bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid chromatographic determination of acetylcholine based on pre‐column alkaline cleavage reaction and post‐column tris(2,2′‐bipyridyl)ruthenium(III) chemiluminescence detection
Authors: Yoshida Hideyuki , Yamada Akifumi , Todoroki Kenichiro , Imakyure Osamu , Nohta Hitoshi , Yamaguchi Masatoshi 
Published: April 2009

AbstractA method for the determination of acetylcholine (ACh) has been developed using liquid chromatography with chemiluminescence detection. This method is based on the pre‐column alkaline cleavage of ACh to form trimethylamine (TMA) and the post‐column tris(2,2′‐bipyridyl)ruthenium(III) chemiluminescence detection of TMA. ACh was converted to TMA with high yield at 180°C in the presence of lithium hydroxide, and the produced TMA was separated on a cation‐exchange/reversed‐phase dual‐functional column using a mixture of 0.2 m potassium phosphate buffer (pH 5.9) and acetonitrile (20:1, v/v) as the mobile phase. The eluate was online mixed with acidic tris(2,2′‐bipyridyl)ruthenium(III) solution, and the generated chemiluminescence was detected. The detection limit (signal‐to‐noise ratio = 3) for ACh was 0.80 nmol/mL, which corresponded to 1.1 pmol TMA per injection volume of 5 µL. This is simple and robust method that does not need an expensive device and unstable enzymes, and was applied to the determination of ACh in pharmaceutical formulations. Copyright © 2009 John Wiley & Sons, Ltd.
The assaying of haemoglobin using luminol chemiluminescence and its application to the dating of human skeletal remains
Authors: Creamer J. I. , Buck A. M. 
Published: April 2009

AbstractThe luminol chemiluminescence reaction has, for some time, been used as a tool for the detection of haemoglobin at crime scenes. More recently, the luminol test has been suggested as a possible tool for estimating the post‐mortem interval (PMI) of skeletal remains. The preliminary results from the following study indicate that the chemiluminescent luminol test is a relatively easy and economical method for distinguishing between remains of medico‐legal (≤100 years) and historical (>100 years) interest. The femur was the preferred bone for PMI measurements using the luminol test, due to its robustness and relative resistance to diagenesis. Initial results suggest that bone that was historical in nature, produced a demonstrably weaker reaction than that of medico‐legal interest. These results suggest that the luminol test is a promising technique, albeit with some limitations, for the assessment of skeletal material that may be potentially of medico‐legal interest. Copyright © 2009 John Wiley & Sons, Ltd.
Directed evolution of a Bacillus chitinase
Authors: Songsiriritthigul Chomphunuch , Pesatcha Putarika , Eijsink Vincent G.H. , Yamabhai Montarop 
Published: April 2009

AbstractChitinases have potential in various industrial applications including bioconversion of chitin waste from crustacean shells into chito‐oligosaccharide‐based value‐added products. For industrial applications, obtaining suitable chitinases for efficient bioconversion processes will be beneficial. In this study, we established a straightforward directed evolution method for creating chitinase variants with improved properties. A library of mutant chitinases was constructed by error‐prone PCR and DNA shuffling of two highly similar (99% identical) chitinase genes from Bacillus licheniformis. Activity screening was done in two steps: first, activity towards colloidal chitin was screened for on culturing plates (halo formation). This was followed by screening activity towards the chitotriose analogue p‐nitrophenyl‐β‐1,4‐N, N'‐diacetyl‐chitobiose at various pH in microtiter plates. From a medium‐throughput screening (517 colonies), we were able to isolate one mutant that demonstrated improved catalytic activity. When using p‐nitrophenyl‐β‐1,4‐N, N'‐diacetyl‐chitobiose as substrate, the overall catalytic efficiency, kcat/Km of the improved chitinase was 2.7‐ and 2.3‐fold higher than the average kcat/Km of wild types at pH 3.0 and 6.0, respectively. The mutant contained four residues that did not occur in either of the wild types. The approach presented here can easily be adopted for directed evolution of suitable chitinases for various applications.
Systemic lupus erythematosus and C1q: A quantitative ELISA for determining C1q levels in serum
Authors: Dillon Skyler P. , D'Souza Anil , Kurien Biji T. , Scofield R. Hal 
Published: April 2009

