bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational Fluid Dynamics Modeling of Chemical Looping Combustion Process with Calcium Sulphate Oxygen Carrier
Authors: Jin Baosheng , Xiao Rui , Deng Zhongyi , Song Qilei
Published: May 2009

To concentrate CO2 in combustion processes by efficient and energy-saving ways is a first and very important step for its sequestration. Chemical looping combustion (CLC) could easily achieve this goal. A chemical-looping combustion system consists of a fuel reactor and an air reactor. Two reactors in the form of interconnected fluidized beds are used in the process: (1) a fuel reactor where the oxygen carrier is reduced by reaction with the fuel, and (2) an air reactor where the reduced oxygen carrier from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO2 and H2O, while the outlet gas stream from the air reactor contains only N2 and some unused O2. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation.Until now, there is little literature about mathematical modeling of chemical-looping combustion using the computational fluid dynamics (CFD) approach. In this work, the reaction kinetic model of the fuel reactor (CaSO4+ H2) is developed by means of the commercial code FLUENT and the effects of partial pressure of H2 (concentration of H2) on chemical looping combustion performance are also studied. The results show that the concentration of H2 could enhance the CLC performance.
Alkali lasers for magnetic resonance imaging
Authors: Zhdanov Boris , Knize Randall
Published: May 2009

Spin-polarized nuclei of such gases as 3He and 129Xe are successfully used for magnetic resonance imaging of lungs and other organs of human body. To produce large numbers of spin-polarized nuclei required for this medical application, a high power narrowband tunable laser source is required. Diode pumped alkali lasers, developed during last several years can be an ideal source for this application. In this paper we present our latest achievements in diode pumped alkali lasers development. We describe optically pumped Cs laser tunable in the range of 14 GHz and operating in single transverse mode with a linewidth less than 3 MHz. We also present continuous wave diode pumped Rb and Cs lasers with output power 17 W and 20 W.
The transcriptional regulation and cell-specific expression of the MAPK-activated protein kinase MK5
Authors: Gerits Nancy , Shiryaev Alexey , Kostenko Sergiy , Klenow Helle , Shiryaeva Olga , Johannessen Mona , Moens Ugo
Published: May 2009

The mitogen-activated protein kinase (MAPK) cascades regulate important cellular processes, including growth, differentiation, apoptosis, embryogenesis, motility and gene expression. Although MAPKs mostly appear to be constitutively expressed, the transcript levels of some MAPK-encoding genes increase upon treatment with specific stimuli. This applies to the MAPKactivated protein kinases MK2 and MK3. By contrast, the transcriptional regulation of the related MK5 has not yet been studied. The MK5 promoters of mouse, rat and human contain a plethora of putative transcription factor sites, and the spatio-temporal expression of MK5 suggests inducible transcription of the gene. We examined the transcription pattern of MK5 in different tissues, and studied the kinetics of MK5 expression at the transcriptional and/or translation level in PC12 cells exposed to arsenite, forskolin, KCl, lipopolysaccharide, spermine NONOate, retinoic acid, serum, phorbol ester, temperature shock, and vanadate. Cells exposed to forskolin display a transient increase in MK5 mRNA, despite their unaltered MK5 protein levels. The MK5 promoters of human, mouse and rat contain a cAMP-responsive element that binds the cAMPresponsive element-binding protein (CREB) in vitro. Luciferase reporter constructs containing an 850-base pair human MK5 promoter fragment encompassing the CRE showed a basal activity that was 10-fold higher than the corresponding construct in which the CRE motif was deleted. siRNA-mediated depletion of CREB had no effect on the endogenous MK5 protein levels. Several binding motifs for heat shock factor are dispersed in the mouse and rat promoter, and temperature shock transiently enhanced the MK5 transcript levels. None of the other tested stimuli had an effect on the MK5 mRNA or protein levels. Our results indicate an inducible regulation of MK5 transcription in response to specific stimuli. However, the MK5 protein levels remained unaffected by all the stimuli tested. There is still no explanation for the discrepancy between the increased mRNA and unchanged MK5 protein levels.
Treadmill Testing of Children Who Have Spina Bifida and Are Ambulatory: Does Peak Oxygen Uptake Reflect Maximum Oxygen Uptake?
Authors: de Groot Janke Frederike , Takken Tim , de Graaff Sanna , Gooskens Rob H.J.M. , Helders Paul J.M. , Vanhees Luc
Published: May 2009

Background

Earlier studies have demonstrated low peak oxygen uptake (V̇o2peak) in children with spina bifida. Low peak heart rate and low peak respiratory exchange ratio in these studies raised questions regarding the true maximal character of V̇o2peak values obtained with treadmill testing.

Objective

The aim of this study was to determine whether the V̇o2peak measured during an incremental treadmill test is a true reflection of the maximum oxygen uptake (V̇o2max) in children who have spina bifida and are ambulatory.

Design

A cross-sectional design was used for this study.

Methods

Twenty children who had spina bifida and were ambulatory participated. The V̇o2peak was measured during a graded treadmill exercise test. The validity of V̇o2peak measurements was evaluated by use of previously described guidelines for maximum exercise testing in children who are healthy, as well as differences between V̇o2peak and V̇o2 during a supramaximal protocol (V̇o2supramaximal).

Results

The average values for V̇o2peak and normalized V̇o2peak were, respectively, 1.23 L/min (SD=0.6) and 34.1 mL/kg/min (SD=8.3). Fifteen children met at least 2 of the 3 previously described criteria; one child failed to meet any criteria. Although there were no significant differences between V̇o2peak and V̇o2supramaximal, 5 children did show improvement during supramaximal testing.

