bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes following a limited approach to radiotherapy in rectal cancer
Authors: Simunovic M , Jacob S , Coates A J , Vogt K , Moran B J , Heald R J
Published: June 2011

Background

Variation in the use of neoadjuvant and adjuvant radiotherapy for rectal cancer suggests an opportunity to avoid it in all but patients at highest risk of local recurrence.

Methods

Between 1 July 1999 and 1 February 2006, patients with primary rectal cancer were treated by a single surgeon operating at McMaster University, Hamilton, Ontario, Canada. Digital rectal examination and pelvic computed tomography were used to determine whether the mesorectal margin was threatened by tumour and thus whether preoperative radiotherapy would be needed. The study outcome was local tumour recurrence.

Results

Forty-six (48 per cent) of 96 patients received preoperative radiation therapy. The median follow-up was 4·2 years. Tumours were fixed or tethered in 31 (67 per cent) of the 46 irradiated patients. In contrast, no tumour was fixed in unirradiated patients and only ten (20 per cent) of the 50 tumours were tethered. The proportion of patients with stage I or II tumours based on final pathology was similar: 61 per cent (28 of 46) and 56 per cent (28 of 50) in irradiated and unirradiated groups respectively (P = 0·287). There were four (9 per cent) and two (4 per cent) local recurrences among irradiated and unirradiated patients respectively (P = 0·422).

Conclusion

Limiting preoperative radiotherapy in rectal cancer to patients with a threatened circumferential margin does not compromise patient outcome.
Operative notes do not reflect reality in laparoscopic cholecystectomy
Authors: Wauben L S G L , van Grevenstein W M U , Goossens R H M , van der Meulen F H , Lange J F
Published: June 2011

Background

Operative notes represent an essential element in safe patient care and should therefore be clear and accurate. This comparative study examined whether operative notes accurately represented the laparoscopic cholecystectomy (LC) as performed.

Methods

Nine Dutch teaching and non-teaching hospitals were invited to record 20 successive LCs each and to collect the corresponding operative notes. The main outcome measures were overall differences and correspondence between video recordings and notes based on the Dutch guideline for LC and the occurrence of iatrogenic gallbladder perforation. A comparison was made of the cumulative results of recordings and operative notes, and individual recordings were compared with the corresponding notes.

Results

Seven hospitals participated in the study; 125 video recordings and operative notes were fully analysed. Recordings showed more steps of the procedure than did notes. Individual comparisons showed significant differences (P≤0·001) between the recording and the corresponding note for the steps ‘Introducing trocars under vision’, ‘Condition of the gallbladder’, ‘Critical view of safety’ and ‘Removing first and second trocar under vision’. Iatrogenic gallbladder perforation with spilled bile occurred in 31 patients (24·8 per cent), and was both recorded and reported in 29 patients. Iatrogenic gallbladder perforation with spilled bile and spilled stones occurred in 15 patients (12·0 per cent), and was recorded and reported in 11 patients.

Conclusion

Operative notes do not adequately represent the actual LCs performed as they describe fewer important procedural steps. It is suggested that operative notes should include video recordings.
Migrants' Integration in Western Europe: Bridging Social Psychology and Political Science
Authors: Scuzzarello Sarah
Published: June 2011

This article presents the possibilities and advantages of integrating social psychology and political science in the study of intergroup relations in diverse societies in Western Europe. Social psychology provides interesting insights in understanding the emotional and cognitive consequences of increased diversity. However, this literature tends to overlook the role of institutional discourses and correlated practices in stimulating or constraining positive intergroup relations. In order to fill these lacunae, the article suggests the integration of social psychology and a ‘political opportunity structure’ approach. This article maintains that the political opportunity structures operating in a context are not only important for understanding actors' mobilisation, as usually maintained in the literature, but also for studying the extent to which change at the micro‐level of social interaction can be stimulated or constrained. We illustrate the arguments of the article with an analysis of the narrative constructions and the correlated practices of integration as adopted by the city councils of Malmö and Bologna. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of a Sugar‐O‐methyltransferase TiaS5 Affords New Tiacumicin Analogues with Improved Antibacterial Properties and Reveals Substrate Promiscuity
Authors: Niu Siwen , Hu Tao , Li Sumei , Xiao Yi , Ma Liang , Zhang Guangtao , Zhang Haibo , Yang Xiaohong , Ju Jianhua , Zhang Changsheng
Published: June 2011

The 18‐membered macrocyclic glycoside tiacumicin B, an RNA polymerase inhibitor, is of great therapeutic significance in treating Clostridium difficile infections. The recent characterization of the tiacumicin B biosynthetic gene cluster from Dactylosporangium aurantiacum subsp. hamdenensis NRRL 18085 revealed the functions of two glycosyltransferases, a C‐methyltransferase, an acyltransferase, two cytochrome P450s, and a tailoring dihalogenase in tiacumicin biosynthesis. Here we report the genetic confirmation and biochemical characterization of TiaS5 as a sugar‐O‐methyltransferase, requisite for tiacumicin B biosynthesis. The tiaS5‐inactivation mutant is capable of producing 14 tiacumicin analogues (11 of which are new), all lacking the 2′‐O‐methyl group on the internal rhamnose moiety. Notably, two tiacumicin analogues exhibit improved antibacterial properties. We have also biochemically verified TiaS5 as an S‐adenosyl‐L‐methionine‐dependent O‐methyltransferase, requiring divalent metal ions for activity. Substrate probing revealed TiaS5 to be a promiscuous enzyme, recognizing 12 tiacumicin analogues. These findings unequivocally establish that TiaS5 functions as a 2′‐O‐methyltransferase and provide direct biochemical evidence that TiaS5‐catalyzed methylation is a tailoring step after glycosyl coupling in tiacumicin B biosynthesis.
STEM HAADF Image Simulation of the Orthorhombic M1 Phase in the Mo‐V‐Nb‐Te‐O Propane Oxidation Catalyst
Authors: Blom Douglas A. , Li Xin , Mitra Sonali , Vogt Thomas , Buttrey Douglas J.
Published: June 2011

