bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy Landscape of Aptamer/Protein Complexes Studied by Single‐Molecule Force Spectroscopy
Authors: Yu Junping , Jiang Yaxin , Ma Xinyong , Lin Yi , Fang Xiaohong 
Published: January 2007

AbstractAptamers are single‐stranded nucleic acid molecules selected in vitro to bind to a variety of target molecules. Aptamers bound to proteins are emerging as a new class of molecules that rival commonly used antibodies in both therapeutic and diagnostic applications. With the increasing application of aptamers as molecular probes for protein recognition, it is important to understand the molecular mechanism of aptamer–protein interaction. Recently, we developed a method of using atomic force microscopy (AFM) to study the single‐molecule rupture force of aptamer/protein complexes. In this work, we investigate further the unbinding dynamics of aptamer/protein complexes and their dissociation‐energy landscape by AFM. The dependence of single‐molecule force on the AFM loading rate was plotted for three aptamer/protein complexes and their dissociation rate constants, and other parameters characterizing their dissociation pathways were obtained. Furthermore, the single‐molecule force spectra of three aptamer/protein complexes were compared to those of the corresponding antibody/protein complexes in the same loading‐rate range. The results revealed two activation barriers and one intermediate state in the unbinding process of aptamer/protein complexes, which is different from the energy landscape of antibody/protein complexes. The results provide new information for the study of aptamer–protein interaction at the molecular level.
Boomerang‐Type Substitution Reaction: Reactivity of Fullerene Epoxides and a Halofullerenol
Authors: Jia Zhenshan , Zhang Xiang , Zhang Gaihong , Huang Shaohua , Fang Hao , Hu Xiangqing , Li Yuliang , Gan Liangbing , Zhang Shiwei , Zhu Daoben 
Published: January 2007

AbstractThe Cs‐symmetric fullerene chlorohydrin C60(Cl)(OH)(OOtBu)4 reacts with 4‐dimethylaminopyridine (DMAP) and 1,4‐diazabicyclo[2.2.2]octane (DABCO) to yield two isomers with the formula C60(O)(OOtBu)4 in good yields. These isomers differ with respect to the location of the epoxy functionality. The one from DMAP is Cs symmetric, whereas that from DABCO is C1 symmetric with the epoxy group on the central pentagon. Two different mechanisms are proposed to explain the chemoselectivity of these reactions. The reaction with DMAP involves single‐electron transfer as the key step; DMAP acts as the electron donor. A combination of an oxygen‐atom shift and SN2′′ processes (boomerang substitution) are responsible for the formation of isomer with DACBO. Various related reactions support the proposed mechanisms. The structures of new fullerene derivatives were determined by spectroscopy, single‐crystal X‐ray analysis, and chemical correlation experiments.
Photoluminescent and Liquid‐Crystalline Properties of Donor–Acceptor‐Type 2,5‐Diarylthiazoles
Authors: Shikuma Junichi , Mori Atsunori , Masui Kentaro , Matsuura Ryuichi , Sekiguchi Akitoshi , Ikegami Haruka , Kawamoto Masuki , Ikeda Tomiki 
Published: January 2007

AbstractThe synthesis of donor–acceptor‐type 2,5‐diarylthiazoles that bear electron‐donating N,N‐dialkylamine and electron‐withdrawing cyano groups at the 2‐ and 5‐position, respectively, were carried out with transition‐metal‐catalyzed CH arylation reactions developed by us. The compounds were synthesized by the CH arylation of unsubstituted thiazole at the 2‐position with a palladium/copper catalyst in the presence of tetrabutylammonium fluoride (TBAF) as an activator. Further CH arylation of the 2‐arylated thiazole at the 5‐position was carried out by the palladium‐catalyzed reaction in the presence of silver(I) fluoride to afford the donor–acceptor‐type 2,5‐diarylthiazoles with N,N‐dialkylamine groups of different chain lengths. The UV/Vis absorption, photoluminescence, and electrochemical behavior were similar regardless of chain length, whereas liquid‐crystalline behavior and thermal characteristics were found to be dependent on the alkyl‐chain length. The compounds with N,N‐diethylamine or N‐butyl‐N‐methyl groups showed a stable liquid‐crystalline phase over a wide temperature range as well as higher stability to thermal decomposition.
Easily Accessible Benzamide‐Derived P,O Ligands (Bphos) for Palladium‐Catalyzed Carbon–Nitrogen Bond‐Forming Reactions
Authors: Chen Guoshu , Lam Wai Har , Fok Wai Shan , Lee Hang Wai , Kwong Fuk Yee 
Published: January 2007

