bluuebunny/crossref_metadata_2025 huggingface dataset:
Ovule number per flower in a world of unpredictable pollination
Authors: Burd Martin , Ashman Tia‐Lynn , Campbell Diane R. , Dudash Michele R. , Johnston Mark O. , Knight Tiffany M. , Mazer Susan J. , Mitchell Randall J. , Steets Janette A. , Vamosi Jana C.
Published: June 2009

The number of ovules per flower varies over several orders of magnitude among angiosperms. Here we consider evidence that stochastic uncertainty in pollen receipt and ovule fertilization has been a selective factor in the evolution of ovule number per flower. We hypothesize that stochastic variation in floral mating success creates an advantage to producing many ovules per flower because a plant will often gain more fitness from occasional abundant seed production in randomly successful flowers than it loses in resource commitment to less successful flowers. Greater statistical dispersion in pollination and fertilization among flowers increases the frequency of windfall success, which should increase the strength of selection for greater ovule number per flower. We therefore looked for evidence of a positive relationship between ovule number per flower and the statistical dispersion of pollen receipt or seed number per flower in a comparative analysis involving 187 angiosperm species. We found strong evidence of such a relationship. Our results support the hypothesis that unpredictable variation in mating success at the floral level has been a factor in the evolution of ovule packaging in angiosperms.
Selenium protects the hyperaccumulator Stanleya pinnata against black‐tailed prairie dog herbivory in native seleniferous habitats
Authors: Freeman John L. , Quinn Colin F. , Lindblom Stormy Dawn , Klamper Erin M. , Pilon‐Smits Elizabeth A. H.
Published: June 2009

Elemental hyperaccumulation in plants is hypothesized to represent a plant defense mechanism. The objective of this study was to determine whether selenium (Se) hyperaccumulation offers plants long‐term protection from the black‐tailed prairie dog (Cynomys ludovicianus). Prairie dogs are a keystone species. The hyperaccumulator Stanleya pinnata (prince's plume) co‐occurs with prairie dogs in seleniferous areas in the western United States. Stanleya pinnata plants pretreated with high or low Se concentrations were planted on two prairie dog towns with different levels of herbivory pressure, and herbivory of these plants was monitored over 2 years. Throughout this study, plants with elevated Se levels suffered less herbivory and survived better than plants with low leaf Se concentrations. This study indicates that the Se in hyperaccumulator S. pinnata protects the plant in its natural habitat from herbivory by the black‐tailed prairie dog. The results from this study support the hypothesis that herbivory by prairie dogs or similar small mammals has been a contributing selection pressure for the evolution of plant Se hyperaccumulation in North America. This study is the first to test the ecological significance of hyperaccumulation over a long period in a hyperaccumulator's natural habitat.
Reproductive implications of combined and separate sexes in a trioecious population of Opuntia robusta (Cactaceae)
Authors: del Castillo Rafael F. , Argueta Sonia Trujillo
Published: June 2009

Opuntia robusta has hermaphroditic, dioecious, and trioecious populations. To enhance our understanding of this breeding system diversity, we compared the reproductive output of males, females, and hermaphrodites in a trioecious population using field evaluations, controlled crosses, and progeny tests. Unisexuals were fully sterile in one sex function. Hermaphrodites were fully fertile for both functions. Consistent with the sex‐allocation theory, unisexuality increased the quality and quantity (in males) of the gametes of the functional sex, relative to those of hermaphrodites, probably explained by maternal and paternal effects. The increase was higher in males than in females, suggesting a more expensive female function. Theoretically, this disproportional increase is required for unisexuals to invade a hermaphroditic population with prior selfing, negligible pollen discounting, and undetectable inbreeding depression, features found in O. robusta, therefore helping to explain dioecious populations. However, in the study population, the actual seed output of females was lower and had a higher variance than that of hermaphrodites, which also reproduce through pollen. Unisexuals are unlikely to be maintained by their actual reproductive output in this pollen‐limited environment. Hermaphrodites may persist in this population by producing their seeds autonomously and by reducing interspecific fertilization by prior selfing and ovule discounting.
Serologic Profile and Mortality Rates of Scleroderma Renal Crisis in Italy
Authors: CODULLO VERONICA , CAVAZZANA ILARIA , BONINO CLAUDIA , ALPINI CLAUDIA , CAVAGNA LORENZO , COZZI FRANCO , PAPA NICOLETTA DEL , FRANCESCHINI FRANCO , GUIDUCCI SERENA , MOROZZI GABRIELLA , RUFFATTI AMELIA , FERRI CLODOVEO , GIACOMELLI ROBERTO , MATUCCI-CERINIC MARCO , VALENTINI GABRIELE , MONTECUCCO CARLOMAURIZIO
Published: June 2009

Objective.

To analyze clinical and serological characteristics of subjects with scleroderma renal crisis (SRC) in Italian patients with systemic sclerosis (SSc).

Methods.

A retrospective analysis of medical records from 9 Italian rheumatologic referral centers was carried out. All patients with SRC and an available serum sample at the time of crisis were included. Antinuclear antibodies (ANA) by indirect immunofluorescence, anti-topoisomerase (topo) I by enzyme-linked assay (ELISA), anti-RNA polymerases (RNAP) by ELISA for the subunit III, and immunoprecipitation (IP) were performed.

Results.

Forty-six cases (38 female; 40 diffuse cutaneous SSc) were identified. Mean age at SSc and SRC onset was 52.8 years ± 13.2 and 55.4 years ± 11.8, respectively. ANA were present in 44 patients (96%). Anti-topo I antibodies were detected in 30 (65%), anti-RNAP I–III in 7 (15%). No differences emerged between these 2 groups for their main clinical characteristics. The proportion of patients in the anti-RNAP I–III group developing SRC early (< 18 mo) in the course of SSc was significantly higher (p = 0.03). Cumulative survival rates were 64%, 53%, and 35% at 1, 2, and 10 years of followup, respectively. Survival rates of SSc patients significantly differed according to their autoantibody profile, being lower in the anti-topo I than in the anti-RNAP I–III group (p = 0.034).