A full frozen phonon multislice simulation of high angle annular dark field scanning transmission electron microscopy (HAADF STEM) images from the M1 phase of the Mo‐V‐Nb‐Te‐O propane oxidation catalyst has been performed by using the latest structural model obtained using the Rietveld method. Simulated contrast results are compared with experimental HAADF images. Good agreement is observed at ring sites, however significant thickness dependence is noticed at the linking sites. The remaining discrepancies between the model based on Rietveld refinement and image simulations indicate that the sampling of a small volume element in HAADF STEM and averaging elemental contributions of a disordered site in a crystal slab by using the virtual crystal approximation might be problematic, especially if there is preferential Mo/V ordering near the (001) surface.
Molecular‐Glue‐Triggered DNA Assembly To Form a Robust and Photoresponsive Nano‐Network
Authors: Wang Chunyan , Pu Fang , Lin Youhui , Ren Jinsong , Dohn Chikara , Nakatani Kazuhiko , Qu Xiaogang
Published: June 2011

A robust and photoresponsive DNA network has been designed and constructed from branched DNA and molecular glue. The molecular glue is photoswitchable and can specifically bind to G–G mismatched double‐stranded DNA. The assembly process can be reversibly controlled by manipulating the wavelength of light. The approach is flexible, allowing tuning of the size, morphology as well as the cavity of the network by variation of the molar ratio and the isotropic/anisotropic character of the branched building blocks. The assembled architectures are versatile and heat tolerant. These properties should allow the use of the network in further applications.
Local Measurement Techniques for Multiphase Flows
Authors: Schlüter Michael
Published: June 2011

Mehrphasenströmungen, in denen Tropfen, Blasen oder Feststoffpartikel in einer kontinuierlichen Phase vorliegen, beherrschen die überwiegende Zahl heutiger Prozesse der verfahrenstechnischen Industrie. Trotz der großen Bedeutung von Mehrphasenströmungen können Dispersphasen‐, Temperatur‐ und Konzentrationsverteilungen bisher nicht mit der geforderten Genauigkeit berechnet werden, da durch Grenzschichten und anisotrope Turbulenz sehr komplexe, strömungsmechanische Transportphänomene vorliegen, die auf sehr unterschiedlichen Größenskalen ablaufen. Für ein tieferes Verständnis der skalenübergreifenden Transportphänomene sind folglich lokale Messverfahren für Mehrphasenströmungen erforderlich, die Daten mit hoher räumlicher und zeitlicher Auflösung erfassen und die Strömung möglichst nicht beeinflussen. Es wird ein Überblick über einige derzeit verfügbare lokale Messverfahren gegeben, wobei nicht explizit zwischen Gas‐ und Flüssigströmungen unterschieden wird.
Identification of Xanthones as Selective Killers of Cancer Cells Overexpressing the ABC Transporter MRP1
Authors: Genoux‐Bastide Estelle , Lorendeau Doriane , Nicolle Edwige , Yahiaoui Samir , Magnard Sandrine , Di Pietro Attilio , Baubichon‐Cortay Hélène , Boumendjel Ahcène
Published: June 2011

Multidrug‐resistance protein 1 (MRP1) belongs to the ATP‐binding cassette (ABC) transporter family. MRP1 mediates MDR (multidrug resistance) by causing drug efflux either by conjugation to glutathione (GSH) or by co‐transport with free GSH (without covalent bonding between the drug and GSH). We recently reported that the calcium channel blocker verapamil can activate massive GSH efflux in MRP1‐overexpressing cells, leading to cell death through apoptosis. However, clinical use of verapamil is hampered by its cardiotoxicity. Then, in the search for compounds that act similarly to verapamil, but without major side effects, we investigated xanthones. Herein we show that xanthones induce apoptosis among resistant cells overexpressing MRP1 similarly to the verapamil effect. Among the xanthones studied, 1,3‐dihydroxy‐6‐methoxyxanthone was identified as the most active derivative, able to specifically kill cells transfected with human MRP1 with even greater potency than verapamil. Under the same conditions, the active xanthones have no toxic effect on control (sensitive) cells. Xanthones could therefore be considered as new potential anticancer agents for the selective treatment of MRP1‐positive tumors.
Brønsted Acidity and the Medium: Fundamentals with a Focus on Ionic Liquids
Authors: Mihichuk Lynn M. , Driver Gordon W. , Johnson Keith E.
Published: June 2011

Fundamental aspects of Brønsted acidity in ionic liquid systems, in relation to those of simple protic molecules in the gas phase, pure protic molecules in the condensed phase and solutions of protic molecules in molecular systems, are presented. The variety of acidities possible, beyond those observed in aqueous systems, is emphasised and discussed in terms of differences of solvent levelling, ionisation, dissociation, homo‐/hetero‐conjugate ion speciation and the stabilisation of proton‐transfer products from solvent to solvent. It is argued that data regarding aqueous systems do not necessarily explain acid/base behaviour in other liquids satisfactorily. Methods of measuring acidity are reviewed, particularly by spectrophotometry and electrochemistry and recommendations proffered for estimating speciation and acidity of ionic liquids of various complexities.
Rate adaptation with loss diagnosis on IEEE 802.11 networks
Authors: Wu Shaoen , Biaz Saâd , Wang Honggang
Published: June 2011