AbstractC1q is of interest in systemic lupus erythematosus (SLE) research due to deficiencies in its activity being associated with the disease. Current published protocols for measuring C1q vary greatly in their results and ease of reproducibility. Due to this, average C1q concentrations have been reported between 56 and 276 μg/mL in non‐SLE serum. We present an improved method for quantifying C1q concentrations, which employs a sandwich ELISA. This method has improved precision, cost efficiency, up‐scaling, reproducibility, and uses significantly lesser volumes of serum sample when compared to RID and other methods for quantifying C1q. We report an average concentration of 113 ± 40 μg/mL for C1q in non‐SLE serum. The assay designed here will be useful in the high‐throughput measurement of serum C1q in SLE cases.
Ribosomal Synthesis of Peptides with C‐Terminal Lactams, Thiolactones, and Alkylamides
Authors: Nakajima Eiji , Goto Yuki , Sako Yusuke , Murakami Hiroshi , Suga Hiroaki 
Published: April 2009

AbstractAll change at the C terminus: We have established a novel methodology for the ribosomal synthesis of peptides featuring C‐terminal cyclization and various modifications, including macrocyclization, by making use of genetic code reprogramming. The C‐terminal amide modification of linear and cyclic peptides should enhance their physiological stabilities, and open up the possibility of developing new drug‐like peptides.magnified imageThe C terminus of a peptide expressed by the translation apparatus generally ends in a carboxylate group. On the other hand, the C termini of some naturally occurring peptides have amide moieties instead of carboxylates, which are believed to give better biostability. Here, we describe a new strategy for the ribosomal synthesis of peptides featuring C‐terminal lactam, thiolactone, and alkylamide units. The method was based on the concept of genetic code reprogramming involving the flexizymes (flexible tRNA acylation ribozymes) and the PURE (peptide synthesis using recombinant elements) system, in which vacant codons are reassigned to nonproteinogenic amino acids; this enabled us to convert the C termini of peptides into the above functionalities. We have also applied this method to the synthesis of a macrocyclic peptide closed by an amide bond formed between a lysine side chain and the peptide C terminus. This method thus offers us new opportunities to express various peptides with C‐terminal modifications as well as macrocyclic peptides using the translation apparatus, and potentially to accelerate the discovery of peptidic drugs designed for various therapeutic targets.
Design, Synthesis, and Biological Evaluation of Artificial Macrosphelides in the Search for New Apoptosis‐Inducing Agents
Authors: Matsuya Yuji , Kobayashi Yuta , Kawaguchi Takanori , Hori Ayana , Watanabe Yuka , Ishihara Kentaro , Ahmed Kanwal , Wei Zheng‐Li , Yu Da‐Yong , Zhao Qing‐Li , Kondo Takashi , Nemoto Hideo 
Published: April 2009

AbstractA drug of two halves: New artificial compounds composed of a macrosphelide core skeleton and an epothilone side chain were designed and synthesized. These compounds were more potent inducers of apoptosis than the parent natural‐type macrosphelides.magnified imageVarious artificial macrosphelides were designed and synthesized, including ring‐enlarged analogues and epothilone‐hybrid compounds. Syntheses were accomplished in an efficient manner by using a ring‐closing metathesis (RCM) strategy in a key macrocyclization step. Biological evaluation of these new macrosphelide‐based derivatives revealed that several epothilone hybrids, in which a thiazole‐containing side chain was incorporated, exhibited potent apoptosis‐inducing activity toward human lymphoma cells. These activities were considerably enhanced relative to those of natural macrosphelide compounds. Structure–activity relationship studies revealed that the “ene‐dicarbonyl” substructure is apparently essential for bioactivity.
Design of and Mechanistic Studies on a Biomimetic Iron–Imidazole Catalyst System for Epoxidation of Olefins with Hydrogen Peroxide
Authors: Schröder Kristin , Enthaler Stephan , Bitterlich Bianca , Schulz Thomas , Spannenberg Anke , Tse Man Kin , Junge Kathrin , Beller Matthias 
Published: April 2009