Conclusion.

SRC is a rare manifestation of SSc in Italy but it is still associated with severe prognosis. Anti-topo I reactivity was more frequent than anti-RNAP I–III in our patients with SRC and was associated with delayed onset and high mortality rates.
Clinical Features of Scleroderma Patients With or Without Prior or Current Ischemic Digital Ulcers: Post-Hoc Analysis of a Nationwide Multicenter Cohort (ItinérAIR-Sclérodermie)
Authors: TIEV KIET PHONG , DIOT ELISABETH , CLERSON PIERRE , DUPUIS-SIMÉON FRÉDÉRIQUE , HACHULLA ERIC , HATRON PIERRE-YVES , CONSTANS JOËL , CIRSTÉA DANIÉLA , FARGE-BANCEL DOMINIQUE , CARPENTIER PATRICK H.
Published: June 2009

Objective.

Digital ulcers are the most frequent vascular manifestations of systemic sclerosis (SSc). Clinical features of patients with prior or current digital ulcers have not been extensively described. This cross-sectional analysis of a large multicenter cohort compared the characteristics of SSc patients with prior or current digital ulcers with those never affected.

Methods.

Patients with prior/current digital ulcers or never affected were identified in the cohort of SSc patients enrolled in the French ItinérAIR-Sclérodermie registry. Rodnan skin scores, pulmonary function test results, and clinical and immunological data were analyzed to identify digital ulcerassociated clinical features.

Results.

Of 599 SSc patients, 317 had prior or current digital ulcers. These patients were more frequently male, with impaired diffusing capacity for carbon monoxide (DLCO), and higher Rodnan skin scores than patients never affected by digital ulcers. In a multivariate analysis, male gender, early onset of SSc, increased duration of SSc, high Rodnan skin score, and presence of anti-topoisomerase I antibodies (anti-topo I) were associated with prior or current digital ulcers. Comparison of patients with current digital ulcers versus patients never affected indicated that affected patients had increased duration of SSc, impaired DLCO, increased Rodnan score, and younger age at onset of SSc.

Conclusion.

Male patients with early onset SSc, more severe skin fibrosis, impaired DLCO, and anti-topo I were most likely to exhibit prior or current digital ulcers. Confirmation of these results in a prospective longitudinal study may enable identification of patients at greatest risk of developing digital ulcers, facilitating management of this disabling complication.
Once-Weekly Oral Alendronate 70 mg in Patients with Glucocorticoid-Induced Bone Loss: A 12-Month Randomized, Placebo-Controlled Clinical Trial
Authors: STOCH S. AUBREY , SAAG KENNETH G. , GREENWALD MARIA , SEBBA ANTHONY I. , COHEN STANLEY , VERBRUGGEN NADIA , GIEZEK HILDE , WEST JOSEPH , SCHNITZER THOMAS J.
Published: June 2009

Objective.

Glucocorticoid-induced osteoporosis is the most common iatrogenic form of osteoporosis. We evaluated the efficacy and safety of once-weekly bisphosphonate therapy for prevention and treatment of bone loss in patients on glucocorticoid therapy.

Methods.

We conducted a 12-month, multicenter, randomized, double-blind, placebo-controlled trial with 114 and 59 patients in the treatment and placebo arms, respectively. Participants were stratified according to the duration of prior oral glucocorticoid therapy at randomization. Participants received alendronate 70 mg once weekly (ALN OW) or placebo; all received supplemental daily calcium (1000 mg) and 400 IU vitamin D. Clinical evaluations were performed at baseline, 3, 6, 9, and 12 months.

Results.

At 12 months, there was a significant mean percentage increase from baseline in the ALN OW group for lumbar spine (2.45%), trochanter (1.27%), total hip (0.75%), and total body (1.70%) bone mineral density (BMD). Comparing ALN OW versus placebo at 12 months, a significant treatment difference for the mean percentage change from baseline was observed for lumbar spine (treatment difference of 2.92%; p ≤ 0.001), trochanter (treatment difference 1.66%; p = 0.007), and total hip (treatment difference 1.19; p = 0.008) BMD. Biochemical markers of bone remodeling also showed significant mean percentage decreases from baseline.

Conclusion.

Over 12 months ALN OW significantly increased lumbar spine, trochanter, total hip, and total body BMD compared with baseline among patients taking glucocorticoid therapy. A significant treatment difference versus placebo was observed at 12 months for the mean percentage change from baseline for lumbar spine, trochanter, and total hip.
Lack of Specificity of the 6-Minute Walk Test as an Outcome Measure for Patients with Systemic Sclerosis
Authors: SCHOINDRE YOLAND , MEUNE CHRISTOPHE , DINH-XUAN ANH TUAN , AVOUAC JÉRÔME , KAHAN ANDRÉ , ALLANORE YANNICK
Published: June 2009

Objective.

The 6-minute walk test (6MWT) is an important prognostic tool in various cardiovascular diseases and has been considered as a surrogate endpoint. However, conflicting results have been reported in systemic sclerosis (SSc). Our objective was to evaluate the relationships of the 6-min walking distance (6MWD) and organ damage in SSc.

Methods.

Eighty-seven consecutive patients with SSc were included and prospectively investigated; they underwent 6MWT in addition to conventional assessment of possible lung, heart, kidney, skin, and muscle involvement, and disease activity scoring, severity, and quality of life determination.

Results.