AbstractEasily accessible benzamide‐derived hemilabile phosphine ligands were efficiently prepared through ortho‐directed lithiation of the corresponding N,N‐diethylbenzamide followed by quenching with chlorodialkylphosphines. These structurally simple hemilabile ligands were found to be highly effective in palladium‐catalyzed amination of aryl and heteroaryl chlorides. Various sterically congested and functionalized aryl halide substrates were compatible in these reaction conditions. By using optimized reaction conditions, remarkable catalyst productivity (total turnover number up to 8400) was obtained.
Synthesis and Application of a Bidentate Ligand Based on Decafluoro‐3‐phenyl‐3‐pentanol: Steric Effect of Pentafluoroethyl Groups on the Stereomutation of O‐Equatorial C‐Apical Spirophosphoranes
Authors: Jiang Xin‐Dong , Kakuda Ken‐ichiro , Matsukawa Shiro , Yamamichi Hideaki , Kojima Satoshi , Yamamoto Yohsuke 
Published: January 2007

Abstract1,1,1,2,2,4,4,5,5,5‐Decafluoro‐3‐phenyl‐3‐pentanol was prepared by a Cannizzaro‐type disproportionation reaction, and the dimetallated compound was used as a bidentate ligand, which is bulkier than the Martin ligand (1,1,1,3,3,3‐hexafluoro‐2‐phenyl‐2‐propanol). A PH spirophosphorane was synthesized by utilizing the new bidentate ligand, and the structure of the product was essentially the same as that of the PH phosphorane with Martin ligands. Phosphoranes that exhibit reversed apicophilicity (O‐equatorial) were also synthesized and could be converted into the corresponding stable stereoisomers (O‐apical). The crystal structures of O‐equatorial phosphoranes and the O‐apical isomers were slightly affected by the steric repulsion of pentafluoroethyl groups. Kinetic measurements revealed that the stereomutation of O‐equatorial methylphosphorane to the O‐apical isomer was slowed. The activation enthalpy for the stereomutation of the former to the latter was higher than that of the phosphorane with Martin ligands by 5.1 kcal mol−1.
Veränderung der Steifigkeit und des Dehnungsverhaltens von Normalbeton bei zyklischer Druckschwellbeanspruchung mit Ruhephasen
Authors: Breitenbücher Rolf , Ibuk Hursit , Osterminski Kai 
Published: January 2007

AbstractBetonbauwerke werden häufig neben rein statischen Lasten auch durch zyklische Lasten beansprucht. Durch Letztere kann bereits während zahlreicher Lastwechsel eine Degradation des Betongefüges eintreten, die zu größeren Dehnungen und zu reduzierten Steifigkeiten führen. Unklar ist, wie sich Ruhephasen innerhalb dieser zyklischen Beanspruchung auf das Dehnungsverhalten und die Steifigkeitsentwicklung auswirken. Im Rahmen des Sonderforschungsbereiches 398 werden lebensdauerorientierte Entwurfskonzepte unter Schädigungs‐ und Deteriorationsaspekten entwickelt. Hierin wird im Teilprojekt A13 die Degradation der Materialeigenschaften des Betons infolge von zyklischer Druckschwellbelastung untersucht. Im folgenden Beitrag wird vom Einfluss von einmalig auftretenden Ruhephasen innerhalb sinusförmiger Druckschwellbelastungen auf das Dehnungs‐ und Steifigkeitsverhalten von Normalbeton berichtet. Dazu wurden Betonproben zwei unterschiedlichen Belastungsregimen (Lastniveau, Frequenz) ausgesetzt. Innerhalb dieser wurden verschieden lang andauernde Ruhephasen eingebaut. Während der Belastungs‐ und Ruhephasen wurden die Probekörperdehnungen und indirekt der E‐Modul (über Ultraschalllaufzeitmessungen) bestimmt. Die Versuchsergebnisse besagten, dass bei den betrachteten Belastungshistorien Ruhephasen keinen signifikanten Einfluss auf das Dehnungsverhalten der Betonprobekörper besaßen. Geringfügige Erholungen infolge des verzögert‐elastischen Verhaltens des Betons in der Ruhephase waren nach erneuter Aufnahme der Beanspruchung rasch wieder aufgebraucht. Gleiches gilt für die Auswirkungen auf die Steifigkeit des Betons.
Bemessungsvorschlag für die verstärkte Querbewehrung bei mehrgeschossigen Ortbetonstützen ohne Übergreifungsstoß der Längsbewehrung. “Stumpfstoß von Ortbetonstützen”
Authors: Minnert Jens , Günther Gerd 
Published: January 2007

