bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using the local elevation method to construct optimized umbrella sampling potentials: Calculation of the relative free energies and interconversion barriers of glucopyranose ring conformers in water
Authors: Hansen Halvor S. , Hünenberger Philippe H. 
Published: May 2009

AbstractA method is proposed to combine the local elevation (LE) conformational searching and the umbrella sampling (US) conformational sampling approaches into a single local elevation umbrella sampling (LEUS) scheme for (explicit‐solvent) molecular dynamics (MD) simulations. In this approach, an initial (relatively short) LE build‐up (searching) phase is used to construct an optimized biasing potential within a subspace of conformationally relevant degrees of freedom, that is then used in a (comparatively longer) US sampling phase. This scheme dramatically enhances (in comparison with plain MD) the sampling power of MD simulations, taking advantage of the fact that the preoptimized biasing potential represents a reasonable approximation to the negative of the free energy surface in the considered conformational subspace. The method is applied to the calculation of the relative free energies of β‐D‐glucopyranose ring conformers in water (within the GROMOS 45A4 force field). Different schemes to assign sampled conformational regions to distinct states are also compared. This approach, which bears some analogies with adaptive umbrella sampling and metadynamics (but within a very distinct implementation), is shown to be: (i) efficient (nearly all the computational effort is invested in the actual sampling phase rather than in searching and equilibration); (ii) robust (the method is only weakly sensitive to the details of the build‐up protocol, even for relatively short build‐up times); (iii) versatile (a LEUS biasing potential database could easily be preoptimized for small molecules and assembled on a fragment basis for larger ones). © 2009 Wiley Periodicals, Inc. J Comput Chem 2010
Fourier‐transform infrared and Raman spectra, vibrational assignment and density functional theory calculations of 1,4,5‐triazanaphthalene
Authors: Krishnakumar V. , Ramasamy R. 
Published: May 2009

AbstractThe Fourier‐transform infrared (FT‐IR) (4000–50 cm−1) and Raman spectra (3500–100 cm−1) of 1,4,5‐triazanaphthalene in polycrystalline state were measured. Comparison between the spectra by two techniques, a series of density functional theory (DFT) calculations and the spectral behaviour upon deuteration were used for the assignment of the vibrational spectra of the title compound. The calculated vibrational wavenumbers by the B3LYP density functionals are generally consistent with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd.
Kinetic studies of biological interactions by affinity chromatography
Authors: Schiel John E. , Hage David S. 
Published: April 2009

AbstractThe rates at which biological interactions occur can provide important information on the mechanism and behavior of such processes in living systems. This paper will discuss how affinity chromatography can be used as a tool to examine the kinetics of biological interactions. This approach, referred to here as biointeraction chromatography, uses a column with an immobilized binding agent to examine the association or dissociation of this agent with other compounds. The use of HPLC‐based affinity columns in kinetic studies has received particular attention in recent years. Advantages of using HPLC with affinity chromatography for this purpose include the ability to reuse the same ligand within a column for a large number of experiments, and the good precision and accuracy of this approach. A number of techniques are available for kinetic studies through the use of affinity columns and biointeraction chromatography. These approaches include plate height measurements, peak profiling, peak fitting, split‐peak measurements, and peak decay analysis. The general principles for each of these methods are discussed in this paper and some recent applications of these techniques are presented. The advantages and potential limitations of each approach are also considered.
1H HR/MAS NMR in the suspended state: Molecular recognition processes in liquid chromatography between steroids and a silica hydride‐based cholesterol phase
Authors: Friebolin Volker , Bayer Marc P. , Matyska Maria T. , Pesek Joseph J. , Albert Klaus 
Published: April 2009

AbstractA mixture of eight steroids was separated by HPLC on a silica hydride‐based stationary phase modified with a moiety of cholesteryl 10‐undecanoate. Within the steroid mixture progesterone showed the longest retention time suggesting the strongest interaction with the stationary phase material. To obtain more detailed information upon the effective separation process, interaction studies were performed by high resolution/magic angle spinning (HR/MAS) NMR spectroscopy recorded in the suspended state. 1H saturation transfer difference (STD) NMR experiments with T1ρ suppression showed significant hydrophobic binding affinities of progesterone toward the cholesterol column material. These NMR results can be correlated directly to the chromatographic data obtained by HPLC.
Neuroanatomical substrate of visuospatial and visuoperceptual impairment in Parkinson's disease
Authors: Pereira Joana B. , Junqué Carme , Martí María‐Jośe , Ramirez‐Ruiz Blanca , Bargalló Nuria , Tolosa Eduardo 
Published: May 2009