Twenty-six patients (30%) had an abnormal 6MWT and the mean 6MWD was 461.8 ± 103.0 m. When considering 6MWT as a binary variable — normal or abnormal — C-reactive protein (CRP) was the only independent variable associated with abnormal 6MWT. Considered as a continuous variable, the 6MWD was associated with measures of lung involvement and inflammation, with the activity and severity of disease, and also with quality of life; nevertheless, calcinosis was the only independent factor associated in multivariate analyses with a trend for an association for CRP.

Conclusion.

The 6MWD relates to broad factors in SSc and these results raise doubts about the specificity of the 6MWD in this systemic disease, and its relevance to monitoring therapy.
La caracterización económica de la lengua y su relación con el capital social
Authors: Maneiro José Manuel , Sotelsek Daniel
Published: June 2009

En el contexto de su caracterización económica, la lengua puede ser tratada como un bien preferente y por lo tanto se puede considerar como la precondición para la existencia del capital social. por otra parte, ese capital social provoca que la pertenencia a un grupo tenga efectos beneficiosos para sus miembros, lo cual sucede en casos de agregados humanos diversos, como una empresa, un barrio, una ciudad. Estos efectos beneficiosos se traducen en mejoras de la eficiencia productiva en el caso de empresas y mejoras en el estatus socioeconómico de los individuos. El lenguaje, por tanto, tiene un papel importante en la creación de capital social, esto es especialmente importante en el caso de los inmigrantes que residen en un país con una lengua distinta a la suya.
A qualitative investigation of South African cigarette smokers’ perceptions of fear appeal messages in anti-smoking advertising
Authors: Lynch Ingrid , De Bruin Lauren M. , Cassimjee Nafisa , Wagner Claire
Published: June 2009

Cigarette smoking continues to pose a global health risk, including in developing countries. Fear appeal messages have been widely employed in health communication to reduce cigarette smoking, but studies provide conflicting results on their efficacy. The present qualitative study explores smokers’ perceptions of fear appeal messages used in anti-smoking advertising. Focus group discussions were conducted with male and female smokers from Gauteng. A thematic analysis found that participants negatively viewed advertisements that use unrealistic images and failed to relate to the message portrayed. Information about the risks associated with smoking was perceived as patronising and as positioning smokers as ignorant and unintelligent. In addition, fear appeal messages that only focus on long-term consequences of smoking were perceived as ineffective. Participants failed to identify with content that solely relied on factual information at the expense of an emotive appeal. The findings suggest that anti-smoking communication could benefit from content that evokes shock without sacrificing realism, that it should include information about short-term and immediately visible consequences of smoking and that it should avoid negative depictions of smokers that alienate them from the message being portrayed.OpsommingSigaretrook dra steeds ’n wêreldwye gesondheidsrisiko, met inbegrip van in ontwikkelende lande. Vrees-oproepende boodskappe word algemeen in gesondheidskommunikasie gebruik om rookgedrag te verminder, maar studies toon teenstrydige resultate rakende die doeltreffendheid daarvan. Die huidige kwalitatiewe studie ondersoek rokers se persepsies van vrees-oproepende boodskappe soos in antirook-advertensies gebruik. Fokusgroepbesprekings is met manlike en vroulike rokers in Gauteng gehou. ’n Tematiese ontleding het gevind dat deelnemers advertensies wat onrealistiese beelde gebruik, negatief beskou en dat hulle nie met die boodskap identifi seer nie. Inligting oor die risiko’s geassosieer met rook is as neerbuigend gesien en dat dit rokers as onkundig en onintelligent voorstel. Verder is gevind dat vrees-oproepende boodskappe wat slegs op langtermyngevolge van rook fokus ondoeltreffend beskou word. Deelnemers het nie met inhoud geïdentifiseer wat slegs op feitlike inligting steun ten koste van ’n emotiewe beroep nie. Die bevindinge stel voor dat antirook-kommunikasie uit inhoud kan baat wat skok uitlok, sonder om realisme prys te gee. Inhoud moet oor inligting van korttermyn- en onmiddellik sigbare gevolge van rook beskik en negatiewe uitbeeldings wat rokers van die boodskap distansieer, moet vermy word.
Erratum: Durable and generalized effects of spatial experience on mental rotation: Gender differences in growth patterns
Authors: Terlecki Melissa S. , Newcombe Nora S. , Little Michelle
Published: June 2009

The above article (DOI: 10.1002/acp.1420) was published online on 26 November 2007 and in print in Volume 22: 996‐1013, 2008. A printing error was subsequently identified in the article.

Page 996: Missing author information. Should read Dr. Nora S. Newcombe, Temple University, Philadelphia, USA, National Science Foundation Grants REC‐0337360 and SBE0541957.
Scaffold Design and Manufacturing: From Concept to Clinic
Authors: Hollister Scott J.
Published: June 2009

Since Robert Langer and colleagues pioneered the concept of reconstructing tissue using cells transplanted on synthetic polymer matrices in the early 1990s, research in the field of tissue engineering and regenerative medicine has exploded. This is especially true in the development of new materials and structures that serve as scaffolds for tissue reconstruction. The basic tenet of the last two decades holds scaffolds as degradable materials providing temporary function while enhancing tissue regeneration through the delivery of biologics. Although a number of new scaffolding materials and structures have been developed in research laboratories, the application of such materials practice even has been extremely limited. This paper argues that better integration of all these factors is needed to bring scaffolds from “concept to clinic”. It reviews current work in all these areas and suggests where future work and funding is needed.
Tuning the Amphiphilicity of Building Blocks: Controlled Self‐Assembly and Disassembly for Functional Supramolecular Materials
Authors: Wang Yapei , Xu Huaping , Zhang Xi
Published: June 2009

