bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfactant‐Encapsulated Polyoxometalates as Immobilized Supramolecular Catalysts for Highly Efficient and Selective Oxidation Reactions
Authors: Qi Wei , Wang Yizhan , Li Wen , Wu Lixin 
Published: January 2010

AbstractA type of interesting immobilized supramolecular catalysts based on surfactant‐encapsulated polyoxometalates has been developed for oxidation reactions. Through a sol‐gel process with tetraethyl orthosilicate, hydroxyl‐terminated surfactant‐encapsulated polyoxometalate complexes have been covalently and uniformly bound to a silica matrix with unchanged complex structure. The formed hybrid catalysts possess a defined hydrophobic nano‐environment surrounding the inorganic clusters, which is conducive to compatibility between the polyoxometalate catalytic centres and organic substrates. The supramolecular synergy between substrate adsorption, reaction, and product desorption during the oxidation process has been found to have an obvious influence on the reaction kinetics, with the activity of the catalyst being greatly improved. The supramolecular catalysts performed effectively in the selective oxidation of several different kinds of organic compounds, such as alkenes, alcohols, and sulfides, and the main products were the corresponding epoxides, ketones, sulfoxides, and sulfones. More significantly, the catalyst could be easily recovered by simple filtration, and the catalytic activity was well retained for at least five cycles. Finally, the present strategy has proved to be a general route for the fabrication of supramolecular hybrid catalysts containing common polyoxometalates suitable for various purposes.
A Selective 3‐Acylation of Tetramic Acids and the First Synthesis of Ravenic Acid
Authors: Schlenk Andrea , Diestel Randi , Sasse Florenz , Schobert Rainer 
Published: January 2010

Abstract3‐Acyltetramic acids, including delicate 3‐oligoenoyl derivatives, such as the Penicillium metabolite ravenic acid, were prepared in two high‐yielding steps. Reaction of tetramic acids with the ylide Ph3PCCO afforded exclusively the corresponding 3‐acylylidenetetramic acids. These were amenable to Wittig olefinations with aliphatic, aromatic, saturated and unsaturated aldehydes after deprotonation with KOtBu. Due to its simplicity, selectivity and tolerance of pH‐sensitive groups this method is superior to the established acylation protocols by Jones and Yoshii. It is also applicable to the synthesis of 3‐acyltetronic acids. The new 3‐oligoenoyl tetramic acids exhibited structure‐dependent antimicrobial and cytotoxic activity.
Self‐Association of Bis‐Dendritic Organogelators: The Effect of Dendritic Architecture on Multivalent Cooperative Interactions
Authors: Seo Myungeun , Kim Jung Hak , Kim Jisung , Park Nojin , Park Jeyoung , Kim Sang Youl 
Published: January 2010

AbstractA series of bis‐dendritic gelators consisting of a benzamide dendron and an alkyl dendron were synthesized to investigate the dendritic effect on self‐assembly. The gelators with a first‐generation benzamide (benzamide‐G1) dendron or a first‐generation alkyl (alkyl‐G1) dendron formed stable gels in most aromatic solvents, and their self‐assembled fibrillar networks were imaged by electron microscopy. The unbranched molecule (G0‐G0) or the molecule possessing a second‐generation benzamide (benzamide‐G2) dendron did not form gels. Differential scanning calorimetry, powder X‐ray diffraction, and Fourier transform IR studies revealed that introduction of a dendritic branch strongly affected the molecular packing as well as the strength of intermolecular interactions. Furthermore, concentration‐dependent diffusion coefficient measurements and the evaluation of association constants by1H NMR spectroscopy indicated that bis‐dendritic gelators with a benzamide‐G1dendron possessed high association constants and formed large aggregates, whereas molecules with a single benzamide formed dimers in chloroform. The formation of self‐assembled fibrillar networks was driven by the multivalent and cooperative hydrogen bonding observed in the benzamide‐G1dendrons. π–π stacking of aromatic groups and van der Waals interactions between alkyl chains also played roles in the self‐assembly process, thus indicating that a spatial balance between two dendrons is important.
Spontaneous Hierarchical Assembly of Crown Ether‐like Macrocycles into Nanofibers and Microfibers Induced by Alkali‐Metal and Ammonium Salts
Authors: Hui Joseph K.‐H. , Frischmann Peter D. , Tso Chien‐Hsin , Michal Carl A. , MacLachlan Mark J. 
Published: January 2010

