bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Cu‐ZSM‐5 Zeolites and Cu‐MOF‐505 Metal‐Organic Frameworks as Heterogeneous Catalysts for the Mukaiyama Aldol Reaction: A DFT Mechanistic Study
Authors: Yadnum Sudarat , Choomwattana Saowapak , Khongpracha Pipat , Sirijaraensre Jakkapan , Limtrakul Jumras 
Published: February 2013

AbstractThe density functional theory (DFT) model ONIOM(M06L/6‐311++G(2df,2p):UFF was employed to reveal the catalytic activity of CuII in the paddle‐wheel unit of the metal‐organic framework (MOF)‐505 material in the Mukaiyama aldol reaction compared with the activity of Cu‐ZSM‐5 zeolites. The aldol reaction between a silyl enol ether and formaldehyde catalyzed by the Lewis acidic site of both materials takes place through a concerted pathway, in which the formation of the CC bond and the transfer of the silyl group occurs in a single step. MOF‐505 and Cu‐ZSM‐5 are predicted to be efficient catalysts for this reaction as they strongly activate the formaldehyde carbonyl carbon electrophile, which leads to a considerably lower reaction barrier compared with the gas‐phase system. Both MOF‐505 and Cu‐ZSM‐5 catalysts stabilize the reacting species along the reaction coordinate, thereby lowering the activation energy, compared to the gas‐phase system. The activation barriers for the MOF‐505, Cu‐ZSM‐5, and gas‐phase system are 48, 21, and 61 kJ mol−1, respectively. Our results show the importance of the enveloping framework by stabilizing the reacting species and promoting the reaction.
MODELING TOXIC STRESS BY ATRAZINE IN A MARINE CONSUMER-RESOURCE SYSTEM
Authors: De Hoop Lisette , De Troch Marleen , Hendriks A. Jan , De Laender Frederik 
Published: February 2013

Abstract

The present study combines short-term experiments with food chain modeling to explore the long-term effects of the herbicide atrazine on consumer-resource dynamics in a marine intertidal ecosystem. Short-term (28 d) lab experiments indicated that the intrinsic rate of increase (r) and carrying capacity (K) of the marine diatom Seminavis robusta decreased with increasing atrazine exposure. This decrease did not show the concave shape expected from the lifetime productivity for nonexposed diatoms and from single-species toxicity data in the literature but instead was described best by a linear model. These experimentally observed atrazine-induced decreases of r and K were used to parameterize a Rosenzweig-MacArthur model representing a simple food chain including the tested diatom and its grazer, the harpacticoid copepod Delavalia palustris var. palustris. Stable oscillation zoo-phytobenthos systems were produced at diatom exposures of 0, 100, and 150 µg/L atrazine. An atrazine concentration of 150 µg/L contributed to a 15% increase of the oscillation periods of both diatoms and copepods as well as a 52% reduction of oscillation amplitudes compared with the control situation. Although the amplitudes of copepods increased only 7% at 150 µg/L atrazine, the maximum and minimum copepod densities at that concentration were reduced by 61 and 63%, respectively. The effects of atrazine on periodicity and amplitudes were robust to 20% changes in the food-chain model parameters that represented allometric relationships. The simulations in the present study suggest food chain–mediated indirect effects on zoobenthos populations, indicating a reduced diatom and copepod availability throughout the year. Environ. Toxicol. Chem. 2013;32:1088–1095. © 2013 SETAC
Estimating source regions for snowmelt runoff in a Rocky Mountain basin: tests of a data‐based conceptual modeling approach
Authors: Kampf Stephanie K. , Richer Eric E. 
Published: February 2013