AbstractAn der Fachhochschule Gießen‐Friedberg wurden zahlreiche Untersuchungen zum Tragverhalten von stumpf gestoßenen Ortbetonstützen durchgeführt. Anhand gezielter Versuche wurde das Verhalten der Stützen zunächst im Labor untersucht. Anschließend erfolgten die Nachrechnung der Versuche und eine weiterführende Parameterstudie mit einem nichtlinearen FEMProgramm. Darauf aufbauend wurde ein Bemessungsvorschlag entwickelt.
Näherungsweise Spannungsberechnung vorgespannter Betonbauteile
Authors: Mertzsch Olaf 
Published: January 2007

AbstractMit Einführung der DIN 1045‐1 (07.2001) erfolgt die Bemessung von Stahlbeton‐ und Spannbetontragwerken nach einer einheitlichen Berechnungsvorschrift. Hiermit besteht die Möglichkeit einer besseren Auslastung der Konstruktion. Dies hat zur Folge, dass den Nachweisen der Gebrauchstauglichkeit eine größere Bedeutung zukommt. Ziel der nachfolgenden Betrachtungen ist es, wirklichkeitsnahe Berechnungsansätze zur Vorhersage der Beton‐ und Stahlspannungen abzuleiten. Diese Berechnungsansätze ermöglichen eine einfache Abschätzung der Spannungen und sind auch für Handrechnungen geeignet.
Rissbreitenberechnung bei “Kombibewehrung”
Authors: Henke Volker , Empelmann Martin 
Published: January 2007

AbstractStahlfaserbeton findet in den letzten Jahren eine immer weiter verbreitete Anwendung im konstruktiven Ingenieurbau. Dies gilt für Bauteile aus reinem Stahlfaserbeton, aber auch für die Kombination mit normaler Betonstahlbewehrung (Kombibewehrung), wo dann auch immer wieder die Frage der Rissbreitenberechnung zu klären ist. Besonders zu beachten ist dabei das Zusammenwirken von Bewehrungsstahl und Stahlfasern. Einige Bemessungsansätze für reinen Stahlfaserbeton und Bauteile mit Kombibewehrung sind in der Literatur vorhanden, wobei die Bemessungsansätze für Kombibewehrung die Grundlagen der DIN 1045‐1 verwenden. In diesem Aufsatz soll die Anwendbarkeit dieser Ansätze für eine Kombibewehrung, auf der Basis vorhandener Versuchsergebnisse, überprüft und auf einige Besonderheiten beim Ansatz der Nachrisszugfestigkeit des Stahlfaserbetons hingewiesen werden.
Anwendungserfahrungen mit der neuen DIN 1055 Teil 6 bei der Sanierung zweier Rohmehlsilos
Authors: Kaldenhoff Martin , Schütte Jens , Hauser Arthur 
Published: January 2007