Limitations

These results apply to children who have spina bifida and are at least community ambulatory.

Conclusions

The V̇o2peak measured during an incremental treadmill test seems to reflect the true V̇o2max in children who have spina bifida and are ambulatory, validating the use of a treadmill test for these children. When confirmation of maximal effort is needed, the addition of supramaximal testing of children with disability is an easy and well-tolerated method.
Gendering the Jubilee: Gender and Modernity in the Diamond Jubilee of Confederation Celebrations, 1927
Authors: Nicholas Jane
Published: May 2009

This article explores the nexus of gender, modernity, and visuality in the Diamond Jubilee of Confederation celebrations in 1927. Using the jubilee as a case study of the continuing conservative elements after the First World War, this essay argues that jubilee material promoted the idea that certain men had the ability to see the potential of the nation in relation to particular spaces, especially the North. Further, in privileging a specific group of modern men, jubilee organizers argued that this ‘sight’ echoed the foresight of the Fathers of Confederation. The appeal to men's allegedly innate vision also helped shore up a perceived embattled modern, white, bourgeois masculinity. This article also briefly discusses the impact of this gendering of vision in regard to women's perceived roles in nation-building, particularly in relation to Miss Canada and the underlying ambiguities concerning modernity.
Pyrrolidine‐Camphor Derivative as an Organocatalyst for Asymmetic Michael Additions of α,α‐Disubstituted Aldehydes to β‐Nitroalkenes: Construction of Quaternary Carbon‐Bearing Aldehydes under Solvent‐Free Conditions
Authors: Chang Chihliang , Li Ssu‐Hsien , Reddy Raju Jannapu , Chen Kwunmin
Published: May 2009

magnified image

A novel pyrrolidine‐camphor organocatalyst 3 was designed, synthesized and proven to be an efficient catalyst for the asymmetric Michael reaction. Treatment of α,α‐disubstituted aldehydes with β‐nitroalkenes in the presence of 20 mol% organocatalyst 3 and 20 mol% benzoic acid under solvent‐free conditions provided the desired Michael product possessing an all‐carbon quaternary center with high chemical yields (up to 99% yield) and high levels of enantioselectivities (up to 95% ee).
Mathematical modeling of water uptake through diffusion in 3D inhomogeneous swelling substrates
Authors: van den Doel L. R. , Mohoric A. , Vergeldt F. J. , van Duynhoven J. , Blonk H. , van Dalen G. , van As H. , van Vliet L. J.
Published: May 2009

Diffusion‐driven water uptake in a substrate (imbibition) is a subject of great interest in the field of food technology. This is a particular challenge for rice grains that are preprocessed to accelerate the water uptake, i.e., to reduce the cooking time. Rice preprocessing disrupts the mesostructural order of starch and induces a microporous structure in the grains. The meso‐ and microstructural length scales have not been considered in joint approach until now. The (re)hydration of rice grains can be modeled by free (concentration‐driven) diffusion or by water demand‐driven diffusion. The latter is driven by the ceiling moisture content related to the extent of gelatinization of the rice substrate network. This network can be regarded as a fractal structure. As the spatial resolution of our models is limited, we choose to model the apparent water transport by a set of coupled partial differential equations (PDEs). Current models of water uptake are often limited to a single dimension, and the swelling of the substrate is not taken into account. In this article, we derive a set of PDEs to model water uptake in a three‐dimensional (3D) inhomogeneous substrate for different types of water diffusion as well as the swelling of the substrate during water uptake. We will present simulation results for different 3D (macroscopic) structures and diffusion models and compare these results, qualitatively, with the experimental results acquired from magnetic resonance imaging. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Using surveillance data to promote occupational health and safety policies and practice at the state level: A case study
Authors: Calvert Geoffrey M. , Higgins Sheila A.
Published: May 2009

Background

Following the investigation of a birth defects cluster involving migrant farmworkers employed in North Carolina and Florida, it became clear that greater efforts were needed to protect agricultural workers from pesticide exposure.

Methods

Documentation is drawn from peer‐reviewed published articles, government reports and news accounts.

Results

The birth defects cluster was identified and investigated by state and federal pesticide poisoning surveillance system staff. Following the investigation, efforts were initiated to highlight pesticides as an important public health issue needing more attention. A series of subsequent events led to the creation and passage of important legislation recently enacted in North Carolina. The legislation resulted in funding to promote various activities to prevent harm from pesticides including strengthening surveillance, improving the quality of pesticide compliance inspections, and increasing and improving pesticide safety training. The legislation also broadened the coverage of anti‐retaliation rules to include agricultural workers, and increased recordkeeping requirements pertaining to pesticide applications.

