bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of theoretical methods for the calculation of methyl cation affinities
Authors: Wei Y. , Singer T. , Mayr H. , Sastry G. N. , Zipse H. 
Published: June 2007

AbstractThe methyl cation affinity (MCA; 298 K) of a variety of neutral and anionic bases has been examined computationally with a wide variety of theoretical methods. These include high‐level composite procedures such as W1, G3, G3B3, and G2, conventional ab initio methods such as CCSD(T) and MP2, as well as a selection of density functional theory (DFT) methods. Experimental results for a variety of small model systems are well reproduced with practically all these methods, and the performance of DFT based methods are far superior in comparison to their MP2 analogs for these small models. For larger model, systems including motifs frequently encountered in organocatalysts, the performance deteriorates somewhat for DFT methods, while it improves significantly for MP2, rendering the former methods unreliable for common organic bases. Thus, MP2 calculations performed in combination with basis sets such as 6‐31+G(2d, p) or larger, appear to offer a practical and reliable approach to compute MCAs of organic bases. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Intracellular phospholipase A2 expression and location in human macrophages: Influence of synthetic material surface chemistry
Authors: Dinnes Donna Lee M. , Santerre J. Paul , Labow Rosalind S. 
Published: June 2007

AbstractPhospholipase A2 (PLA2) enzymes participate in a potent inflammatory pathway through the liberation of arachidonic acid upon hydrolysis of membrane glycerophospholipids. The presence of implanted polycarbonate‐urethane (PCNU) materials, used in several medical applications, has the ability to influence inflammatory responses of human macrophages that are recruited to a tissue‐material interface; however, the specific inflammatory pathways that are activated upon macrophage attachment to PCNU are largely unknown. Previous studies suggested the participation of PLA2 pathways in material degradation with the use of chemical inhibitors, such as aristolochic acid (ARIST), however not accurately defining the specific PLA2 enzymes involved. The current study aimed to establish specific groups of PLA2 involved in the macrophage foreign body response to PCNU. ARIST was assessed for specific effects on secretory PLA2 (sPLA2) protein expression and non‐specific effects on key proteins, β‐actin and monocyte‐specific esterase, implicated in the macrophage attack on PCNU materials. Macrophage attachment to PCNU materials induced increased intracellular expression of cytosolic PLA2 (cPLA2), but not sPLA2, relative to tissue culture polystyrene (TCPS) as detected by immunoblot analysis, demonstrating an early and delayed stimulation during the time course of increased cPLA2 protein expression. Laser scanning confocal microscopy images indicated a change in location of cPLA2 in macrophages adherent to PCNU surfaces compared to TCPS. This study has illustrated changes in macrophage cPLA2 expression in response to cell‐attachment to PCNU surfaces, demonstrating that the macrophage foreign body response to biomaterials induces a potent inflammatory pathway, which may lead to tissue damage near the site of material implantation. J. Cell. Physiol. 214:136–144, 2008. © 2007 Wiley‐Liss, Inc.
Alcohol biomarker analysis: simultaneous determination of 5‐hydroxytryptophol glucuronide and 5‐hydroxyindoleacetic acid by direct injection of urine using ultra‐performance liquid chromatography‐tandem mass spectrometry
Authors: Stephanson Nikolai , Helander Anders , Beck Olof 
Published: June 2007