Amphiphilicity is one of the molecular bases for self‐assembly. By tuning the amphiphilicity of building blocks, controllable self‐assembly can be realized. This article reviews different routes for tuning amphiphilicity and discusses different possibilities for self‐assembly and disassembly in a controlled manner. In general, this includes irreversible and reversible routes. The irreversible routes concern irreversible reactions taking place on the building blocks and changing their molecular amphiphilicity. The building blocks are then able to self‐assemble to form different supramolecular structures, but cannot remain stable upon loss of amphiphilicity. Compared to the irreversible routes, the reversible routes are more attractive due to the good control over the assembly and disassembly of the supramolecular structure formed via tuning of the amphiphilicity. These routes involve reversible chemical reactions and supramolecular approaches, and different external stimuli can be used to trigger reversible changes of amphiphilicity, including light, redox, pH, and enzymes. It is anticipated that this line of research can lead to the fabrication of new functional supramolecular assemblies and materials.
Remarkable Electronic Effect on the Diastereoselectivity of the Heck Reaction of Methyl Cinnamate with Arenediazonium Salts: Formal Total Synthesis of (±)‐Indatraline and (±)‐Sertraline
Authors: Pastre Julio Cezar , Correia Carlos Roque Duarte
Published: June 2009

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An efficient and stereoselective protocol for the preparation of β,β‐disubstituted acrylates in good to high yields by means of a Heck–Matsuda arylation was accomplished. The method employs a base‐ and ligand‐free Heck arylation reaction of methyl cinnamate using both electron‐deficient and electron‐rich arenediazonium salts as electrophiles. The Heck reaction displays a remarkable electronic dependence regarding the diastereoselectivity of the arylation process, which correlates with the electronic nature of the arenediazonium salts employed. A rationale for the observed diastereoselectivity is presented. The overall methodology provides a convenient route to 3‐arylindanones and 4‐aryltetralones allowing the concise formal total syntheses of the therapeutically important psychoactive compounds (±)‐indatraline and (±)‐sertraline.
Copper‐Catalyzed Stereoselective Hydroarylation of 3‐Aryl‐2‐ propynenitriles with Arylboronic Acids
Authors: Yamamoto Yoshihiko , Asatani Tsuyoshi , Kirai Naohiro
Published: June 2009

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The selective synthesis of 3,3‐diarylacrylonitriles has been achieved by copper‐catalyzed hydroarylation of 3‐aryl‐2‐propynenitriles with arylboronic acids. The starting cyanoalkynes were efficiently prepared from the appropriate aromatic aldehydes and diethyl cyanomethylphosphonate in two steps. The hydroarylation of the obtained cyanoalkyne substrates proceeded in methanol at ambient temperature to produce 3,3‐diarylacrylonitriles in good to high yields with excellent syn selectivity. The present method was successfully applied to the regiospecific synthesis of both stereoisomers of CC‐5079, which was recently reported as a potent anticancer drug.
Versatile Supramolecular Copper(II) Complexes for Henry and Aza‐Henry Reactions
Authors: Zhang Guoqi , Yashima Eiji , Woggon Wolf‐D.
Published: June 2009

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Chiral supramolecular metal‐organic frameworks assembled from copper complexes catalyse Henry and aza‐Henry reactions of aromatic and aliphatic aldehydes and N‐protected aromatic imines in high yield and good to excellent enantioselectivity. Reactions can be performed in the absence of base in ethanol or water.
Cobalt/Rhodium Heterobimetallic Nanoparticle‐Catalyzed Oxidative Carbonylation of Amines in the Presence of Carbon Monoxide and Molecular Oxygen to Ureas
Authors: Park Ji Hoon , Yoon Jae Chun , Chung Young Keun
Published: June 2009

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An environmentally friendly oxidative carbonylation of aliphatic and aromatic primary amines to ureas has been successfully achieved in the presence of a catalytic amount of cobalt/rhodium heterobimetallic nanoparticles without any promoters. The catalyst system could be reused with only a slight loss of catalytic activity.
Simple and Fast Synthesis of New Axially Chiral Bipyridine N,N′‐Dioxides for Highly Enantioselective Allylation of Aldehydes
Authors: Kadlčíková Aneta , Hrdina Radim , Valterová Irena , Kotora Martin
Published: June 2009

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Unsymmetrically 3,3′‐substituted axially chiral bis(tetrahydroisoquinoline) N,N′‐dioxides can be prepared in just three steps. They exhibit unique catalytic activity (turnover frequency, enantioselectivity, substrate scope) in the asymmetric allylation of aromatic aldehydes (up to 96% ee). The product of the enantioselective allylation of benzaldehyde served as a building block for the preparation of an intermediate useful in the enantioselective synthesis of diospongines.
Wachstumsmechanismen Metall‐organischer Gerüststrukturen: Einblicke in die Keimbildung anhand einer schrittweisen Methodik
Authors: Shekhah Osama , Wang Hui , Zacher Denise , Fischer Roland A. , Wöll Christof
Published: June 2009

Eins nach dem anderen: Die In‐situ‐Beobachtung der schrittweisen Bildung von Metall‐organischen Gerüstverbindungen (MOFs) mithilfe von Oberflächenplasmonenresonanz ermöglicht mechanistische Studien zur Keimbildung und zur Entstehung sekundärer Baueinheiten sowie Untersuchungen zu den Wachstumsgeschwindigkeiten auf funktionalisierten organischen Oberflächen mit unterschiedlicher kristallographischer Ausrichtung.

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α‐Chiral Acetylenes Having an All‐Carbon Quaternary Center: Phase Transfer Catalyzed Enantioselective α Alkylation of α‐Alkyl‐α‐alkynyl Esters
Authors: Hashimoto Takuya , Sakata Kazuki , Maruoka Keiji
Published: June 2009

Ein mehrphasiger Prozess: Untersuchungen der Titelreaktion ergaben, dass sie als basenvermittelte Isomerisierung zu Allenylester und anschließende phasentransferkatalysierte Alkylierung an der α‐Position des Esters verläuft (siehe Schema).