Rate adaptation in wireless networking aims to seek the optimal data transmission rate most appropriate for current wireless channel conditions to make full use of the channel potentials. It is important in wireless networks because (1) most of them support multiple data rates, and (2) wireless channel is unstable with fast changes on which a single rate thereby may not be proper for long. Based on a comprehensive survey of the rate adaptation for IEEE 802.1 networks in literature, this work proposes a rate adaptation scheme, dubbedeffective rate adaptation(ERA), for IEEE 802.11 networks. ERA takes advantage of the fragmentation technique in IEEE 802.11 standard and utilizes the lowest rate retransmission in diagnosing frame loss cause (collision or channel degradation), diffusing collision, and promptly recovering frame losses. It also adopts an adaptive rate increase threshold concept to exploit channel potentials. Different from other rate adaptation schemes, ERA effectively addresses two challenges in rate adaptation on IEEE 802.11 networks: (1) it does not require RTS/CTS for loss diagnosis purpose; the use of RTS/CTS that are optional in IEEE standard results in inefficiency on channel utilization; (2) itpromptlyresponds to frame failure due to channel degradation, unlike others waiting till the end of a transmission window or cycle. With extensive simulation, ERA shows its unique strength in different lossy environments, especially in collision‐prone environments. Copyright © 2011 John Wiley & Sons, Ltd.
Effective allied network security system based on designed scheme with conditional legitimate probability against distributed network attacks and intrusions
Authors: Chen Ruey‐Maw , Hsieh Kuo‐Ta
Published: June 2011

Dependence on the Internet is increasing dramatically. Therefore, many researchers have given great attention to the issue of how to tighten Internet security. This study proposes a new scheme for the distributed intrusion prevention system (DIPS), in which the concept of ‘union’ is presented for satisfying the increasing requirements of Internet security issues. In this proposed design, the network intrusion detection system (NIDS) applies a misuse detection technique to detect well‐known intrusion behavior on the Internet. Meanwhile, for anomaly detection technique, a tool named ‘Scent’ (a network traffic sniffer) is combined with conditional legitimate probability to reveal previously undiscovered intrusion packets that do not match the intrusion signatures in NIDS. Moreover, blocking distributed denial‐of‐service (DDoS) attacks inside the protected allied network is also covered. To increase the detection accuracy, reduction of false positives and false negatives is also accomplished. Experimental results reveal that the suggested network security system scheme is effective and efficient in resolving the intrusion activity problem of real network environments. Copyright © 2011 John Wiley & Sons, Ltd.
Antigen‐presentation capacity of dendritic cells is impaired in ongoing enterovirus myocarditis
Authors: Rahnefeld Anna , Ebstein Frédéric , Albrecht Nadine , Opitz Elisa , Kuckelkorn Ulrike , Stangl Karl , Rehm Armin , Kloetzel Peter M. , Voigt Antje
Published: June 2011

Coxsackievirus B3 (CVB3)‐infection is a frequent cause of acute myocarditis, which may result in chronic myocarditis and virus persistence. Investigation of the initial immune responses to CVB3 may shed light on the mechanisms that contribute to ongoing disease. DCs, as key professional APCs, were investigated in two MHC‐matched hosts: while C57BL/6 mice are resistant to chronic CVB3‐myocarditis, the A.BY/SnJ mouse strain exhibits susceptibility. DC maturation and activation were critically impaired in A.BY/SnJ mice, as reflected by the failure of DCs to induce co‐stimulatory molecules and cytokine/chemokine responses. MHC class I‐restricted antigen presentation via the cross‐presentation pathway was also affected in DCs from A.BY/SnJ mice. DC maturation involves the accumulation of DC aggresome‐like induced structures (DALISs) and the transient storage of defective ribosomal products (DRiPs). DCs from A.BY/SnJ mice showed permanent DALIS accumulation; the detection of poly‐ubiquitinylated CVB3 proteins in these DALISs suggested a limitation in the MHC class I antigenic supply in this host. In conclusion, ongoing chronic disease in A.BY/SnJ mice due to a failure to clear the virus may be attributed to defects in DC maturation/activation and DC MHC class I antigen processing.
Adaptive immune defects against glycoantigens in chronic granulomatous disease via dysregulated nitric oxide production
Authors: Lewis Colleen J. , Cobb Brian A.
Published: June 2011

Chronic granulomatous disease (CGD) is a primary immunodeficiency defined by mutations in the NADPH oxidase complex leading to reduced superoxide production, increased susceptibility to infection, chronic inflammation, and recurring abscess and granuloma formation. Here, we found that CGD mice were hyperresponsive to abscess‐inducing T‐cell‐dependent carbohydrate antigens (glycoantigens) due to a ten‐fold increase in NO production within APCs, which is known to be necessary for glycoantigen presentation on MHC class II. CGD mice exhibited increased Th1 pro‐inflammatory T‐cell responses in vitro and in vivo, characterized by more severe abscess pathology. This phenotype was also seen in WT animals following adoptive transfer of neutrophil‐depleted APCs from CGD animals, demonstrating that this phenotype was independent of neutrophil and T‐cell defects. Finally, pharmacological attenuation of NO production to WT levels in vivo reduced abscess incidence and severity in CGD without overt increases in inflammation or the ability to clear infection, suggesting a potential new treatment option for early stage CGD‐associated infections.
T‐zone localized monocyte‐derived dendritic cells promote Th1 priming to Salmonella
Authors: Flores‐Langarica Adriana , Marshall Jennifer L. , Bobat Saeeda , Mohr Elodie , Hitchcock Jessica , Ross Ewan A. , Coughlan Ruth E. , Khan Mahmood , Van Rooijen Nico , Henderson Ian R. , MacLennan Ian C.M. , Cunningham Adam F.
Published: June 2011