AbstractA direct ultra‐performance liquid chromatography‐tandem mass spectrometry method (UPLC‐MS/MS) for simultaneous measurement of urinary 5‐hydroxytryptophol glucuronide (GTOL) and 5‐hydroxyindoleacetic acid (5‐HIAA) was developed. The GTOL/5‐HIAA ratio is used as an alcohol biomarker with clinical and forensic applications. The method involved dilution of the urine sample with deuterated analogues (internal standards), reversed‐phase chromatography with gradient elution, electrospray ionisation and monitoring of two product ions per analyte in selected reaction monitoring mode. The measuring ranges were 6.7–10 000 nmol/l for GTOL and 0.07–100 µmol/l for 5‐HIAA. The intra‐ and inter‐assay imprecision, expressed as the coefficient of variation, was below 7%. Influence from ion suppression was noted for both compounds but was compensated for by the use of co‐eluting internal standards. The accuracy in analytical recovery of added substance to urine samples was 96 and 98%, respectively, for GTOL and 5‐HIAA. Method comparison with GC‐MS for GTOL in 25 authentic patient samples confirmed the accuracy of the method with a median ratio between methods (GC‐MS to UPLC‐MS/MS) of 1.14 (r2 = 0.975). The difference is explained by the fact that the GC‐MS method also measures unconjugated 5‐hydroxytryptophol naturally present in urine. The comparison with data for 5‐HIAA obtained by an HPLC method demonstrated a median ratio of 1.05 between the methods. The UPLC‐MS/MS method was capable of measuring endogenous GTOL and 5‐HIAA levels in urine, which agreed with the literature data. In conclusion, a fully validated and robust direct method for the routine measurement of urinary GTOL and 5‐HIAA was developed. Copyright © 2007 John Wiley & Sons, Ltd.
Analysis of intracellular short organic acid‐coenzyme A esters from actinomycetes using liquid chromatography‐electrospray ionization‐mass spectrometry
Authors: Park Je Won , Jung Won Seok , Park Sung Ryeol , Park Byoung Chul , Yoon Yeo Joon 
Published: June 2007

AbstractA method employing silicone oil density centrifugation, solid‐phase extraction (SPE) cleanup, and LC‐ESI‐MS/MS analysis was developed for the rapid, selective, sensitive, and quantitative detection of an intracellular pool of short organic acid‐CoA esters in actinomycetes. The detection limit was determined to be approximately 0.8 pmol (1.2 ng/ml) for each standard CoA‐ester analyzed by the present LC‐ESI‐MS/MS method. A selected ion chromatogram for a typical fragment ion (m/z 428) specific to CoA‐esters enabled the detection of eight intracellular CoA‐esters involved in both primary and secondary metabolisms. The application of this method to bacterial metabolomic study is demonstrated by the profiling of the intracellular CoA‐ester pools in the wild‐type Streptomyces venezuelae strain producing polyketide antibiotics (methymycin and pikromycin), a polyketide synthase (PKS)‐deleted S. venezuelae mutant, and a S. venezuelae mutant expressing the heterologous PKS genes. By quantifying the individual CoA‐esterlevel in three different genotypes of the S. venezuela e strain, further insight could be gained into the role of CoA‐estersin polyketide biosynthesis. This analytical approach can be extended to the quantification of the size and composition of in vivo CoA‐ester pools in various microbes, and can provide a detailed understanding of the relationship between the in vivo CoA‐ester pool and the production of pharmaceutically important polyketides. Copyright © 2007 John Wiley & Sons, Ltd.
The relationship of rainfall variability in West Central Africa to sea‐surface temperature fluctuations
Authors: Balas N. , Nicholson S. E. , Klotter D. 
Published: June 2007

AbstractThis study examines the interannual variability of rainfall in western equatorial Africa and its links to sea‐surface temperatures (SSTs). Five geographical regions within the latitudes 10°N–5°S are delineated for the analysis. The links to SSTs in the tropical Atlantic, Pacific and Indian Oceans are examined via seasonal composites of wet and dry years and via linear correlations.The results show that interannual variability is extremely complex in this region and that several factors govern it. The most important include SST anomalies along the Benguela Coast, a general warming or cooling of the tropical oceans, Atlantic SSTs specifically, the contrast between the Atlantic and Indian Oceans, and the Pacific El Niño‐Southern Oscillation (ENSO). These factors differ seasonally. In much of the region, rainfall variability is linked to the Pacific El Niño and the western Indian Ocean early in the year, but to the Atlantic during the boreal summer months. The Indian Ocean again becomes important in late summer/early fall.The role of the Atlantic appears to be the modulation of the north–south excursion of the Intertropical convergence Zone (ITCZ). Hence the polarity of the SST/rainfall association depends on location. The association between SSTs near the coast and rainfall is positive if the influence is direct but can be positive or negative for indirect influences. An opposition between the Indian and Atlantic Oceans appears to displace convection in an east–west direction.Our results suggest several generic conclusions concerning the link between SSTs and continental rainfall. One is that the influence of the three oceans is seasonally dependent. The impact of a specific SST anomaly is also seasonally dependent. The same SST pattern may enhance rainfall in one season, but reduce it in the following season. Finally, the SST/rainfall associations are generally not symmetric. That is, the factors producing wet conditions are not the reverse of those producing dry conditions. In order to understand these associations, the underlying mechanisms via the general atmospheric circulation must be determined. Copyright © 2007 Royal Meteorological Society
Spatio‐temporal climatic change of rainfall in East Java Indonesia
Authors: Aldrian Edvin , Djamil Yudha Setiawan 
Published: June 2007