Conclusion

The important and positive impacts that can occur through surveillance activities are highlighted. As such, it is important to continue to support and improve occupational illness and injury surveillance programs. Am. J. Ind. Med. 53:188–193 2010. Published 2009 Wiley‐Liss, Inc.
An association between Epac‐1 gene variants and anxiety and depression in two independent samples
Authors: Middeldorp Christel M. , Vink Jacqueline M. , Hettema John M. , de Geus Eco J.C. , Kendler Kenneth S. , Willemsen Gonneke , Neale Michael C. , Boomsma Dorret I. , Chen Xiangning
Published: May 2009

Deficiency in signal transduction might play a role in the development of anxiety and depression, as suggested by a study on the involvement of the PKA‐independent Epac pathway. We investigated the association between Epac‐1 gene variants, also known as RapGEF‐3, and measures of anxiety and depression in a Dutch twin‐family sample. Replication was sought in a USA sample consisting of unrelated individuals. Genotype and phenotype data were available for 910 Dutch and 684 USA individuals. Longitudinal self‐report measures of neuroticism, anxiety and depression and genetic factor scores (GFS‐NL), based on these measures, were analyzed in the Dutch sample. In the USA sample, neuroticism and Genetic Factor Scores (GFS‐USA), based on neuroticism and diagnoses of anxiety disorders and depression, were analyzed. Three intronic SNPs were genotyped. Analyses were performed in QTDT. Genotype and haplotype frequencies differed significantly between the samples. In the Dutch sample, rs2072115 showed a significant dominant effect for anxiety and depression. Subjects with haplotype G‐C‐C (ordered rs2072115‐rs757281‐2074533) had significantly lower anxiety, neuroticism and GFS‐NL scores. In the USA sample, a significant additive effect of rs2074533 on GFS‐USA was found. Subjects with haplotypes G‐C‐C and A‐C‐T had significantly higher and lower GFS‐USA scores, respectively. Both samples showed an association between Epac‐1 gene variants and anxiety and depression, but for different variants or in opposite directions. The divergent results could be due to differences in linkage disequilibrium between the investigated SNPs and a functional polymorphism in the Dutch and USA sample. © 2009 Wiley‐Liss, Inc.
Non‐replication of association for six polymorphisms from meta‐analysis of genome‐wide association studies of Parkinson's disease: Large‐scale collaborative study
Authors: Evangelou Evangelos , Maraganore Demetrius M. , Annesi Grazia , Brighina Laura , Brice Alexis , Elbaz Alexis , Ferrarese Carlo , Hadjigeorgiou Georgios M. , Krueger Rejko , Lambert Jean‐Charles , Lesage Suzanne , Markopoulou Katerina , Mellick George D. , Meeus Bram , Pedersen Nancy L. , Quattrone Aldo , Van Broeckhoven Christine , Sharma Manu , Silburn Peter A. , Tan Eng‐King , Wirdefeldt Karin , Ioannidis John P.A. ,   for the Genetic Epidemiology of Parkinson's Disease (GEOPD) Consortium
Published: May 2009

Early genome‐wide association (GWA) studies on Parkinson's disease (PD) have not been able to yield conclusive, replicable signals of association, perhaps due to limited sample size. We aimed to investigate whether association signals derived from the meta‐analysis of the first two GWA investigations might be replicable in different populations. We examined six single‐nucleotide polymorphisms (SNPs) (rs1000291, rs1865997, rs2241743, rs2282048, rs2313982, and rs3018626) that had reached nominal significance with at least two of three different strategies proposed in a previous analysis of the original GWA studies. Investigators from the “Genetic Epidemiology of Parkinson's Disease” (GEOPD) consortium were invited to join in this study. Ten teams contributed replication data from 3,458 PD cases and 3,719 controls. The data from the two previously published GWAs (599 PD cases, 592 controls and 443 sibling pairs) were considered as well. All data were synthesized using both fixed and random effects models. The summary allelic odds ratios were ranging from 0.97 to 1.09 by random effects, when all data were included. The summary estimates of the replication data sets (excluding the original GWA data) were very close to 1.00 (range 0.98–1.09) and none of the effects were nominally statistically significant. The replication data sets had significantly different results than the GWA data. Our data do not support evidence that any of these six SNPs reflect susceptibility markers for PD. Much stronger signals of statistical significance in GWA platforms are needed to have substantial chances of replication. Specifically in PD genetics, this would require much larger GWA studies and perhaps novel analytical techniques. © 2009 Wiley‐Liss, Inc.
Neuroprotective effects of estrogen therapy for cognitive and neurobiological profiles of monkey models of menopause
Authors: Voytko Mary Lou , Tinkler Gregory Paul , Browne Carole , Tobin Joseph R.
Published: May 2009

Many postmenopausal women question whether to start or continue hormone therapy because of recent clinical trial negative results. However, evidence from other studies of postmenopausal women, and from studies in menopausal monkeys, indicate that estrogen has neurocognitive protective effects, particularly when therapy is initiated close to the time of menopause before neural systems become increasingly compromised with age. In this review, we present studies of menopausal women and female monkeys that support the concept that estrogen therapies protect both cognitive function and neurobiological processes. Am. J. Primatol. 71:794–801, 2009. © 2009 Wiley‐Liss, Inc.
Macaque–human interactions and the societal perceptions of macaques in Singapore
Authors: Sha John Chih Mun , Gumert Michael D. , Lee Benjamin P.Y‐H. , Jones‐Engel Lisa , Chan Sharon , Fuentes Agustín
Published: May 2009