AbstractIn many mountain basins, river discharge measurements are located far away from runoff source areas. This study tests whether a basic snowmelt runoff conceptual model can be used to estimate relative contributions of different elevation zones to basin‐scale discharge in the Cache la Poudre, a snowmelt‐dominated Rocky Mountain river. Model tests evaluate scenarios that vary model configuration, input variables, and parameter values to determine how these factors affect discharge simulation and the distribution of runoff generation with elevation. Results show that the model simulates basin discharge well (NSCE and R >0.90) when input precipitation and temperature are distributed with different lapse rates, with a rain‐snow threshold parameter between 0 and 3.3 °C, and with a melt rate parameter between 2 and 4 mm °C−1 d−1 because these variables and parameters can have compensating interactions with each other and with the runoff coefficient parameter. Only the hydrograph recession parameter can be uniquely defined with this model structure. These non‐unique model scenarios with different configurations, input variables, and parameter values all indicate that the majority of basin discharge comes from elevations above 2900 m, or less than 25% of the basin total area, with a steep increase in runoff generation above 2600 m. However, the simulations produce unrealistically low runoff ratios for elevations above 3000 m, highlighting the need for additional measurements of snow and discharge at under‐sampled elevations to evaluate the accuracy of simulated snow and runoff patterns. Copyright © 2013 John Wiley & Sons, Ltd.
Determination of the radiochemical purity of 99mTc medronate injection by thin layer chromatography on iTLC‐SG: effect of medronate concentration on the value measured
Authors: Cunnane Caroline M. , O'Brien Lesley M. , Waight Lynn A. , Millar Alistair M. 
Published: February 2013

BackgroundWhen using iTLC‐SG thin layer chromatography plates to measure radiochemical impurities in 99mTc medronate, falsely high values were obtained for 99mTc pertechnetate impurity. Preliminary investigations indicated that the mass of 99mTc medronate applied to the plate influences the value.AimThe goal of this study was to determine if the concentration of medronate influences the value obtained for 99mTc pertechnetate impurity.Experimental99mTc medronate was prepared at two concentrations: 4 mg/mL and 0.2 mg/mL. Impurity levels were measured using three stationary phases: dried and undried iTLC‐SG and 54SFC paper. Two mobile phases were used: methyl ethyl ketone to detect 99mTc pertechnetate and sodium acetate 136 g/L to detect hydrolysed and colloidal 99mTc. Sample spot drying and volume were also investigated.ResultsWith 4 mg/mL samples, the three stationary phases measured similar impurity levels (p > 0.05). With the 0.2 mg/mL samples, higher levels of 99mTc pertechnetate were measured with iTLC‐SG than with paper (p < 0.05). Neither sample spot drying nor volume was found to affect impurity levels measured.ConclusionsWhen using iTLC‐SG to measure the radiochemical purity of 99mTc medronate, an artefactually high level of 99mTc pertechnetate impurity is measured when the medronate concentration in the sample is low. The iTLC‐SG stationary phase may be unsatisfactory for measuring the radiochemical purity of 99mTc medronate. Copyright © 2013 John Wiley & Sons, Ltd.
Effect of processing conditions on the orientation and properties of polyethylene blown film
Authors: Gilbert Marianne , Hemsley Derek A. , Patel Suresh R. 
Published: February 2013

AbstractThe amorphous and crystallite orientation in a number of films produced from characterised grades of high density polyethylene has been examined and some tensile properties measured. The films were produced under commercial production conditions with various blow ratios, freeze line heights and thicknesses.Orientation was assessed using optical and X‐ray methods. The relative contributions of the crystallite and amorphous components were calculated for a limited number of the films produced.Amongst the properties measured the ultimate tensile strength and elongation at break appeared to be the most variable. Birefringence was more affected by variation in blow ratio and film thickness than by freeze height changes.Attempts have been made to correlate these variations with crystallite and amorphous orientation as well as the individual behaviour of the polyethylene grades. In carrying out this correlation it became clear that the films could not generally be described by established low or high stress models of crystallite orientation. For these films produced on full‐scale commercial equipment it appears that transcrystallisation behaviour is frequently observed, with a tendency towards the low stress model.
Construction of ploidy series of Saccharomyces cerevisiae by the plasmid YCplac33-GHK
Authors: Hou Lihua , Li Xiaoyang , Wang Cong , Cao Xiaohong , Wang Haiyong 
Published: February 2013

