bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of nanotube preparation in Aquatic Bioassays
Authors: Kennedy Alan J. , Gunter Jonas C. , Chappell Mark A. , Goss Jennifer D. , Hull Matthew S. , Kirgan Robert A. , Steevens Jeffery A. 
Published: April 2009

Abstract
Knowledge gaps in nanomaterial fate and toxicity currently limit the ability of risk assessments to characterize the environmental implications of nanomaterials. This problem is further complicated by the lack of standardized characterization and preparation methodologies for researchers to gain the needed information to assist risk assessors. In the present study, data were generated to determine if multiwalled nanotube (MWNT) fate and toxicity are altered by engineered surface modifications or by different dispersal methods. While dissolved organic matter was a good dispersing agent of MWNTs in water, the humic acid fraction was a more effective dispersant than the fulvic acid fraction. When stabilized in organic matter, the functional group attached to the MWNT controlled its toxicity. Underivatized MWNTs induced relatively moderate toxicity to Ceriodaphnia dubia after 96 h (25 ± 19% survival at 26 mg/L), while hydrophilic groups (hydroxyl, carboxyl) reduced this toxicity (93 ± 12% survival at 48 mg/L). However, other functional groups (alkyl, amine) increased toxicity (0 ± 0% survival at &lt;15 mg/L). In dispersal method studies, sonication of MWNTs increased fragmentation relative to magnetic stirring. The sonication treatment of MWNTs also slightly reduced the mortality of C. dubia in the water column but increased toxicity in the sediment to Leptocheirus plumulosus and Hyalella azteca. Findings in the present study indicate that nanotubes engineered for specific applications need to be managed independently and that laboratory methods to disperse and test nanotubes in bioassays need to be standardized to obtain repeatable results for comparison of materials.
Comparative studies on conventional and microwave-assisted synthesis of a series of 2,4-di and 2,3,4-trisubstituted benzimidazo[1,2-a] pyrimidines and their antimicrobial activities
Authors: Algul Oztekin , Meric Asiye , Polat Serpil , Didem Yuksek N. , Serin Mehmet 
Published: April 2009

Abstract
Comparative studies were performed on a series of 2,4-di and 2,3,4-trisubstituted benzimidazo[1,2-a]pyrimidines, which were synthesized with conventional and microwave heating methods. In microwave irradiation method, approximately, 95–97.5% of the reaction time was increased and 1–45% yield increase was obtained. All compounds were able to inhibit the growth of the screened microorganisms in vitro with MIC values between 3.9–250 μg mL−1. The highest activity was expressed by compound IIId (2,4-diphenyl-benzo[4,5]imidazo[1,2-a] pyrimidine), which has the MIC value of 3.9 μg mL−1 and 31.2 μg mL-1 for Penicillium natatum ATCC 24791 and E. faecalis ATCC 29212, respectively.
Quick bioanalytical method of quantification and validation of sulbactam in plasma using high performance liquid chromatography
Authors: Abu-Shandi Khalid 
Published: April 2009

Abstract
A quick method of quantitative determination of sulbactam in human plasma, using liquid chromatography-UV spectroscopy, has been developed and validated. After derivatization with imidazole, plasma samples were treated by direct deproteinization with acetonitrile as an extraction solvent. After ultracentrifugation, sulbactam extract was directly injected onto the LC column. Chromatographic separation was performed on TSK Gel Super ODS (50 mm × 4.6 mm i.d., 2 μm) using methanol and phosphate buffer with tetrabutylammonium hydroxide solution as a mobile phase. Gradient elution was employed. The method was fully validated according to the United States Food and Drug Administration requirements (linearity, precision, trueness, quantification limit, detection limit, recovery, specificity and stability). The calibration curves were linear within the concentration range of 0.05–4.0 μg mL−1. Good method/system precision and accuracy of the method were demonstrated.
Structural, electronic and elastic properties of Ti2TlC, Zr2TlC and Hf2TlC
Authors: Bouhemadou Abdelmadjid 
Published: April 2009