Control of intracellular Salmonella infection requires Th1 priming and IFN‐γ production. Here, we show that efficient Th1 priming after Salmonella infection requires CD11c+CD11bhiF4/80+ monocyte‐derived dendritic cells (moDCs). In non‐infected spleens, moDCs are absent from T‐cell zones (T zones) of secondary lymphoid tissues, but by 24 h post‐infection moDCs are readily discernible in these sites. The accumulation of moDCs is more dependent upon bacterial viability than bacterial virulence. Kinetic studies showed that moDCs were necessary to prime but not sustain Th1 responses, while ex vivo studies showed that antigen‐experienced moDCs were sufficient to induce T‐cell proliferation and IFN‐γ production via a TNF‐α‐dependent mechanism. Importantly, moDCs and cDCs when co‐cultured induced superior Th1 differentiation than either subset alone, and this activity was independent of TNF‐α. Thus, optimal Th1 development to Salmonella requires the rapid accumulation of moDCs within T zones and their collaboration with cDCs.
Molecular Assemblies Based on Polytungstate Clusters and the Flexible Organic Ligand 1,3‐Bis(4‐pyridyl)propane
Authors: Han Zhangang , Wang Yanna , Song Xuejun , Zhai Xueliang , Hu Changwen
Published: June 2011

Four polyoxometalate (POM) assemblies based on the flexible organic ligand 1,3‐bis(4‐pyridyl)propane (bpp) have been synthesized and fully characterized, including (Hbpp)3[PW12O40] (1), [Cu(bpp)]2[Cu2(bpp)3][SiW12O40] (2), [Cu2(Hbpp)4](H2bpp)0.5H2[SbW18O60]·3H2O (3), and (H2bpp)5[Ni4(OH2)2(AsW9O34)2]·0.5H2O (4). Compounds 1 and 2 were prepared by the reaction of the classical Keggin‐type anions with organic bpp under hydrothermal conditions. The difference between these compounds is that protonated bpp is found in 1, whereas in 2 CuI‐bpp fragments are present. In the framework of 1, organic and hybrid chains, built upon supramolecular interactions, coexist. Compound 2, which crystallizes in a chiral space group, has a 2D wave‐like structure consisting of {Cu6(bpp)6} grids that accommodate {[Cu2(bpp)2][SiW12O40]}2– fragments. The nonclassical anionic clusters in 3 and 4 are obtained from simple inorganic salts or oxides under hydrothermal conditions. The inorganic moiety in 3 exhibits a pseudo‐Dawson‐like [SbW18O60]9– cluster, and in 4 a sandwich‐type [Ni4(H2O)2(AsW9O34)2]10– anion is present. The organic ligand bpp, with a freely rotatable –(CH2)3– group, is present in various conformations in the four compounds. Structure‐analyses results indicate that the flexibility of bpp plays a significant role in the fabrication of these kinds of inorganic‐organic arrangements. The thermal and electrochemistry properties of all four compounds have also been studied.
Disorder in Rare Earth Metal Halide Carbide Nitrides
Authors: Schaloske Manuel C. , Kienle Lorenz , Mattausch Hansjürgen , Duppel Viola , Simon Arndt
Published: June 2011

Single‐crystal X‐ray structure determinations of Ce4I6CN and disordered Ce6I9C2N phases are described together with electron‐microscopy studies of Ce6I9C2N and Y6I9C2N. Ce4I6CN crystallizes in the tetragonal space group P42/mnm with a = 13.877(2) Å, c = 9.665(2) Å. Compounds β′‐Ce6I9C2N and β″‐Ce6I9C2N crystallize in space group P6/m with a = 41.774(6) Å, c = 13.719(3) Å and a = 20.958(3) Å, c = 13.793(3) Å, respectively. The main structural feature of these compounds are rods of RE6C2 octahedra and RE4N tetrahedra (RE = lanthanide) interconnected in different sequences. These rods are linked into Kagomé‐type frameworks with additional rods located in the centres of thehexagonal channels. The disorder patterns for these additional rods can be rationalized in terms of nearest‐neighbour interactions.
Synthesis of Homo‐ and Hetero‐Bimetallic Arsenic Complexes by Means of Regioselective Monoinsertion of Alkynylarsane into the Pd–C Bond of a Palladacycle
Authors: Chen Shuli , Pullarkat Sumod A. , Li Yongxin , Leung Pak‐Hing
Published: June 2011

Cyclopalladated and cycloplatinated complexes, which incorporated the N,N‐dimethylbenzylamine and N,N‐dimethylnaphthylamine motifs, were successfully employed to promote a series of intermolecular monoinsertion reactions of diphenyl‐1‐propynylarsane, Ph2AsC≡CMe, into the Pd–C bond of the chiral α‐methyl N,N‐dimethylbenzylamine palladacycles. The precursor complexes were prepared by means of the coordination of the Ph2AsC≡CMe moiety onto the metal center trans to the benzylamine– or naphthylamine–N donor atom of the cyclometallated complexes. Subsequently a series of monoinsertion reactions were carried out between these precursor complexes and the enantiomerically pure N,N‐dimethyl benzylamine palladacycles. These insertion reactions showed high regioselectivity under mild conditions and a variety of homo‐ and heterobimetallic arsenic functionalized complexes were formed. The coordination chemistry and the absolute stereochemistry of the monoinsertion products were determined by X‐ray crystallography.
Copper(I) Complexes of Normal and Abnormal Carbenes and Their Use as Catalysts for the Huisgen [3+2] Cycloaddition between Azides and Alkynes
Authors: Hohloch Stephan , Su Cheng‐Yong , Sarkar Biprajit
Published: June 2011