AbstractOne step further in bio‐inspired catalytic epoxidation reactions was made in investigations on iron/imidazole catalyst systems (see the crystal of one example) with hydrogen peroxide as the terminal oxidant, in which it was shown for the first time that defined iron–imidazole complexes are capable of epoxidizing challenging aliphatic olefins. X‐ray studies, UV/Vis titrations, and NMR studies were carried out to clarify the mechanism.magnified imageNovel iron catalysts, both defined and in situ generated, for the epoxidation of aromatic and aliphatic olefins with hydrogen peroxide as terminal oxidant are described. Our catalyst approach is based on bio‐inspired 1‐aryl‐substituted imidazoles in combination with cheap and abundant iron trichloride hexahydrate. We show that the free 2‐position of the imidazole ligand motif plays a key role for catalytic activity, as substitution leads to a dramatic depletion of yield and conversion. X‐ray studies, UV/Vis titrations, and NMR studies were carried out to clarify the mechanism.
Cover Picture: Solid‐State Structural Characterization of Cutinase–ECE‐Pincer–Metal Hybrids (Chem. Eur. J. 17/2009)
Authors: Rutten Lucy , Wieczorek Birgit , Mannie Jean‐Paul B. A. , Kruithof Cornelis A. , Dijkstra Harm P. , Egmond Maarten R. , Lutz Martin , Klein Gebbink Robertus J. M. , Gros Piet , van Koten Gerard 
Published: April 2009

AbstractThe interfacial enzyme cutinase…︁ shown at the air–water interface on the cover, was site‐selectively modified with two different ECE‐pincer–metal complexes. The resulting cutinase–pincer–metal hybrids crystallized under halide‐rich conditions to give monomeric crystal structures, but also crystallized under halide‐poor conditions to form a metal‐induced dimer. See the Full Paper by R. J. M. Klein Gebbink, P. Gros, G. van Koten et al. on page 4270 ff., for details of the chemistry and the crystal structures. Photograph: View from the island of Saba (Netherlands Antilles) taken by Birgit Wieczorek. Design: Birgit Wieczorek and Cornelis A. Kruithof.magnified image
Conversion of Furfuryl Alcohol into Ethyl Levulinate using Solid Acid Catalysts
Authors: Lange Jean‐Paul , van de Graaf Wouter D. , Haan René J. 
Published: April 2009

AbstractCellulosic biofuel: Ethyl levulinate is a promising biofuel that can be obtained from lignocellulosic residues. A byproducts, furfural, can be converted into ethyl levulinate in an acid‐based process. Here, the use of solid acid catalysts for the conversion of furfuryl alcohol into ethyl levulinate is reported.magnified imageFurfural, a potential coproduct of levulinic acid, can be converted into levulinic acid via hydrogenation to furfuryl alcohol and subsequent ethanolysis to ethyl levulinate. The ethanolysis reaction is known to proceed in the presence of H2SO4. We show here that several strongly acidic resins are comparably effective catalysts for this reaction. Optimal performance is achieved by balancing the number of acid sites with their accessibility in the resin. Acidic zeolites such as H‐ZSM‐5 also catalyze this reaction, although with a lower activity and a higher coproduction of diethyl ether.
Utility of HoxB2 enhancer‐mediated Cre activity for functional studies in the developing inner ear
Authors: Szeto Irene Y.Y. , Leung Keith K.H. , Sham Mai Har , Cheah Kathryn S.E. 
Published: April 2009

AbstractThe rhombomere 4(r4)‐restricted expression of the mouse Hoxb2 gene is regulated by a 1.4‐kb enhancer‐containing fragment. Here, we showthat transgenic mouse lines expressing cre driven by this fragment (B2‐r4‐Cre), activated the R26R Cre reporter in rhombomere 4 and the second branchial arch, the epithelium of the first branchial arch, apical ectodermal ridge of the limb buds and the tail region. Of particular interest is Cre activity in the developing inner ear. Cre activity was found in the preotic field and otic placode at E8.5 and otocyst at E9.5–E12.5, in the cochleovestibular and facio‐acoustic ganglia at E10.5 and the vestibular and spiral ganglia and all the otic epithelia derived from the otocyst at E15.5 and P0. Our data suggest that the B2‐r4‐Cre transgenic mice provide an important tool for conditional gene manipulation and lineage tracing in the inner ear. In combination with other transgenic lines expressing cre exclusively in the otic vesicle, the relative contributions of the hindbrain, periotic mesenchyme and otic epithelium in otic development can be dissected. genesis 47:361–365, 2009. © 2009 Wiley‐Liss, Inc.
Synthesis and in vitro Efficacy Studies of Silver Carbene Complexes on Biosafety Level 3 Bacteria
Authors: Panzner Matthew J. , Deeraksa Arpaporn , Smith Alyssa , Wright Brian D. , Hindi Khadijah M. , Kascatan‐Nebioglu Aysegul , Torres Alfredo G. , Judy Barbara M. , Hovis Christine E. , Hilliard Julia K. , Mallett Rebekah J. , Cope Emily , Estes D. Mark , Cannon Carolyn L. , Leid Jeff G. , Youngs Wiley J. 
Published: April 2009