AbstractTo determine magnetic resonance imaging patterns of gray matter (GM) atrophy underlying visuospatial and visuoperceptual impairment in Parkinson's disease (PD), we applied voxel‐based morphometry to 36 nondemented PD patients and correlated their whole brain GM density with performance on three visuospatial and visuoperceptual tests. In addition, group comparisons between patients and 20 healthy controls were also performed. Correlations between visuospatial performance and GM density were found in the superior parietal lobules and the superior occipital gyrus of PD patients. Poor performance on visuoperceptual tests was also found to be significantly associated with GM decreases in the fusiform, the parahippocampus, and the middle occipital gyrus. Finally, group comparisons between controls and patients showed widespread GM cortical reductions in PD, involving posterior temporal and parietal regions. Taken together, these findings suggest that visuospatial and visuoperceptual dysfunctions reflect structural GM changes in temporo‐parietal cortical regions of PD patients. © 2009 Movement Disorder Society
Differentiation of configurations of the phenylbutenoid dimer derivatives from Zingiber cassumunar by tandem mass spectrometry
Authors: Chen Juanjuan , Lu Yanbin , Lin Lin , Sun Zhen , Sun Cuirong , Pan Yuanjiang 
Published: May 2009

AbstractHigh‐performance liquid chromatography/electrospray tandem mass spectrometry was developed to distinguish isomers and compounds of similar structures with different configurations in the rhizomes of Z. cassumunar. Energy‐resolved breakdown curves were utilized to differentiate four compounds. Compounds 2 (3R,4S) and 4 (3R,4R) were a pair of stereoisomers which could be distinguished easily by breakdown curves. The breakdown curve of compound 1 was identical to that of compound 2, which suggested that the configuration of compound 1 was (3R,4S) or (3S,4R). The breakdown curve of compound 3 was completely different from those of compounds 1, 2 and 4, and it might be that the configuration of the double bond of compound 3 was different from the other three compounds. Hence, the described method using breakdown curves has great potential in the distinguishing of isomers and compounds of similar structure with different configurations. Copyright © 2009 John Wiley & Sons, Ltd.
Identification of organic hydroperoxides and hydroperoxy acids in secondary organic aerosol formed during the ozonolysis of different monoterpenes and sesquiterpenes by on‐line analysis using atmospheric pressure chemical ionization ion trap mass spectrometry
Authors: Reinnig Marc‐Christopher , Warnke Jörg , Hoffmann Thorsten 
Published: May 2009

AbstractOn‐line ion trap mass spectrometry (ITMS) enables the real‐time characterization of reaction products of secondary organic aerosol (SOA). The analysis was conducted by directly introducing the aerosol particles into the ion source. Positive‐ion chemical ionization at atmospheric pressure (APCI(+)) ITMS was used for the characterization of constituents of biogenic SOA produced in reaction‐chamber experiments. APCI in the positive‐ion mode usually enables the detection of [M+H]+ ions of the individual SOA components. In this paper the identification of organic peroxides from biogenic volatile organic compounds (VOCs) by on‐line APCI‐ITMS is presented. Organic peroxides containing a hydroperoxy group, generated by gas‐phase ozonolysis of monoterpenes (α‐pinene and β‐pinene) and sesquiterpenes (α‐cedrene and α‐copaene), could be detected via on‐line APCI(+)‐MS/MS experiments. A characteristic neutral loss of 34 Da (hydrogen peroxide, H2O2) in the on‐line MS/MS spectra is a clear indication for the existence of an organic peroxide, containing a hydroperoxy functional group. Copyright © 2009 John Wiley & Sons, Ltd.
A postpartum separation induces c‐Fos expression in the supramammillary nucleus of lactating rats
Authors: Kromkhum Pudcharaporn , Nagai Asa , Ichikawa Masumi , Saito Toru R. , Yokosuka Makoto 
Published: April 2009