Humans and long‐tailed macaques (Macaca fascicularis) interface in several locations in Singapore. We investigated six of these interface zones to assess the level of conflict between the two species. We observed macaque‐to‐human interactions and distributed questionnaires to residents and visitors of nature reserves. We observed an average of two macaque‐to‐human interactions per hour at the sites, which included affiliative or submissive behaviors (46.9%), aggression (19.1%), taking food and other items (18.5%) searching bins, cars, and houses (13.4%), and nonaggressive contact (2.1%). Two‐thirds of interactions occurred when a human was carrying food or food cues, and one‐quarter occurred when a human provoked macaques. Only 8% of interactions occurred without a clear human‐triggered context. Our interview showed one‐third of respondents experienced nuisance problems from macaques. They had items taken from them (50.5%) and received threats (31.9%). Residents reported more nuisance problems than visitors, and their perceptions toward macaques differed. Residents were more aware of the consequences of food provisioning and that there were regulations against feeding. Residents fed macaques less and held more negative sentiments toward macaques. Nearly half of the interviewed people held neutral attitudes toward macaques and only 26.2% of respondents thought conflict with macaques warranted urgent action. Nearly two‐thirds of the respondents supported education programs to ameliorate human–macaque conflict, and less than 15% supported removing or eradicating macaques. 87.6% felt that it is importance to conserve and protect macaques. Our results show that human–macaque conflict exists in Singapore, but that it may not be severe. Human behavior is largely responsible for macaque‐to‐human interactions, and thus could be lessened with management of human behavior in interface zones (i.e. restrict food carrying and provocation). Moreover, our interviews shows people living in Singapore value macaques, do not wish them entirely removed, prefer education‐based solutions, and consider conservation and protection of them important. Am. J. Primatol. 71:825–839, 2009. © 2009 Wiley‐Liss, Inc.
Cerebral developmental venous anomalies: Current concepts
Authors: San Millán Ruíz Diego , Yilmaz Hasan , Gailloud Philippe
Published: May 2009

Cerebral developmental venous anomalies are the most frequently encountered cerebral vascular malformation, and as such, are frequently reported as fortuitous findings in computed tomography (CT) and magnetic resonance imaging (MRI) studies. Developmental venous anomalies (DVAs) are generally considered extreme anatomical variations of the cerebral vasculature, and follow a benign clinical course in the vast majority of cases. Here we review current concepts on DVAs with the aim of helping clinicians understand this complex entity. Morphological characteristics that are necessary to conceptualize DVAs are discussed in depth. Images modalities used in diagnosing DVAs are reviewed, including new MRI or CT techniques. Clinical presentation, association with other vascular malformations and cerebral parenchymal abnormalities, and possible physiopathological processes leading to associated imaging or clinical findings are discussed. Atypical forms of DVAs are also reviewed and their clinical significance discussed. Finally, recommendations as to how to manage asymptomatic or symptomatic patients with a DVA are advanced. Ann Neurol 2009;66:271–283
Functionalized Inorganic Monolithic Microreactors for High Productivity in Fine Chemicals Catalytic Synthesis
Authors: El Kadib Abdelkrim , Chimenton Ricardo , Sachse Alexander , Fajula François , Galarneau Anne , Coq Bernard
Published: May 2009

Hochproduktiv: Gepfropfte monolithische Kieselgel‐Mikroreaktoren verarbeiten sperrige Moleküle effizienter als Batch‐Reaktoren. Gründe dafür sind eine größere Kontaktfläche, ein kürzerer Diffusionsweg und weniger Inhibierung durch die Produkte im dünnen Monolithgerüst. Diese Materialien bieten einen neuen Zugang in der heterogenen Katalyse zur Synthese von Feinchemikalien.

magnified image
Klick‐Chemie jenseits von metallkatalysierten Cycloadditionen
Authors: Becer C. Remzi , Hoogenboom Richard , Schubert Ulrich S.
Published: May 2009

Auch ohne Kupfer auf Erfolgskurs: In den letzten Jahren wurden zahlreiche metallfreie Klick‐Reaktionen auf der Grundlage von radikalischen Thiol‐En‐Additionen, Diels‐Alder‐Reaktionen und Michael‐Additionen beschrieben. Dieser Kurzaufsatz wägt die Vorteile und Einschränkungen der verschiedenen Methoden ab, um zu beurteilen, ob sie den überwältigenden Erfolg der Kupfer(I)‐katalysierten Azid‐Alkin‐Cycloaddition noch übertreffen können.

magnified image

Der überwältigende Erfolg der Klick‐Chemie ermutigt viele Forscher, auch andere “spannungsgeladene” chemische Reaktionen zu entwickeln und in verschiedenen Bereichen der Chemie anzuwenden. Ursprünglich stellte die Kupfer(I)‐katalysierte Azid‐Alkin‐Cycloaddition die einzige Klick‐Reaktion dar. In den letzten Jahren rückten jedoch auch metallfreie [3 + 2]‐Cycloadditionen, Diels‐Alder‐Reaktionen und radikalische Thiol‐Alken‐Additionen als Klick‐Reaktionen in den Vordergrund, weil sie bei einfachen Synthesevorschriften zu hohen Ausbeuten führen. Außerdem sind die metallfreien Reaktionen vielseitig und physiologisch verträglich. Diese und andere alternative Klick‐Reaktionen erweitern die Möglichkeiten bei der Synthese von sowohl niedermolekularen Verbindungen als auch maßgeschneiderten Makromolekülen und Biokonjugaten. Dieser Kurzaufsatz setzt sich mit den Erfolgsmöglichkeiten und der Anwendbarkeit von neu entwickelten, im Speziellen metallfreien Klick‐Reaktionen auseinander.
Selective Production of Reactive and Nonreactive Oxygen Atoms on Pd(001) by Rotationally Aligned Oxygen Molecules
Authors: Vattuone Luca , Gerbi Andrea , Cappelletti David , Pirani Fernando , Gunnella Roberto , Savio Letizia , Rocca Mario
Published: May 2009

