bluuebunny/crossref_metadata_2025_split huggingface dataset:
Second Generation Artificial Hydrogenases Based on the Biotin‐Avidin Technology: Improving Activity, Stability and Selectivity by Introduction of Enantiopure Amino Acid Spacers
Authors: Rusbandi Untung E. , Lo Cheikh , Skander Myriem , Ivanova Anita , Creus Marc , Humbert Nicolas , Ward Thomas R. 
Published: August 2007

AbstractWe report on our efforts to create efficient artificial metalloenzymes for the enantioselective hydrogenation of N‐protected dehydroamino acids using either avidin or streptavidin as host proteins. Introduction of chiral amino acid spacers – phenylalanine or proline – between the biotin anchor and the flexible aminodiphosphine moiety 1, combined with saturation mutagenesis at position S112X of streptavidin, affords second generation artificial hydrogenases displaying improved organic solvent tolerance, reaction rates (3‐fold) and (S)‐selectivities (up to 95 % ee for N‐acetamidoalanine and N‐acetamidophenylalanine). It is shown that these artificial metalloenzymes follow Michaelis–Menten kinetics with an increased affinity for the substrate and a higher kcat than the protein‐free catalyst (compare kcat 3.06 min−1 and KM 7.38 mM for [Rh(COD)Biot‐1]+ with kcat 12.30 min−1 and KM 4.36 mM for [Rh(COD)Biot‐(R)‐Pro‐1]+ ⊂ WT Sav). Finally, we present a straightforward protocol using Biotin‐Sepharose to immobilize artificial metalloenzymes (>92 % ee for N‐acetamidoalanine and N‐acetamidophenylalanine using [Rh(COD)Biot‐(R)‐Pro‐1]+ ⊂ Sav S112W).
Synthesis of Hexahydrocyclopenta[c]furans by an Intramolecular Iron‐Catalyzed Ring Expansion Reaction
Authors: Hilt Gerhard , Bolze Patrick , Heitbaum Maja , Hasse Katrin , Harms Klaus , Massa Werner 
Published: August 2007

AbstractThe intramolecular iron‐catalyzed ring expansion reaction of epoxyalkenes was investigated with a preformed iron(salen) [Fe(Salen)] complex. The formal insertion of the alkene into the epoxide generated hexahydrocyclopenta[c]furan derivatives in moderate to good yields and diastereoselectivities depending on other functional groups present in the starting materials. In addition, oxygen‐tethered epoxyalkenes were used for the synthesis of lignan isomers. The scope and limitations of the Fe(Salen)‐catalyzed process of the reaction are discussed.
Palladium‐Catalyzed Regioselective Cross‐Coupling Reactions of 3‐Bromo‐4‐tosyloxyquinolin‐2(1H)‐one with Arylboronic Acids. A Facile and Convenient Route to 3,4‐Disubstituted Quinolin‐2(1H)‐ones
Authors: Wang Zhiyong , Fan Renhua , Wu Jie 
Published: August 2007

AbstractThe palladium‐catalyzed regioselective cross‐coupling reaction of 3‐bromo‐4‐tosyloxyquinolin‐2(1H)‐one with arylboronic acid is described, which provides a simple, general, efficient, and practical route for the synthesis of 3,4‐disubstituted quinolin‐2(1H)‐ones.
Substituted Benzocarbocycles by Palladium‐Catalyzed Cascade Reactions Featuring a C(sp3)H Activation Step
Authors: Hitce Julien , Baudoin Olivier 
Published: August 2007

AbstractValuable 4‐ and 5‐membered benzocarbocycles were synthesized via selective palladium‐catalyzed cascade reactions which combined C(sp3)H activation, Heck cyclization, Heck arylation or olefin hydrogenation. In all cases, all mechanistically independent steps were catalyzed by a single multi‐functional catalyst.
An Improved Protocol for the Direct Asymmetric Aldol Reaction in Ionic Liquids, Catalysed by Onium Ion‐Tagged Prolines
Authors: Lombardo Marco , Pasi Filippo , Easwar Srinivasan , Trombini Claudio 
Published: August 2007

AbstractTwo onium ion‐tagged prolines, imidazolium bis(trifluoromethylsulfonyl)imide‐substituted proline 6 and butyldimethylammonium bis(trifluoromethylsulfonyl)imide‐substituted proline 7, were synthesised and their catalytic activity in the direct asymmetric aldol condensation was studied in ionic liquids. For the reaction of acetone with various aldehydes, using 5 % of the catalyst, the yields of the aldols varied between 50–85 % while the ee values were in the 80–85 % range. Other ketones were studied too, the yields obtained in those cases being in the 35–78 % range while the enantioselectivities varied between 75–94 %.
Chiral Phosphoric Acid‐Catalyzed Enantioselective Aza‐Friedel–Crafts Reaction of Indoles
Authors: Terada Masahiro , Yokoyama Shigeko , Sorimachi Keiichi , Uraguchi Daisuke 
Published: August 2007