Abstract
Using First-principle calculations, we have studied the structural, electronic and elastic properties of M2TlC, with M = Ti, Zr and Hf. Geometrical optimization of the unit cell is in good agreement with the available experimental data. The effect of high pressures, up to 20 GPa, on the lattice constants shows that the contractions are higher along the c-axis than along the a axis. We have observed a quadratic dependence of the lattice parameters versus the applied pressure. The band structures show that all three materials are electrical conductors. The analysis of the site and momentum projected densities shows that bonding is due to M d-C p and M d-Tl p hybridizations. The M d-C p bonds are lower in energy and stiffer than M d-Tl p bonds. The elastic constants are calculated using the static finite strain technique. We derived the bulk and shear moduli, Young’s modulus and Poisson’s ratio for ideal polycrystalline M2TlC aggregates. We estimated the Debye temperature of M2TlC from the average sound velocity. This is the first quantitative theoretical prediction of the elastic properties of Ti2TlC, Zr2TlC, and Hf2TlC compounds that requires experimental confirmation.
q-Gaussian approximants mimic non-extensive statistical-mechanical expectation for many-body probabilistic model with long-range correlations
Authors: Thistleton William , Marsh John , Nelson Kenric , Tsallis Constantino 
Published: April 2009

Abstract
We study a strictly scale-invariant probabilistic N-body model with symmetric, uniform, identically distributed random variables. Correlations are induced through a transformation of a multivariate Gaussian distribution with covariance matrix decaying out from the unit diagonal, as ρ/r
α for r =1, 2, ..., N-1, where r indicates displacement from the diagonal and where 0 ⩽ ρ ⩽ 1 and α ⩾ 0. We show numerically that the sum of the N dependent random variables is well modeled by a compact support q-Gaussian distribution. In the particular case of α = 0 we obtain q = (1-5/3 ρ) / (1- ρ), a result validated analytically in a recent paper by Hilhorst and Schehr. Our present results with these q-Gaussian approximants precisely mimic the behavior expected in the frame of non-extensive statistical mechanics. The fact that the N → ∞ limiting distributions are not exactly, but only approximately, q-Gaussians suggests that the present system is not exactly, but only approximately, q-independent in the sense of the q-generalized central limit theorem of Umarov, Steinberg and Tsallis. Short range interaction (α > 1) and long range interactions (α < 1) are discussed. Fitted parameters are obtained via a Method of Moments approach. Simple mechanisms which lead to the production of q-Gaussians, such as mixing, are discussed.
Food Niche ofPuma concolorin Central Mexico
Authors: Monroy‐Vilchis Octavio , Gómez Yuriana , Janczur Mariusz , Urios Vicente 
Published: April 2009

Optimal foraging theory predicts that predators choose the most energetically profitable prey. At the northern limit of its distribution the pumaPuma concolortends to prey on large mammals, whereas at the southern limit its prey comprises medium‐sized and small mammals. We analysed the puma's food habits in Central Mexico, and concluded that the nine‐banded armadilloDasypus novemcinctusis the main prey, followed by the white‐nosed coatiNasua naricaand white‐tailed deerOdocoileus virginianus.The puma's standardised niche breadth (B') was 0.21 and was in accordance with the expected in the exponential model. We compared this with niche breadths recorded in other studies carried out in the Americas. After a forest fire, puma changed their feeding habits and began to hunt prey > 6.1 kg more frequently. Food preferences of puma in Central Mexico resemble those recorded for puma in South America rather than the preferences recorded for puma in other North American populations.
Cause of Death in Willow Ptarmigan Lagopus l. lagopus Chicks and the Effect of Intensive, Local Predator Control on Chick Production
Authors: Steen Johan B. , Haugvold Odd A. 
Published: April 2009

Population dynamics of willow ptarmigan Lagopus l. lagopus are dominated by varying numbers of successful recruits to the population. One important component that determines this number is the survival of chicks from hatching to fledging at about two weeks of age. We studied the causes of death of chicks and the effects of intensive, local predator control on chick production in two areas of south‐central Norway from 1997–2004. During 1997–2000, 253 chicks were captured and radio‐tagged in a 2,000 ha area in Dalsbygda, Norway. Average survival for all years from hatching to two weeks of age was 33%. Predation accounted potentially for up to 73% of all deaths. Research‐related deaths accounted for 17% of deaths, while 10% died of other natural causes than predation. In no case did disease or lack of food appear to be the ultimate cause of death. The localisation of broods could not be predicted from brood position the previous day and there was no correlation between brood behaviour and chick death.Intensive local predator control was conducted in a 2,000 ha area in Numedal, Norway during 1998–2004. Red fox Vulpes vulpes, marten Martes martes, mink Mustela erminea, raven Corvus c. corax and hooded crow Corvus c. cornix were trapped or shot. Chick production was calculated based on pigmentation of wing feathers from all birds harvested in September. Mean chick production for all years was 3.1 chicks per two adults in the treatment area and 2.4 in an adjacent area without predator control, but the differences were not significant. In our study, therefore, predator control had no measurable effect on chick production or survival.
Factors Influencing the Survival of Neonate Sharp‐Tailed GrouseTympanuchus phasianellus
Authors: Goddard Alicia D. , Dawson Russell D. 
Published: April 2009