Abstract
An effective approach, using the plasmid YCplac33-GHK, is developed to construct a ploidy series of Saccharomyces cerevisiae. YCplac33-GHK harbors the HO gene under the control of galactose-inducible promoter and KanMX4 as the selective marker. The simple method can solve the problem of industrial applications of strains with resistance genes.
Older adults' perceptions of age-friendly communities in Canada: a photovoice study
Authors: NOVEK SHEILA , MENEC VERENA H. 
Published: February 2013

ABSTRACTThe concept of age-friendly communities has garnered international attention among researchers, policy makers and community organisations since the World Health Organization launched its Global Age-friendly Cities Project in 2006. Despite the growth of the age-friendly communities movement, few studies have examined age-friendly characteristics within different community contexts. The goal of the present study was to use a participatory methodology to explore older adults’ perceptions of age-friendliness. The study employed the photovoice technique with 30 community-based older adults in one urban community and three rural communities in the province of Manitoba, Canada. Participants were provided with cameras and took photographs to illustrate the relative age-friendliness of their communities and to generate discussion in interviews and focus groups. Themes from photographs, interviews and focus groups were organised into three broad categories: age-friendly features, contextual factors and cross-cutting themes. The age-friendly features we identified in this study generally correspond to the World Health Organization domains of age-friendliness. In addition, we identified three contextual factors that impact the experiences of older adults within their community environment: community history and identity, ageing in urban, rural and remote communities, and environmental conditions. Finally, independence, affordability and accessibility were identified as cross-cutting themes that intersect with various community features and contextual factors.
Forest dynamics of a subtropical monsoon forest in Dinghushan, China: recruitment, mortality and the pace of community change
Authors: Shen Yong , Santiago Louis S. , Ma Lei , Lin Guo-Jun , Lian Ju-Yu , Cao Hong-Lin , Ye Wan-Hui 
Published: February 2013

Abstract:Structure and demographics in many tropical forests is changing, but the causes of these changes remain unclear. We studied 5 y (2005–2010) of species turnover, recruitment, mortality and population change data from a 20-ha subtropical forest plot in Dinghushan, China, to identify trends in forest change, and to test whether tree mortality is associated with intraspecific or interspecific competition. We found the Dinghushan forest to be more dynamic than one temperate and two tropical forests in a comparison of large, long-term forest dynamics plots. Within Dinghushan, size-class distributions were bell-shaped only for the three most dominant species and reverse J-shaped for other species. Bell-shaped population distributions can indicate a population in decline, but our data suggest that these large and long-lived species are not in decline because the pattern is driven by increasing probabilities of transition to larger size class with increasing size and fast growth in saplings. Spatially aggregated tree species distributions were common for surviving and dead individuals. Competitive associations were more frequently intraspecific than interspecific. The competition that induced tree mortality was more associated with intraspecific than interspecific interactions. Intraspecific competitive exclusion and density-dependence appear to play important roles in tree mortality in this subtropical forest.
Insights into the biology and phylogeny of Chloromonas polyptera (Chlorophyta), an alga causing orange snow in Maritime Antarctica
Authors: Remias Daniel , Wastian Hans , Lütz Cornelius , Leya Thomas 
Published: February 2013

AbstractIn Antarctica, mass accumulations of psychrophilic algae cause striking phenomena like green, orange, or red snow. This occurs during summer, when coastal snowfields start to melt, become waterlogged and photoautotrophs can thrive. Chloromonas polyptera (Fritsch) Hoham, Mullet & Roemer is a unicellular species that causes orange snow in the vicinity of penguin rockeries. It has been recognized for many decades because of the distinct habitat and the characteristic morphology of cysts with elongated flanges on the outer cell wall. However, closer investigations concerning the ecology or physiology have been sparse so far. Field material was collected from two sites on the Antarctic Peninsula to find out more about metabolic and cellular strategies. The results were compared with a closely related species from high alpine locations, Chloromonas nivalis (Chodat) Hoham & Mullet. Despite the geographical distance, C. polyptera shares several physiological strategies with the alpine relative, such as the formation of cyst stages, saccharose and glycerol as main soluble carbohydrates and the abundant accumulation of the carotenoid astaxanthin. Moreover, photosynthesis is adapted to temperatures of about 1°C. The molecular phylogeny confirmed a close relationship of C. polyptera to other Chloromonas species isolated from snow. Chloromonas polyptera seems to be exclusive to coastal Antarctic ecosystems influenced by animal nutrient input.
BDNF parabrachio-amygdaloid pathway in morphine-induced analgesia
Authors: Sarhan Maysa , Pawlowski Sophie Anne , Barthas Florent , Yalcin Ipek , Kaufling Jennifer , Dardente Hugues , Zachariou Venetia , DiLeone Ralph Joseph , Barrot Michel , Veinante Pierre 
Published: February 2013

