bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, characterization and crystal structures of triorganotin(IV) complexes of 4‐[(E)‐2‐(3‐formyl‐4‐ hydroxyphenyl)‐1‐diazenyl]‐ and 4‐{(E)‐4‐hydroxy‐3‐[(E)‐4‐(aryl)iminomethyl]phenyldiazenyl}‐benzoic acids and toxicity studies of their tri‐n‐butyltin(IV) derivatives on the Aedes aegypti and Anopheles stephensi mosquito larvae
Authors: Basu Baul Tushar S. , Singh Keisham Surjit , Lyčka Antonin , Linden Anthony , Song Xueqing , Zapata Alejandra , Eng George
Published: September 2006

Triorganotin(IV) complexes of 4‐[(E)‐2‐(3‐formyl‐4‐hydroxyphenyl)‐1‐diazenyl]‐ and 4‐{(E)‐4‐hydroxy‐3‐[(E)‐4‐(aryl)iminomethyl]phenyldiazenyl}‐benzoic acids (aryls = 4‐CH3, 4‐Br, 4‐Cl, 4‐OCH3) have been synthesized. The structures have been characterized by 1H, 13C, 119Sn NMR, IR and 119mSn Mössbauer spectroscopies. The crystal structures of Ph3Sn[O2CC6H4{NN(C6H3‐4‐OH[C(H)NC6H4CH3‐4])}‐p] and nBu3Sn[O2CC6H4{NN(C6H3‐4‐OH[C(H)NC6H4Br‐4])}‐p] are also reported. The 119Sn Mössbauer and 119Sn NMR data indicate that the tri‐n‐butyltin(IV) and triphenyltin(IV) complexes have a tetrahedral geometry in the solid state as well as in solution. Toxicity studies of the tri‐n‐butyltin(IV) complexes on the second larval instar of the Aedes aegypti and Anopheles stephensi mosquito larvae indicated that the complexes are effective larvicides. The LC50 values range from 1.21 to 3.38 µM for the Ae. aegypti and from 0.83 to 2.31 µM for the An. stephensi. Copyright © 2006 John Wiley & Sons, Ltd.
Preparation of uniform and nano‐sized NaA zeolite using silatrane and alumatrane precursors
Authors: Kuanchertchoo N. , Kulprathipanja S. , Aungkavattana P. , Atong D. , Hemra K. , Rirksomboon T. , Wongkasemjit S.
Published: September 2006

Nano‐sized Na A zeolite was successfully synthesized via the sol–gel process and microwave techniques. The synthesis parameters, such as hydroxide ion concentration, seed amount, as well as heating time and temperature, were studied to obtain the most uniform and very small sized NaA zeolite using the composition of SiO2:Al2O3:xNa2O:410H2O; 3 ≤ x ≤ 6. It was found that hydroxide ion concentration affects the crystal size and heating time, whereas a higher amount of seed provides smaller sized NaA zeolite. The zeolite product can be synthesized using a higher temperature for a shorter time or lower temperature for a longer time. The best conditions for synthesizing the smallest size, 0.1–0.2 µm, and the most homogeneous NaA zeolite is to use the composition of SiO2:Al2O3:3Na2O:410H2O and 3 wt% crystal seed at 80 °C microwave heating for 6 h. The synthesized NaA zeolite was characterized using XRD and SEM. Copyright © 2006 John Wiley & Sons, Ltd.
Mapping the imprint of bone remodeling by atomic force microscopy
Authors: Hassenkam Tue , Jørgensen Henrik L. , Lauritzen Jes Bruun
Published: September 2006

Understanding bone remodeling is essential for understanding bone as a whole. Bone remodeling takes place through a stepwise cellular process, with osteoclasts carving small cavities, also known as resorption pits, into the surface of trabecular bone, followed by osteoblasts, which refill the pits with new soft bone collagen matrix tissue (osteoid). The detailed structure of the surface in the frontier of a resorption pit before, during, and after the osteoid is being laid down is not well known. We present detailed atomic force microscope (AFM) images from the edge, the front end, and the bottom of a resorption pit in a human trabecular bone sample that showed signs of incomplete remodeling. The images reveal a scalloped surface left behind by the osteoclasts and the surface morphology of preexisting bone tissue and new bone tissue. In addition, we display the bone formation front in the pit showing the anchor points between the new bone and the existing bone. We also found evidence of microcracking in the front end of the pit, suggesting that microcracking was the initiator of this particular resorption pit. We anticipate that AFM may initiate a more detailed understanding of the influence of the remodeling process on the structure of bone, as well as a better understanding of the surface on which new bone tissue can be anchored. Anat Rec Part A, 288A:1087–1094, 2006. © 2006 Wiley‐Liss, Inc.
Horse soleus muscle: Postural sensor or vestigial structure?
Authors: Meyers Ron A. , Hermanson John W.
Published: September 2006