Wer bindet wo und warum? Die Belegung verschiedener Positionen durch Sauerstoffatome, die bei der Dissoziation von O2 an Pd(100) entstehen, wird durch die ursprüngliche Orientierung der gespaltenen Moleküle vorgegeben. Die Atomlagen zeigen unterschiedliche chemische Reaktivitäten bei der Bildung von CO2 aus CO (siehe Bild). Dieser Prozess wurde in Experimenten mit Überschallmolekülstrahlen (SMBs) und Synchrotronstrahlung (SR) untersucht.

magnified image
Symmetry‐Guided Design and Fluorous Synthesis of a Stable and Rapidly Excreted Imaging Tracer for 19F MRI
Authors: Jiang Zhong‐Xing , Liu Xin , Jeong Eun‐Kee , Yu Yihua Bruce
Published: May 2009

FIT werden: Der hantelförmige 19F‐Marker 19FIT hat einige Vorteile gegenüber Perfluorkohlenstoff‐19F‐Markern, da er in Organen nicht zurückgehalten wird und keine komplizierte Formulierung erforderlich macht. Kontrastmittel wie 19FIT können die 19F‐Kernspintomographie zu einem wichtigen Instrument der medikamentösen Therapie machen, so wie das 1H‐Verfahren in der Diagnose eine große Rolle spielt.

magnified image
Time‐Resolved In Situ Synchrotron X‐ray Study and Large‐Scale Production of Magnetite Nanoparticles in Supercritical Water
Authors: Bremholm Martin , Felicissimo Marcella , Iversen Bo B.
Published: May 2009

Allgemeine Lösung: In‐situ‐Synchrotron‐Röntgenbeugung in einem Reaktor, in den pulsförmig Eisenammoniumcitrat bei hohem Druck injiziert wird (siehe Bild), zeigt, dass Magnetitkeimbildung und ‐wachstum zeitlich getrennt ablaufen. Grammmengen kristalliner, reinphasiger, superparamagnetischer Magnetitnanopartikel wurden ohne Tenside in überkritischem Wasser in weniger als einer Stunde in einem kontinuierlich betriebenen Laborreaktor synthetisiert.

magnified image
Titan‐Binolat‐katalysierte Aminolyse von meso‐Aziridinen – ein hochenantioselektiver und direkter Zugang zu 1,2‐Diaminen
Authors: Peruncheralathan Saravanan , Teller Henrik , Schneider Christoph
Published: May 2009

Einfacher geht's nicht: Mit einem in situ aus den käuflichen Verbindungen Ti(OiPr)4 und (R)‐Binol gewonnenen chiralen Katalysator gelingt die hochenantioselektive Ringöffnung von meso‐Aziridinen 1 mit Anilinen 2 zu wertvollen chiralen 1,2‐Diaminen 3 in hohen Ausbeuten und bis zu 99 % ee. (R)‐Binol=[(R)‐2,2′‐Dihydroxy‐1,1′‐binaphthyl].

magnified image
Etching and Growth: An Intertwined Pathway to Silver Nanocrystals with Exotic Shapes
Authors: Cobley Claire M. , Rycenga Matthew , Zhou Fei , Li Zhi‐Yuan , Xia Younan
Published: May 2009

Nanokristalle mit zwei Gesichtern: Die Zugabe einer zweiten Silbernitrat‐Portion bei einer Polyol‐Synthese von Silbernanowürfeln führte durch oxidatives Ätzen und Anwachsen zu anisotrop gestutzten Oktaedern. Drei benachbarte Flächen der Nanowürfel wuchsen schneller als die übrigen drei, was in den nichtzentrosymmetrischen Strukturen resultierte (siehe Bild).

magnified image
Kontrollierte iterative Kreuzkupplung: auf dem Weg zur Automatisierung der organischen Synthese
Authors: Wang Congyang , Glorius Frank
Published: May 2009

Wiederholung schadet nicht! Neue Strategien für die Modulierung der Reaktivität von difunktionellen Bausteinen ermöglichen die Pd‐katalysierte, kontrollierte iterative Kreuzkupplung und dadurch die effiziente Synthese komplexer Moleküle von definierter Größe und Struktur (siehe Schema). Diese Arbeiten sollten zur Automatisierung dieser Kreuzkupplungen analog zu der Peptidsynthese führen.

magnified image
Structural Link between Giant Molybdenum Oxide Based Ions and Derived Keggin Structure: Modular Assemblies Based on the [BW11O39]9− Ion and Pentagonal {M′M5} Units (M′=W; M=Mo,W)
Authors: Leclerc‐Laronze Nathalie , Marrot Jérôme , Thouvenot René , Cadot Emmanuel
Published: May 2009

Linked to the Pentagon: The addition of molybdate to [HBW11O39]8− ions leads to the formation of mixed pentagonal units {W(Mo5)} and {W(WMo4)} trapped as linkers in the resulting modular assemblies, thus establishing the first link between the conventional Keggin ion derivatives and the giant molybdenum oxide and keplerate ions.

magnified image
Crystalline Amyloid Structures at Interfaces
Authors: Lepère Mathilde , Chevallard Corinne , Brezesinski Gerald , Goldmann Michel , Guenoun Patrick
Published: May 2009

Laying the groundwork: The interfacial self‐assembly properties of an amyloid peptide were used to develop crystalline nanostructures at air–water interfaces, which were studied by both AFM microscopy and X‐ray diffraction (see image). These structures generate regular arrays of functional groups and pave the way to controlled deposition of inorganic materials like that observed in biomineralization.