AbstractA highly enantioselective 1,2‐aza‐Friedel–Crafts reaction of N‐tert‐butyldimethylsilylindole with N‐tert‐butoxycarbonyl aromatic imines is demonstrated using a BINOL‐derived monophosphoric acid catalyst. The present approach provides efficient access to 3‐indolylmethaneamines with aryl substituents in excellent enantioselectivities (up to 98 % ee). An inversion in the sense of enantioselection was found between monophosphoric acid catalysts bearing different substituents introduced at the 3,3′‐position of binaphthyl backbone. We also calculated the three‐dimensional structure of the monophosphoric acid catalysts to speculate on the inversion of the stereochemical outcome.
Olefin Metathesis of Amine‐Containing Systems: Beyond the Current Consensus
Authors: Compain Philippe 
Published: August 2007

AbstractOlefin metathesis is one of the most powerful synthetic tool to access amine‐containing heterocycles and alkaloids. A major drawback associated with the use of amines concerns their ability to coordinate to metal‐alkylidene complexes and to interfere unproductively with catalytic activity. Based on literature precedents, it has been established as a “dogma” that efficient metathesis reactions are suppressed in the presence of basic amines and that such substrates must invariably be deactivated by conversion of the amines to the corresponding carbamates or ammonium salts. However, an increasing number of examples of amine‐containing compounds that are good substrates for metathesis is being reported in the literature. How can this “non‐classical” reactivity be rationalized and exploited? The purpose of this review is to provide an overview of successful metathesis reactions performed with amine‐containing compounds in order to allow some guidelines to be formulated. A special emphasis is placed on the different parameters that may influence the outcome of the reaction such as steric effects, amine basicity, and the nature of the catalyst.
Triphasic Liquid Systems for Improved Separations. Trioctylmethylammonium Chloride‐Immobilised Rhodium Trichloride: A Phosphine‐Free Hydroformylation Catalytic System
Authors: Paganelli Stefano , Perosa Alvise , Selva Maurizio 
Published: August 2007

AbstractA liquid triphasic system made of isooctane, water, and trioctylmethylammonium chloride allows one to carry out the hydroformylation of model olefins using neat RhCl3 as catalyst precursor. By using the triphasic system, the catalyst is kept separate from the reagents and products. This allows one to simply remove the product and to recycle the catalyst numerous times. No leaching of rhodium into the organic phase is observed.
Evaluation of opioid induced nausea and vomiting in sickle cell disease
Authors: Shord Stacy Shifflett , Chew Lita , Villano John 
Published: August 2007

AbstractA common side effect of opioids is nausea and vomiting; however, the incidence in hospitalized patients receiving opioids for acute pain is unknown. We performed a retrospective study in adult patients with sickle cell disease admitted for an acute pain crisis during a six‐month period to evaluate the incidence of nausea and vomiting and characterize the prescribing of antiemetics. Eligibility included normal hepatic and renal function. Thirty‐four subjects with a total of 97 admissions were evaluated. As expected, opioids were prescribed during all admissions. Fifty percent of the subjects experienced nausea or vomiting during the study period and these same patients accounted for the majority of the admissions, 17 subjects with 71 admissions (Group I). Nausea was reported in 18 (25%) of these admissions and vomiting was reported in 24 (34%) of these admissions. The most common antiemetics prescribed were: prochlorperazine, metoclopramide, and promethazine and antiemetics were ordered during 22 (23%) separate admissions for all subjects included in the study. The clinical benefit of these medications is limited due to uneven documentation. In conclusion, many of our patients experienced nausea or vomiting with antiemetics infrequently prescribed on an as needed basis. This suggests a need for better approaches to manage nausea and vomiting in patients receiving opioids. Am. J. Hematol., 2008. © 2007 Wiley‐Liss, Inc.
Daily differences in patterns of physical activity among overweight/obese children engaged in a physical activity program
Authors: Aires Luísa , Santos Rute , Silva Pedro , Santos Paula , Oliveira José , Ribeiro José C. , Rego Carla , Mota Jorge 
Published: August 2007