AbstractDem Sanierungskonzept war aufgrund von vielen Randbedingungen ein enges Korsett vorgegeben. Unter anderem war die neue deutsche Silonorm DIN 1055‐6: 2005‐03 einzuhalten. Die Anwendung der neuen Silonorm ist anspruchsvoll und zeitintensiv. Die neue Konstruktion ist in allen Belangen durch die neue Norm beeinflusst worden. Augenfällig ist die externe Vorspannung, welche als Neuheit gänzlich während des Gleitens von einem zweiten Nachläufer aus aufgebracht wurde.Ein Siloprojekt kann und soll nicht auf die rechnerische Anwendung einer Silonorm reduziert werden. Drei Ziele führen zum ganzheitlichen Erfolg:– Schüttguteigenschaften kennen und abdecken– Rechnerische Auslegung mittels Silonorm aber nicht ohne Erfahrungswerte– Professionelle Bauausführung und BauüberwachungDie neue Silonorm DIN 1055‐6 hilft beim Erreichen dieser Ziele auf weiten Strecken. Ihre Anwendung erfordert entsprechende Erfahrung im Silobau und gesunden Ingenieurverstand.
Teilüberdeckelung einer innerstädtischen Bundesstraße mit Spannbetonfertigteilen
Authors: Sobek Werner , Straub Wolfgang , Ploch Jan 
Published: January 2007

AbstractDie Stuttgarter Innenstadt wird von einer breiten Bundesstraße durchschnitten, die unter einigen großen Kreuzungen in Unterführungen verläuft. Durch die teilweise Überdeckelung der Unterführungseinfahrten können zusätzliche Grünflächen und ebenerdige Fußgängerüberwege geschaffen werden. Die erste Teilüberdeckelung konnte durch integrierte Planung und den Einsatz von Spannbetonfertigteilen nach einer extrem kurzen Planungs‐ und Bauzeit eingeweiht werden.
Diskussionsforum: Nanobewehrung von Schaumbeton
Authors: Yakovlev Grigory , Kerienė Jadvyga , Plechanova Tatyana , Krutikov Vyacheslav 
Published: January 2007

AbstractIn der hier vorgestellten Studie wurden Nanoröhren aus Karbon, die aus aromatischen Kohlenwasserstoffen synthetisiert werden, untersucht. Ebenso sollten die Produktionsmöglichkeiten und grundsätzlichen technischen Eigenschaften eines Betons untersucht werden, der mit Nanoröhren aus Karbon verstärkt ist und auf Portlandzement basiert.Für die Herstellung der Nanoröhren aus Karbon wurde die Methode der Stimulation der Dehydropolykondensation und Verkokung der aromatischen Kohlenwasserstoffe in chemisch aktiver Umgebung gewählt (Schmelzen von Aluminium‐, Kupfer‐, Nickel‐ und Eisensalzen). Die Untersuchung der synthetisierten Nanoröhren aus Karbon mittels photoelektrischer Röntgenspektroskopie ergab einen Karbonanteil von 80–90%. Unter dem Elektronenmikroskop konnte festgestellt werden, dass Nanoröhren aus Karbon eine zylindrische Form mit Durchmessern bis zu 100 nm und Längen bis 20 μm aufweisen. Sie sind zu faserförmigen Agglomeraten mit Durchmessern von bis zu 30 μm und Längen bis zu 10 mm zusammengeballt.Die Nanoröhren aus Karbon wurden als hochfeste verteilte Bewehrung zur Herstellung von nicht autoklaviertem Schaumbeton verwendet. Die Untersuchung dieses Schaumbetons ergab, dass durch den Einsatz von Nanoröhren aus Karbon (0, 05% der Masse) eine Abnahme derWärmeleitfähigkeit um 12–20% sowie eine Zunahme der Druckfestigkeit um bis zu 70% erreichet werden kann.
Recent progress in the field of glycopeptide synthesis
Authors: Hojo Hironobu , Nakahara Yoshiaki 
Published: February 2007