magnified image
Symmetry‐Guided Design and Fluorous Synthesis of a Stable and Rapidly Excreted Imaging Tracer for 19F MRI
Authors: Jiang Zhong‐Xing , Liu Xin , Jeong Eun‐Kee , Yu Yihua Bruce
Published: May 2009

Getting FIT: A bispherical 19F imaging tracer, 19FIT, was designed and synthesized. 19FIT is advantageous over perfluorocarbon‐based 19F imaging agents, as it is not retained in the organs and does not require complex formulation procedures. Imaging agents such as 19FIT can lead to 19F magnetic resonance imaging (MRI) playing an important role in drug therapy, analogous to the role played by 1H MRI in disease diagnosis.

magnified image
Time‐Resolved In Situ Synchrotron X‐ray Study and Large‐Scale Production of Magnetite Nanoparticles in Supercritical Water
Authors: Bremholm Martin , Felicissimo Marcella , Iversen Bo B.
Published: May 2009

A general solution: In situ synchrotron X‐ray scattering in a high‐pressure pulsed injection reactor (see picture) shows that magnetite nucleation and growth are temporally separated. Gram‐scale crystalline, pure phase, superparamagnetic magnetite nanoparticles were synthesized without surfactants in supercritical water in less than one hour using a laboratory‐scale continuous‐flow reactor.

magnified image
Experimental study on the comprehensive behavior of combustion for blended coals
Authors: Xu Yuangang , Zhang Cheng , Xia Ji , Duan Yonghua , Yin Junjun , Chen Gang
Published: May 2009

The combustion behaviors and kinetic parameters of two parent coals (lignite and bituminous) and their blends were evaluated to meet specifications of power plants. Nonisothermogravimetric experiments were conducted in air atmosphere. The flow rate was set at 100 ml/min within the temperature range from ambient temperature to 1100 °C and heating rate at 20 °C/min. The particle size used in the experiment was smaller than 0.09 mm. The combustion performance of blended coals, such as the ignition temperature and maximum weight loss rate, can be improved by the co‐combustion of the blends. Thermal analysis, burnout and combustibility index S of the coal samples were used to demonstrate the impact of blending ratio on the combustion characteristic of blended coals; results of blends displayed the nonadditive effect of the parent coals. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
In situ bimodal or broad particle size distribution using miniemulsion polymerization
Authors: Sood Ashwini
Published: May 2009

Calculations for maximum volume fraction (φm) for a monomodal and a bimodal dispersion are given. These are extended to express the volume fraction of dispersed phase (φ < φm) for a bimodal distribution. By substituting the volume fraction, so obtained, various semiempirical laws relating relative viscosity to the volume fraction of the dispersed phase for monomodal dispersions can be extended to bimodal dispersions also. It was mathematically shown that the viscosity of a bimodal dispersion shows a minimum for a particular size ratio of small to large particles for a given relative number concentrations of small to large particles and the interspacing between the small and the large particles. Also, it was shown that an increase in the relative number concentrations of small to large particles, keeping the size ratio of small to large particles and the interspacing between the small and the large particles constant, always increases viscosity. These findings also have practical significance because they can be used to obtain high solid content dispersions with minimum viscosity. Candidate recipe and operating variables that can be varied to obtain either bimodal or very broad distributions through miniemulsion polymerization are finally identified. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Rheological behavior of alginate solutions for biomanufacturing
Authors: Rezende Rodrigo Alvarenga , Bártolo Paulo Jorge , Mendes Ausenda , Filho Rubens Maciel
Published: May 2009

The rheological behavior of alginate solutions were investigated for the optimal design of a biomanufacturing system to produce alginate structures for tissue engineering. Its rheological properties were determined by a rheometer through rotational and oscillatory tests. Experimental results were used to model the alginate solutions characteristics. The findings suggest that alginate solutions undergo shear‐thinning effects with increasing shear rates. It is also possible to observe that its loss modulus is higher than the storage modulus ones being both modulus dependent upon the frequency, which is a typical characteristic of dilute solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Grafting polymerization of 2‐[3‐(2h‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on vinyltriethoxysilane‐treated cotton for the preparation of ultraviolet‐protective fabrics
Authors: Tragoonwichian Suchada , O'Rear Edgar A. , Yanumet Nantaya
Published: May 2009

Vinyltriethoxysilane was used to modify the surface of cotton to provide polymerizable vinyl groups on the fiber surface. An ultraviolet‐absorbing monomer, 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate, was polymerized on the vinyltriethoxysilane‐treated fabric to prepare ultraviolet‐protective cotton. The effects of the amounts of the solvent, silane coupling agent, and 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate on the surface morphology and ultraviolet‐protection factor of the treated cotton fabric were investigated. With a suitable process, poly{2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate} was successfully coated onto the fabric, and it significantly reduced ultraviolet transmission through the fabric, resulting in a cotton fabric with excellent ultraviolet‐protection properties. The use of a silane coupling agent helped to ensure a polymer coating with good uniformity and good resistance to washing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Surface modification of PET fibers with the use of β‐cyclodextrin
Authors: Voncina Bojana , Vivod Vera , Chen Wen‐Tung
Published: May 2009