AbstractA series of N‐heterocyclic carbene silver complexes have been synthesized and tested against the select group of biosafety level 3 bacteria Burkholderia pseudomallei, Burkholderia mallei, Bacillus anthracis, methicillin‐resistant Staphylococcus aureus and Yersinia pestis. Minimal inhibitory concentrations, minimal bactericidal and killing assays demonstrated the exceptional efficacy of the complexes against these potentially weaponizable pathogens. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Transition States of the Asymmetric Michael Reactions of Aldehydes Catalyzed by Trimethylsilyl‐Protected Diphenylprolinol
Authors: Zhao Jian‐Qiang , Gan Li‐Hua 
Published: April 2009

AbstractThe asymmetric Michael reactions of aldehydes and nitroalkenes catalyzed by trimethylsilyl‐protected diphenylprolinol were investigated by using density functional theory calculations. As a result of the stereospecific blockade of the bulky diphenylsiloxymethyl group on the pyrrolidine ring, the Re face of the enamine double bond is effectively shielded. For acetaldehyde, there are two different conformers of the enamine intermediate. On the basis of the two conformers of the enamine intermediate, four different reaction pathways were considered and four different transition states were searched for the enantioselective asymmetric Michael reaction of acetaldehyde and nitroalkene. The lowest‐ and second‐lowest‐energy transition states are both formed via the same intermediate IM2. The enantiomeric excess, calculated to be 96 % ee, is in good agreement with the experimental value. For propanal, on the basis of the four different conformers of the prolinol–enamine intermediate, eight different reaction pathways were considered and eight transition states were searched for the enantioselective asymmetric Michael reaction. The calculated ee value is 99.5 %, which is in good agreement with the experimental ee value of 99 %. The lowest‐ and second‐lowest‐energy transition states are formed via different enamine intermediates, which is different from the case of acetaldehyde. The calculations also reveal that the intermediates play an important role in the reactions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of New Analogues of the Tetraponerines
Authors: Rouchaud Anne , Braekman Jean‐Claude 
Published: April 2009

AbstractTo evaluate the influences of the tetraponerine alkyl chains and tricyclic ring systems on their cytotoxic activities, we have prepared a series of alkyl derivatives (3a, 3b and 4a–f) of the non‐natural tricyclic skeletons decahydro‐2H,6H‐dipyrido[1,2‐a:1′,2′‐c]pyrimidine (3, 6–6–6 skeleton) and dodecahydro‐2H‐1,8a‐diazaphenanthrene (4, iso‐6–6–6 skeleton). In this study, two ways to synthesise the 6–6–6 analogues have been developed and compared. One is based on the condensation of α‐tripiperideine with diethyl malonate (DEM) in water at pH 11. This yielded oxo ester 11, precursor of the amino nitrile 8, but only in moderate yield. In the second pathway, the key intermediate 8 was more efficiently synthesised by starting from 2‐(2‐piperidyl)ethanol. Treatment of 8 with alkyl Grignard reagents led to the 6–6–6 analogues 3a and 3b. When the one‐pot reaction between α‐tripiperideine and DEM was performed in water at pH 8, the lactam 12, precursor of the iso‐6–6–6 skeleton, was obtained in a yield of 76 %. The same lactam was also obtained in a yield of 86 % by treatment of tetrahydroanabasine 14 with DEM in water at pH 8. Lactam 12 was transformed into the iso‐6–6–6 analogues 4a–4f. The cytotoxic activities of the 6–6–6 and iso‐6–6–6 analogues against HT29 cancer cells were compared with those of the 5–6–5 and 6–6–5 tetraponerines and with those of solenopsin analogues. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Facile Access to Bicyclic Sultams with Methyl 1‐Sulfonylcyclopropane‐1‐carboxylate Moieties
Authors: Rassadin Valentin A. , Tomashevskiy Aleksandr A. , Sokolov Viktor V. , Ringe Arne , Magull Jörg , de Meijere Armin 
Published: April 2009

