bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigating the IMF cone angle control of Pc3‐4 pulsations observed on the ground
Authors: Bier Elianna A. , Owusu Nana , Engebretson Mark J. , Posch Jennifer L. , Lessard Marc R. , Pilipenko Viacheslav A. 
Published: February 2014

AbstractMany studies have shown that Pc3‐4 pulsations (~0.014–0.1 Hz) observed in Earth's magnetosphere during daytime hours originate in the ion foreshock region of the solar wind, just upstream from Earth's bow shock. They occur when the interplanetary magnetic field (IMF) is primarily radial—when the IMF cone angle θxB ≤ 45°. However, our knowledge of ion foreshock conditions is often incomplete because of the very limited number of spacecraft providing upstream data. In this study we compared 13 months of wave observations at two widely separated ground stations (Hornsund, Svalbard and Halley, Antarctica) to IMF values in the OMNI database in order to test this relation. Values of θxB and the empirically predicted wave frequency (fcalc = 0.06 BIMF) were compared to daily Fourier spectrograms displaying pulsation power and frequency. Although there was often good temporal agreement between low θxB and increased Pc3‐4 wave power, numerous counterexamples were also evident. A statistical study of wave activity in quarter hour increments showed that Pc3‐4 pulsations were associated with low θxB values, 81% of the time at Hornsund and 83% at Halley. IMF cone angle data from all available upstream monitors were compared to wave observations for a more limited number of days; many of these showed inconsistent IMF orientations. This study indicates some of the limitations of the existing upstream monitors and provides a quantitative estimate (~80%) of the accuracy of the OMNI data set in characterizing conditions near the nose of Earth's bow shock under predominantly radial IMF conditions.
Machine learning and linear regression models to predict catchment‐level base cation weathering rates across the southern Appalachian Mountain region, USA
Authors: Povak Nicholas A. , Hessburg Paul F. , McDonnell Todd C. , Reynolds Keith M. , Sullivan Timothy J. , Salter R. Brion , Cosby Bernard J. 
Published: February 2014

AbstractAccurate estimates of soil mineral weathering are required for regional critical load (CL) modeling to identify ecosystems at risk of the deleterious effects from acidification. Within a correlative modeling framework, we used modeled catchment‐level base cation weathering (BCw) as the response variable to identify key environmental correlates and predict a continuous map of BCw within the southern Appalachian Mountain region. More than 50 initial candidate predictor variables were submitted to a variety of conventional and machine learning regression models. Predictors included aspects of the underlying geology, soils, geomorphology, climate, topographic context, and acidic deposition rates. Low BCw rates were predicted in catchments with low precipitation, siliceous lithology, low soil clay, nitrogen and organic matter contents, and relatively high levels of canopy cover in mixed deciduous and coniferous forest types. Machine learning approaches, particularly random forest modeling, significantly improved model prediction of catchment‐level BCw rates over traditional linear regression, with higher model accuracy and lower error rates. Our results confirmed findings from other studies, but also identified several influential climatic predictor variables, interactions, and nonlinearities among the predictors. Results reported here will be used to support regional sulfur critical loads modeling to identify areas impacted by industrially derived atmospheric S inputs. These methods are readily adapted to other regions where accurate CL estimates are required over broad spatial extents to inform policy and management decisions.
Seasonal variation of peripheral blood leukocyte telomere length in Costa Rica: A population‐based observational study
Authors: Rehkopf David H. , Dow William H. , Rosero‐Bixby Luis , Lin Jue , Epel Elissa S. , Blackburn Elizabeth H. 
Published: February 2014