The soleus muscle of horses is rather diminutive with respect to the overall size of adjacent synergist muscles in the hind limb of the horse. Whether or not such a muscle might be vestigial or may be providing some essential function has not been determined. We have studied the horse's soleus muscle using histochemical (ATPase), immunocytochemical (myosin isoform identification), and SDS‐PAGE analysis to demonstrate that it is largely composed of 100% type I, presumed slow‐twitch fibers. Only one soleus muscle studied (out of 13 adult horses) contained any type II muscle fibers. Given this consistent high percentage of slow‐oxidative fibers, we hypothesized that the soleus muscle could have a significant role in proprioceptive function, essentially functioning as a proprioceptive organ instead of a significant force‐generating muscle during locomotion. We tested this by examining three whole soleus muscles and assessing their muscle spindle content, which proved to have a spindle index of about 12. This value provided equivocal support for the hypothesis since it did not approach values reported for other mammalian proprioceptive muscles that were approximately 40–50 spindles per gram of muscle mass. Other parameters, such as motoneuron number and muscle unit size, may be useful in understanding these data. Anat Rec Part A, 288A:1068–1076, 2006. © 2006 Wiley‐Liss, Inc.
High‐pressure freezing and freeze substitution of rat myocardium for immunogold labeling of connexin 43
Authors: Mühlfeld Christian , Richter Joachim
Published: September 2006

The value of high‐pressure freezing (HPF) and freeze substitution (FS) for immunoelectron microscopy (immuno‐EM) of the heart was investigated in bioptic specimens taken from isolated hearts of 0‐, 5‐, and 14‐day‐old rats at baseline and at 15, 30, 45, and 60 min after induction of ischemia. The target antigen chosen here was the gap junction protein connexin 43 (Cx43). After HPF and FS, immunogold labeling was applied for detection of Cx43. Gold particles associated with gap junction areas, free plasma membrane, and annular gap junctions (AGJs) were counted and distributions compared by contingency table analysis. HPF and FS resulted in excellent preservation of antigenicity for Cx43. The mostly good preservation of the ultrastructure was limited by mechanical damage at the border and by ice crystal formation in the center of the tissue blocks. In normal myocardium of newborns, gold particles associated with free plasma membrane were frequently observed, with AGJs only seldom. In older rats, the opposite relation was found. During ischemia, no distribution changes occurred in newborn or 14‐day‐old rats. In 5‐day‐old rats, however, ischemia induced a shift of Cx43 from gap junction plaques to AGJs. In conclusion, HPF and FS are an ideal alternative to chemical fixation for immuno‐EM as the excellent preservation of antigenicity is combined with a well‐preserved ultrastructure. The results indicate that the process of degradation of gap junctions via AGJs gradually increases during postnatal rat heart development, a process that may be accelerated by ischemia in an early developmental state. Anat Rec Part A, 288A:1059–1067, 2006. © 2006 Wiley‐Liss, Inc.
Dietary consistency and plasticity of masseter fiber architecture in postweaning rabbits
Authors: Taylor Andrea B. , Jones Kelly E. , Kunwar Ravinder , Ravosa Matthew J.
Published: September 2006

Dietary consistency has been shown to influence cross‐sectional area and fiber type composition of the masticatory muscles. However, little is known about the effects of dietary consistency on masticatory muscle fiber architecture. In this study, we explore the effects of dietary consistency on the internal architecture of rabbit masseter muscle. Because activity patterns of the rabbit chewing muscles show inter‐ and intramuscular heterogeneity, we evaluate if alterations in fiber architecture are homogeneous across various portions of the superficial masseter muscle. We compared masseter muscle fiber architecture between two groups of weanling rabbits raised on different diets for 105 days. One group was raised on a diet of ground rabbit pellets to model underuse of the masticatory complex, while the other group was fed a diet of intact pellets and hay blocks to model an overuse diet. In all portions of the superficial masseter, physiological cross‐sectional areas (PCSAs) are greater in the overuse compared to underuse diet rabbits. Thus, the mechanical demands for larger muscle and bite forces associated with early and prolonged exposure to a tough diet are met by an increase in PCSA of the superficial masseter. The larger PCSA is due entirely to increased muscle mass, as the two rabbit groups show no differences in either fiber length or angle of pinnation. Thus, increasing pinnation angle is not a necessary biomechanical solution to improving muscle and bite force during growth. The change in PCSA but not fiber length suggests that variation in dietary consistency has an impact on maximum force production but not necessarily on excursion or contraction velocity. Anat Rec Part A, 288A:1105–1111, 2006. © 2006 Wiley‐Liss, Inc.
Web crawling ethics revisited: Cost, privacy, and denial of service
Authors: Thelwall Mike , Stuart David
Published: September 2006