AbstractSchiff base macrocycle 1, which has a crown ether like central pore, was combined with different alkali‐metal and ammonium salts in chloroform, resulting in one‐dimensional supramolecular aggregates. The ion‐induced self‐assembly was studied with solid‐state NMR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that the lengths and widths of the superstructures depend on the cation and counteranion of the salts. Among the salts being used, Na+ and NH4+ ions with BF4− ions showed the most impressive fibrous structures that can grow up to 1 μm in diameter and hundreds of microns in length. In addition, the size of the fibers can be controlled by the evaporation rate of the solvent. A new macrocycle with bulky triptycenyl substituents that prevent supramolecular assembly was prepared and did not display any nanofibers with alkali‐metal ions in chloroform when studied with TEM.
Self‐Assembly of Discrete Homochiral, Helical, Hydrogen‐Bonded Nanocages: From Vesicles to Microspheres and Tubules Capable of Gelating Solvents
Authors: Yan Liwei , Xue Ying , Gao Ge , Lan Jingbo , Yang Fan , Su Xiaoyu , You Jingsong 
Published: January 2010

AbstractThe chiral tris‐monodentate imidazolinyl ligands 1 a–c exhibit a strong tendency to form the discrete, helical [2+3] nanocages 3 ([12⋅23]) with tartaric acids 2. Circular dichroism (CD) spectra and theoretical calculations reveal that supramolecular handedness of capsulelike architectures is determined only by the chirality of the imidazolinyl ligands rather than tartaric acids. The chirality of imidazolinyl ligands is transferred to the helicity of the complexes through the directed hydrogen bonds between the N3 atom of imidazoline rings and the carboxyl of tartaric acids. These hydrogen‐bonded nanocages can spontaneously self‐assemble into spherical vesicles, during which the hydrogen bonding that arises from the hydroxyl groups of tartaric acids plays a crucial issue. The vesicles formed by [{(S,S,S)‐1 a}2(2L)3] (3 a) may further evolve into microspheres that gelate organic solvents after being aged at −20 °C for 24 h, and can also be unprecedentedly transformed to tubular assemblies capable of rigidifying the solvents when subjected to ultrasound irradiation.
Synthesis, Structures, and Properties of Fused Thiophenes for Organic Field‐Effect Transistors
Authors: Liu Ying , Di Chong‐an , Du Chunyan , Liu Yunqi , Lu Kun , Qiu Wenfeng , Yu Gui 
Published: January 2010

AbstractA series of fused thiophenes composed of fused α‐oligothiophene units as building blocks, end‐capped with either styrene or 1‐pentyl‐4‐vinylbenzene groups, has been synthesized through Stille coupling reactions. The compounds have been fully characterized by means of 1H NMR spectrometry, high‐resolution mass spectrometry, and elemental analysis. The molecules present a trans–trans configuration between their double bonds, which has been verified and confirmed by Fourier‐transform infrared spectroscopy and single‐crystal X‐ray diffraction analysis. The X‐ray crystal structures showed π–π overlap and sulfur–sulfur interactions between the adjacent molecules. The decomposition temperatures were all found to be above 300 °C, indicating that compounds of this series possess excellent thermal stability. The fact that no phase transition occurs at low temperature indicates that they should be well‐suited for application in devices. Moreover, they possess low HOMO energy levels, based on cyclic voltammetry measurements, and suitable energy gaps, as determined from their thin‐film UV/Vis spectra. Thin‐film X‐ray diffraction analysis and atomic force microscopy revealed high crystallinity on supporting substrates. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity, the device performance could be optimized by varying the substrate temperature. These materials were found to exhibit optimal field‐effect performance, with a mobility of 0.17 cm2 V−1 s−1 and an on/off ratio of 105, at a substrate temperature of 70 °C.
Radical Arylation of Phenols, Phenyl Ethers, and Furans
Authors: Wetzel Alexander , Pratsch Gerald , Kolb Roman , Heinrich Markus R. 
Published: January 2010