ABSTRACTObjectivesPeripheral blood leukocyte telomere length (LTL) is increasingly being used as a biomarker of aging, but its natural variation in human populations is not well understood. Several other biomarkers show seasonal variation, as do several determinants of LTL. We examined whether there was monthly variation in LTL in Costa Rica, a country with strong seasonal differences in precipitation and infection.MethodsWe examined a longitudinal population‐based cohort of 581 Costa Rican adults age 60 and above, from which blood samples were drawn between October 2006 and July 2008. LTL was assayed from these samples using the quantitative PCR method. Multivariate regression models were used to examine correlations between month of blood draw and LTL.ResultsTelomere length from peripheral blood leukocytes varied by as much as 200 base pairs depending on month of blood draw, and this difference is not likely to be due to random variation. A moderate proportion of this association is statistically accounted for by month and region specific average rainfall. We found shorter telomere length associated with greater rainfall.ConclusionsThere are two possible explanations of our findings. First, there could be relatively rapid month‐to‐month changes in LTL. This conclusion would have implications for understanding the natural population dynamics of telomere length. Second, there could be seasonal differences in constituent cell populations. This conclusion would suggest that future studies of LTL use methods to account for the potential impact of constituent cell type. Am. J. Hum. Biol. 26:367–375, 2014. © 2014 Wiley Periodicals, Inc.
A novel prodrug‐based strategy to increase effects of bumetanide in epilepsy
Authors: Töllner Kathrin , Brandt Claudia , Töpfer Manuel , Brunhofer Gerda , Erker Thomas , Gabriel Mario , Feit Peter W. , Lindfors Jenna , Kaila Kai , Löscher Wolfgang 
Published: February 2014

ObjectiveThere is considerable interest in using bumetanide, a chloride importer Na‐K‐Cl cotransporter antagonist, for treatment of neurological diseases, such as epilepsy or ischemic and traumatic brain injury, that may involve deranged cellular chloride homeostasis. However, bumetanide is heavily bound to plasma proteins (∼98%) and highly ionized at physiological pH, so that it only poorly penetrates into the brain, and chronic treatment with bumetanide is compromised by its potent diuretic effect.MethodsTo overcome these problems, we designed lipophilic and uncharged prodrugs of bumetanide that should penetrate the blood–brain barrier more easily than the parent drug and are converted into bumetanide in the brain. The feasibility of this strategy was evaluated in mice and rats.ResultsAnalysis of bumetanide levels in plasma and brain showed that administration of 2 ester prodrugs of bumetanide, the pivaloyloxymethyl (BUM1) and N,N‐dimethylaminoethylester (BUM5), resulted in significantly higher brain levels of bumetanide than administration of the parent drug. BUM5, but not BUM1, was less diuretic than bumetanide, so that BUM5 was further evaluated in chronic models of epilepsy in mice and rats. In the pilocarpine model in mice, BUM5, but not bumetanide, counteracted the alteration in seizure threshold during the latent period. In the kindling model in rats, BUM5 was more efficacious than bumetanide in potentiating the anticonvulsant effect of phenobarbital.InterpretationOur data demonstrate that the goal of designing bumetanide prodrugs that specifically target the brain is feasible and that such drugs may resolve the problems associated with using bumetanide for treatment of neurological disorders. ANN NEUROL 2014;75:550–562
Encapsulation with the Protrusion of Cruciform 9,10‐Bis(arylethynyl)anthracene Derivatives in a Self‐Assembled Boronic Ester Cavitand Capsule: Photochemical and Photophysical Properties
Authors: Hirumi Yohei , Tamaki Kento , Namikawa Tomotaka , Kamada Kenji , Mitsui Masaaki , Suzuki Kengo , Kobayashi Kenji 
Published: February 2014

AbstractThe self‐assembled boronic ester cavitand capsule 3 quantitatively and tightly encapsulates 2,6‐diacetoxy‐9,10‐bis(arylethynyl)anthracene derivatives 4 a–4 c as highly fluorescent cruciform guests to form complexes 4 a@3, 4 b@3, and 4 c@(3)2. The structural features of capsule 3, which possesses two polar bowl‐shaped aromatic cavity ends and four large equatorial windows connected by dynamic boronic ester bonds, made it possible to encapsulate cruciform 4 with protection of the reactive anthracene core inside the capsule and with two protruding arylethynyl groups, the π‐conjugated arms of compound 4, through two of the equatorial windows of the capsule. Thus, complexes 4 a@3, 4 b@3, and 4 c@(3)2 show greater resistance to photochemical reactions in solution and fluorescence quenching in the powder state compared to free guests 4. In addition to the improved photostability, restriction of the free rotation of the arylethynyl groups of guests 4 upon encapsulation results in sharpening of the UV/Vis absorption peaks with a red‐shift and a significant increase in some of the two‐photon‐absorption peaks of complexes 4 a@3, 4 b@3, and 4 c@(3)2 compared with free guests 4.
Design of a Maximally Permissive Liveness‐enforcing Supervisor with Reduced Complexity for Automated Manufacturing Systems
Authors: Wang ShouGuang , Zhou MengChu , Wu WenHui 
Published: February 2014