Ethical aspects of the employment of Web crawlers for information science research and other contexts are reviewed. The difference between legal and ethical uses of communications technologies is emphasized as well as the changing boundary between ethical and unethical conduct. A review of the potential impacts on Web site owners is used to underpin a new framework for ethical crawling, and it is argued that delicate human judgment is required for each individual case, with verdicts likely to change over time. Decisions can be based upon an approximate cost‐benefit analysis, but it is crucial that crawler owners find out about the technological issues affecting the owners of the sites being crawled in order to produce an informed assessment.
Elementdecken bei nicht vorwiegend ruhender Belastung. Hinweise zur Anwendung von Gitterträgern nach Zulassung
Authors: Furche Johannes , Bauermeister Ulrich
Published: September 2006

Elementdecken aus vorgefertigten Stahlbetonplatten mit Gitterträgern und aufbetonierter Ortbetonschicht werden seit Jahren auch bei nicht vorwiegend ruhender Belastung eingesetzt. Die Anwendungsgrenzen und Bemessungsregeln für diese Anwendung wurden aus Bauteilversuchen abgeleitet. Die Regelungen innerhalb bauaufsichtlicher Zulassungen für Gitterträger wurden mit Einführung der neuen DIN 1045‐1 an das neue Bemessungskonzept angepaßt. Zusätzlich zu den Regelungen, welche für reine Ortbetonkonstruktionen gelten, ist eine Querkraftobergrenze einzuhalten und der Ermüdungsnachweis für die Gitterträgerdiagonalen zu führen. Dabei ist das Querkraftmodell mit variabler Druckstrebenneigung zu berücksichtigen. Die Herleitung der neuen Zulassungsregelungen wird erläutert und eine Bemessungshilfe vorgestellt.
Teilversagen eines Rohwaschkohlebunkers – Ursachen und Schlußfolgerungen
Authors: Fastabend Michael , Kähler Armin , Schäfers Tobias , Reißmann Frank
Published: September 2006

Der nach 30 Jahren Betrieb zu verzeichnende Einsturz einer Seitenwand eines Rohwaschkohlebunkers gab Anlaß zur Überprüfung von gleichartigen Bauwerken auf der Grundlage der Schadensursachen. Bedingt durch hochmechanisierte Abbaumethoden in den Steinkohlebergwerken, haben sich die bodenmechanischen Randbedingungen des Füllgutes geändert. Ebenso liegen mittlerweile vertiefte Erkenntnisse über die anzunehmende Erddrucktheorie vor, die bei derart steifen Bauwerken stets die Berücksichtigung zumindest eines Anteils des Erdruhedrucks notwendig machen.
Querkraftmodell für Bauteile aus Normalbeton und Hochleistungsbeton
Authors: Hegger Josef , Görtz Stephan
Published: September 2006

Zur Überprüfung der aktuellen Querkraftmodelle für Bauteile aus Normal‐ und Hochleistungsbeton wurden 31 Versuche und begleitende theoretische Untersuchungen durchgeführt. Aufbauend auf den Forschungsergebnissen wird ein Ingenieurmodell entwickelt und an einer Versuchsdatenbank verifiziert. Ausgangsbasis ist das Modell nach DIN 1045‐1, für das in einigen Punkten Vorschläge zur Modifizierung erarbeitet werden.
Fundamentplatten aus Stahlbeton und Stahlfaserbeton. Experimentelle Untersuchungen zur Gebrauchstauglichkeit und Tragfähigkeit
Authors: Gossla Ulrich , Stormberg Michael
Published: September 2006

Ein‐ und Mehrfamilienhäuser werden zunehmend statt auf Streifenfundamenten auf Fundamentplatten gegründet. Vorteile ergeben sich neben der wirtschaftlicheren Ausführung der Aushubarbeiten durch die einfachere Herstellung der Platte. Bei der Ausführung als Stahlfaserbetonplatte ergeben sich besonders wirtschaftliche Lösungen dann, wenn an die Gebrauchstauglichkeit keine besonderen Anforderungen wie Wasserdichtheit oder Rißbreitenbeschränkung gestellt werden.