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How Does Electrostatic Activation Control Iminium‐Catalyzed Cyclopropanations?
Authors: Lakhdar Sami , Appel Roland , Mayr Herbert
Published: June 2009

Prediction of lg k=s(N+E) verified: In contrast to previous statements, ordinary α,β‐unsaturated iminium ions do react with sulfur ylides. Electrostatic interactions accelerate the reactions by a factor of more than 105 and are responsible for the high stereoselectivity.

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Synthesis and Reactivity of a Strained Silicon‐Bridged [1]Ferrocenophanium Ion
Authors: Masson Georgeta , Herbert David E. , Whittell George R. , Holland Jason P. , Lough Alan J. , Green Jennifer C. , Manners Ian
Published: June 2009

Not blue but red‐brown: A [1]ferrocenophanium ion has been synthesized and isolated as a red‐brown crystalline salt, surprisingly different in color from characteristically blue‐green unstrained ferrocenium ions. Compared to the neutral iron(II) counterpart, the [1]ferrocenophanium ion displays a considerably higher ring tilt and an increased propensity for ring‐opening reactions.

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Decarboxylative Grob‐Type Fragmentations in the Synthesis of Trisubstituted Z Olefins: Application to Peloruside A, Discodermolide, and Epothilone D
Authors: Prantz Kathrin , Mulzer Johann
Published: June 2009

Discriminating elimination: A new method for the synthesis of methyl‐branched trisubstituted Z olefins, a structural motif in many polyketides with anticancer activity, relies on an −OH‐induced decarboxylative Grob‐type fragmentation (see scheme; Ms=mesyl). The starting materials are β‐mesyloxy lactones with a quaternary α center, which are prepared by aldol reactions in a diastereo‐ and enantioselective manner.

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α‐Chiral Acetylenes Having an All‐Carbon Quaternary Center: Phase Transfer Catalyzed Enantioselective α Alkylation of α‐Alkyl‐α‐alkynyl Esters
Authors: Hashimoto Takuya , Sakata Kazuki , Maruoka Keiji
Published: June 2009

Going through the phases: The title reaction was found to proceed by an initial base‐mediated isomerization to allenyl esters and subsequent phase transfer catalyzed alkylation at the α position of the ester (see scheme).

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Microwave‐assisted Synthesis, Structure, and Tunable Liquid‐Crystal Properties of 2,5‐Diaryl‐1,3,4‐Thiadiazole Derivatives through Peripheral n‐Alkoxy Chains
Authors: Han Jie , Chang Xiao‐Yong , Zhu Li‐Rong , Pang Mei‐Li , Meng Ji‐Ben , Chui Stephen Sin‐Yin , Lai Siu‐Wai , Roy V. A. L.
Published: June 2009

Chain change: Variations in the position, number, and chain length of the n‐alkoxy chains readily tune the liquid‐crystalline properties of 2,5‐diaryl‐1,3,4‐thiadiazole derivatives from smectic to hexagonal columnar mesophases at room temperature. The calamitic S‐heterocyclic compounds show electrical conductivity in both solid and liquid‐crystal states.

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A series of substituted 2,5‐diaryl‐1,3,4‐thiadiazole derivatives are prepared by microwave‐assisted synthesis in the absence of an organic solvent. All derivatives are well characterized by 1H and 13C NMR, MS, and elemental analyses. The X‐ray crystal structure of 2,5‐di‐(4‐decyloxyphenyl)‐1,3,4‐thiadiazole reveals the tilt lamellar arrangement of rod‐shaped molecules, which are stabilized by a variety of weak non‐covalent interactions. The liquid crystalline properties are studied by polarized‐light optical microscopy (POM), differential scanning calorimetry (DSC), and in situ variable temperature X‐ray diffraction (VTXRD). By variations in the peripheral n‐alkoxy chains, the calamitic mesogens exhibit enantiotropic smectic (SmC and/or SmA) mesophases with wide mesomorphic temperature ranges, whilst the disc‐like mesogens form hexagonal columnar mesophase (Colh) at room temperature. The bulk electrical conductivity values of the smectic mesophases of 1–3 are in the range of 10−3–10−4 S cm−1, which are slightly higher than that of their solid films. In contrast, the solid film made from 2,5‐di‐(3,4,5‐trioctyloxyphenyl)‐1,3,4‐thiadiazole shows poor conductivity (2×10−7 S cm−1).
Rissbildung und Zugtragverhalten von mit Fasern verstärktem Stahlbeton am Beispiel ultrahochfesten Betons
Authors: Leutbecher Torsten , Fehling Ekkehard
Published: June 2009

Bei Kombination konventioneller Betonstahl‐ oder Spannbewehrung und Fasern ergeben sich Unterschiede im Trag‐ und Verformungsverhalten eines zugbeanspruchten Betonbauteils gegenüber dem bekannten Stahl‐ und Spannbeton. Dies gilt für Betone unterschiedlicher Festigkeit gleichermaßen, erreicht bei ultrahochfesten Betonen (UHPC) jedoch besondere Aktualität, da aus Gründen der Duktilität der Einsatz von Fasern bei diesen Betonen die Regel ist. Im Hinblick auf die Dauerhaftigkeit und Dichtigkeit ist vor allem der günstige Einfluss der Fasern auf den Rissbildungsprozess und die Rissbreiten im Gebrauchszustand von Bedeutung. Besonders bei erhöhten Anforderungen an die Rissbreite (Größenordnung: unter 0, 1 mm) kann durch gemischte Bewehrung aus Stabstahl und Fasern eine wesentliche Verbesserung gegenüber Stahlbeton erzielt werden. Die Analyse der Vorgänge bei Rissbildung setzt zunächst das Verständnis der unterschiedlichen Wirkungsweisen der beiden Bewehrungselemente ”Stabstahl” und ”Fasern” voraus. Im Teil 1 dieses Beitrags werden die hierzu erforderlichen mechanischen Zusammenhänge dargestellt und unter Berücksichtigung des Gleichgewichts und der Verträglichkeit miteinander verknüpft. Im Teil 2 erfolgt eine Überprüfung der abgeleiteten Beziehungen anhand experimenteller Untersuchungen an gemischt bewehrten Zugelementen aus UHPC. Ihre Anwendung wird zudem an zwei Rechenbeispielen veranschaulicht. Aufgrund seiner allgemeingültigen Formulierung ist der vorgestellte Ansatz auf alle mit Stabstahl und Fasern bewehrten Betone anwendbar, d. h. nicht auf ultrahochfeste Betone beschränkt.
Advected river textures
Authors: Burrell Tim , Arnold Dirk , Brooks Stephen
Published: June 2009