AbstractThis paper deals with the problems of computational and structural complexity in designing maximally permissive liveness‐enforcing supervisors for a class of Petri nets called Systems of Simple Sequential Processes with Resources (S3PR) without ξ‐resources. The supervisor consists of two parts: the first part proposes an algorithm to extract a desired emptied strict minimal siphon (SMS) from a given emptied siphon based on loop resource subsets. This is faster than the existing ones. The second part proposes a siphon‐based deadlock prevention policy, which can obtain a maximally permissive liveness‐enforcing supervisor with reduced structural complexity and no weighted monitors, owing to the contribution of the first part, which can compute a desired SMS such that one with the smallest number of resource places is selected first for control. Several flexible manufacturing systems are used to show the proposed method and its superior performance over the previous ones.
Investigation of Maternal Genotype Effects in Autism by Genome‐Wide Association
Authors: Yuan Han , Dougherty Joseph D. 
Published: February 2014

Like most psychiatric disorders, autism spectrum disorders have both a genetic and an environmental component. While previous studies have clearly demonstrated the contribution of in utero (prenatal) environment on autism risk, most of them focused on transient environmental factors. Based on a recent sibling study, we hypothesized that environmental factors could also come from the maternal genome, which would result in persistent effects across siblings.In this study, the possibility of maternal genotype effects was examined by looking for common variants (single‐nucleotide polymorphisms or SNPs) in the maternal genome associated with increased risk of autism in children. A case/control genome‐wide association study was performed using mothers of probands as cases, and either fathers of probands or normal females as controls. Autism Genetic Resource Exchange and Illumina Genotype Control Database were used as our discovery cohort (n = 1616). The same analysis was then replicated on Simon Simplex Collection and Study of Addiction: Genetics and Environment datasets (n = 2732).We did not identify any SNP that reached genome‐wide significance (P < 10−8), and thus a common variant of large effect is unlikely. However, there was evidence for the possibility of a large number of alleles of effective size marginally below our power to detect. Autism Res 2014, 7: 245–253. © 2014 International Society for Autism Research, Wiley Periodicals, Inc.
Antibody approaches to prepare clinically transplantable cells from human embryonic stem cells: Identification of human embryonic stem cell surface markers by monoclonal antibodies
Authors: Choi Hong Seo , Kim Won‐Tae , Ryu Chun Jeih 
Published: February 2014

AbstractHuman embryonic stem cells (hESCs) are unique cell populations, possessing both unlimited self‐renewal capacity and pluripotency, i.e. the potential to give rise to all kinds of specialized cells in the human body. Marker molecules expressed on the surface of hESCs are important for the identification, characterization, and clinical application of hESCs. Compared with conventional genomics‐ or proteomics‐based approaches, generating monoclonal antibody (mAb) libraries against hESCs using alternative methodologies expands the repertoire of mAbs raised against non‐protein markers, for example, glycolipid antigens. Additional information about the conformation and post‐translational modification of surface molecules can also be obtained. In this article, we review how mAb libraries against hESC surface markers have been developed using whole‐cell and decoy immunization strategies.
Correlation analysis of targeted proteins and metabolites to assess and engineer microbial isopentenol production
Authors: George Kevin W. , Chen Amy , Jain Aakriti , Batth Tanveer S. , Baidoo Edward E.K. , Wang George , Adams Paul D. , Petzold Christopher J. , Keasling Jay D. , Lee Taek Soon 
Published: February 2014

ABSTRACTThe ability to rapidly assess and optimize heterologous pathway function is critical for effective metabolic engineering. Here, we develop a systematic approach to pathway analysis based on correlations between targeted proteins and metabolites and apply it to the microbial production of isopentenol, a promising biofuel. Starting with a seven‐gene pathway, we performed a correlation analysis to reduce pathway complexity and identified two pathway proteins as the primary determinants of efficient isopentenol production. Aided by the targeted quantification of relevant pathway intermediates, we constructed and subsequently validated a conceptual model of isopentenol pathway function. Informed by our analysis, we assembled a strain which produced isopentenol at a titer 1.5 g/L, or 46% of theoretical yield. Our engineering approach allowed us to accurately identify bottlenecks and determine appropriate pathway balance. Paired with high‐throughput cloning techniques and analytics, this strategy should prove useful for the analysis and optimization of increasingly complex heterologous pathways. Biotechnol. Bioeng. 2014;111: 1648–1658. © 2014 Wiley Periodicals, Inc.
Methane Activation by Diatomic Molybdenum Carbide Cations
Authors: Li Zi‐Yu , Yuan Zhen , Zhao Yan‐Xia , He Sheng‐Gui 
Published: February 2014