An der Fachhochschule Aachen wurden vergleichende experimentelle Untersuchungen an Bodenplatten aus Beton, Stahlbeton und Stahlfaserbeton unter Lastbeanspruchung durchgeführt. Es konnte nachgewiesen werden, daß Stahlfaserbeton für Fundamentplatten ein geeigneter Werkstoff ist, wenn Mindestanforderungen an die Steifigkeit des Bodens eingehalten werden. Bei erhöhten Anforderungen an die Gebrauchstauglichkeit werden Stahlbeton oder Kombinationen aus Stahlfaserbeton und Stahlbeton als sinnvoll erachtet, wenn diese auf Basis einer elastischen Schnittgrößenermittlung bemessen werden.
Berechnung der mittleren Höchstlast von Schraubankern in gerissenem und ungerissenem Beton
Authors: Küenzlen Jürgen H. R.
Published: September 2006

Das Tragverhalten von Befestigungselementen wie Metall‐ und Verbunddübel wurde in den vergangenen Jahrzehnten in zahlreichen Forschungsarbeiten behandelt. Untersuchungen mit Schraubankern wurden bisher kaum durchgeführt. Ziel des Forschungsvorhabens war es, das Trag‐ und Versagensverhalten von Schraubankern zu untersuchen und über ein Bemessungskonzept die Umsetzung der Forschungsergebnisse in die Praxis zu ermöglichen. In der vorliegenden Veröffentlichung werden Berechnungsgleichungen für die mittlere Höchstlast von Schraubankern unter zentrischer Zugbelastung bei Betrachtung von Eck‐ und Randeinfluß, Gruppenbefestigungen, Gewindelänge und gerissenem Beton zusammengefaßt.
Vorgespannte Decken ohne schlaffe Bewehrung
Authors: Ambro Sebastian Zoran , Burtscher Stefan L. , Loeffler Veronika , Kollegger Johann
Published: September 2006

Die Vorspannung von Bauwerken und Bauteilen ist eine Bauweise, die in den 30er Jahren des 20. Jahrhunderts entwickelt wurde. Durch diese Bauweise werden die Beanspruchungen und Verformungen von Bauwerken gezielt beeinflußt. Man erkannte bereits damals, daß durch das Vorspannen die Rißbildung im Beton reduziert bzw. vermieden werden kann. Diese Bauweise wurde besonders im Brückenbau mit großem Erfolg angewandt. Obwohl die Vorteile der Vorspannung im Hochbau in einigen Ländern wie z. B. in den USA und Australien sehr effizient genutzt werden, hat sich die Anwendung der Vorspannung im Hochbau in Europa bis jetzt noch nicht durchgesetzt. In Australien werden vorgespannte Decken ohne schlaffe Bewehrung schon seit längerem erfolgreich eingesetzt und die hierfür notwendigen Bemessungsregeln sind im AS 3600 (Australian Standard) festgehalten. Im Unterschied zu den USA, wo die Vorspannung ohne Verbund bevorzugt wird, werden in Australien nur Spannglieder mit Verbund verwendet.

Dieser Beitrag zeigt, daß bei vorgespannten Decken auf die schlaffe Bewehrung verzichtet werden kann und beschreibt die Entwicklung einer Bauweise, die es ermöglicht, Betondecken im Hochbau effizienter und wirtschaftlicher zu bauen.
Schiffsanprall an die Eisenbahnbrücke in Krems. Erstmalige Anwendung des neuen Eurocode EN 1991‐1‐7 für Außergewöhnliche Einwirkungen
Authors: Simandl Thomas , Glatzl Johann , Schweighofer Bernhard , Blovsky Stefan
Published: September 2006

Am 17. Dezember 2005 wurde der Mittelpfeiler der Kremser Eisenbahnbrücke um ca. 3.40 Uhr von einem stromaufwärts auf der Donau fahrenden Schubverband frontal angefahren und schwer beschädigt. Der Pfeilerschaft – ein Granitmauerwerk aus der Bahnbauzeit 1889 – wurde auf Höhe des Wasserspiegels abgeschert und 2, 17 m flußaufwärts und 10 cm in Richtung Bahnachse verschoben. Sowohl der Bahnverkehr als auch der neben dem Pfeiler verlaufende Schiffsverkehr mußte gesperrt, die über die Brücke verlaufenden Energieträger (Gashochdruckleitung, Starkstromleitung, Datenleitungen etc.) mußten umgelegt bzw. außer Betrieb gesetzt werden.