AbstractGlycosylation is a common post‐translational modification of proteins. Although its significance in biological system is well recognized, approaches to analyze carbohydrate function are limited. This is because of difficulty in obtaining homogeneous glycoproteins from natural sources. Due to the progress of the carbohydrate and peptide chemistry, syntheses of various homogeneous glycopeptides and glycoproteins, which are suitable for biological studies, have been achieved by chemical means. In this review, we briefly summarize recent advances in the field of glycopeptide synthesis after 1999. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 308–324, 2007.This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Seven-year follow-up of a randomized clinical trial comparing proton-pump inhibition with surgical therapy for reflux oesophagitis
Authors: Lundell L , Miettinen P , Myrvold H E , Hatlebakk J G , Wallin L , Malm A , Sutherland I , Walan A 
Published: January 2007

Abstract

Background
This randomized clinical trial compared long-term outcome after antireflux surgery with acid inhibition therapy in the treatment of chronic gastro-oesophageal reflux disease (GORD).

Methods
Patients with chronic GORD and oesophagitis verified at endoscopy were allocated to treatment with omeprazole (154 patients) or antireflux surgery (144). After 7 years of follow-up, 119 patients in the omeprazole arm and 99 who had antireflux surgery were available for evaluation. The primary outcome variable was the cumulative proportion of patients in whom treatment failed. Secondary objectives were evaluation of the treatment failure rate after dose adjustment of omeprazole, safety, and the frequency and severity of post-fundoplication complaints.

Results
The proportion of patients in whom treatment did not fail during the 7 years was significantly higher in the surgical than in the medical group (66·7 versus 46·7 per cent respectively; P = 0·002). A smaller difference remained after dose adjustment in the omeprazole group (P = 0·045). More patients in the surgical group complained of symptoms such as dysphagia, inability to belch or vomit, and rectal flatulence. These complaints were fairly stable throughout the study interval. The mean daily dose of omeprazole was 22·8, 24·1, 24·3 and 24·3 mg at 1, 3, 5 and 7 years respectively.

Conclusion
Chronic GORD can be treated effectively by either antireflux surgery or omeprazole therapy. After 7 years, surgery was more effective in controlling overall disease symptoms, but specific post-fundoplication complaints remained a problem. There appeared to be no dose escalation of omeprazole with time.
Randomized clinical trial comparing botulinum toxin injections with 0·2 per cent nitroglycerin ointment for chronic anal fissure
Authors: Brisinda G , Cadeddu F , Brandara F , Marniga G , Maria G 
Published: January 2007

Abstract

Background
In recent years treatment of chronic anal fissure has shifted from surgical to medical. This study compared the ability of two non-surgical treatments—botulinum toxin injections and nitroglycerin ointment—to induce healing in patients with idiopathic anal fissure.

Methods
One hundred adults were assigned randomly to receive treatment with either type A botulinum toxin (30 units Botox® or 90 units Dysport®) injected into the internal anal sphincter or 0·2 per cent nitroglycerin ointment applied three times daily for 8 weeks.

Results
After 2 months, the fissures were healed in 46 (92 per cent) of 50 patients in the botulinum toxin group and in 35 (70 per cent) of 50 in the nitroglycerin group (P = 0·009). Three patients in the botulinum toxin group and 17 in the nitroglycerin group reported adverse effects (P &lt; 0·001). Those treated with botulinum toxin had mild incontinence to flatus that lasted 3 weeks after treatment but disappeared spontaneously, whereas nitroglycerin treatment was associated with transient, moderate-to-severe headaches. Nineteen patients who did not have a response to the assigned treatment crossed over to the other therapy.

Conclusion
Although treatment with either topical nitroglycerin or botulinum toxin is effective as an alternative to surgery for patients with chronic anal fissure, botulinum toxin is the more effective option.
A systematic review of the impact of volume of surgery and specialization on patient outcome
Authors: Chowdhury M M , Dagash H , Pierro A 
Published: January 2007