AbstractSpatial and temporal rainfall analysis of the Brantas Catchment Area (DAS Brantas), East Java, from 1955 to 2005 based on 40 rainfall stations with monthly rainfall data derived from daily rainfall data has been performed. To identify the climatic trend and annual changes in the area over the last five decades, we use the empirical orthogonal function (EOF) method based on multivariate statistics, followed by the fast Fourier transform (FFT) method for the power density spectrum analysis, the non‐parametric Mann‐Kendall trend test and the wavelet transform method. With EOF, we found the monsoonal rainfall pattern as the most dominant in this area, which explains about 72% of all variances. Without the annual signal, the leading EOF shows significant ENSO‐modulated inter‐annual and seasonal variabilities, especially during the second transitional period. We found a common and significant negative trend of accumulated rainfall and a negative trend of the monsoonal strength and dominance. This finding leads to changes in the annual pattern, which are increase in the ratio of rainfall during the wet season and increase of the dry spell period or the imbalance of the annual pattern. The increased ratio of the rainfall in the wet season has led to an increased threat of drought in the dry season and extreme weather in the wet season in recent decades. The role of the orographic effect had been detected from the decadal pattern, in which the high‐altitude areas have greater rainfall amount all year round. From the decadal isohyets in December/January/February (DJF) and June/July/August (JJA), the rainfall amount decreased significantly during the last five decades as shown by a persistent increase of areas with low rainfall amount. By comparing the time series of rainfall data in two locations, the mountain and coastal areas, we discovered that the dry periods have increased, mainly in the low altitude area. Copyright © 2007 Royal Meteorological Society
Cloudiness variations in Łódź in the second half of the 20th century
Authors: Wibig Joanna 
Published: June 2007

AbstractIn Łódź, the total cloud cover has significantly decreased in the second half of the 20th century. This change is opposite to that of the low‐level cloud cover in the warm part of the year. But the most important are variations in frequencies of different cloud types. The stratiform clouds, St and Ns, became less frequent, whereas the convective ones, Cu and Cb, became more frequent. The rise in Ac and high‐level clouds and the fall in As clouds were also observed. These changes are consistent with other observations in central and eastern Europe. Because different cloud types are created in different conditions, their variability is a valuable tool for assessment of changes in processes taking place in the troposphere. Such reorganization in cloud types distribution indicates significant changes in the vertical structure of the troposphere: fall of the frequency of temperature inversions in the lower troposphere and stronger lapse rate. Copyright © 2007 Royal Meteorological Society
Detecting summer rainfall enhancement within metropolitan Atlanta, Georgia USA
Authors: Diem Jeremy E. 
Published: June 2007