We present a new method for the realistic real‐time simulation of rivers. Our solution includes a 2D fluid solver that simulates the flow of a river's surface, an efficient method for adaptively computing 3D flow information and an animated 3D procedural wave texture that is advected through the fluid via advection particles in order to mimic the highly detailed fluid surfaces that are characteristic of rivers. Our technique that couples animated texture advection with a pseudo‐3D fluid simulation produces stable results that are representative of large‐scale real‐world rivers and suitable for use in real‐time applications. Our system surpasses prior work on real‐time river rendering both with regards to efficiency and visual quality, which we establish through the rendering of rivers tens of kilometers long. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and Evaluation of New Thiodigalactoside‐Based Chemical Probes to Label Galectin‐3
Authors: van Scherpenzeel Monique , Moret Ed E. , Ballell Lluis , Liskamp Rob M. J. , Nilsson Ulf J. , Leffler Hakon , Pieters Roland J.
Published: June 2009

Light up galectin: Photoprobes based on thiodigalactoside were prepared for galectin‐3, a lectin linked to cancer. The probes contained either benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. One particular probe labeled galectin‐3 selectively, even in the presence of cell lysate.

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New chemical probes were synthesized to label galectin‐3. They are based on the high affinity thiodigalactoside ligand. The probes were synthesized with benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. Besides labeling the protein, these aromatic photolabels also greatly enhance the affinity of the probes towards galectin‐3, due to the interaction of the photolabel with two arginine guanidinium groups of the protein. The linkage between the sugar and the photolabel was varied as an ester, an amide, and a triazole. For the amide and triazole derivatives, a versatile synthetic route towards a symmetrical 3‐azido‐3‐deoxy‐thiodigalactoside was developed. The new probes were evaluated for their binding affinity of human galectin‐3. They were subsequently tested for their labeling efficiency, as well as specificity in the presence of a protein mixture and a human cancer cell lysate.
Probing Intermolecular Interactions in Ionic Liquid–Water Mixtures by Near‐Infrared Spectroscopy
Authors: Wu Bo , Liu Yang , Zhang Yumei , Wang Huaping
Published: June 2009

In this contribution, an insight into the interactions between ionic liquids (ILs), 1‐butyl‐3‐methylimidazolium tetrafluoroborate, [Bmim]BF4, and 1‐allyl‐3‐methylimidazolium chloride, [Amim]Cl, and water is presented using near‐infrared (NIR) spectroscopic measurements. Distinct differences were found in the NIR spectra of pure [Amim]Cl and [Bmim]BF4, whereby we propose optimized conformations. It was found that the relative position of the anion with respect to imidazolium cation is different in these two ILs. The geometry difference determined their different interaction modes with water, for example, the NIR spectra in alkyl group region were different for these two ILs/H2O mixtures, irrespective of being in a water‐rich region or IL‐rich region. However, their NIR spectra for aromatic group were similar, whereby we deduced that for both ILs, the water molecules were favorable to form hydrogen bonds with the proton H2 on imidazolium ring, rather than H4 and H5. Furthermore, it was shown that water molecules preferred to interact with BF4−, but Cl− interacted more specifically with aromatic C‐H groups compared with BF4−. This was confirmed by the fact that the supramolecular structure of aqueous [Bmim]BF4 solution was destroyed as mole fraction of water surpasses 0.3979, which was lower than the value of 0.5822 for [Amim]Cl/H2O. These results would have important directive significance for the study of the aggregation behavior and recovery of hydrophilic ILs in water.
Conformational Preferences of the Full Chicken Prion Protein in Solution and Its Differences with Respect to Mammals
Authors: Pietropaolo Adriana , Muccioli Luca , Zannoni Claudio , Rizzarelli Enrico
Published: June 2009

Chicken nugget: Simulations of the full chicken prion protein (see picture) and chirality analysis provide possible explanations for its resistance to proteases—and for the fold stability of the avian prion globular core. The three alpha helices exhibit different flexibilities and secondary structure propensities.