Um die Sicherheit für die Bahn‐ und Schiffskunden zu erhöhen, wird sowohl der beschädigte Pfeiler saniert, als auch die anderen Flußpfeiler entsprechend des Eurocodes prEN 1991‐1‐7 verstärkt. Dieser Bericht beschreibt das Schadensereignis, die Rahmenbedingungen der Planung und die Anwendung des neuen Eurocodes prEN 1991‐1‐7. Diese Projektierung mußte zufolge der hohen Ausfallskosten unter enormen Zeitdruck erfolgen.
Increased heterologous protein production by Saccharomyces cerevisiae growing on ethanol as sole carbon source
Authors: van de Laar Teun , Visser Chris , Holster Marianne , López Cristina García , Kreuning Dennes , Sierkstra Laurens , Lindner Nigel , Verrips Theo
Published: September 2006

Saccharomyces cerevisiae is a widely used host organism for the production of heterologous proteins, often cultivated in glucose‐based fed‐batch processes. This production system however has many factors limiting the productivity, mainly towards the end of the fermentation. For the optimised production of a Camelid antibody fragment this process was evaluated. In shake flask cultivations, it was found that ethanol has a strong effect on productivity increase and therefore glucose and ethanol fed‐batch fermentations were compared. It appeared that specific heterologous protein production was up to five times higher in the ethanol cultivation and could be further optimised. Then the key characteristics of ethanol fed‐batch fermentations such as growth rate and specific production were determined under ethanol limitation and accumulation and growth limiting conditions in the final phase of the process. It appeared that an optimal production process should have an ethanol accumulation throughout the feed phase of approximately 1% v/v in the broth and that production remains very efficient even in the last phase of the process. This productivity increase on ethanol versus glucose was also proven for several other Camelid antibody fragments some of which were heavily impaired in secretion on glucose, but very well produced on ethanol. This leads to the suggestion that the ethanol effect on improved heterologous protein production is linked to a stress response and folding and secretion efficiency. Biotechnol. Bioeng. 2007;96: 483–494. © 2006 Wiley Periodicals, Inc.
Codon optimized Thermobifida fusca hydrolase secreted by Bacillus megaterium
Authors: Yang Yang , Malten Marco , Grote Andreas , Jahn Dieter , Deckwer Wolf‐Dieter
Published: September 2006

Production and secretion of a 28,172 Da hydrolase from Thermobifida fusca (TFH) in Bacillus megaterium MS941 and WH323 was investigated in shake flask and pH controlled bioreactors. Successful production of heterologous TFH was achieved by adapting the original tfh gene to the optimal codon usage of B. megaterium. A codon adaption index close to one was reached. The codon optimized tfh was cloned into an open reading frame with DNA sequence for the N‐terminal signal peptide of B. megaterium lipase A and a C‐terminal His6‐tag, all under the control of a xylose inducible promoter. Successful TFH production and secretion were observed using batch reactor cultivations with complex medium. Expression of the tfh gene from the PxylA promoter and secretion of produced TFH were compared in detail to batch reactor cultivations with semi‐defined growth medium. For the first time, significant TFH secretion was achieved using a semi‐defined medium in glucose limited fed batch cultivations yielding 10‐fold higher cell densities compared to LB medium cultivation. Comparable volumetric TFH activities were obtained for both cultivation strategies. Surprisingly, measured specific TFH activities exhibited drastic discrepancies between preparations from LB and semi‐defined medium grown B. megaterium. TFH recovery by Ni‐chelate affinity chromatography resulted in higher purification factors when LB medium was used. These results indicated that secreted TFH is favorably produced by batch cultures of B. megaterium WH323 in LB medium. Biotechnol. Bioeng. 2007;96:780–794. © 2006 Wiley Periodicals, Inc.
Efficient regeneration of NADPH using an engineered phosphite dehydrogenase
Authors: Johannes Tyler W. , Woodyer Ryan D. , Zhao Huimin
Published: September 2006

The in situ regeneration of reduced nicotinamide cofactors (NAD(P)H) is necessary for practical synthesis of many important chemicals. Here, we report the engineering of a highly stable and active mutant phosphite dehydrogenase (12x‐A176R PTDH) from Pseudomonas stutzeri and evaluation of its potential as an effective NADPH regeneration system in an enzyme membrane reactor. Two practically important enzymatic reactions including xylose reductase‐catalyzed xylitol synthesis and alcohol dehydrogenase‐catalyzed (R)‐phenylethanol synthesis were used as model systems, and the mutant PTDH was directly compared to the commercially available NADP+‐specific Pseudomonas sp. 101 formate dehydrogenase (mut Pse‐FDH) that is widely used for NADPH regeneration. In both model reactions, the two regeneration enzymes showed similar rates of enzyme activity loss; however, the mutant PTDH showed higher substrate conversion and higher total turnover numbers for NADP+ than mut Pse‐FDH. The space‐time yields of the product with the mutant PTDH were also up to fourfold higher than those with mut Pse‐FDH. In particular, a space‐time yield of 230 g L−1 d−1 xylitol was obtained with the mutant PTDH using a charged nanofiltration membrane, representing the highest productivity compared to other existing biological processes for xylitol synthesis based on yeast D‐xylose converting strains or similar in vitro enzyme membrane reactor systems. Biotechnol. Bioeng. 2007;96: 18–26. © 2006 Wiley Periodicals, Inc.
Limits to productivity of the algaPleurochrysis carterae(Haptophyta) grown in outdoor raceway ponds
Authors: Moheimani, Navid Reza , Borowitzka Michael A.
Published: September 2006