AbstractMetal carbide species have been proposed as a new type of chemical entity to activate methane in both gas‐phase and condensed‐phase studies. Herein, methane activation by the diatomic cation MoC+ is presented. MoC+ ions have been prepared and mass‐selected by a quadrupole mass filter and then allowed to interact with methane in a hexapole reaction cell. The reactant and product ions have been detected by a reflectron time‐of‐flight mass spectrometer. Bare metal Mo+ and MoC2H2+ ions have been observed as products, suggesting the occurrence of ethylene elimination and dehydrogenation reactions. The branching ratio of the C2H4 elimination channel is much larger than that of the dehydrogenation channel. Density functional theory calculations have been performed to explore in detail the mechanism of the reaction of MoC+ with CH4. The computed results indicate that the ethylene elimination process involves the occurrence of spin conversions in the CC coupling (doublet→quartet) and hydrogen atom transfer (quartet→sextet) steps. The carbon atom in MoC+ plays a key role in methane activation because it becomes sp3 hybridized in the initial stages of the ethylene elimination reaction, which leads to much lower energy barriers and more stable intermediates. This study provides insights into the CH bond activation and CC coupling involved in methane transformation over molybdenum carbide‐based catalysts.
Triggered Liposomal Release through a Synthetic Phosphatidylcholine Analogue Bearing a Photocleavable Moiety Embedded within the sn‐2 Acyl Chain
Authors: Bayer Andrew M. , Alam Shahrina , Mattern‐Schain Samuel I. , Best Michael D. 
Published: February 2014

AbstractLiposomes represent promising carriers for drug delivery applications. To maximize this potential, there has been significant interest in developing liposomal systems encapsulating molecular cargo that are highly stable until their contents are released remotely in a controlled manner. Herein, we describe the design, synthesis, and analysis of a photocleavable analogue of the ubiquitous lipid phosphoatidylcholine (PC) for the development of highly stable and controllable photodisruptable membranes. Our strategy was to develop a lipid that closely mimics the structure of PC to optimize favorable properties including biocompatibility and stability of subsequent liposomes when mixed with lipids possessing a broad range of physicochemical properties. Thus, NB‐PC was designed, which contains a photocleavable 2‐nitrobenzyl group embedded within the acyl chain at the sn‐2 position. Following the synthesis of NB‐PC, liposome disruption efficacy was evaluated through photolysis studies involving the detection of nile red release. Studies performed using a range of liposomes with different percentages of NB‐PC, PC, phosphatidylethanolamine (PE), cholesterol, and polyethylene glycol‐PE (PEG‐PE) demonstrated minimal background release in controls, release efficacies that correlate directly with the amount of NB‐PC incorporation, and that release is only minimally impacted by the inclusion of the lipids PE and cholesterol that possess disparate properties. These results demonstrate that the NB‐PC system is a highly stable, flexible, and tunable system for photoinitiated release from liposomal systems.
Ru–η6‐Arene Cations [{(Ph2PC6H4)2B(η6‐Ph)}RuX]+ (X=Cl, H) as Lewis Acids
Authors: Boone Michael P. , Stephan Douglas W. 
Published: February 2014

AbstractThe reactivity of [{(Ph2PC6H4)2B(η6‐Ph)}RuCl][B(C6F5)4] (1) as a Lewis acid was investigated. Treatment of 1 with mono and multidentate phosphorus Lewis bases afforded the Lewis acid–base adducts with the ortho‐carbon atom of the coordinated arene ring. Similar reactivity was observed upon treatment with N‐heterocyclic carbenes; however, adduct formation occurred at both ortho‐ and para‐carbon atoms of the bound arene with the para‐position being favoured by increased steric demands. Interestingly treatment with isocyanides resulted in adduct formation with the B‐centre of the ligand framework. The hydride‐cation [{(Ph2PC6H4)2B(η6‐Ph)}RuH] [B(C6F5)4] was prepared via reaction of 1 with silane. This species in the presence of a bulky phosphine behaves as a frustrated Lewis pair (FLP) to activate H2 between the phosphorus centre and the ortho‐carbon atom of the η6‐arene ring.
A Single‐Molecule‐Level Mechanistic Study of Pd‐Catalyzed and Cu‐Catalyzed Homocoupling of Aryl Bromide on an Au(111) Surface
Authors: Adisoejoso Jinne , Lin Tao , Shang Xue Song , Shi Ke Ji , Gupta Aditi , Liu Pei Nian , Lin Nian 
Published: February 2014