Complexes of general formula [(NHC)Cu(μ‐I)2Cu(NHC)] (NHC = 1‐benzyl‐3‐butylbenzimidazolin‐2‐ylidene for 7; NHC = 1‐benzyl‐3‐isopropylbenzimidazolin‐2‐ylidene for 8 NHC = 1‐butyl‐3‐isopropylbenzimidazolin‐2‐ylidene for 9) and [(aNHC)CuI] {aNHC = 1‐benzyl‐3‐methyl‐4‐phenyl‐1H‐1,2,3‐triazol‐3‐ium‐5‐ylidene for 10; 3‐methyl‐1‐[2‐(methylthio)phenyl]‐4‐phenyl‐1H‐1,2,3‐triazol‐3‐ium‐5‐ylidene for 11} were synthesized from CuI and the corresponding azolium salts. All complexes were fully characterized by spectroscopic methods, and single‐crystal X‐ray structural analyses were performed for 7 and 11. Complex 7 exhibits an iodido‐bridged dicopper(I) form in the solid state. The copper centers in 7 adopt a trigonal coordination. The intramolecular Cu–Cu distance is 2.896(2) Å. In contrast to 7, 11 is mononuclear, and the copper center has a linear coordination. All the complexes were tested for their efficiency as catalysts in the [3+2] cycloaddition reaction between azides and alkynes. The benzimidazolin‐2‐ylidene‐containing complexes 7–9 as well as the triazol‐3‐ium‐5‐ylidene‐containing complexes 10–11 turned out to be highly efficient catalysts for the 1,3‐cycloaddition reaction, both under neat conditions and in water. Short reaction times as well as low catalyst loadings could be achieved, and all the manipulations were carried out under proper “click” conditions with simple product isolation and no purification steps. The efficiency of the catalysts seems to correlate well with the σ‐donor ability of the NHCs. Cycloaddition reaction with an internal alkyne was also achieved with these catalysts. Finally a bulky azide was used as a substrate to prepare compound 1‐(2,6‐dimesityl)phenyl‐4‐(2‐pyridyl)‐1,2,3‐triazole (14) with the above mentioned copper catalysts. Such bulky azides are usually unreactive towards cycloaddition reactions with alkynes in the presence of the CuII/ascorbate/tbta catalytic system.
Metal‐Free Asymmetric 1,3‐Dipolar Cycloaddition of N‐Arylmaleimides to Azomethine Ylides Catalyzed by Chiral Tertiary Amine Thiourea
Authors: Bai Jian‐Fei , Wang Liang‐Liang , Peng Lin , Guo Yun‐Long , Ming Jun‐Nan , Wang Fei‐Ying , Xu Xiao‐Ying , Wang Li‐Xin
Published: June 2011

The first metal‐free asymmetric 1,3‐dipolar cycloaddition of N‐arylmaleimides to azomethine ylides catalyzed by chiral tertiary amine thiourea to form multiply substituted pyrrolidines in excellent yields (up to 89 %) and enantioselectivities (up to 96 % ee) is presented. This procedure allows a rapid diversity‐oriented synthesis of chiral pyrrolidine derivatives with high optical purity.
Heterogenized Wilkinson‐Type Catalyst for Transfer Hydrogenation of Carbonyl Compounds
Authors: Bogár Krisztián , Krumlinde Patrik , Bacsik Zoltán , Hedin Niklas , Bäckvall Jan‐E.
Published: June 2011

Wilkinson's catalyst [RhCl(PPh3)3] was heterogenized on common silica by the use of a grafting/anchoring technique. The immobilized catalyst showed high activity and selectivity in transfer hydrogenation reactions of a range of carbonyl compounds in 2‐propanol. Reactions carried out in 2‐propanol at reflux afforded the corresponding alcohols in high yields in short reaction times. The heterogeneous feature of the catalyst allows for easy recovery and efficient reuse in the same reaction up to 5 times without any detectible loss of catalytic activity.
NMR and Computational Investigations of the Chiral Discrimination Processes Involving a Cyclic Tetraamidic Chiral Selector
Authors: Uccello‐Barretta Gloria , Balzano Federica , Martinelli Jonathan , Gasparrini Francesco , Pierini Marco , Villani Claudio
Published: June 2011

The chiral recognition mechanism of a macrocyclic tetraamidic receptor for the enantiomers of N‐(3,5‐dinitrobenzoyl)valine‐N‐hexylamide has been investigated in detail through a combination of NMR spectroscopy and molecular modeling studies. Intra‐ and intermolecular ROE effects provided information on the conformations of the free and complexed partners, and also on their relative arrangement in solution during complexation. Molecular mechanics calculations and molecular docking studies gave results in agreement with the spectroscopic data, correctly reproducing the relative stability of the two diastereoisomeric complexes. A stereochemical model for the complexed species is presented in which hydrogen‐bonding interactions between amide fragments drive the association process, and the enantioselectivity is modulated by aromatic–aromatic interactions and steric hindrance.
Longeracemosones A–F, Aromatase Inhibitors from Dunbaria longeracemosa
Authors: Prachyawarakorn Vilailak , Mahidol Chulabhorn , Ruchirawat Somsak
Published: June 2011

Six dihydroflavonols, longeracemosones A–F (1–6), together with two known flavonoids, mundulinol (7) and sericetin (8), have been isolated from Dunbaria longeracemosa. The structures of the isolated compounds were elucidated by spectroscopic analysis and the absolute configurations were determined by analysis of the CD spectra and by the modified Mosher's method. A novel conversion of the linear chromene in 1 to the angular chromene in 2 was observed and the mechanism of this unique transformation is proposed. The isolated compounds were evaluated for their cytotoxic and antioxidant activity and compounds 3, 4, and 7 exhibited potent aromatase inhibitory activity with IC50 values of 0.3, 0.4, and 1.2 μM, respectively.
Daphmalenines A and B: Two New Alkaloids with Unusual Skeletons from Daphniphyllum himalense
Authors: Zhang Yu , Di Yingtong , He Hongping , Li Shifei , Lu Yang , Gong Ningbo , Hao Xiaojiang
Published: June 2011