Offspring survival after leaving the nest is a critical element of population viability and in the management of game species. We estimated brood survival to 35 days and examined the factors thought to influence individual chick survival during the first two weeks post‐hatching in a population of sharp‐tailed grouseTympanuchus phasianellusnear Fort St. John, British Columbia, Canada, during 2004–2005. Using program MARK and an informationtheoretic approach, we assessed the importance of female attributes, date of hatching, distance moved from the nest and weather conditions experienced prior to hatching and during brood‐rearing for survival of offspring. During 2004–2005, 67% of broods had at least one chick that survived to 35 days of age, but within these broods only 34% of the chicks survived. Later hatching dates were positively related to survival during the 0–14 day age interval, whereas the distance moved from the nest by a brood and inclement weather conditions during the first seven days post‐hatching significantly reduced the survival rate of chicks to 14 days of age. Further, inclement weather prior to hatching was positively related to the survival of offspring to 14 days, perhaps because wet weather created favourable foraging environments and habitat characteristics during brood rearing. Cohesive management of nesting and brood‐rearing habitats is required to reduce offspring mortality associated with increased travel between suitable habitats, and may minimize mortality during periods when weather is unfavourable.
Foraging Behaviour and Flight Characteristics of Eurasian Griffons Gyps fulvus in the Island of Crete, Greece
Authors: Xirouchakis Stavros M. , Andreou Giorgos 
Published: April 2009

We studied the foraging behaviour of Eurasian griffons Gyps fulvus on the island of Crete during 1997–2005 by direct observations in four colonies and by monitoring the movements of seven radio‐equipped individuals. The estimated foraging range of griffon colonies, based on direct observations, ranged from 206–851 km2 by using the Minimum Convex Polygon method, and 195–527 km2 by using the Adaptive Kernel method, with corresponding means of 472 and 380 km2, respectively. Meanwhile, radio‐tracking showed that foraging vultures covered an area ranging from 390–1300 km2. The mean foraging radius was calculated at ca 15 km and the mean maximum one at 29.9 km. On windless days, griffons' mean cross‐country speed was 5.1 m/second (maximum = 13.3 m/second), with a mean climbing rate of 0.6 m/second and a mean inter‐thermal gliding speed of 18.8 m/second. Any livestock carrion located up to 9 km from a colony was exploited by its members with minimum competition from individuals of adjacent areas. In total, we recorded 23 feeding incidences which took place at a mean distance of 8.4 km from the colonies. The food types identified were sheep carcasses located near stock‐farms and offal disposed in waste dumps in the vicinity of the colonies. On average, the griffons allocated 7.6 hour/day to food searching. This varied significantly between months and seasons. The shortest foraging time was recorded in December (6.4 hour/day) and the longest in June (9.3 hour/day). A significant difference of one hour after sunrise was detected in the departure time from the colony between seasons revealing that griffons departed earlier during winter trying to maintain their foraging budget within the available daytime limits.
Titelbild: Total Synthesis and Absolute Configuration of the Bisanthraquinone Antibiotic BE‐43472B (Angew. Chem. 19/2009)
Authors: Nicolaou K. C. , Lim Yee Hwee , Becker Jochen 
Published: April 2009

AbstractEine Reaktionskaskade aus einer Diels‐Alder‐Reaktion, einer Lactolisierung und einer SN(Ar)‐Substitution liefert das Kerngerüst von BE‐43472B. K. C. Nicolaou et al. beschreiben die erste Totalsynthese dieses Bisanthrachinon‐Antibiotikums in ihrer Zuschrift auf S. 3496 ff. Als Hintergrund des Titelbilds dient ein Foto von Ecteinascidia turbinata (von John Easley Photography), der marinen Quelle des Streptomyces‐Stamms, der das Antibiotikum produziert.magnified image
Innentitelbild:Thallium(I) as a Coordination Site Protection Agent: Preparation of an Isolable Zero‐Valent Nickel Tris‐Isocyanide (Angew. Chem. 19/2009)
Authors: Fox Brian J. , Millard Matthew D. , DiPasquale Antonio G. , Rheingold Arnold L. , Figueroa Joshua S. 
Published: April 2009