AbstractThis paper presents a methodology for detecting summer rainfall enhancement within a metropolitan area. The chosen study domain is the Atlanta, Georgia USA metropolitan area, and the time period covers summer (i.e. June–August) seasons from 1949 to 2005. In order to determine if observed heavy‐rainfall frequencies at nine candidate stations in the metropolitan area are enhanced, predicted frequencies are derived from heavy‐rainfall frequencies at seven reference stations located more than 50 km from downtown Atlanta. Both parametric and non‐parametric tests are used to test for significant differences between observed frequencies and predicted frequencies within 29 overlapping 30 year periods (i.e. climatological periods). Norcross, which was ∼30 km northeast of downtown Atlanta and thus was typically downwind of urbanized Atlanta on heavy‐rainfall days at all candidate stations, was the only station to exhibit significant rainfall enhancement. The final ten climatological periods exhibited enhancement, with observed frequencies of ≥ 30 mm days for those periods being at least 20% larger than predicted frequencies. It is hoped the methods employed in this paper can be used in other metropolitan areas. Copyright © 2007 Royal Meteorological Society
Mesoscale wind climate analysis: identification of anemological regions and wind regimes
Authors: Burlando M. , Antonelli M. , Ratto C. F. 
Published: June 2007

AbstractFollowing the idea that the climatological study of a physical variable should aim at the comprehension of its mean state as well as the characterization of its dynamics, cluster analysis has been applied to study the wind climate of Corsica (France) in order to identify the anemological regions (mean state) and the wind regimes (weather variability) which characterize its coastal areas. The analysis is based on a 3‐year long time‐series of measurements of the wind velocity from 11 anemometric stations located along the perimeter of the island. Since the present study was an analysis preliminary to the subsequent assessment of the wind potential of Corsica, we have worked only with wind intensities. Nevertheless, at the end of our analysis, we have also considered wind directions for the final interpretation of the results. The anemological regions are defined through the comparison of 15 different clustering techniques resulting from the combination of three distance measures and five agglomerative methods. As confirmed by geographical considerations, the results identify three distinct anemological regions: the eastern region (ER), the north‐western region (NWR), the south‐western region (SWR). The wind regimes are identified by means of a two‐stage classification scheme based on a hierarchical cluster analysis followed by a partitional clustering. The final classification identifies eight regimes: the four wind regimes corresponding to the main weather patterns of Western Europe, as proposed by Plaut and Simonnet, and another four clusters corresponding to breeze regimes. Copyright © 2007 Royal Meteorological Society
Tibiofemoral force following total knee arthroplasty: Comparison of four prosthesis designs in vitro
Authors: Nicholls Rochelle L. , Schirm Andreas C. , Jeffcote Benjamin O. , Kuster Markus S. 
Published: June 2007

AbstractDespite ongoing evolution in total knee arthroplasty (TKA) prosthesis design, restricted flexion continues to be common postoperatively. Compressive tibiofemoral force during flexion is generated through the interaction between soft tissues and prosthesis geometry. In this study, we compared the compressive tibiofemoral force in vitro of four commonly used prostheses: fixed‐bearing PCL (posterior cruciate ligament)‐retaining (PFC), mobile‐bearing posterior‐stabilized (PS), posterior‐stabilized with a High Flex femoral component (HF), and mobile‐bearing PCL‐sacrificing (LCS). Fourteen fresh‐frozen cadaver knee joints were tested in a passive motion rig, and tibiofemoral force measured using a modified tibial baseplate instrumented with six load cells. The implants without posterior stabilization displayed an exponential increase in force after 90° of flexion, while PS implants maintained low force throughout the range of motion. The fixed‐bearing PFC prosthesis displayed the highest peak force (214 ± 68 N at 150° flexion). Sacrifice of the PCL decreased the peak force to a level comparable with the LCS implant. The use of a PCL‐substituting post and cam system reduced the peak force up to 78%, irrespective of whether it was a high‐flex or a standard PS knee. However, other factors such as preoperative range of motion, knee joint kinematics, soft tissue impingement, and implantation technique play a role in postoperative knee function. The present study suggests that a posterior‐stabilized TKA design might be advantageous in reducing soft tissue tension in deep flexion. Further research is necessary to fully understand all factors affecting knee flexion after TKA. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1506–1512, 2007
Novel function of TWEAK in inducing intervertebral disc degeneration
Authors: Wako Masanori , Haro Hirotaka , Ando Takashi , Hatsushika Kyosuke , Ohba Tetsuro , Iwabuchi Sadahiro , Nakao Atsuhito , Hamada Yoshiki 
Published: June 2007