Abstract
In addition to its neurotrophic role, brain-derived neurotrophic factor (BDNF) is involved in a wide array of functions, including anxiety and pain. The central amygdaloid nucleus (CeA) contains a high concentration of BDNF in terminals, originating from the pontine parabrachial nucleus. Since the spino-parabrachio-amygdaloid neural pathway is known to convey nociceptive information, we hypothesized a possible involvement of BDNF in supraspinal pain-related processes. To test this hypothesis, we generated localized deletion of BDNF in the parabrachial nucleus using local bilateral injections of adeno-associated viruses in adult floxed-BDNF mice. Basal thresholds of thermal and mechanical nociceptive responses were not altered by BDNF loss and no behavioural deficit was noticed in anxiety and motor tests. However, BDNF-deleted animals displayed a major decrease in the analgesic effect of morphine. In addition, intra-CeA injections of the BDNF scavenger TrkB-Fc in control mice also decreased morphine-induced analgesia. Finally, the number of c-Fos immunoreactive nuclei after acute morphine injection was decreased by 45% in the extended amygdala of BDNF-deleted animals. The absence of BDNF in the parabrachial nucleus thus altered the parabrachio-amygdaloid pathway. Overall, our study provides evidence that BDNF produced in the parabrachial nucleus modulates the functions of the parabrachio-amygdaloid pathway in opiate analgesia.
The aperiodic variability of the Ultraluminous X-ray source in NGC 5408
Authors: Caballero-Garcia M. D. , Motta S. E. , Belloni T. M. , Wolter A. 
Published: February 2013

AbstractUltra-Luminous X-ray sources are accreting black holes that might represent strong evidence of the Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies but with no firm detection (as a class) so far. We analyze the best X-ray timing and spectral data from the ULX in NGC 5408 provided by XMM-Newton. The main goal is to study the broad-band noise variability of the source. We found an anti-correlation of the fractional root-mean square variability versus the intensity of the source, similar to black-hole binaries during hard states.
Coupling of the accretion disk and corona around black holes
Authors: Liu B. F. 
Published: February 2013

AbstractThe interaction between a hot corona and a cold thin disk can drive cold gas evaporating into the corona or hot gas condensing into the thin disk. The evaporation is caused by heat conduction downwards to the disk; while condensation is caused by overcooling of corona gas through inverse Compton scattering. Evaporation occurs at low accretion rates when the corona cannot efficiently radiate the viscous heat, thereby part of which is conducted down and heats up gas. Condensation occurs at high accretion rates when the Compton cooling of disk photons is strong enough to efficiently cool the corona gas. An important consequence of the evaporation is complete removal of the disk at a certain distances. In contrast, condensation can lead to a weak corona or complete collapse of the corona. This causes the observed transitions between various spectral states, at which the accretion flows are dominated respectively by ADAF, disk+ corona, and thin disk from low to high accretion rates, providing a natural explanation to the low, intermediate and high spectral states in BHXRBs, as well as their transitions. The same process can also be applied to accretion around supermassive black holes.
Constraining neutron star masses and radii using thermonuclear X-ray bursts
Authors: Miller M. Coleman , Boutloukos Stratos , Lo Ka Ho , Lamb Frederick K. 
Published: February 2013