AbstractAimElucidation of the neural mechanism of maternal behaviors is a medically and biologically important research task. The rat is the laboratory animal most extensively analyzed for maternal behaviors. However, the neural mechanism that maintains the motivation of postpartum rats for maternal behaviors has not yet been elucidated. In this study, we aimed to identify brain regions involved in the maintenance of motivation for maternal behaviors by detecting brain regions that exhibit changes in nerve activity when the mother rat is separated from her pups.MethodsLactating mother rats were separated from their pups on postpartum day 3 and kept away from the pups for a certain period of time, and brain regions that exhibited changes in nerve activity when the rats were separated from their pups and those that exhibited changes in nerve activity when the pups are returned were detected by immunohistochemistry using anti‐c‐Fos antibody, a marker for increased nerve activity.ResultsRats that were separated from their pups and with the pups returned later showed increases in the number of c‐Fos immunoreactive (c‐Fos‐IR) cells in the medial preoptic area (MPA), the bed nucleus of the stria terminalis (BST), the caudal portion of posterior hypothalamic area (PH) and the supramamillary nucleus (SUM). In mother rats permanently separated from their pups, only the PH and SUM exhibited an increase in the number of c‐Fos‐IR cells.ConclusionIn rats, the SUM is involved in aversive memory and changes in the postpartum anxiety level. The observed increase in the number of c‐Fos‐IR cells in the SUM of mother rats separated from their pups suggests that the nerve activity change in the SUM, which is involved in aversive memory and anxiety, is involved in the maintenance of maternal behaviors.
Cross-bedding in the Calciferous Sandstone Series of Fife and West Lothian
Authors: Greensmith J. T. 
Published: May 2009

AbstractCross-bedding within the sandstones of eastern Fife indicates a predominant north to north-easterly source for the clastic debris. This inference is in accordance with cross-bedding data from sandstones of similar age in southern Fife and West Lothian.
Coal from the Legionary Fortress of Caerleon, Monmouthshire
Authors: Adams H. F. , Bradburn E. , Boon George C. 
Published: May 2009

AbstractFragments of coal found in contexts of the third century A.D. at the legionary fortress of Caerleon (Isca) are assigned from intrinsic evidence to a local source. A brief comment on the use of coal in Roman Britain follows.
The Role of Cooling Cracks Formed at High Temperatures and of Released Gas in the Formation of Chilled Basic Margins in Net-veined Intrusions
Authors: Windley B. 
Published: May 2009

AbstractCooling cracks form at high temperatures when a basic magma is either viscous or crystalline and hot. It is postulated that fine-grained margins form along the fractures by release of gas through the fracture network. This takes place (a) by raising the liquidus-solidus boundary due to release of volatiles, (b) by expansion of the released gas with consequent cooling. Granitic material introduced along the fractures post-dates and may recrystallize the “chilled” margins.
Welded glass-breccias from Marysvale, Utah
Authors: Kerr P. F. , Gavesci A. T. , Bowes D. R. 
Published: May 2009

SummaryGlass-breccias and volcanic glass from Marysvale are shown to be welded ash-flow tuffs of rhyolitic composition. They are interpreted as resulting from intermittent volcanic activity.
Raham Conglomerate – new evidence for Neogene tectonism in the southern part of the Dead Sea Rift
Authors: Garfunkel Z. , Bartov J. , Eyal Y. , Steinitz G. 
Published: May 2009

SummaryA newly discovered, mainly continental, deformed, Neogene formation – the Raham Conglomerate – records the early existence of the southern part of the Dead Sea Rift. The field relations, the predominance of clasts derived from formations which have been virtually completely eroded, and the presence of pebbles of Precambrian rocks, all attest that a considerable structural relief – possibly exceeding 2 km – already existed in the Middle (?) Miocene. Brackish marine fossils indicate that an ancestral Gulf of Elat (Aqaba) also already existed.
Sedimentation in an intracratonic extensional basin: the Karoo of the Central Morondava Basin, Madagascar
Authors: Nichols G. J. , Daly M. C. 
Published: May 2009