Two new biogenetically related yuzurine‐type Daphniphyllum alkaloids of the rare (14R,15S) series, daphmalenines A (1) and B (2), have been isolated from the leaves of Daphniphyllum himalense. Their structures and absolute configurations were elucidated by a combination of spectroscopic data, X‐ray crystallographic, and computational methods. A plausible biosynthetic pathway of 1 and 2 was also proposed.
[8π+2π] Cycloaddition of meso‐Tetra‐ and 5,15‐Diarylporphyrins: Synthesis and Photophysical Characterization of Stable Chlorins and Bacteriochlorins
Authors: Pereira Nelson A. M. , Fonseca Sofia M. , Serra Arménio C. , Pinho e Melo Teresa M. V. D. , Burrows Hugh D.
Published: June 2011

The synthesis of new types of stable 4,5,6,7‐tetrahydropyrazolo[1,5‐a]pyridine‐fused chlorins and bacteriorins through [8π+2π] cycloaddition of diazafulvenium methides with porphyrins and chlorins is reported. Detailed absorption and fluorescence spectral and quantum yield measurements have been made on all new compounds. These show potential for various biomedical applications.
Predicting alternative strategies for preserving a belief in a just world: The case of repressive coping style
Authors: Hafer Carolyn L. , Gosse Leanne
Published: June 2011

Researchers suggest that observers of innocent suffering will negatively evaluate the victim as a strategy for maintaining their belief in a just world. We propose an alternative class of strategies and test whether individual differences in repressive coping style predict the type of strategy people will use. In the first two studies, we exposed repressors versus nonrepressors to victims whose suffering should pose a high versus low threat to the need to believe in a just world. Repressors had a greater tendency to positively reappraise the high threat victim's suffering. Nonrepressors had a greater tendency to negatively evaluate the high threat victim. A third study replicated the results for the high threat conditions and suggested that repressors' positive reappraisal is not because of a tendency to minimize suffering. Our research (i) demonstrates a class of strategies for preserving the belief in a just world other than negatively evaluating the victim and (ii) is among the first to examine directly an individual difference predictor of alternative just‐world preservation strategies. Copyright © 2011 John Wiley & Sons, Ltd.
An augmented Lagrangian approach to simulating yield stress fluid flows around a spherical gas bubble
Authors: Zhang Jianying
Published: June 2011

We simulated the flow of a yield stress fluid around a gas bubble using an augmented Lagrange approach. The piecewise linear equal‐order finite elements for both the velocity and the pressure approximations proposed and analyzed by Latché and Vola in 2004 were applied. A mesh adaptive strategy based on this element‐pair choice was also proposed to render the yield surfaces of desired resolution. The corresponding numerical scheme was formulated for general Herschel–Bulkley fluids. Numerical results on Bingham fluid flows around a slowly rising spherical gas bubble were provided to validate the proposed algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Assessing the impact of high deductible health plans on health‐care utilization and cost: a changes‐in‐changes approach
Authors: Borah Bijan J. , Burns Marguerite E. , Shah Nilay D.
Published: June 2011

High deductible health plans (HDHPs) have become an increasingly common form of benefit design used by employers to manage health‐care costs. Numerous studies have evaluated the uptake and impact of HDHPs on health‐care utilization. Most studies have employed the standard difference‐in‐differences (DID) methodology. In this paper, we employ three alternative methodologies to evaluate a natural experiment in which a traditional health plan was fully replaced by a HDHP. We implement the standard DID and the quantile difference‐in‐differences (QDID) estimators to evaluate the impact of the HDHP on following six outcomes: overall cost, medical cost, pharmacy cost, outpatient visit count, inpatient visit count and emergency room visit count. We compare these results to a changes‐in‐changes (CIC) estimator, a generalized version of the standard (DID) estimator. We find that both the DID and CIC models yielded similar results, while the QDID model provided additional insights on the HDHP impact across different parts of the outcome distributions. Overall, introduction of HDHP had no impact on health‐care costs, positive impact on the number of outpatient visits and mixed impacts on the inpatient and emergency room visit counts. The QDID estimates suggest HDHP introduction generally impacted subjects in upper percentiles (50th, 75th and 90th). Copyright © 2011 John Wiley & Sons, Ltd.
A preliminary investigation of the influence of basal and surface topography on supraglacial lake distribution near Jakobshavn Isbrae, western Greenland
Authors: Lampkin D. J. , VanderBerg J.
Published: June 2011

The spatial distribution of supraglacial lakes has been hypothesized to be dominantly controlled by the component of surface roughness influenced by basal topography. Basal topography and surface roughness profiles within the Jakobshavn Isbrae drainage basin in western Greenland, acquired from an ice‐penetrating radar echo sounder, were analysed through fourier and wavelet decompositions. Spectral analyses of basal‐to‐surface transfer under a range of ice thickness were compared with spatial distribution of lakes mapped from high‐resolution Landsat imagery. Fourier analysis identifies dominant signals in both the basal and surface profiles to be ranging between wavelengths of 1·25–12·5 km. The strongest peaks of transfer of basal signals to the surface were identified at wavelengths ∼11∼5 km. Wavelet analysis identifies these peaks with thicker (1200–1400 m) and thinner (500–700 m) ice respectively and also identifies surface frequencies not present in the basal signal indicating some influence from other factors. Spatial autocorrelation analysis of supraglacial lake distribution indentifies high correlations at 1·9, 5·6, 11, 24, and 30 km lags. Lags at 5·6 and 11 km correspond to dominant frequencies present in the basal and surface profiles over thinner and thicker ice respectively. These ∼5 and ∼11 km frequency components present in the basal topography, surface roughness, and lake distribution are within the theoretical transfer window of basal‐to‐surface transfer as a function of ice thickness. The transect analysed in this study does not contain wavelengths in the surface structure that are less than the ice thickness, even though there are relatively higher frequencies present in the surface profile between 0 and 15 km that have less power in the basal profile. Copyright © 2011 John Wiley & Sons, Ltd.
Steam oxidation of X20CrMoV121: Comparison of laboratory exposures and in situ exposure in power plants
Authors: Montgomery M. , Hansson A. N. , Vilhelmsen T. , Jensen S. A.
Published: June 2011