AbstractBackground and methodsVolume of surgery and specialization may affect patient outcome. Articles examining the effects of one or more of three variables (hospital volume of surgery, surgeon volume and specialization) on outcome (measured by length of hospital stay, mortality and complication rate) were analysed. Reviews, opinion articles and observational studies were excluded. The methodological quality of each study was assessed, a correlation between the variables analysed and the outcome accepted if it was significant.ResultsThe search identified 55 391 articles published between 1957 and 2002; 1075 were relevant to the study, of which 163 (9 904 850 patients) fulfilled the entry criteria. These 163 examined 42 different surgical procedures, spanning 13 surgical specialities. None were randomized and 40 investigated more than one variable. Hospital volume was reported in 127 studies; high-volume hospitals had significantly better outcomes in 74·2 per cent of studies, but this effect was limited in prospective studies (40 per cent). Surgeon volume was reported in 58 studies; high-volume surgeons had significantly better outcomes in 74 per cent of studies. Specialization was reported in 22 studies; specialist surgeons had significantly better outcomes than general surgeons in 91 per cent of studies. The benefit of high surgeon volume and specialization varied in magnitude between specialities.ConclusionHigh surgeon volume and specialization are associated with improved patient outcome, while high hospital volume is of limited benefit.
Systematic review of enhanced recovery programmes in colonic surgery (Br J Surg 2003; 93: 800–809)
Authors: Walter C , Collin J 
Published: January 2007

Abstract
The Editors welcome topical correspondence from readers relating to articles published in the Journal. Responses should be sent electronically via the BJS website (www.bjs.co.uk). All letters will be reviewed and, if approved, appear on the website.A selection of these will be edited and publishe in the Journal. Letters must be no more than 250 words in length.
Electrochemiluminescent Cells Based on Zeolite‐Encapsulated Host–Guest Systems: Encapsulated Ruthenium Tris‐bipyridyl
Authors: Álvaro Mercedes , Cabeza Jose F. , Fabuel David , Corma Avelino , García Hermenegildo 
Published: February 2007

AbstractAn electrochemiluminescent cell has been developed that has an active layer consisting of ruthenium tris‐bipyridyl encapsulated inside zeolite Y supercages. Operation of the cell requires the addition of polyethylene glycol as the solid electrolyte. The cell, which exhibits electrical conductivity behavior typical of a semiconductor, has an optimum operating voltage of 3 V. Ion exchange of sodium by cesium and vapor deposition of calcium metal inside the zeolite pores enhance the electrochemiluminescent efficiency of the cell by a factor of 4.
Stille–Heck Coupling Sequences Applied in a Versatile New Access to Steroid Skeletons
Authors: Sünnemann Hans Wolf , Hofmeister Anja , Magull Jörg , de Meijere Armin 
Published: January 2007

AbstractA variety of enantiomerically pure steroidal compounds was synthesized utilizing a sequence of Stille and Heck cross‐coupling reactions and subsequent thermal 6π‐electrocyclizations. Highly chemoselective Stille couplings on the triflate moiety of several 2‐bromocyclohex‐1‐enyl triflates with cis‐ and trans‐fused bicyclo[4.3.0]nonenylstannanes furnished the corresponding tricyclic bromobutadienes in good to excellent yields (70–97 %). These were subjected to Heck reactions with tert‐butyl acrylate to provide pentasubstituted tricyclic 1,3,5‐hexatrienes. A significant increase in efficiency could be achieved by applying a novel protocol with a precatalyst on the basis of the palladacycle prepared from Pd(OAc)2 and P(o‐Tol)3 with added triarylphosphines as co‐ligands (73–90 % yield). Upon heating to 205–215 °C in decalin or to 140 °C in toluene (for certain cases), these hexatrienes yielded (78–90 %) various unsaturated steroid analogues as single diastereomers. A particular oxohexatriene, obtained after deprotection of an adjacent carbonyl group, underwent 6π‐electrocyclization at the unusually low temperature of 140 °C to yield (75 %) an interesting 7‐carboxyl‐substituted steroidal dienone. Attempts to remove the remaining protecting groups from some of the other new steroidal compounds under acidic conditions furnished a novel 3‐oxo‐7‐carboxyl steroid analogue and a 3‐hydroxy‐substituted steroidal diene. A novel estradiol derivative could be obtained in 69 % yield from the synthesized steroidal dienone. Deprotection furnished the corresponding unprotected 7‐carboxylestradiol in 81 % yield.