AbstractRadical arylations of para‐substituted phenols and phenyl ethers proceeded with good regioselectivity at the ortho position with respect to the hydroxy or alkoxy group. The reactions were conducted with arenediazonium salts as the aryl radical source, titanium(III) chloride as the reductant, and diluted hydrochloric acid as the solvent. Substituted biaryls were obtained from hydroxy‐ and alkoxy‐substituted benzylamines, phenethylamines, and aromatic amino acids. The methodology described offers a fast, efficient, and cost‐effective new access to diversely functionalized biphenyl alcohols and ethers. Free phenolic hydroxy groups, aromatic and aliphatic amines, as well as amino acid substructures, are well tolerated. Two examples for the applicability of the methodology are the partial synthesis of a β‐secretase inhibitor and the synthesis of a calcium‐channel modulator.
Bestimmung kinetischer Parameter der FADH2‐abhängigen Tryptophan‐5‐Halogenase aus Streptomyces rugosporus
Authors: Muffler K. , Kuetchou Ngnigha A. R. , Ulber R. 
Published: January 2010

AbstractBiokatalysatoren zur regioselektiven Halogenierung bestimmter Substrate sind mittlerweile verfügbar. Ein Einsatz solcher Halogenasen zur Bereitstellung halogenierter (Zwischen‐) Produkte bietet im Vergleich zur klassischen Halogenierung den Vorteil, dass sie weitgehend nebenproduktfrei abläuft und keine toxischen Halogenierungsagentien zur Anwendung kommen. Beispielhaft wird hier die Untersuchung kinetischer Parameter einer Tryptophan‐5‐Halogenase beschrieben.
Charakterisierung von Cellulasepräparationen mittels Streulicht
Authors: Spiess A. C. , Wulfhorst H. , Jäger G. , Ellinidou E. , Büchs J. 
Published: January 2010

AbstractDie selektive enzymatische Hydrolyse von Lignocellulose ist einer der kritischen Schritte der stofflichen und energetischen Nutzung von Biomasse und benötigt Methoden zum Screening und zur Charakterisierung der Biokatalysatoren im Hochdurchsatz. Die BioLector‐Technik detektiert den enzymatischen Abbau suspendierter α‐Cellulose anhand abnehmender Streulichtintensität. Es wurden kinetische Parameter und das pH‐Optimum eines kommerziellen Cellulasepräparates ermittelt und so die Eignung der BioLector‐Technik zur Hochdurchsatzcharakterisierung gezeigt.
Potenzial von Prozessintegration mit Adsorbern zur Herstellung seltener Monosaccharide – eine modellbasierte Untersuchung
Authors: Bechtold M. , Füreder M. , Wagner N. , Panke S. 
Published: January 2010

AbstractEnzymatische Isomerisierungsreaktionen ermöglichen die Synthese seltener Monosaccharide wie D‐Psicose oder D‐Tagatose, die potenziell sehr interessant sind als Bausteine für Pharmaprodukte oder Süßstoffe. Um solche Reaktionen industriell anzuwenden, muss aber das Gleichgewichtsproblem gelöst werden: Isomerisierungen weisen typischerweise eine ungünstige Lage des thermodynamischen Gleichgewichts auf und lassen somit nur limitierte Ausbeuten zu. In situ‐Produktabtrennung stellt eine interessante Prozessoption dar, um die Umsatzlimitierung zu überwinden. In dieser Arbeit werden zwei Prozessvarianten zur Integration von enzymatischer Isomerisierung und Adsorption in einer modellbasierten Untersuchung verglichen: zum einen die direkte Integration im Satzreakor, die eine sehr einfache Betriebsweise darstellt. Allerdings kann hier nur mit hochselektiven und hoch beladbaren Adsorbermaterialien, die es zudem erst noch zu entwickeln gilt, eine hohe Ausbeute bei hoher Produktivität erreicht werden. Mit momentan zur Verfügung stehenden Adsorbern ist, wenn überhaupt, nur eine minimale Steigerung möglich. Zum anderen wurde die Integration von kontinuierlicher Simulated Moving Bed (SMB)‐Trennung, Enzymmembranreaktor und Nanofiltration theoretisch untersucht. Konkret konnte mithilfe von modellgestützten Optimierungen gezeigt werden, dass unter Verwendung von kostengünstigem Ionentauschermaterial für die SMB‐Zuckertrennung wettbewerbsfähige Produktivitäten bei praktisch vollständiger Ausbeute erreicht werden können.
Identifizierung und Expression neuer Biokatalysatoren
Authors: Leggewie C. , Puls M. , Eggert T. 
Published: January 2010