AbstractPrecisely measured neutron star masses and especially radii would provide unique constraints on the properties of cold matter at several times nuclear density. Observations using the Rossi X-ray Timing Explorer suggest that such measurements might be possible using thermonuclear X-ray bursts. Here we discuss the prospects for mass and radius constraints, with a particular focus on potential systematic errors.
Modelling the Late-time Hubble Space Telescope Imaging of the Outburst of the Recurrent Nova RS Ophiuchi (2006)
Authors: Ribeiro Valério A. R. M. , Bode Michael F. , Williams Robert 
Published: February 2013

AbstractThe nebular remnant of RS Ophiuchi was modelled using combined HST/ACS imaging and ground-based spectroscopy on day 155 after outburst as a two component bipolar expansion with a low velocity innermost hour-glass over density and a more extended high velocity dumbbell structure. The model was evolved to a much later date, day 455 after outburst, when second epoch HST images were secured. However, due to the lack of simultaneous ground-based spectroscopy the evolved model was much harder to constrain. One suggestion put forward was that the dumbbell structure expanded linearly while the inner hour-glass showed signs of deceleration. Archival data in the form of ground-based spectroscopy on day 415 were subsequently obtained. These new data suggest indeed that a non-linear expansion of the system occurred.
AGN Feedback Driven Molecular Outflow in NGC 1266
Authors: Alatalo K. , Nyland K. E. , Graves G. , Deustua S. , Wrobel J. , Young L. M. , Davis T. A. , Bureau M. , Bayet E. , Blitz L. , Bois M. , Bournaud F. , Cappellari M. , Davies R. L. , de Zeeuw P. T. , Emsellem E. , Khochfar S. , Krajnovic D. , Kuntschner H. , Martín S. , McDermid R. M. , Morganti R. , Naab T. , Sarzi M. , Scott N. , Serra P. , Weijmans A. 
Published: February 2013

AbstractNGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high brightness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies.
Modelling the structure of the hot components in symbiotic binaries during outbursts
Authors: Cariková Zuzana , Skopal Augustin 
Published: February 2013

AbstractDuring outbursts in symbiotic binaries a neutral medium in the form of a flared disk develops around their hot stars. The appearance of the disks is most probably connected with the enhanced wind from the hot star. The wind is compressed towards the equatorial plane of the hot star due to its rotation. To test this idea we calculated the ionization boundaries in the enhanced wind and thus confirmed the possibility of the formation of the neutral disk-like zones around the hot stars in symbiotic binaries during outbursts.
Probing the stellar wind geometry in Vela X-1 with infrared interferometry
Authors: Choquet Élodie , Kervella Pierre , Le Bouquin Jean-Baptiste , Mérand Antoine , Haubois Xavier , Berger Jean-Philippe , Perrin Guy , Petrucci Pierre-Olivier , Lazareff Bernard , Millan-Gabet Rafael 
Published: February 2013

AbstractHigh-mass X-ray Binaries (HMXBs) are keys to study stellar remnants that are otherwise extremely faint and difficult to observe when isolated. Vela X-1 is a well-known eclipsing HMXB composed of a very massive neutron star orbiting a B0.5I supergiant with a period of 9 days. The supergiant wind is the main feeding material for the accreting neutron star, and its properties are of prime interest to understand the physics at stakes in the accretion process.In order to characterize the geometry and physical properties of the dense wind at a scale of a few stellar radii, we obtained infrared interferometric observations of Vela X-1 in 2010 using the VLTI/AMBER instrument in the K band (2.2 μm), and in 2012 using the VLTI/PIONIER instrument in the H band (1.6 μm).Although the apparent disk of the supergiant and the orbital separation of the two objects are beyond the present resolution limit of the VLTI, the K-band observations partially resolve the wind envelope on the two longest baselines. We were able to measure the radius of 265±82 R⊙ for the circumstellar wind at a temperature of 1300 K, assuming a distance of 1.9 kpc. The H-band observations do not resolve the system, and we were able to set an upper limit of 112 R⊙ for the envelope radius at a temperature of 1800 K.