X20CrMoV121 is a 12% Cr martensitic steel which has been used in power plants in Europe for many decades. Specimens have been removed from superheater tubes to investigate long‐term exposure with respect to steam oxidation. These tubes have been exposed for various durations up to 135 000 h in power plants in Denmark at steam temperatures varying from 450–565 °C. This paper collates the data, compares oxide morphologies and assesses to what extent parabolic kinetics can be used to describe the oxidation rate. The steam oxidation behaviour has been investigated in the laboratory in an Ar‐46%H2O mixture at 500, 600 and 700 °C for 336 h. It was observed that the morphology of the oxide layers was strongly influenced by temperature, and some of the same morphologies are also observed for power plant specimens. However, the temperatures at which they occur were different for plant and laboratory specimens, e.g. the presence of Cr rich bands within the oxide occurred at a lower temperature in the plant than in the laboratory. In addition there is a greater variety of oxide morphologies for long‐term plant specimens compared to laboratory specimens.
Corrosion behavior of CuCrFeNiMn high entropy alloy system in 1 M sulfuric acid solution
Authors: Ren B. , Liu Z. X. , Li D. M. , Shi L. , Cai B. , Wang M. X.
Published: June 2011

Immersion tests and potentiodynamic polarization measurements were conducted in 1 M sulfuric acid solution (H2SO4) at ambient temperature (∼25 °C) to investigate the corrosion behavior of CuCrFeNiMn alloy system. The results show that the alloys display a good general corrosion resistance that is mainly influenced by the Cu content and elemental segregation degree. The corrosion resistance degrades when increasing Cu content and elemental segregation degree. Among the tested alloys, the CuCr2Fe2Ni2Mn2 alloy with low Cu content and elemental segregation degree displays a better general corrosion resistance. On the contrary, the Cu2CrFe2NiMn2 alloy with high Cu content and elemental segregation degree exhibits the worst general corrosion resistance.
First‐principles study on influence of alloying elements on electrochemical stability of cobalt‐base alloys
Authors: Lü B. L. , Zhou W. L. , Chen G. Q.
Published: June 2011

The paper studies the impact of the metal elements Nb, Ta, Zr, Mo, W, Al, Si, and Y on electrochemical stability of non‐passivated cobalt‐base alloys by evaluating the chemical potential and the electrode potential shift relative to pure cobalt metal using first‐principles calculations. Nb, Ta, and Si are found to make the surface Co atoms more stable on the {0001} surfaces of the corresponding alloys compared to pure Co {0001} surfaces, whereas Al, W, Mo, Y, and Zr make Co atoms less stable. Among all the considered alloying elements, niobium is the most beneficial to the stability enhancement of alloys. Furthermore, the effects of water adsorption on the electrochemical stability are considered. It is found that the surface adsorption properties may be considerably modified by introducing the Nb atoms. Our results indicate that water adsorption destabilizes both the alloy and pure metal surface. However, the CoNb alloy surface is still more stable than the pure Co surface in the presence of absorbed water. Our calculation reveals that the electrochemical stability of the CoNb alloy is sensitive to water molecular adsorption in comparison with that of the pure Co metal.
Long term assessment of a hybrid electrochemical treatment
Authors: Holmes S. P. , Wilcox G. D. , Robins P. J. , Glass G. K. , Roberts A. C.
Published: June 2011

Monitoring the performance of systems installed to protect against/halt the corrosion of reinforcing steel in concrete is essential in ensuring that the reinforcing bar (rebar) is adequately protected and remains in a non‐corroding state. A chloride contaminated concrete test block containing a hybrid anode system has been periodically monitored over the past 4.5 years to assess the anode current output and thus, the protection offered to the steel. De‐polarisation and impedance analysis data have been acquired to calculate steel corrosion rates. Both tests indicated that the steel was passive in the concrete environment and that the anode was able to protect all of the embedded steel despite the difficult geometry of the sample. It was also found that after 2 years it was still possible to drive a high current from the installed anode.
Automatic Activation of Individual Differences: A Test of the Gatekeeper Model in the Domain of Spontaneous Helping
Authors: Perugini Marco , Conner Mark , O'Gorman Rick
Published: June 2011

The influence of stable individual differences on behaviour need not solely rely upon deliberative processes but can also be exerted through automatic associative processes. In this contribution, three studies that illustrate the role of individual differences in automaticity are presented in the domain of helping behaviour. The first study provides evidence both for a double dissociation and for an additive pattern of implicit and explicit measures in predicting relevant altruistic behaviours. The subsequent two studies show that when the concept of altruism is subliminally primed, individual differences in implicit attitudes significantly predict behaviour. The results are in line with the gatekeeper model, and their implications are discussed focusing on the key role of individual differences in modulating automaticity effects. Copyright © 2011 John Wiley & Sons, Ltd.
High resolution crystal structures of triosephosphate isomerase complexed with its suicide inhibitors: The conformational flexibility of the catalytic glutamate in its closed, liganded active site
Authors: Venkatesan Rajaram , Alahuhta Markus , Pihko Petri M. , Wierenga Rik K.
Published: June 2011