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We investigate the conformations of the full chicken prion protein (ChPrP1‐267) in solution at neutral pH with molecular dynamics simulations. We focus on the persistence of its secondary structure motifs using a recently proposed protein chirality indicator [A. Pietropaolo et al., Proteins 2008, 70, 667–677]. From this, we find a high rigidity of helix 2 (ChPrP178‐195) and of the hexarepeat domain, which is turn rich, and a plasticity of the short β‐sheet, consistent with the available NMR structural details. We also determine the extent of solvation for each residue, revealing local minima for such structured regions. These features hint at a possible origin of the high resistance to proteolysis of the avian prion proteins and of its capability in preventing the aggregation in comparison to mammals.
Homogeneous versus Supported ONN Pincer‐Type Gold and Palladium Complexes: Catalytic Activity
Authors: del Pozo Carolina , Debono Nathalie , Corma Avelino , Iglesias Marta , Sánchez Félix
Published: June 2009

The ONN‐tridentate unsymmetrical pincer‐type (S)‐1‐((6‐(2‐hydroxyphenyl)pyridin‐2‐yl)methyl)‐N‐methyl‐N‐(3‐(triethoxysilyl)pro‐pyl)pyrrolidine‐2‐carboxamide ligand has been synthesized by an easy method, in high purity and good yield. Its respective palladium(II) and gold(III) complexes have been prepared as air‐stable solids. After deprotonation of the OH group the coordination of the metal ion is completely stereospecific and gives rise to only one diastereoisomer. The complexes, immobilized onto ordered mesoporous silica (MCM‐41), are shown to be very active catalysts in the hydrogenation of prochiral olefins (98 % ee was achieved with the heterogenized chiral Au(MCM‐41) complex), hydrosilylation, and Suzuki and Heck CC coupling reactions, under mild conditions. The reactions were studied with the soluble catalysts as well as their heterogenized counterparts. The high accessibility introduced by the structure of the supports allows the preparation of highly efficient immobilized catalysts. The repeated use of the immobilized catalyst in four cycles demonstrates “homogeneous” catalysis with “heterogeneous” catalysts, thus reducing solvent waste and loss of precious metal and/or ligand.
On the two‐port network analysis of common amplifier topologies
Authors: Elwakil A. S. , Maundy B.
Published: June 2009

Using two‐port network transmission parameters, we derive exact expressions for the voltage/current gains and the input/output impedances of common amplifier topologies. The derived expressions are valid both for BJT and MOS‐based amplifiers and are independent of any particular small signal transistor model. Copyright © 2009 John Wiley & Sons, Ltd.
Overview of Strategies for the CVD of Organic Films and Functional Polymer Layers
Authors: Sreenivasan Ramaswamy , Gleason Karen K.
Published: June 2009

Vapor based polymer deposition methods have evolved to address the limitations of solution polymerization. However this field of vapor based polymerization suffers from varied nomenclature and would benefit from a review article that brought together the different approaches to vapor based polymerization with an effort to present existing nomenclature, clearly identify the various approaches within this field and summarize recent results. This review article is written with the purpose of compiling recent advances in vapor based deposition methods of polymers with a focus on applications that will continue to drive research in this field. We hope that this article encourages researchers engineering novel polymer applications to give vapor based polymerization a serious consideration apart from solution polymerization methods.
PECVD of Fluorocarbon Coatings from Hexafluoropropylene Oxide: Glow vs. Afterglow
Authors: Intranuovo Francesca , Sardella Eloisa , Rossini Pasqua , d'Agostino Riccardo , Favia Pietro
Published: June 2009

Smooth and micro/nano‐structured fluorocarbon coatings are obtained by radio frequency (RF), 13.56 MHz, glow discharges fed with hexafluoropropylene oxide (C3F6O, HFPO) both in glow and in afterglow. It is shown that the extent of micro/nanostructuring, as well as the F/C ratio of the coatings, can be precisely tuned with both substrate position and deposition time. Nodular and “stone roses” morphological features are easily obtained, with good reproducibility, by controlling the plasma parameters. Both chemical and morphological features are shown to deeply affect film properties and, in turn, wetability, allowing a move from a hydrophobic behavior to a superhydrophobic one.
Plasticity in the developing brain: Implications for rehabilitation
Authors: Johnston Michael V.
Published: June 2009

Neuronal plasticity allows the central nervous system to learn skills and remember information, to reorganize neuronal networks in response to environmental stimulation, and to recover from brain and spinal cord injuries. Neuronal plasticity is enhanced in the developing brain and it is usually adaptive and beneficial but can also be maladaptive and responsible for neurological disorders in some situations. Basic mechanisms that are involved in plasticity include neurogenesis, programmed cell death, and activity‐dependent synaptic plasticity. Repetitive stimulation of synapses can cause long‐term potentiation or long‐term depression of neurotransmission. These changes are associated with physical changes in dendritic spines and neuronal circuits. Overproduction of synapses during postnatal development in children contributes to enhanced plasticity by providing an excess of synapses that are pruned during early adolescence. Clinical examples of adaptive neuronal plasticity include reorganization of cortical maps of the fingers in response to practice playing a stringed instrument and constraint‐induced movement therapy to improve hemiparesis caused by stroke or cerebral palsy. These forms of plasticity are associated with structural and functional changes in the brain that can be detected with magnetic resonance imaging, positron emission tomography, or transcranial magnetic stimulation (TMS). TMS and other forms of brain stimulation are also being used experimentally to enhance brain plasticity and recovery of function. Plasticity is also influenced by genetic factors such as mutations in brain‐derived neuronal growth factor. Understanding brain plasticity provides a basis for developing better therapies to improve outcome from acquired brain injuries. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:94–101.
Alpha‐melanocyte‐stimulating hormone attenuates behavioral effects of corticotropin‐releasing factor in isolated guinea pig pups
Authors: Schiml‐Webb Patricia A. , Miller Emily , Deak Terrence , Hennessy Michael B.
Published: June 2009

