeping of whole grains. Calcium oxide (CaO) was used to increase the pH of the steep solution to 5.5 and improve enzyme activity. The in vitro and laboratory tests indicated that the enzyme treatment significantly improved starch yields and recoveries; the effect being more pronounced in RSOR. Protease‐treated kernels yielded 3.2% more starch than those steeped regularly. RSOR steeped for 20 h and then treated with the enzyme for 4 h yielded 6.7% more starch than the counterparts steeped regularly. When steep times were compared, kernels soaked regularly for 48 h produced 1.6% more starch than counterparts steeped for 24 h. The protease treatment reduced the amount of inseparables (gluten‐starch complexes) to zero and also lowered the gluten content of starch by about 1.5%. A comparison of protein and ash contents for the refined starches indicated that the process was more efficient for YMZ than for RSOR and for grains steeped regularly for 48 h. YMZ starch started gelatinization at a lower temperature, required less time to reach peak viscosity and had less shear thinning than RSOR.
Color Doppler velocimetry and three‐dimensional color power angiography of cervical carcinoma
Authors: Testa A. C. , Ferrandina G. , Distefano M. , Fruscella E. , Mansueto D. , Basso D. , Salutari V. , Scambia G. 
Published: August 2004

AbstractObjectivesTo investigate the blood flow within invasive cervical carcinoma by transvaginal two‐dimensional (2D) color spectral Doppler and three‐dimensional (3D) color power angiography and to correlate these parameters with the clinicopathological characteristics.MethodsSeventy‐four patients with invasive cervical carcinoma were enrolled for the analysis. Squamous cell carcinoma serum antigen levels (SCC) were obtained for all the patients. Sections of all malignant tissues were analyzed for tumor expression of cyclooxygenase‐2 (COX‐2). All patients underwent color and spectral Doppler examination and 44 patients had 3D color power angiography. Color spectral Doppler parameters (color score, lowest resistance index (RI), highest peak systolic velocity (PSV)) and 3D color power angiography indices (relative color, average color, flow measure) of FIGO I/II cervical cancers were compared with those obtained in a control group of 24 patients with a normal uterine cervix. Pulsed Doppler parameters and the 3D vascular indices were compared with clinicopathological parameters, SCC serum antigen levels and tumor COX‐2 expression.ResultsAt color Doppler analysis 72 patients (97%) showed intralesional detectable vessels. Color spectral Doppler and 3D‐derived parameters were significantly different in FIGO I/II cervical cancers compared with those in women with a normal cervix. A significantly higher color score (P = 0.0008), lower RI (P = 0.032) and higher PSV (P = 0.004) were associated with a tumor diameter ≥4 cm compared with smaller tumors. The highest PSV was significantly higher in patients with FIGO stage III/IV compared with FIGO stage I/II (P = 0.0069). There was a direct correlation between PSV and SCC (r = +0.44, P = 0.003). The median relative color was significantly higher in patients with a higher color score (P = 0.0006). No statistically significant correlations were found between 3D color power angiography parameters and the clinicopathological characteristics or between the 3D vascular parameters and biological factors.ConclusionsAlterations of 3D ultrasound‐derived vascular indices were found in patients with cervical cancer compared with those with a normal cervix. Moreover, some vascular indices proved to be associated with tumor size. The assessment of a possible clinical role of 2D and 3D ultrasound‐derived vascular indices in cervical cancer deserves further investigation. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Doppler assessment of cardiac function at 11–14 weeks' gestation in fetuses with normal and increased nuchal translucency
Authors: Huggon I. C. , Turan O. , Allan L. D. 
Published: August 2004

AbstractObjectiveTo investigate cardiac dysfunction as a potential underlying mechanism for increased nuchal translucency (NT) in fetuses with chromosomal abnormality or heart defects.MethodsMyocardial performance index (MPI) and atrioventricular valve E/A ratios for both sides of the heart were measured by Doppler echocardiography in fetuses at 11–14 weeks' gestation. The study groups consisted of 159 normal control fetuses, 199 otherwise normal fetuses but with increased NT ≥ 4 mm, 142 fetuses with trisomy 21, 58 with trisomy 18, 19 with trisomy 13, 37 with Turner's syndrome and 24 with isolated heart defects. Groups were compared using Student's t‐test and confidence intervals for differences between groups were calculated.ResultsOtherwise normal fetuses with increased NT showed no difference in any of the cardiac Doppler parameters from normal controls. Mean E/A ratio was slightly but significantly increased in trisomy 21 fetuses compared with normal controls (0.604 vs. 0.578 on the right, P = 0.011; 0.581 vs. 0.542 on the left, P = 0.0001). E/A ratio was not significantly different between any of the other groups and the normals but there was a small increase in absolute E‐wave velocity in trisomy 18 fetuses. MPI was significantly decreased in trisomy 21 fetuses, (0.330 vs. 0.378, P = 0.002 on the left) and also in Turner's syndrome fetuses (0.301 vs. 0.352 on the right, P = 0.04; 0.320 vs. 0.378 on the left, P = 0.034) implying better performance, but not in the other groups.ConclusionsThe magnitude and/or direction of the differences shown do not support a major role for cardiac functional abnormality in the development of NT. Important cardiac dysfunction could not be demonstrated in association with increased NT in normal or abnormal fetuses. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Lanthanzirkonat: ein innovatives Wärmedämmschichtmaterial. Lanthanum zirconate: an innovative Thermal Barrier Material
Authors: Lugscheider Erich , Bobzin Kirsten , Lackner Kristijan 
Published: August 2004

AbstractIn diesem Bericht werden die Arbeiten des Forschungsprojekts AiF‐13114 N/1 beschrieben. Im Rahmen des Forschungsvorhabens wurden mittels der Electron Beam Physical Vapour Deposition (EB‐PVD) Schichtsysteme auf Basis der Verbindungen Lanthanzirkonat und Zirkoniumdioxid (YSZ) entwickelt und deren Potenziale für die Anwendung als Wärmedämmschichten (WDS) in der Gastur‐binenapplikation ausgeleuchtet. Basis der Schichtentwicklung war die Verwendung von Lanthanoxid und Yttriumoxid teilstabilisierten Zirkoniumdioxids (YSZ) als pulverförmiges Ausgangsmaterial, welches in einer EB‐PVD‐Anlage aus einem Zweirillen Kupfertiegel verdampft wurde. Es wurden Prozessparameter ermittelt, mit denen langzeitbeständige, kolumnare Lanthanzirkonat EB‐PVD‐Schichten mit einer höheren Phasenstabilität, niedrige Wärmeleitfähigkeit und höheren Sinterträgheit hergestellt werden können, die die Möglichkeit bieten, die Oberflächentemperatur der 1. Turbinenstufe in Gasturbinenanlagen zu steigern [1, 2, 3, 4, 5, 6]. YSZ, eine seit 1989 eingesetzte WDS, wurde als Referenzsystem für die durchgeführten Untersuchungen verwendet. Als Grundwerkstoff wurde die Nickelbasislegierung Inconel Alloy 600 eingesetzt. Bruchgefüge und Topografie der entwickelten Schichtsysteme wurden mittels Rasterelektronenmikroskopie charakterisiert. Mit dem Verfahren der Nanoindentation ist es gelungen, den Steifigkeitsverlauf entlang der Kolumnen zu bestimmen. Mittels Thermozyklustest wurde die Thermowechselbeständigkeit ermittelt.