AbstractDie begrenzten fossilen (Energie‐) Ressourcen der Erde werden in den nächsten Jahren dazu führen, dass in vielen Bereichen ein Umdenken stattfinden muss. Dazu gehört auch die nachhaltige Herstellung von Chemikalien bzw. daraus resultierenden Produkten des täglichen Lebens. Einen bedeutenden Beitrag hierzu kann die Biokatalyse leisten. Chemische (Produktions‐) Prozesse können durch den alternativen Einsatz von enzymatisch katalysierten Umsetzungen durch die so genannten Biokatalysatoren ökologischer und häufig auch ökonomischer durchgeführt werden. Für die meisten Stoffumsetzungen stehen allerdings keine oder nur unzureichend geeignete Biokatalysatoren zur Verfügung. Eine große Herausforderung der kommenden Jahre und Jahrzehnte ist also die Identifizierung neuer, spezifischer Enzyme, die ebenfalls in ausreichenden Mengen produziert werden müssen. Dieser Artikel gibt einen Überblick der neuen Entwicklungen und Fortschritte auf diesem Gebiet.
Early (sentinel lymph node biopsy‐guided) versus delayed lymphadenectomy in melanoma patients with lymph node metastases
Authors: Pasquali Sandro , Mocellin Simone , Campana Luca G. , Bonandini Elena , Montesco Maria C. , Tregnaghi Alberto , Del Fiore Paolo , Nitti Donato , Rossi Carlo R. 
Published: January 2010

AbstractBACKGROUND:It is debated whether patients with melanoma who undergo lymphadenectomy after a positive sentinel lymph node (SN) biopsy (SNB) have a better prognosis compared with patients who are treated for clinically evident disease.METHODS:The records of 190 patients with cutaneous melanoma who underwent radical lymph node dissection after a positive SNB (completion lymph node dissection [CLND]; n = 100) or who had clinically evident lymph node metastasis (therapeutic lymph node dissection [TLND]; n = 90) were analyzed. Moreover, the MEDLINE, EMBASE, and Cochrane databases were searched for studies that investigated the survival impact of SNB‐guided CLND compared with TLND for clinically evident disease. Standard meta‐analysis methods were used to calculate the overall treatment effect across eligible studies.RESULTS:In the authors' series, tumor characteristics did not differ significantly between patients who underwent CLND and those who underwent TLND. After a median follow‐up of 52.6 months, the 5‐year overall survival rate did not differ significantly between CLND patients and TLND patients (68.9% vs 50.4%, respectively; log‐rank test; P = .17). In contrast, a meta‐analysis of 6 studies (n = 2633) that addressed this issue (including the authors' own series) indicated that there was a significantly higher risk of death for patients who underwent TLND compared with that for patients who underwent CLND (hazard ratio, 1.60; 95% confidence interval, 1.28‐2.00; P < .0001).CONCLUSIONS:Although no significant survival difference was observed in either series, the pooling of summary data from all the studies that dealt with this issue suggested that SNB‐guided CLND is associated with a significantly better outcome compared with TLND for clinically evident lymph node disease. Cancer 2010. © 2010 American Cancer Society.
Anxiety and its correlates among older adults accessing aging services
Authors: Richardson Thomas M. , Simning Adam , He Hua , Conwell Yeates 
Published: January 2010