This study examined the effects of oxygen concentration, pond temperature and irradiance on productivity and CaCO3formation of the coccolith‐forming alga,Pleurochrysis carteraeCCMP647 grown in semi‐continuous culture in outdoor raceway ponds. During the day the oxygen content of the pond increases markedly andP. carteraephotosynthesis is inhibited by these high O2concentrations with the inhibition increasing with increasing temperature. The high irradiance outdoors presents less of a problem to photosynthesis and productivity as the algae can acclimate well to high irradiances over a period of several weeks. Pond depth also effects productivity and this effect varies with season. During autumn, productivities were highest at depths of 13 to 16 cm, and decreased when the depth was increased. During summer productivity was much lower at 13 cm pond depth and increased when the depth was increased to 16, 18 and 21 cm. Heating the ponds in the morning by approximately 3 to 5°C improves productivity by 11%–21%, presumably because this allows the algae to photosynthesise faster in the conditions of low [O2] which occur in the early morning. Biotechnol. Bioeng. 2007;96: 27–36. © 2006 Wiley Periodicals, Inc.
Chemometric analysis of in‐line multi‐wavelength fluorescence measurements obtained during cultivations with a lipase producing Aspergillus oryzae strain
Authors: Haack Martin B. , Lantz Anna Eliasson , Mortensen Peter P. , Olsson Lisbeth
Published: September 2006

The filamentous fungus, Aspergillus oryzae, was cultivated in batch and fed‐batch cultivations in order to investigate the use of multi‐wavelength fluorescence for monitoring course of events during filamentous fungi cultivations. The A. oryzae strain applied expressed a fungal lipase from Thermomyces lanuginosus. Spectra of multi‐wavelength fluorescence were collected every 5 min with the BioView® system (DELTA, Denmark) and both explorative and predictive models, correlating the fluorescence data with cell mass and lipase activity, were built. During the cultivations, A. oryzae displayed dispersed hyphal growth and under these conditions no fouling of the multi‐wavelength fluorescence sensor was observed. The scores of a parallel factor analysis (PARAFAC) model, based on the fluorescence spectra, gave clear evidence of, for example, the on‐set of the feeding phase. The predictive models, estimating the cell mass, showed correlations between 0.73 and 0.97 with root mean square error of cross validation (RMSECV) values between 1.48 and 0.77 g · kg−1. A model estimating the lipase activity was also constructed for the fed‐batch cultivations with a correlation of 0.93. The results presented here clearly show that multi‐wavelength fluorescence is a useful tool for monitoring fed‐batch cultivations of filamentous fungi. Biotechnol. Bioeng. 2007;96:904–913. © 2006 Wiley Periodicals, Inc.
Electrochemical screening of recombinant protein solubility in Escherichia coli using scanning electrochemical microscopy (SECM)
Authors: Nagamine Kuniaki , Onodera Shiho , Kurihara Ai , Yasukawa Tomoyuki , Shiku Hitoshi , Asano Ryutaro , Kumagai Izumi , Matsue Tomokazu
Published: September 2006

A microbial array chip with collagen gel spots entrapping living Escherichia coli (E. coli) DH5α was applied for the screening of recombinant protein solubilities. The α‐fragment of β‐galactosidase (βGal) was fused to the target protein, namely, maltose‐binding protein (MBP), to monitor the solubility of MBP. Scanning electrochemical microscopy (SECM) was used to detect the release of p‐aminophenol from E. coli cells catalyzed by intracellular βGal. Comparison of the SECM‐based method with the Western blotting‐based method indicated that the current response obtained using SECM increased with an increase in the βGal activity and therefore, with the soluble fraction of MBP in the host cells. Biotechnol. Bioeng. 2007;96:1008–1013. © 2006 Wiley Periodicals, Inc.
Application of cellulases from an alkalothermophilic Thermomonospora sp. in biopolishing of denims
Authors: Anish Ramakrishnan , Rahman Mohammad Safikur , Rao Mala
Published: September 2006