AbstractThe aim of this study was to compare the physical activity of overweight/obese children during days when they attended a physical activity program, and days when they did not. This is a cross‐sectional intervention study of daily physical activity. The participants were referred by family, doctors, or hospital pediatricians to take part in a 10‐month interdisciplinary, outpatient obesity intervention program for children. The subjects included 41 overweight and obese children aged 8–16 years, 19 boys (46%) and 22 girls (54%); BMI: 25.7 + 3.3 kg m−2. The MTI Actigraph was used as an objective measure of daily physical activity over seven consecutive days. Physical activity program days presented a significantly higher percentage of time (4.68%) spent in moderate‐to‐vigorous activity compared with no physical activity program days (3.16%) and weekend (2.7%). The results of this study suggest that a physical activity program can help increasing daily physical activity in obese children, with a special focus on MVPA level. Our data point that obese children are less active at weekend than during weekdays. Am. J. Hum. Biol., 2007. © 2007 Wiley‐Liss, Inc.
Social inequality in premature mortality among polish urban adults during economic transition
Authors: Kołodziej Halina , Łopuszańska Monika , Bielicki Tadeusz , Jankowska Ewa Anita 
Published: August 2007

AbstractRates of premature mortality among adults are important measures of the economic and psychosocial well‐being of human populations. In many countries, such rates are, as a rule, inversely related to the level of attained education. We examined changes in educational group‐specific mortality rates among urban adults in Poland during the country's rapid transition in the 1990s from a socialist command economy to a free market system. Two census‐based analyses of individual death records of urban dwellers aged 35–64 years were compared. We utilized all records of death, which occurred during the 2‐year periods 1988–89 and 2001–02. Population denominators were taken from the censuses of 1988 and 2002. The age‐specific mortality rates were used to evaluate absolute differences in mortality. To assess relative differences between educational levels, mortality rate ratios (MRRs) with 95% CI (confidence interval) were calculated using Poisson regression. A regular educational gradient in mortality persisted in each 10‐year age group throughout the period covered by our data. Moreover, age‐specific mortality rates declined steadily in all educational groups, and this decline was most marked in the two oldest age groups (45–54 and 55–64 years). The trend was accompanied by widening of educational differences in mortality as expressed by MRRs. Systemic political transformation in Poland has brought a mixture of beneficial and detrimental effects on the well‐being of society. With regard to the changes in rates of premature mortality among adults, the benefits have prevailed, although individuals with the lowest educational level benefited less than those with the highest education. Am. J. Hum. Biol., 2007. © 2007 Wiley‐Liss, Inc.
Spermiogenesis in Soft‐Shelled Turtle, Pelodiscus sinensis
Authors: Zhang Li , Han Xiang‐Kun , Li Mei‐Ying , Bao Hui‐Jun , Chen Qiu‐Sheng 
Published: August 2007

AbstractSpermiogenesis in the soft‐shelled turtle, Pelodiscus sinensis, was examined by transmission electron microscopy. The process includes nuclear elongation, chromatin condensation, acrosomal and flagellar development, and elimination of excess cytoplasm. In stage I, the proacrosomal vesicle occurs next to a shallow fossa of the nucleus, and a dense acrosomal granule forms beneath it. A smaller subacrosomal granule in the middle of the fibrous layer is related to the development of intranuclear tubules. The nucleus begins to move eccentrically. In stage II, the round proacrosomal vesicle is flattened by protrusion of the nuclear fossa, and the dense acrosomal granule diffuses into the vesicle, as the fibrous layer forms the subacrosomal cone. Circular manchettes develop around the nucleus, and the chromatin coagulates into small granules. The movement of the nucleus causes rearrangement of the cytoplasm. In stage III, the front of the elongating nucleus protrudes out of the spermatid and is covered by the flat acrosome; coarse granules replace the small ones within the nucleus. At the posterior pole of the head, mitochondria move backward. Numerous microtubules begin to assemble the axoneme of flagellum. In stage IV, the chromatin concentrates to dense homogeneous phase. The circular manchette is reorganized longitudinally. The Sertoli process covers the acrosome and the residues of the cytoplasmic lobes are eliminated. In stage V, the sperm head matures. After dissolution of the longitudinal manchette, the mitochondria arrange themselves around the proximal and distal centrioles. Caudal to the mitochondrial mass, a fibrous sheath surrounds the proximal portion of the flagellum. Anat Rec, 290:1213‐1222, 2007. © 2007 Wiley‐Liss, Inc.
Ermüdungsbeanspruchungen von Betonbrücken unter zunehmendem Schwerverkehr
Authors: Grünberg Jürgen , Hansen Michael , Liebig Jan Peter 
Published: August 2007