The key residue of the active site of triosephosphate isomerase (TIM) is the catalytic glutamate, which is proposed to be important (i) as a catalytic base, for initiating the reaction, as well as (ii) for the subsequent proton shuttling steps. The structural properties of this glutamate in the liganded complex have been investigated by studying the high resolution crystal structures of typanosomal TIM, complexed with three suicide inhibitors: (S)‐glycidol phosphate ((S)‐GOP, at 0.99 Å resolution), (R)‐glycidol phosphate, ((R)‐GOP, at 1.08 Å resolution), and bromohydroxyacetone phosphate (BHAP, at 1.97 Å resolution). The structures show that in the (S)‐GOP active site this catalytic glutamate is in the well characterized, competent conformation. However, an unusual side chain conformation is observed in the (R)‐GOP and BHAP complexes. In addition, Glu97, salt bridged to the catalytic lysine in the competent active site, adopts an unusual side chain conformation in these two latter complexes. The higher chemical reactivity of (S)‐GOP compared with (R)‐GOP, as known from solution studies, can be understood: the structures indicate that in the case of (S)‐GOP, Glu167 can attack the terminal carbon of the epoxide in a stereoelectronically favored, nearly linear OCO arrangement, but this is not possible for the (R)‐GOP isomer. These structures confirm the previously proposed conformational flexibility of the catalytic glutamate in its closed, liganded state. The importance of this conformational flexibility for the proton shuttling steps in the TIM catalytic cycle, which is apparently achieved by a sliding motion of the side chain carboxylate group above the enediolate plane, is also discussed.
Reprogramming chaperone pathways to improve membrane protein expression in Escherichia coli
Authors: Nannenga Brent L. , Baneyx François
Published: June 2011

Because membrane proteins are difficult to express, our understanding of their structure and function is lagging. In Escherichia coli, α‐helical membrane protein biogenesis usually involves binding of a nascent transmembrane segment (TMS) by the signal recognition particle (SRP), delivery of the SRP‐ribosome nascent chain complexes (RNC) to FtsY, a protein that serves as SRP receptor and docks to the SecYEG translocon, cotranslational insertion of the growing chain into the translocon, and lateral transfer, packing and folding of TMS in the lipid bilayer in a process that may involve chaperone YidC. Here, we explored the feasibility of reprogramming this pathway to improve the production of recombinant membrane proteins in exponentially growing E. coli with a focus on: (i) eliminating competition between SRP and chaperone trigger factor (TF) at the ribosome through gene deletion; (ii) improving RNC delivery to the inner membrane via SRP overexpression; and (iii) promoting substrate insertion and folding in the lipid bilayer by increasing YidC levels. Using a bitopic histidine kinase and two heptahelical rhodopsins as model systems, we show that the use of TF‐deficient cells improves the yields of membrane‐integrated material threefold to sevenfold relative to the wild type, and that whereas YidC coexpression is beneficial to the production of polytopic proteins, higher levels of SRP have the opposite effect. The implications of our results on the interplay of TF, SRP, YidC, and SecYEG in membrane protein biogenesis are discussed.
Photoluminescence of Mg‐doped m‐plane GaN grown by MOCVD on bulk GaN substrates
Authors: Monemar Bo , Paskov Plamen , Pozina Galia , Hemmingsson Carl , Bergman Peder , Lindgren David , Samuelson Lars , Ni Xianfeng , Morkoç Hadis , Paskova Tanya , Bi Zhaoxia , Ohlsson Jonas
Published: June 2011

Photoluminescence (PL) properties are reported for a set of m‐plane GaN films with Mg doping varied from mid 1018 cm−3 to above 1020 cm−3. The samples were grown with MOCVD at reduced pressure on low defect density bulk GaN templates. The sharp line near bandgap bound exciton (BE) spectra observed below 50 K, as well as the broader donor–acceptor pair (DAP) PL bands at 2.9–3.3 eV give evidence of several Mg related acceptors, similar to the case of c‐plane GaN. The dependence of the BE spectra on excitation intensity as well as the transient decay behaviour demonstrate acoustic phonon assisted transfer between the acceptor BE states. The lower energy donor–acceptor pair spectra suggest the presence of deep acceptors, in addition to the two main shallower ones at about 0.23 eV. Similar spectra from Mg‐doped GaN nanowires (NWs) grown by MOCVD are also briefly discussed.
Dislocation reduction in high Al‐content AlGaN films for deep ultraviolet light emitting diodes
Authors: Ahmad Iftikhar , Krishnan Balakrishnan , Zhang Bin , Fareed Qhalid , Lachab Mohamed , Dion Joseph , Khan Asif
Published: June 2011

We report a new approach for growing thicker (>2 µm) low‐defect AlGaN layers over sapphire using pulsed MOCVD procedure. These high content AlGaN layers serve as templates for subsequent n‐AlGaN growth for deep ultraviolet light emitting diodes (DUV LEDs). During the growth of the AlxGa1−xN layer, the pulsed‐growth conditions were cyclically adjusted to reduce the dislocations. This leads to AlGaN templates with an RMS roughness of 9.6 Å and (102) off‐axis X‐ray line‐width 550 arcsec. The transmission electron microscope (TEM) analysis shows 4 × 107 cm−2 edge type and 2 × 106 cm−2 screw type of threading dislocation densities at best regions. On the average dislocation density in these films is 4 × 108 cm−2. A light emitting diode (LED) structure emitting at 280 nm was deposited on these templates. A comparative study showed the EL emission for LEDs on the new low‐defect templates to be more than 1.6 times stronger than our conventional DUV LED structures. In this paper the details of our growth procedure, the epi‐structure X‐ray, atomic force microscopy (AFM), TEM, and other characterizations will be presented. A comparative study of DUV LED structures over conventional and improved templates of this work will be discussed.
Initiating polarity inversion in GaN growth using an AlN interlayer
Authors: Hite Jennifer K. , Twigg Mark E. , Mastro Michael A. , Eddy Charles R. , Kub Francis J.
Published: June 2011

In this work, we show that the polarity of GaN grown on N‐polar material can be controlled through a combination of surface conditioning and introduction of a non‐Mg inversion layer (IL). The IL we use is a thin, low‐temperature AlN layer deposited by metal organic chemical vapor deposition (MOCVD). The subsequent inverted films are Ga‐polar that do not contain inversion domain boundaries and with crystal quality similar to MOCVD films grown on sapphire. The polarity inversion technique is enhanced by the addition of an etching step prior to AlN deposition.