During a 3‐hr period of social isolation in a novel environment, guinea pig pups exhibit an initial active phase of behavioral responsiveness, characterized primarily by vocalizing, which is then followed by a stage of passive responsiveness in which pups display a distinctive crouch, eye‐closing, and extensive piloerection. Prior treatment of pups with alpha‐melanocyte‐stimulating hormone (α‐MSH) reduces each of the passive behaviors. The onset of passive responding during separation can be accelerated with peripheral injection of corticotropin‐releasing factor (CRF). To examine whether CRF produces its effects through a mechanism similar to that of prolonged separation, we examined the effect of administering α‐MSH to pups injected with CRF. As expected, CRF markedly enhanced passive responding during a 60‐min period of separation. α‐MSH delivered by either intracerebroventricular infusion or intraperitoneal injection significantly reduced each of the passive behavioral responses without significantly affecting active behavior. These findings, together with previous results indicating that it is the anti‐inflammatory property of α‐MSH that is responsible for its behavioral effects during prolonged separation, suggest that peripheral CRF speeds the induction of passive responding through a mechanism involving enhanced proinflammatory activity. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 399–407, 2009.
Aktuelle Forschungsergebnisse zur Rissbildung in feuerverzinkten Stahlkonstruktionen
Authors: Feldmann Markus , Ulbrich Detlef , Breitschaft Gerhard
Published: June 2009

1. Vorbemerkung

2. Kurzfassung des Forschungsberichtes 16.132 “Stichprobe zur Erfassung der Verzinkungsschäden an in den Jahren 2000 bis 2005/2006 hergestellten Stahlbauten im Gebiet der Bundesrepublik Deutschland”

2.1. Anlass und Zielsetzung

2.2. Erste Maßnahmen

2.3. Maßnahmen für den gebauten Bestand

2.4. Zusammenstellung der geprüften Konstruktionen

2.5. Durchführung der Prüfungen vor Ort

2.6. Ergebnis der Prüfungen

2.7. Zusammenfassung, Schlussfolgerungen und Empfehlungen
High glucose‐induced changes in steroid production in adrenal cells
Authors: Astort F. , Repetto E. M. , Calejman C. Martínez , Cipelli J. M. , Sánchez R. , Di Gruccio J. M. , Mercau M. , Pignataro O. P. , Arias P. , Cymeryng C. B.
Published: June 2009

Background

Increased activity of the hypothalamic‐pituitary‐adrenal (HPA) axis, resulting in enhanced adrenocorticotropin (ACTH) and serum glucocorticoid levels, has been described in patients with diabetes mellitus and in animal models of this disease; however, altered steroid production by adrenocortical cells could result from local changes triggered by increased reactive oxygen species (ROS), induced in turn by chronic hyperglycaemia. Experiments were designed (1) to analyse the effects of incubating murine adrenocortical cells in hyperglycaemic media on the generation of oxidative stress, on steroid synthesis and on its modulation by the activity of haeme oxygenase (HO); and (2) to evaluate the effect of antioxidant treatment on these parameters.

Methods

Y1 cells were incubated for 7 days with either normal or high glucose (HG, 30 mmol/L) concentrations, with or without antioxidant treatment. Parameters of oxidative stress and expression levels of haeme oxygenase‐1 (HO‐1), nitrite levels, L‐arginine uptake and progesterone production were determined.

Results

HG augmented ROS and lipoperoxide production, decreasing glutathione (GSH) levels and increasing antioxidant enzymes and HO‐1 expression. Basal progesterone production was reduced, while a higher response to ACTH was observed in HG‐treated cells. The increase in HO‐1 expression and the effects on basal steroid production were abolished by antioxidant treatment. Inhibition of HO activity increased basal and ACTH‐stimulated steroid release. Similar results were obtained by HO‐1 gene silencing while the opposite effect was observed in Y1 cells overexpressing HO‐1.

Conclusions

HG induces oxidative stress and affects steroid production in adrenal cells; the involvement of HO activity in the modulation of steroidogenesis in Y1 cells is postulated. Copyright © 2009 John Wiley & Sons, Ltd.
Sediment transmission and storage: the implications for reconstructing landform development
Authors: Chiverrell R. C. , Foster G. C. , Thomas G. S. P. , Marshall P.
Published: June 2009

The late Holocene (last 3000 years) development of the lower Ribble valley (northwest England) displays evidence for a complex response to a sediment recharge event forced by land‐use change induced increases in erosion and sediment delivery. The deposition of fluvial sediments during the late Holocene was restricted to a series of reaches or depocenters separated by zones with no sediment accumulation constrained by older glacial and fluvial terrain. Apparent reach‐wide correlations of fluvial terraces break down under the scrutiny applied by comprehensive and extensive radiocarbon control. Bayesian testing of relative order models show that large‐scale geomorphological changes, e.g. the progression from one terrace level to another, were time transgressive between different depocenters. The different histories of sediment delivery and storage are probably a function of local‐ and process‐scale variations in these depocenters, and reflect (dis)connectivity relationships within a reach in propagating a basin‐scale change (superslug) in the sediment regime. Disconnectivity in the depositional regime through a fluvial reach limits what we can reconstruct in terms of sediment budgets, but radiocarbon dating of multiple palaeochannels offers considerable potential for landform‐based research to uncover rates of change within individual depocenters. Copyright © 2009 John Wiley & Sons, Ltd.
Beating capillarity in thin film flows
Authors: Sellier Mathieu , Panda Satyananda
Published: June 2009

The combination of substrate unevenness and capillarity is known to induce far‐reaching perturbations at the free surface of thin liquid films. These might be undesired and this paper explores the possibility to control the free surface of thin liquid films to give it a prescribed profile by a suitable design of the underlying substrate. This corresponds to the inverse of the widely studied forward problem, which considers the effect of substrate unevenness on a free surface. Assuming that the steady free surface profile can be described by the lubrication approximation, this optimal control problem is shown to be governed by a first‐order partial differential equation, which is solved numerically using the method of characteristics. The proposed method is successfully tested for a range of desired free surface profiles and the domain of existence of a solution to the inverse problem is probed. Expectedly, it is shown that, owing to surface tension, not all free surface profiles can be achieved but in some cases capillarity can be beaten and a prescribed free surface profile obtained. Copyright © 2009 John Wiley & Sons, Ltd.