AbstractDer erwartete Anstieg des Schwerverkehraufkommens führt zu größeren Ermüdungsbeanspruchungen an Brückentragwerken. Dabei sind die Auswirkungen in Längsrichtung der Brücken abhängig von dem Lastmodellgewicht und dem Verhältnis zwischen der Lastmodelllänge und der Tragwerkstützweite. Das Institut für Massivbau der Leibniz Universität Hannover hat im Auftrag des Bundesministers für Verkehr, Bau und Stadtentwicklung (BMVBS) ein Forschungsvorhaben durchgeführt, in dem Brückentragwerke aus Beton mit verschiedenen Querschnittsausbildungen (Kastenträger, schiefwinklige Platte, zweistegiger Plattenbalken) im Hinblick auf ihren Ermüdungswiderstand analysiert worden sind. Die Beanspruchungen für den Beton und den Bewehrungsstahl sind mit aufwändigen numerischen Modellen in Längs‐ und Quertragrichtung der Brücken ermittelt worden. Neben den Einwirkungskombinationen nach DIN‐Fachbericht für die Nachweise der Ermüdungsbeanspruchungen wurden auch die Beanspruchungen infolge der 60 t‐Fahrzeugkombination nach dem modularen Nutzfahrzeugkonzept bestimmt, um die zukünftige Entwicklung des Schwerlastverkehrs einzubeziehen.
Sicherheitskonzept von unterspannten Konstruktionen
Authors: Ploch Jan , Novák Balthasar 
Published: August 2007

AbstractStändige Einwirkungen und Vorspannung werden in den Regelwerken als unabhängige Einwirkungen behandelt und mit unterschiedlichen (Teil‐)Sicherheitsbeiwerten versehen. Dem gegenüber gibt es Vorschläge, bei Tragwerken, deren Geometrie während des Vorspannens kontrolliert wird, Eigenlasten und Vorspannung als gemeinsamen Lastfall “ständige Einwirkungen” anzusehen und somit denselben Sicherheitsbeiwert auf sie anzuwenden. Diese beiden Ansätze werden systematisch hinsichtlich der Sicherheit der Tragwerke verglichen. Es wird gezeigt, dass die Auffassung von Eigenlasten und Vorspannung als gemeinsamer Lastfall nicht zu einem ausreichenden Sicherheitsniveau führt. Aus den Ergebnissen der Untersuchungen wird ein Vorschlag entwickelt, der den Einfluss von Geometriekontrollen während des Vorspannens durch Modifikation des Teilsicherheitsbeiwerts für die Vorspannung berücksichtigt und zum geforderten Zuverlässigkeitsniveau bei gleichzeitig wirtschaftlicheren Dimensionierungen führt.
Neue Sichtbetontechnologie im Praxistest an einer 12 Meter hohen Wand
Authors: Lohaus Ludger , Fischer Karen , Gläser Thomas , Fuchs Andreas 
Published: August 2007

AbstractAm Institut für Baustoffe der Leibniz Universität Hannover wurden mit Hilfe von zwei Prüfschalungen neue betontechnologische Ansätze für robuste Sichtbetonzusammensetzungen entwickelt. Da das Verhalten dieser sehr weichen bis fließfähigen Frischbetone von herkömmlichen Rüttelbetonen abweicht, wird ein Weg zur Umsetzung der neuen Sichtbetontechnologie in die Praxis vorgeschlagen. Beim Betonieren einer rund 12 Meter hohen Sichtbetonwand beim Neubau eines Wissenschaftszentrums im Kompetenzzentrum für nachwachsende Rohstoffe in Straubing ist ein erster Praxistest gelungen. Hierbei führten die Ansätze der neuen Sichtbetontechnologie im Zusammenspiel mit der Nutzung von Sichtbetonprüfschalungen sowie der Herstellung von Erprobungsflächen zu einem guten Gesamtergebnis der unter schwierigen Betonierbedingungen erstellten Sichtbetonwand.
Optimal Response‐Adaptive Designs for Continuous Responses in Phase III Trials
Authors: Biswas Atanu , Bhattachary Rahul , Zhang Lanju 
Published: August 2007