AbstractObjectivesTo assess the characteristics of anxiety in aging services network (ASN) clients.MethodsInterviews were conducted as part of an academic‐community partnership for studying the mental health needs of community‐dwelling older adults. Participants consisted of ASN clients in Monroe County, NY, that were aged 60 years and older and received an in‐home assessment for care management services. The Goldberg Anxiety Scale screened for anxiety symptoms, and instruments covering the domains of associated mental health, physical health and disability, social support, negative life events, and other areas relevant to delivery of aging services were administered.ResultsOf 378 subjects enrolled, 27% had clinically significant levels of anxiety. In bivariate analyses anxiety was associated with having a current major depressive episode (MDE), five or more medical conditions, pain, younger age, less income, and negative life events. After controlling for MDE in multivariate analyses, medical conditions, pain, negative life events, and younger age were significant correlates of anxiety in ASN clients.ConclusionsAnxiety was common among ASN clients who received in‐home care management services. These anxious clients suffered from a combination of mental, medical, and social issues that suggests the need for multidisciplinary care. Because aging services providers work with their clients to ameliorate conditions that are highly correlated with anxiety, the ASN represents a promising venue for detecting, managing, and preventing anxiety among older adults. Copyright © 2010 John Wiley & Sons, Ltd.
The Brazilian national health system: an unfulfilled promise?
Authors: Ocké‐Reis Carlos Octávio , Marmor Theodore R. 
Published: January 2010

AbstractIn 1988, Brazil became one of the first countries in Latin America to frame access to health care as a constitutional right. However, it would be misleading to call Brazil's Unified Health System (Sistema Único de Saúde, or SUS) a public health system that provides universal access and comprehensive care. This paper reveals a strong contradiction between the re‐distribution model set out in the Brazilian Constitution and the inadequate level of public spending on health care. The law states that health care is a basic social right, allocated by need rather than means. Meanwhile, in 2003, Brazil spent US$ 597 per capita on health, or 7.6 per cent of its gross domestic product (GDP), while the average country from the Organization for Economic Cooperation and Development (OECD) spent US$ 3145, or 10.8 per cent, and Argentina spent US$ 1067, or 8.9 per cent of its GDP. Copyright © 2010 John Wiley & Sons, Ltd.
On the use of planning models in the operating theatre: results of a survey in Flanders
Authors: Cardoen Brecht , Demeulemeester Erik , Van der Hoeven Jessie 
Published: January 2010

AbstractThis paper presents an overview of the operating theatre planning and scheduling practice of hospitals in Flanders (Belgium). An electronic survey was sent to 95 hospitals in which surgeries are performed, which eventually resulted in a response set of 52 hospitals (55%). The questionnaire did not only focus on issues related to the elective (inpatient and outpatient) planning and scheduling process, but also questioned how hospitals currently deal with the occurrence of non‐elective surgeries (urgencies and emergencies). We indicate what goals health managers try to achieve and how this planning is established. We furthermore pay attention to some possible disruptions to the schedule and the corresponding anticipatory methods. Despite the proliferation of computerized planning and scheduling procedures proposed by the scientific community, the implementation rate of satisfying technological planning or evaluation systems still seems to be low. In order to increase the operating theatre efficiency, a closer cooperation between the academic institutions and the practitioners should be encouraged. Copyright © 2010 John Wiley & Sons, Ltd.
Hospitalization in Tajikistan: determinants of admission, length of stay, and out‐of‐pocket expenditures. Results of a national survey
Authors: Habibov Nazim 
Published: January 2010

AbstractObjectiveTo assess factors explaining hospitalization in Tajikistan and discuss policy implications for reforms in hospital care.MethodsThis study involves a secondary analysis of micro‐data collected from a nationally‐representative household survey conducted in Tajikistan in 2003. Three empirical models are employed: binomial logit regression for the admission to the hospital; zero truncated negative binomial (ZTNB) regression for the length of hospital stay; and ordinary least square (OLS) for the amount of out‐of‐pocket expenditures for hospitalization.FindingsVariation in hospital admission is due to the differences in ability to pay, long‐standing illness, gender, age, and educational level. Factors explaining out‐of‐pocket expenditures include ability to pay, having long‐standing illness, and having surgery and receiving intensive care. The most important out‐of‐pocket expenditures are payments for pharmaceuticals and supplies. Finally, long hospital stay that is the result of outdated treatment protocols, rigid financial and management system, lack of funding, and weakness of primary and long‐tem care. As a result, long time in inpatient care is mostly used ineffectively.ConclusionStrategies to address the existing deficiencies include voluntary community‐based health insurance for rural areas, targeted subsidized care for the neediest, improvements in procurement of pharmaceuticals and supplies, and rationalization of hospital primary and long‐term care. Copyright © 2010 John Wiley & Sons, Ltd.