AbstractOn‐surface Pd‐ and Cu‐catalyzed CC coupling reactions between phenyl bromide functionalized porphyrin derivatives on an Au(111) surface have been investigated under ultra‐high vacuum conditions by using scanning tunneling microscopy and kinetic Monte Carlo simulations. We monitored the isothermal reaction kinetics by allowing the reaction to proceed at different temperatures. We discovered that the reactions catalyzed by Pd or Cu can be described as a two‐phase process that involves an initial activation followed by CC bond formation. However, the distinctive reaction kinetics and the CC bond‐formation yield associated with the two catalysts account for the different reaction mechanisms: the initial activation phase is the rate‐limiting step for the Cu‐catalyzed reaction at all temperatures tested, whereas the later phase of CC formation is the rate‐limiting step for the Pd‐catalyzed reaction at high temperature. Analysis of rate constants of the Pd‐catalyzed reactions allowed us to determine its activation energy as (0.41±0.03) eV.
Efficient Asymmetric Hydrogenation of α‐Acetamidocinnamates through a Simple, Readily Available Monodentate Chiral H‐Phosphinate
Authors: Wang Xiang‐Bo , Goto Midori , Han Li‐Biao 
Published: February 2014

AbstractAn air‐stable, simple (RP)‐mentylbenzylphosphinate, readily available in large quantities, can efficiently induce the rhodium‐catalyzed asymmetric hydrogenation of α‐acetamidocinnamates with high enantioselectivity (up to 99.6 % ee). Intramolecular hydrogen bonding plays an important role in this asymmetric induction.
Facile Mechanochemical Synthesis of Nano SnO2/Graphene Composite from Coarse Metallic Sn and Graphite Oxide: An Outstanding Anode Material for Lithium‐Ion Batteries
Authors: Ye Fei , Zhao Bote , Ran Ran , Shao Zongping 
Published: February 2014

AbstractA facile method for the large‐scale synthesis of SnO2 nanocrystal/graphene composites by using coarse metallic Sn particles and cheap graphite oxide (GO) as raw materials is demonstrated. This method uses simple ball milling to realize a mechanochemical reaction between Sn particles and GO. After the reaction, the initial coarse Sn particles with sizes of 3–30 μm are converted to SnO2 nanocrystals (approximately 4 nm) while GO is reduced to graphene. Composite with different grinding times (1 h 20 min, 2 h 20 min or 8 h 20 min, abbreviated to 1, 2 or 8 h below) and raw material ratios (Sn:GO, 1:2, 1:1, 2:1, w/w) are investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, field‐emission scanning electron microscopy and transmission electron microscopy. The as‐prepared SnO2/graphene composite with a grinding time of 8 h and raw material ratio of 1:1 forms micrometer‐sized architected chips composed of composite sheets, and demonstrates a high tap density of 1.53 g cm−3. By using such composites as anode material for LIBs, a high specific capacity of 891 mA h g−1 is achieved even after 50 cycles at 100 mA g−1.
PBlaman: performance blame analysis based on Palladio contracts
Authors: Brüseke Frank , Wachsmuth Henning , Engels Gregor , Becker Steffen 
Published: February 2014

SUMMARYIn performance‐driven software engineering, the performance of a system is evaluated through models before the system is assembled. After assembly, the performance is then validated using performance tests. When a component‐based system fails certain performance requirements during the tests, it is important to find out whether individual components yield performance errors or whether the composition of components is faulty. This task is called performance blame analysis. Existing performance blame analysis approaches and also alternative error analysis approaches are restricted, because they either do not employ expected values, use expected values from regression testing, or use static developer‐set limits. In contrast, this paper describes the new performance blame analysis approach PBlaman that builds upon our previous work and that employs the context‐portable performance contracts of Palladio. PBlaman decides what components to blame by comparing the observed response time data series of each single component operation in a failed test case to the operation's expected response time data series derived from the contracts. System architects are then assisted by a visual presentation of the obtained analysis results. We exemplify the benefits of PBlaman in two case studies, each of which representing applications that follow a particular architectural style. Copyright © 2014 John Wiley & Sons, Ltd.