AbstractN‐(2,3‐Dibromopropyl)‐ and N‐(3,4‐dibromobutyl)(methoxycarbonyl)methanesulfanilides upon treatment with potassium carbonate in DMF furnish methyl 3‐aryl‐2,2‐dioxo‐2‐thia‐3‐azabicyclo[n.1.0]alkane‐1‐carboxylates in yields ranging from 54 to 84 % (10 examples). The starting materials were obtained by sulfonylation of N‐alkenylanilines with methyl (chlorosulfonyl)acetate and subsequent bromination. For the N‐alkenylanilines (10 examples, 60–77 % yield) an efficient new synthesis employing a 2‐nitrophenylsulfonyl substituent as a protective as well as an activating group has been developed. The 4‐methoxyphenyl (PMP) group could easily be removed from the sultam nitrogen atom by treatment with cerium(IV) ammonium nitrate.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Geospatial analysis of controls on subglacial bedform morphometry in the New York Drumlin Field – implications for Laurentide Ice Sheet dynamics
Authors: Hess Dale P. , Briner Jason P. 
Published: April 2009

AbstractThe outline and trend of 6566 subglacial bedforms in the New York Drumlin Field have been digitized from digital elevation data. A spatial predictive model has been used to extend values of bedform elongation over an area measuring 200 km × 110 km. The resulting surface is used in conjunction with depth‐to‐bedrock data and an assumed duration of ice residence to test three proposed controls on bedform elongation. Upon comparison, the resulting display of morphometry is best explained by differences in ice velocity across the field of study. The existence of multiple zones of fast‐moving ice located along the southern margin of the Laurentide Ice Sheet is implied by the observed patterns of bedform elongation and orientation. We present two interpretations that are consistent with the observations. First, enhanced basal sliding caused by decreasing effective pressure near a calving margin is suggested as a possible mechanism by which localized fast ice flow is initiated and maintained. Second, topographically controlled ice streams likely occupied the fjord‐like troughs of the Appalachian Upland northern rim. Contrary to previous understanding of the Laurentide southern margin in New York State, the resulting palaeoglaciological reconstruction illustrates a dynamic mosaic of ice stream and/or outlet glacier activity. Copyright © 2009 John Wiley & Sons, Ltd.
Improving advance rates of TBMs in adverse ground conditions
Authors: Home Lok 
Published: April 2009

AbstractA new approach is required to TBM tunneling where adverse ground conditions exist if predictable advance rates are to be achieved. It is well understood that when good ground conditions exist, TBMs vastly outperform drill and blast advance rates. However, with today's available TBMs, these high performance rates can soon be negated if adverse ground conditions are encountered. It is a common misconception that a shielded TBM will be able to cope with all adverse conditions. This is definitely not the case, as projects like Pinglin in Taiwan, Hallandsås in Sweden and San Francisco in Ecuador, will attest to.This paper describes adverse ground conditions as related to TBM tunneling, including squeezing ground, rock bursts, fault zones, and high water pressure. Optimal ground support techniques and potential problems with specific TBM types are discussed. Finally, a new concept TBM that integrates both ground conditioning and ground control techniques is introduced. This new concept TBM endeavors to facilitate predictable advance rates, even in difficult conditions, using novel concepts such as a retractable front shield and improved rock support systems in L2 area. This retractable front shield incorporated into a Double Shield feature allows for immediate ground conditioning behind the cutter head and 360 degree probe drilling, while still maintaining the increased safety and simultaneous tunnel lining characteristic of Double Shield TBMs.Excellent access immediately behind the cutter head is maintained by eliminating the peripheral thrust cylinder utilized in standard shields and using the basic floating gripper design to pass thrust to the cutter head via a main beam.
Simple and practical TBM performance prediction
Authors: Tarkoy Peter J. 
Published: April 2009

AbstractThe prediction of excavation rates for tunnel boring was originally developed for rock boring machines. One of the earliest working methods for predicting TBM performance was developed at the University of Illinois. The method was simple, reliable, inexpensive, and the data available to the public. Since then, various methods, more sophisticated, more time consuming and more expensive have been developed by various researchers. Some of them were quite exacting in the prediction despite a limited knowledge of anticipated conditions. Others were ever changing and unavailable for public use.Predictions of penetration rates and disc cutter consumption were tied to rock properties and machine variables while the prediction of TBM utilization was ignored even though in many cases it was the most variable element having the greatest impact. Prediction of TBM utilization was substantially more difficult since it was a function of time and length dependent downtimes, project conditions, TBM design features, work force, construction management, and site limitations. Many of these influences were simply a function of the impact of the human element and therefore tenuous to predict.The development of machines designed to negotiate soil, rock, and a combination of both inherently imposed additional influences on the productivity. An increase in the use of electronic technology in tunnel boring, both for control functions and recording of instantaneous machine variables have allowed the imposition of additional constraints, such as thrust & torque limitations.How do we take all of these additional variables into account in the forecasting of TBM performance?