AbstractOptimal response‐adaptive designs in phase III clinical trial set up are gaining more interest. Most of the available designs are not based on any optimal consideration. An optimal design for binary responses is given by Rosenberger et al. (2001) and one for continuous responses is provided by Biswas and Mandal (2004). Recently, Zhang and Rosenberger (2006) proposed another design for normal responses. This paper illustrates that the Zhang and Rosenberger (2006) design is not suitable for normally distributed responses, in general. The approach cannot be extended for other continuous response cases, such as exponential or gamma. In this paper, we first describe when the optimal design of Zhang and Rosenberger (2006) fails. We then suggest the appropriate adjustments for designs in different continuous distributions. A unified framework to find optimal response‐adaptive designs for two competing treatments is proposed. The proposed methods are illustrated using some real data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Maternity Length of Stay Modelling by Gamma Mixture Regression with Random Effects
Authors: Lee Andy H. , Wang Kui , Yau Kelvin K. W. , McLachlan Geoffrey J. , Ng Shu Kay 
Published: August 2007

AbstractMaternity length of stay (LOS) is an important measure of hospital activity, but its empirical distribution is often positively skewed. A two‐component gamma mixture regression model has been proposed to analyze the heterogeneous maternity LOS. The problem is that observations collected from the same hospital are often correlated, which can lead to spurious associations and misleading inferences. To account for the inherent correlation, random effects are incorporated within the linear predictors of the two‐component gamma mixture regression model. An EM algorithm is developed for the residual maximum quasi‐likelihood estimation of the regression coefficients and variance component parameters. The approach enables the correct identification and assessment of risk factors affecting the short‐stay and long‐stay patient subgroups. In addition, the predicted random effects can provide information on the inter‐hospital variations after adjustment for patient characteristics and health provision factors. A simulation study shows that the estimators obtained via the EM algorithm perform well in all the settings considered. Application to a set of maternity LOS data for women having obstetrical delivery with multiple complicating diagnoses is illustrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Automated docking to explore subsite binding by glycoside hydrolase family 6 cellobiohydrolases and endoglucanases
Authors: Mertz Blake , Hill Anthony D. , Mulakala Chandrika , Reilly Peter J. 
Published: August 2007

AbstractCellooligosaccharides were computationally docked using AutoDock into the active sites of the glycoside hydrolase Family 6 enzymes Hypocrea jecorina (formerly Trichoderma reesei) cellobiohydrolase and Thermobifida fusca endoglucanase. Subsite –2 exerts the greatest intermolecular energy in binding β‐glucosyl residues, with energies progressively decreasing to either side. Cumulative forces imparting processivity exerted by these two enzymes are significantly less than by the equivalent glycoside hydrolase Family 7 enzymes studied previously. Putative subsites –4, –3, +3, and +4 exist in H. jecorina cellobiohydrolase, along with putative subsites –4, –3, and +3 in T. fusca endoglucanase, but they are less important than subsites –2, –1, +1, and +2. In general, binding adds 3–7 kcal/mol to ligand intramolecular energies because of twisting of scissile glycosidic bonds. Distortion of β‐glucosyl residues to the 2SO conformation by binding in subsite –1 adds ∼7 kcal/mol to substrate intramolecular energies. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 249–260, 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
The lipase‐catalyzed hydrolysis of lutein diesters in non‐aqueous media is favored at extremely low water activities
Authors: Mora‐Pale J. Mauricio , Pérez‐Munguía Sandra , González‐Mejía Jessica C. , Dordick Jonathan S. , Bárzana Eduardo 
Published: August 2007

AbstractThe enzymatic hydrolysis of a mixture of lutein diesters from Marigold flower (Tagetes erecta) was performed both in organic solvents and supercritical CO2 (SC‐CO2) using two commercial lipases: lipase B from Candida antarctica (Novozym 435) and the lipase from Mucor miehei (Lipozyme RM IM). Both lipases showed an unexpected dependence of initial reaction rate with the initial water activity (awi) in hexane, with the highest rates of hydrolysis taking place at the lowest awi of the biocatalyst particles. The same result was observed using isooctane, toluene, or SC‐CO2. It is proposed that an increase in awi generates a hydrophilic microenvironment that prevents efficient partitioning of the highly hydrophobic lutein diesters to the enzyme. The critical role of water in this system has not been reported for other hydrolytic reactions in low water media. Calculations of water available for hydrolysis from isotherm analysis, Karl‐Fischer titration, and substrate conversion at awi = 0.13, indicate that the extent of reaction is not limited by the amount of available water. Accordingly, the enzyme that holds the largest amount of water after prehydration at the same awi (0.13) will yield the greatest substrate conversion and concentration of the free lutein product. The highest conversion occurred in SC‐CO2, which opens up new opportunities to develop a combined extraction–reaction process for the environmentally benign synthesis of lutein, an important nutraceutical compound. Biotechnol. Bioeng. 2007;98: 535–542. © 2007 Wiley Periodicals, Inc.