Use of cellulase for denim washing is a standard eco‐friendly technique to achieve desirable appearance and softness for cotton fabrics and denims. But enzymatic washing of denim till date involved acid cellulase (Trichoderma reesei) and neutral cellulase (Humicola isolens) the use of which has a drawback of backstaining of the indigo dye on to the fabric. Though it has been suggested that pH is a major factor in controlling backstaining there are no reports on use of cellulase under alkaline conditions for denim washing. In this study for the first time an alkali stable endoglucanase from alkalothermophilic Thermomonospora sp. (T‐EG) has been used for denim biofinishing under alkaline conditions. T‐EG is effective in removing hairiness with negligible weight loss and imparting softness to the fabric. Higher abrasive activity with lower backstaining was a preferred property for denim biofinishing exhibited by T‐EG. The activities were comparable to acid and neutral cellulases that are being regularly used. The enzyme was also effective under non‐buffering conditions which is an added advantage for use in textile industry. A probable mechanism of enzymatic finishing of cotton fabric has been represented based on the unique properties of T‐EG. Biotechnol. Bioeng. 2007;96: 48–56. © 2006 Wiley Periodicals, Inc.
Quantitative real‐time PCR for rapid and accurate titration of recombinant baculovirus particles
Authors: Hitchman Richard B. , Siaterli Evangelia A. , Nixon Clare P. , King Linda A.
Published: September 2006

We describe the use of quantitative PCR (QPCR) to titer recombinant baculoviruses. Custom primers and probe were designed to gp64 and used to calculate a standard curve of QPCR derived titers from dilutions of a previously titrated baculovirus stock. Each dilution was titrated by both plaque assay and QPCR, producing a consistent and reproducible inverse relationship between CT and plaque forming units per milliliter. No significant difference was observed between titers produced by QPCR and plaque assay for 12 recombinant viruses, confirming the validity of this technique as a rapid and accurate method of baculovirus titration. Biotechnol. Bioeng. 2007;96:810–814. © 2006 Wiley Periodicals, Inc.
Methodological analysis for determination of enzymatic digestibility of cellulosic materials
Authors: Zhang Y.‐H. Percival , Schell Daniel J. , McMillan James D.
Published: September 2006

Accurate measurement of enzymatic cellulose digestibility (X) is important in evaluating the efficiency of lignocellulose pretreatment technologies, assessing the performance of reconstituted cellulase mixtures, and conducting economic analysis for biorefinery processes. We analyzed the effect of sugars contained in enzymes solutions, usually added as a preservative, and random measurement errors on the accuracy of X calculated by various methods. The analysis suggests that exogenous sugars at levels measured in several commercial enzyme preparations significantly bias the results and that this error should be minimized by accounting for these sugars in the calculation of X. Additionally, a method of calculating X equating the ratio of the soluble glucose equivalent in the liquid phase after hydrolysis to the sum of the soluble glucose equivalent in the liquid phase and the insoluble glucose equivalent in the residual solid after hydrolysis was found to be the most accurate, particularly at high conversion levels (>ca. 50%). Biotechnol. Bioeng. 2007;96: 188–194. © 2006 Wiley Periodicals, Inc.
Effect of solvent concentration on the extraction kinetics and diffusivity of Cyclosporin A in the fungus Tolypocladium inflatum
Authors: Ly May , Margaritis Argyrios , Jajuee Babak
Published: September 2006

The kinetics of solid‐liquid extraction and extraction yields of the immunosuppressant drug Cyclosporin A (CyA) from the mycelia of Tolypocladium inflatum were examined in this study. A 2 L stirred, baffled vessel was used to extract CyA from wet mycelia mass. Three different organic solvents were used, namely, methanol, acetone, and isopropanol at different concentrations in aqueous mixtures at room temperature. It was found that the best solvent was acetone at 50% v/v concentration achieving 100% extraction of CyA from the mycelia of T. inflatum. Although acetone proved to be the better solvent for CyA extraction, further studies were performed using methanol. A linear relationship was found between extraction yield of CyA and methanol concentration with 100% CyA extraction at 90% v/v methanol. The partition coefficients of CyA between the solid mycelia phase and the aqueous solvent phase were found to decrease exponentially with increasing methanol concentration. A liquid extraction model was developed based on the diffusion equation to correlate the kinetic data of CyA extraction from the solid mycelia of T. inflatum. Non‐linear regression analysis of experimental data was used with the diffusion equation in order to calculate the effective diffusivities of CyA in the mycelia of T. inflatum. For all three organic solvents used, the effective diffusivities of CyA were found to be between 4.41 × 10−15 and 6.18 × 10−14 m2/s. This is the first time CyA effective diffusivities in T. inflatum are reported in the literature. Biotechnol. Bioeng. 2007;96: 67–79. © 2006 Wiley Periodicals, Inc.
A study of the growth for the microalga Chlorella vulgaris by photo‐bio‐calorimetry and other on‐line and off‐line techniques
Authors: Patiño Rodrigo , Janssen Marcel , von Stockar Urs
Published: September 2006