AbstractDie Bindung von Thallium(I) durch niedervalentes Nickel ist ein Beispiel für die Verwendung von Hauptgruppenionen zum Schutz von Koordinationsstellen von Übergangsmetallzentren. Wie J. S. Figueroa et al. in der Zuschrift auf S. 3525 ff. schildern, eröffnet die Koordination von Thallium(I) einen Zugang zu einem koordinativ ungesättigten Nickel‐Tris(isocyanid)‐Komplex. Thallium wirkt als Schutzgruppe gegen Lewis‐Basen und kann durch Zugabe von Halogenidionen leicht entfernt werden.magnified image
Functional Molecular Flasks: New Properties and Reactions within Discrete, Self‐Assembled Hosts
Authors: Yoshizawa Michito , Klosterman Jeremy K. , Fujita Makoto 
Published: April 2009

AbstractInsider dealing: Self‐assembled hosts applied as “molecular flasks” can alter and control the reactivity and properties of molecules encapsulated within their well‐defined, confined spaces. A variety of functional hosts of differing sizes, shapes, and utility have been prepared by using the facile and modular concepts of self‐assembly.magnified imageThe application of self‐assembled hosts as “molecular flasks” has precipitated a surge of interest in the reactivity and properties of molecules within well‐defined confined spaces. The facile and modular synthesis of self‐assembled hosts has enabled a variety of hosts of differing sizes, shapes, and properties to be prepared. This Review briefly highlights the various molecular flasks synthesized before focusing on their use as functional molecular containers—specifically for the encapsulation of guest molecules to either engender unusual reactions or unique chemical phenomena. Such self‐assembled cavities now constitute a new phase of chemistry, which cannot be achieved in the conventional solid, liquid, and gas phases.
Jurors' perceptions of juvenile defendants: the influence of intellectual disability, abuse history, and confession evidence
Authors: Najdowski Cynthia J. , Bottoms Bette L. , Vargas Maria C. 
Published: April 2009

AbstractUnderstanding jurors' perceptions of juvenile defendants has become increasingly important as more and more juvenile cases are being tried in adult criminal court rather than family or juvenile court. Intellectual disability and child maltreatment are overrepresented among juvenile delinquents, and juveniles (particularly disabled juveniles) are at heightened risk for falsely confessing to crimes. In two mock trial experiments, we examined the effects of disability, abuse history, and confession evidence on jurors' perceptions of a juvenile defendant across several different crime scenarios. Abused juveniles were treated more leniently than nonabused juveniles only when the juvenile's crime was motivated by self‐defense against the abuser. Jurors used disability as a mitigating factor, making more lenient judgments for a disabled than a nondisabled juvenile. Jurors also completely discounted a coerced confession for a disabled juvenile, but not for a nondisabled juvenile. In fact, compared with when it was portrayed as voluntary, jurors generally discounted a juvenile's coerced confession. Implications for public policy and directions for future research are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Die „Erweiterung”︁ des Redox‐Begriffs mit Stoffen aus dem Alltag
Authors: Rossow Marco , Flint Alfred 
Published: April 2009