The purpose of our research was to prepare nanoencapsulated PET textile materials, which would be used as odor carriers (underwear and bed sheets with aromatherapy activities) or would act as malodorous absorbers (absorption of cigarette smell). We grafted β‐cyclodextrin onto PET textile materials by using a polyfunctional reagent 1,2,3,4‐butanetetracarboxylic acid. To reduce the curing temperature of the reaction, catalysts such as sodium hypophosphite and cyanamide were used. We prepared nanoencapsulated polyester textile materials with increased adsorption capacity and with delayed release of volatile or active compounds. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Reduction in tactoid size as a means for reinforcing high‐density polyethylene/montmorillonite nanocomposites
Authors: Marega Carla , Causin Valerio , Marigo Antonio , Ferrara Giuseppe
Published: May 2009

Nanocomposites were prepared by adding montmorillonite clay to a high‐density polyethylene matrix. Their structure, morphology, thermal behavior, and physical– mechanical properties were studied. The filler did not alter much the structure and morphology of the matrix, with the exception of a disruptive effect on the lamellar stacks. The crystallization behavior, equilibrium melting temperature, and work of chain folding of the nanocomposites were also unaltered with respect to that of the PE base polymer. However, significant improvements in physical–mechanical properties were observed. The reason for this increase in performance was ascribed to the interaction between the filler and the matrix, especially because of a reduction in size of the original tactoids to stacks of just a few layers, albeit not intercalated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of magnesium methacrylate and zinc methacrylate on bond properties of thermal insulation material based on NBR/EPDM blends
Authors: Gao Guoxin , Zhang Zhicheng , Zheng Yuansuo , Jin Zhihao
Published: May 2009

To improve the bond property between thermal insulation composites and metal surface, magnesium methacrylate (MDMA) and zinc methacrylate (ZDMA) were added into NBR/EPDM blends, respectively. The results indicated that the dispersion of MDMA powder was very well and its content changes much smaller in the composites than that of ZDMA. As a result, with the dosage of MDMA increasing from 0 phr to 7 phr, the polarity of MDMA/composites was improved gradually due to the increasing of ionic crosslink density and the decreasing of contact angle. Therefore, the bond strength of the composites to metal increased continuously. And the failures of bonding samples were all in MDMA/composites. After adding ZDMA instead of MDMA into the rubber, however, ZDMA powder would agglomerate during being vulcanized. Therefore, the bond strength of the composites firstly increased slightly and then decreased sharply once ZDMA was over 2 phr, whereas the contact angle of ZDMA/composites is much lower than that of MDMA/vulcanizates. Moreover, all the bonding samples failed at the interface of metal. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Enzyme‐based hydrogels containing dextran as drug delivery carriers: Preparation, characterization, and protein release
Authors: Lai Junying , Fang Rui , Wang Li‐Qun , Tu Kehua , Zhao Changsheng , Qian Xiaoqian , Zhan Shulin
Published: May 2009

Novel enzyme‐based hydrogels for drug delivery were prepared by combining dextran with 5,5′‐azodisalicylic acid using isophorone diisocyanate as the crosslinking agent. The structure of the resultant dextran/5,5′‐azodisalicylic acid hydrogels was determined by infrared spectra, and the properties of the hydrogels were characterized by swelling measurements and scanning electron microscopy analysis. It was found that changing the concentration of 5,5′‐azodisalicylic acid affected the crosslinking density of the hydrogels and resulted in significant differences in the water swelling property and degradability of the hydrogels. Compared with their degradability, the degradation of the hydrogels seemed to be more pronounced by azoreductase in cecum content medium than that by hydrolysis in phosphate buffer solution (PBS). Also, the release rate of the protein in cecum content medium was faster than that in PBS. Attributing to the results of the resultant hydrogels described earlier, it could be concluded that dextran/5,5′‐azodisalicylic acid hydrogels could be used as a potential enzyme‐based carrier for colon‐specific drug delivery. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The role of a novel p‐phenylen‐bis‐maleamic acid grafted atactic polypropylene interfacial modifier in polypropylene/mica composites as evidenced by tensile properties
Authors: García‐Martínez J. M. , Areso S. , Collar E. P.
Published: May 2009

Present work is devoted to the study of the tensile behavior of polypropylene (PP)/mica composites with improved interfacial interactions from the matrix side caused by the presence of a p‐phenylen‐bis‐maleamic acid grafted atactic polypropylene (aPP‐pPBM) as an interfacial agent. Hence, aPP‐pPBM was previously obtained, in our laboratories, by reactive processing in the melt of a by‐product (atactic PP) from industrial polymerization reactors. Present article is two‐fold, on one hand it has been planned to evidence the so called interfacial effects caused by this novel interfacial agent (aPP‐pPBM) yielding better final properties of the heterogeneous system as a whole as revealed by tensile mechanical properties, and on the other to obtain models to forecast the overall behavior of the system. For such purpose, a Box‐Wilson experimental design considering the amount of mica particles and of interfacial agent as independent variables was used to obtain polynomials to forecast the behavior of the PP/Mica system in the experimental space scanned. The existence of a critical amount of aPP‐pPBM to optimize mechanical properties appears to emerge. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization of highly filled wood flour–PVC composites: Morphological and thermal studies
Authors: Marathe D. S. , Joshi P. S.
Published: May 2009

Composites with polyvinyl chloride (PVC) as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer and wood flour (WF) and fly ash (FA) as filler were extruded. Morphology of the samples was studied using scanning electron microscopy (SEM). Morphological study indicated good dispersion of the constituents. Infrared spectroscopy (IR) indicates interaction between EVA and PVC and also between the polymeric matrix and WF. The effect of various constituents on glass transition temperature (Tg) was evaluated using differential scanning calorimetry. Addition of EVA decreased the Tg, whereas Tg was increased due to addition of WF and FA. Study indicated that reduction in Tg on addition of EVA was compensated by increase in Tg due to addition of WF. The contribution of FA to change in Tg was not significant. Resulting composites have Tg close to that of PVC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of ultra‐low molecular weight poly(vinyl alcohol) graft copolymer
Authors: Guo MinJie , Xia JianJun , Fan Zhi , Zhao Zhuo , Mi HuaiFeng
Published: May 2009