AbstractThe late Carboniferous to Triassic Karoo Supergroup of Madagascar is a sequence of predominantly continental clastic sediments deposited during a long period of regional crustal extension. In the Morondava Basin of western Madagascar the lower two divisions of the Karoo sediments – the Sakoa and the Sakamena – are deposits of fluvial and lacustrine sedimentation systems supplied from the Precambrian metamorphic basement terrain to the east. East–west crustal extension produced a series of graben and half-graben structures after the Sakoa period which were reactivated after the Sakamena. The position and orientation of these half graben, which were marginal to a larger rift system to the west, were partly controlled by the steep NNE–SSW mylonitic fabric in the metamorphic basement. Palaeocurrents in the braided river deposits of the Sakoa and Lower Sakamena indicate flow to the southwest and west in both sequences. The rivers followed a regional palaeoslope to the southwest/west and were apparently not significantly influenced by the local structural trends which were oriented perpendicular to this slope. The absence of local structural control is attributed to extensive erosional events which followed each tectonic episode and preceded the onset of further sedimentation which took place on an essentially peneplained surface. The tectonic episodes brought about changes in base level which caused this part of the basin to fluctuate between erosion and deposition.
The Adola Fold and Thrust Belt, southern Ethiopia: a re-examination with implications for Pan-African evolution
Authors: “Beraki W. H. , Bonavia F. F. , Getachew T. , Schmerold R. , Tarekegn T. 
Published: May 2009

AbstractThe Adola Fold and Thrust Belt of Ethiopia is a late- Precambrian, north–south trending belt of volcanic-sedimentary and ophiolite–like units overlying ‘basement rocks’ (gneisses and granitic gneisses). Detailed structural analysis and data from microfabrics have documented two thrusting events (D1, D5) and three folding phases (F2, F3, F4). All deformations have affected both the rocks of the Adola Fold and Thrust Belt and the ‘older basement’. The structural history is recorded as follows: (1) formation of ductile shear zones (Dl); (2) progressive development of recumbent folds (F2); (3) a superimposed north-south trending, tight to isoclinal, upright penetrative folding phase (F3), which imparted the dominant structure of the region; (4) F3 was later gently affected, at right angles to F3, by the last folding event (F4). Metamorphic conditions during this deformational cycle reached highest greenschist to medium amphibolite facies conditions. Close to major thrust contacts imbrication produced metamorphic discontinuities. Marked retrograde metamorphism in narrow horizons indicates a continuation of minor movements along the major thrusts, postdating the metamorphic peak. Evidence of a second thrusting/faulting episode (D5) is only recorded at the mesoscale. This latter event was accompanied by very low to low grade metamorphic conditions. In accepting the previously reported age of 1030±40 Ma for the volcanic–sedimentary unit of the Adola Fold and Thrust Belt, and the interpretation of these units as an immature island arc, a possibly early Pan-African oceanic accretion is postulated.
Probable microbial origin of Ordovician (Arenig) phosphatic pebble coats (‘ Bolopora ’) from North Wales, U.K.
Authors: Niedermeyer R.-O. , Langbein R. 
Published: May 2009

AbstractResults are presented of thin-section, SEM, X-ray and microprobe investigations on problematical phosphatic accretions (‘ Bolopora ’) from the St Tudwal's area of North Wales. The data supplement investigations made by H. J. Hofmann on the genesis of the accretions, and indicate a microbial (bacteriogenic) origin. The bacteriogenic pebble coats are of dahllite. Microbial relics suggest water–sediment interface-linked formation of the coatings under subtidal, and oxic to anoxic, environmental conditions during a sedimentary hiatus.
Palaeomagnetism of the Bayan Gol Formation, western Mongolia
Authors: Evans D. A. , Zhuravlev A. Yu. , Budney C. J. , Kirschvink J. L. 
Published: May 2009