AbstractIn so gut wie allen Bereichen des täglichen Lebens finden in kleinerem und größerem Umfang ständig Redoxreaktionen statt. Dabei handelt es sich teilweise um scheinbar sehr einfache und uns aus dem Alltag geläufige Reaktionen, wie das Verbrennen einer Kerze, das Verbrennen von Benzin, das Rosten eines Eisengegenstandes oder das Anlaufen von Kupferrohren und ‐dächern.Weit weniger geläufig und dennoch von sehr großer Bedeutung sind die Redoxreaktionen, die in Batterien und Akkumulatoren ablaufen (vgl. [6]). Der Grund für den geringen Bekanntheitsgrad ist, dass man den Verlauf dieser Reaktionen nicht sehen kann. Während des Betriebes verändern sich die elektrochemischen Spannungsquellen rein äußerlich nicht. Ist eine Batterie oder ein Akkumulator entleert, so wird sie ersetzt bzw. man lädt ihn auf. Eine Stoffumwandlung ist in keinem der Fälle wahrnehmbar.Weitere Bereiche des alltäglichen Lebens, in denen Redoxreaktionen eine große Rolle spielen, jedoch kaum wahrgenommen werden, sind sowohl Einfärbungs‐ als auch Entfärbungsprozesse. Dabei nimmt in einer Zeit, in der man günstig Kleidung kaufen kann, die Alltagsrelevanz der Färbeprozesse ab. Das Entfärben von unerwünschten Rotwein‐ oder Grasflecken ist jedoch nach wie vor im täglichen Leben von großer Bedeutung.Nicht nur im Alltag, sondern auch in der Wissenschaft Chemie spielen die Redox‐Reaktionen eine ganz entscheidende Rolle. Sie sind neben den Säure‐Base‐Reaktionen die am häufigsten ablaufenden und ihnen liegt ein ganz wesentliches Donator‐Akzeptor‐Prinzip zu Grunde. Dieser Bedeutung tragen auch die derzeitigen Rahmen‐ und Lehrpläne Rechnung, Redox‐Reaktionen nehmen in der Schule einen großen Raum ein. Wir finden sie z.B. im Anfangsunterricht bei den Verbrennungs‐ bzw. Metall‐Metalloxid‐Reaktionen, später bei der Behandlung der Organischen Chemie und der Oxidation von Alkoholen und Aldehyden sowie in der Oberstufe im Bereich der Elektrochemie oder auch bei den Farbstoffen.
Vorstellungen deutscher Chemielehrkräfte über die Bedeutung und Ausrichtung des Chemielernens
Authors: Markic Silvija , Eilks Ingo , van Driel Jan , Ralle Bernd 
Published: April 2009

AbstractIn einer Fragebogenstudie wurden 1142 Chemielehrkräfte verschiedener Schulformen aus sieben Bundesländern über ihre Vorstellungen bzgl. des Lernens und Lehrens von Chemie befragt. Grundlage der Befragung ist das Konzept der ‚Curriculum Emphases’︁ von Roberts [1], also ein Konzept, nach dem jedem Curriculum neben dem Lernen von Inhalten auch eine bestimmte Anzahl von Botschaften inhärent ist. Benutzt wird eine Interpretation von van Berkel [2], die drei wesentliche Ausprägungen für den Chemieunterricht beschreibt: a) Reine Chemie, b) Chemie‐Technik‐Gesellschaft und c) Chemie als lebendige Wissenschaft. In diesem Aufsatz wird aufgezeigt, dass deutsche Chemielehrerinnen und ‐lehrer eine unterschiedliche Orientierung des Curriculums bzgl. verschiedener Schulformen und ‐stufen sehen. Teilweise konnten auch zwischen einzelnen Bundesländern signifikante Unterschiede festgestellt werden. Ausgewählte Ergebnisse aus der Studie werden diskutiert.
A Bilingual Teaching Material for the Chemical Elements
Authors: Franco‐Mariscal Antonio Joaquín , Cano‐Iglesias María José 
Published: April 2009

AbstractThe „Elemental Germany”︁ is an engaging activity for bilingual teaching that encourages high school chemistry students to match the names of the elements with their chemical symbols in order to spell out the names of the German states and their main cities. By completing the puzzle, students reinforce their knowledge of both chemical elements and the names of the German states.
Stable generation of serum‐ and feeder‐free embryonic stem cell‐derived mice with full germline‐competency by using a GSK3 specific inhibitor
Authors: Sato Hiromu , Amagai Keiko , Shimizukawa Rie , Tamai Yoshitaka 
Published: April 2009

AbstractC57BL/6 (B6)‐derived embryonic stem (ES) cells are not widely used to generate knockout mice despite the advantage of a well‐defined genetic background because of poor developmental potential. We newly established serum‐ and feeder‐free B6 ES cells with full developmental potential by using leukemia inhibitory factor (LIF) and 6‐bromoindirubin‐3′‐oxime (BIO), a glycogen synthase kinase‐3 (GSK3) inhibitor. BIO treatment significantly increased the expression levels of 364 genes including pluripotency markers such as Nanog and Klf family. Unexpectedly, by aggregating or microinjecting those ES cells to each eight‐cell‐stage diploid embryo, we stably generated germline‐competent ES‐derived mice. Furthermore, founder mice completely derived from female XO, heterozygous, or homozygous mutant B6 ES cells were directly available for intercross breeding and phenotypic analysis. We hereby propose that serum‐ and feeder‐free B6 ES cells stimulated with LIF plus GSK3 inhibitor are valuable for generating mouse models on B6 background. genesis 47:414–422, 2009. © 2009 Wiley‐Liss, Inc.