AbstractThe goal of this research was to examine the role of TWEAK in normal disc cells and to investigate its potential role in disc degeneration. We performed histological examinations of disc tissues and assessed the role of the novel cytokine TWEAK using murine organ disc culture. The expression of both TWEAK and its receptor, Fn14, in discs was confirmed by immunohistochemistry and quantitative real‐time PCR. TWEAK induced disc cells to generate MMP‐3 in a dose‐ and time‐dependent manner. This induction was strongly inhibited in the presence of a neutralizing antibody to TWEAK or a chimeric Fn14/Fc fusion protein. In disc tissues derived from TNF‐α receptor 1‐ or TNF‐α receptor 2‐deficient mice, recombinant TWEAK modestly induced MMP‐3. In contrast, in disc cultures lacking TWEAK, tissues from wild‐type mice or receptor‐deficient mice failed to express MMP‐3. Furthermore, aggrecan expression was potently abrogated in a time‐dependent manner in the presence of recombinant TWEAK. This is the first report to confirm expression of TWEAK and its receptor Fn14 in murine intervertebral disc tissues. The data suggest that TWEAK plays a role in MMP‐3 up‐regulation and aggrecan down‐regulation in disc tissues, resulting in proteoglycan degradation and promotion of disc degeneration. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:1438–1446, 2007
Micro‐Raman study of Zr‐substituted Bi4Ti3O12 ceramics
Authors: Das S. R. , Dobal P. S. , Sundarakannan B. , Das R. R. , Katiyar R. S. 
Published: June 2007

AbstractWe have studied the lattice vibrational modes of Zr‐substituted Bi4Ti3O12 ceramics using micro‐Raman spectroscopy. Replacement of Zr at the Ti site in the perovskite block is found from the increase in the lattice parameters as a function of Zr contents. Combined X‐ray diffraction patterns and Raman analysis suggested less than 40 mole% Zr solubility in Bi4Ti3O12. At 40 mole% of Zr substitution or above, the unreacted monoclinic‐phase ZrO2 is observed in the X‐ray diffraction patterns and the Raman spectra. The incorporation of Zr in Bi4Ti3O12 reduces the soft mode wavenumber and the transition temperature. Moreover, temperature dependent studies confirmed the ferroelectric to paraelectric transition in Bi4Ti3O12 at about 675 °C. On increasing the Zr content up to 40% on the Ti sites of Bi4Ti3O12, a systematic decrease in the phase transition temperature from 675 to 630 °C was observed. Copyright © 2007 John Wiley & Sons, Ltd.
Multiplex spectroscopy of stable and transient species in a molecular beam
Authors: Tulej M. , Meisinger M. , Knopp G. , Walser A. M. , Gerber T. , Radi P. P. 
Published: June 2007

AbstractA new apparatus is described that uses nonlinear and linear spectroscopic techniques simultaneously for the characterization of stable and transient molecules in a molecular beam environment. Short‐lived species are generated by applying a well‐defined discharge on a suitable precursor prior to supersonic expansion. Femtosecond ionization and mass spectrometry is used to optimize the discharge source. Degenerate and two‐color resonant four‐wave mixing spectroscopy (DFWM and TC‐RFWM, respectively) are used in tandem with laser‐induced fluorescence (LIF) and cavity ring‐down spectroscopy (CRD). We demonstrate initial experiments on the 4051 Å band of C3 ($\tilde{A}^{1}\Pi_{u} - \tilde{X}^{1}\Sigma_{g}^{+}$], 000–000). DFWM, LIF and CRD display similarities in the general shape and position of the rovibronic transitions. A more detailed view, however, reveals the complementary character of the methods and the potential of simultaneously measured spectra. High signal‐to‐noise ratios and well‐structured spectra are obtained by DFWM. LIF is favorable for the observation of weak features but strongly dependent on the relaxation mechanism of the upper excited state. CRD suffers generally from a large background signal but yields quantitative information. By applying the methods in parallel, quantitative measurements of molecular number densities, transitions dipole moments and relaxation rates are accessible. Copyright © 2007 John Wiley & Sons, Ltd.