Graft reaction of acrylamide (AM) and 4‐vinyl pyridine (4‐VP) onto ultra‐low molecular weight poly(vinyl alcohol) by ceric (IV) ion initiation had been systematically investigated; and the graft conditions were optimized by studying the effect of monomer/initiator concentration, solvents composition, reaction time and temperature. At optimized conditions, the maximum grafting efficiency and grafting ratio was ∼ 50% and 51%, respectively with the presence of AM, whereas they decreased to 19% and 23%, respectively, without the presence of AM. Thermogravimetric analysis showed that as‐resulted graft copolymer had a lower thermal stability than homopolymer PVA. FTIR and 1H‐NMR confirmed chemical structure of as‐synthesized graft copolymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Shear‐induced crystallization of injection molded vetiver grass‐polypropylene composites
Authors: Somnuk Usa , Suppakarn Nitinat , Sutapun Wimonlak , Ruksakulpiwat Yupaporn
Published: May 2009

Vetiver grass was used as an alternative filler in polypropylene (PP) composites in this study. Chemical treatment of vetiver grass by alkalization was carried out to obtain alkali‐treated vetiver grass. It was shown that alkali‐treated vetiver grass exhibited higher thermal stability than untreated vetiver grass. Injection molding was used to prepare the composites. The microstructure of injection molded samples showed a distinct skin layer due to shear‐induced crystallization. It was found that normalized thickness of shear‐induced crystallization layer of the composite was lower than that of neat PP. The effect of vetiver particle sizes on shear‐induced crystallization and physical properties of the composites were elucidated. Furthermore, the effect of processing conditions on shear‐induced crystallization, degree of crystallinity, gapwise crystallinity distribution, and mechanical properties of the composite were investigated. It was shown that injection speed and mold temperature affected the normalized thickness of shear‐induced crystallization layer and degree of crystallinity of the composites. However, processing conditions showed insignificant effect on the mechanical properties of vetiver fiber‐PP composites. The degree of crystallinity showed no distribution throughout the thickness direction of the composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Aqueous dispersions of DBSA‐doped polyaniline: One‐pot preparation, characterization, and properties study
Authors: Babazadeh Mirzaagha
Published: May 2009

Aniline was polymerized in the presence of dodecylbenzene sulfonic acid (DBSA) as a functionalized protonic acid, in an aqueous medium to directly synthesize polyaniline (PANI)‐DBSA particles. DBSA acted as a dopant and a surfactant with stabilizing PANI‐DBSA dispersions by formation of strong hydrogen bonds. The NH+…SO interactions between the PANI chains and the DBSA appeared at 1026 cm−1 in Fourier transform infrared (FTIR) spectrum. Elemental analysis was used to determine the degree of sulfonation (S/N ratio) of PANI chains and resulted that the sulfur‐to‐nitrogen ratio is 0.35. Thermogravimetric analysis (TGA) technique was used to analyze thermal properties of the particles and resulted that the synthesized PANI‐DBSA particles have high thermal stability. The moisture, DBSA and PANI contents of the PANI‐DBSA were estimated from TGA curve, and then the number of aniline repeating units doped with one DBSA molecule was approximately calculated. X‐ray diffraction (XRD) analysis confirmed that a chemical crosslinking reaction occurs between the PANI chains during thermal treatment of PANI‐DBSA. The morphology of PANI‐DBSA powder was investigated by scanning electron microscopy technique and showed that the PANI particles develops from round particles to a smooth surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Adhesion of surface‐grafted low‐density polyethylene plates with enzymatically modified chitosan solutions
Authors: Noto Katsuhiko , Matsumoto Saeko , Takahashi Yasuhiro , Hirata Mitsuo , Yamada Kazunori
Published: May 2009

An investigation was undertaken on application of dilute chitosan solutions modified by tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenetylamine (dopamine) to adhesion of the low‐density polyethylene (LDPE) plates surface‐grafted with hydrophilic monomers. Tensile shear adhesive strength effectively increased with an increase in the grafted amount for methacrylic acid‐grafted and acrylic acid‐grafted LDPE (LDPE‐g‐PMAA and LDPE‐g‐PAA) plates. In particular, substrate breaking was observed at higher grafted amounts for LDPE‐g‐PAA plates. The increase in the amino group concentration of the chitosan solutions and molecular mass of the chitosan samples led to the increase in adhesive strength. Adhesive strength of the PE‐g‐PMAA plates prepared at lower monomer concentrations sharply increased at lower grafted amounts, which indicates that the formation of shorter grafted PMAA chains is an effective procedure to increase adhesive strength at lower grafted amounts. Infrared measurements showed that the reaction of quinone derivatives enzymatically generated from dopamine with carboxyl groups was an important factor to increase adhesive strength in addition to the formation of the grafted layers with a high water absorptivity. The above‐mentioned results suggested that enzymatically modified dilute chitosan solutions can be applied to an adhesive to bond polymer substrates. The emphasis is on the fact that water is used as a solvent for preparation of chitosan solutions and photografting without any organic solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009