AbstractOriented samples of the Lower Cambrian Bayan Gol Formation from Salaany Gol, Mongolia, were collected at roughly 5 m stratigraphic intervals for palaeomagnetic analysis. Progressive alternatingfield and thermal demagnetization isolated two magnetic components: a present-field overprint, typically removed by 10 mT fields and ~200°C heating; and a high-coercivity, high-unblocking-temperature (550–600 °C), predominantly single-polarity component that was imparted to the rocks prior to early or middle Palaeozoic deformation. Single-polarity magnetization at Salaany Gol contrasts with results from Lower Cambrian rocks on the Siberian platform, previously considered correlative with the Bayan Gol Formation, which show a prominent change in polarity bias near the top of the Tommotian Stage. Two hypotheses can explain this discrepancy. First, the entire Bayan Gol Formation may correlate with the predominantly reversely polarized, lower half of the Tommotian Stage in Siberia. This model is consistent with plausible interpretations of δ13C profiles for the Zavkhan basin and the Siberian platform. Alternatively, the characteristic magnetic direction from our samples may be a pre-fold overprint. If post-accretionary, then comparison with Siberian palaeomagnetic results suggest a Silurian–Devonian remagnetization age, and existing bioand chemostratigraphic correlations provide the most reliable spatial and temporal links between the Zavkhan basin and the Siberian platform. If the observed magnetic directions are primary or an immediate overprint then they may be used to constrain the early Cambrian palaeogeography of the Zavkhan basin and the Palaeo-Pacific Ocean. Mean inclination of 62 ±4° corresponds to a palaeolatitude of 44 ±5°, several thousand kilometres from the equatorial Siberian craton
Geology and geochronology of Inaccessible Island, South Atlantic
Authors: Chevallier L. , Rex D. C. , Verwoerd W. J. 
Published: May 2009

AbstractInaccessible Island is the eroded remnant of an extinct, comparatively small intraplate volcano dominated by flows of alkaline olivine basalt. The oldest stratigraphie unit is a hydrothermally altered basement of somewhat questionable early Pliocene (6.5 Ma) age. This is unconformably overlain by a volcanic superstructure built up during the last three million years. The two formations have different trace element signatures that may be attributed to different mantle sources. Boulders of gabbro are common but the presence of an in situ plutonic intrusion could not be confirmed. Their K-Ar age of 12.8 Ma may be spurious and their possible relationship with the volcano is uncertain. Reliable age determinations of 0.95–0.72 Ma were obtained on lava flows of the second volcanic stage, subdivided into four units or stratigraphie members. The latest unit consists of plugs, sills and flows of an evolved magma fraction (benmoreite and trachyte) of which benmoreite is considered to be the more voluminous. Several dyke swarms of different ages reveal the internal structure of the volcano. It is concluded that the main volcanic centre was located immediately offshore to the northwest and that the edifice was attached to an east–west volcanic rift zone. Apart from marine erosion, massive land-sliding probably took part in shaping the island and its submarine platform.
Global ocean—atmosphere change across the Precambrian—Cambrian transition
Authors: Brasier M. D. 
Published: May 2009

AbstractThe late Precambrian and Cambrian world experienced explosive evolution of the biosphere, including the development of biomineral skeletons, and notably of phosphate and siliceous skeletons in the initial stages of the adaptive radiation. Ongoing research indicates profound changes in climate and atmospheric carbon dioxide over this span of time. Glacial conditions of the Varangian epoch occur enigmatically at low latitudes, associated with carbonate rocks. Later changes in palaeogeography, sea level rise and salinity stratification encouraged prolonged ‘greenhouse’ conditions in both latest Precambrian and Cambrian times, with indications of relatively low primary production in the oceans. The Precambrian–Cambrian boundary interval punctuated this trend with evaporites, phosphogenic events and carbon isotope excursions; these suggest widespread eutrophication and conjectured removal of carbon dioxide from the atmosphere. Whatever the cause, nutrient–enriched conditions appear to have coincided with the development of phosphatic and siliceous skeletons among the earliest biomineralized invertebrates.
The Devonian System in Iran: a review
Authors: Dastanpour Mohammad 
Published: May 2009

AbstractUpper Devonian strata are distributed widely throughout Iran. A review of all available literature on the Devonian, together with information from recent studies in the Kerman region, provides a basis for correlation and description of facies successions for the whole country. In most sections the local base of the Upper Devonian sits disconformably on older rocks, whilst the upper contact with the Carboniferous is almost everywhere transitional. There is everywhere an apparent hiatus spanning a probable early and mid Devonian interval. Lower and Middle Devonian fossils have not yet been discovered, but for the Upper Devonian there are abundant fossil data indicating the widespread occurrence of Frasnian and Famennian shallow marine deposits. A palaeogeographical map for the Upper Devonian of Iran is constructed.