Calorimetry and other on‐line techniques are used for the first time as complement to the traditional off‐line methods in order to follow the growth of the green Chlorella vulgaris microalgae. A 2‐L photo‐bio‐reactor was adapted from a commercial calorimeter used previously to study heterotrophic microbial growth. An external source of light was added to favor the photosynthesis of the autotrophic cells. Heterotrophic growth was also tested with external glucose in the broth. A third mode, mixotrophic, allowed faster autotrophic plus heterotrophic growth. Calorimetric measurements were performed considering the corresponding calibrations in order to consider only the energy involved during the microalgal growth. The three different modes of Chlorella cultures were energetically characterized. Besides calorimetry, the weight of diluted nitric acid added to maintain the pH of the culture was correlated with the cellular growth and the nitrogen composition of the algae. Additionally, the on‐line infrared spectroscopy proved to be an efficient technique to follow the composition of the broth in glucose, nitrates, and phosphates. These results were compared and complemented with some classic off‐line techniques used to track this kind of cultures. Biotechnol. Bioeng. 2007;96:757–767. © 2006 Wiley Periodicals, Inc.
Protein instability during HIC: Hydrogen exchange labeling analysis and a framework for describing mobile and stationary phase effects
Authors: Xiao Yunzhi , Jones Tara T. , Laurent Abigail H. , O'Connell John P. , Przybycien Todd M. , Fernandez Erik J.
Published: September 2006

Unfolding of marginally stable proteins is a significant factor in commercial application of hydrophobic interaction chromatography (HIC). In this work, hydrogen‐deuterium isotope exchange labeling has been used to monitor protein unfolding on HIC media for different stationary phase hydrophobicities and as a function of ammonium sulfate concentration. Circular dichroism and Raman spectroscopy were also used to characterize the structural perturbations experienced by solution phase protein that had been exposed to media and by protein adsorbed on media. As expected, greater instability is seen on chromatographic media with greater apparent hydrophobicity. However, increased salt concentrations also led to more unfolding, despite the well‐known stabilizing effect of ammonium sulfate in solution. A thermodynamic framework is proposed to account for the effects of salt on both adsorption and stability during hydrophobic chromatography. Using appropriate estimates of input quantities, analysis with the framework can explain how salt effects on stability in chromatographic systems may contrast with solution stability. Biotechnol. Bioeng. 2007;96: 80–93. © 2006 Wiley Periodicals, Inc.
Continuous Symmetry Analysis of NMR Chemical Shielding Anisotropy
Authors: Steinberg Avital , Karni Miriam , Avnir David
Published: September 2006

Molecular symmetry is a key parameter which dictates the NMR chemical shielding anisotropy (CSA). Whereas correlations between specific geometrical features of molecules and the CSA are known, the quantitative correlation with symmetry—a global structural feature—has been unknown. Here we demonstrate a CSA/symmetry quantitative relation for the first time: We study how continuous deviation from exact symmetry around a nucleus affects its shielding. To achieve this we employed the continuous symmetry measures methodology, which allows one to quantify the degree of content of a given symmetry. The model case we use for this purpose is a population of distorted SiH4 structures, for which we follow the 29Si CSA as a function of the degree of tetrahedral symmetry and of square‐planar symmetry. Quantitative correlations between the degree of these symmetries and the NMR shielding parameters emerge.
On the Mechanism of the Ascorbic Acid‐Induced Release of Nitric Oxide from N‐Nitrosated Tryptophan Derivatives: Scavenging of NO by Ascorbyl Radicals
Authors: Kytzia Anna , Korth Hans‐Gert , Sustmann Reiner , de Groot Herbert , Kirsch Michael
Published: September 2006

During the past years, there has been increasing interest in endogenous nitric oxide storage compounds. Recently, we briefly reported on the ascorbate‐dependent release of nitric oxide (.NO) from N‐nitrosotryptophan derivatives. In the present study, the underlying mechanism of .NO release is studied in more detail, primarily utilizing N‐acetyl‐N‐nitrosotryptophan (NANT) as a model compound. The initial rate of the ascorbate‐induced release of nitric oxide has been found to correspond to the rate of NANT decay. In this process, N‐acetyltryptophan (NAT) is produced almost quantitatively. The final yield of nitrite amounted to around 90 % with respect to the applied amount of NANT. However, the total release of nitric oxide was only 60 %, as determined by using an FNOCT‐4(fluorescent nitric oxide cheletropic trap number 4) assay. Besides nitric oxide, a second volatile product, dinitrogen oxide (N2O), has been identified by using 15N NMR spectrometry, strongly indicating the intermediacy of nitroxyl (HNO). The formation of intermediate ascorbyl radical anions during the NANT–ascorbate reaction has been monitored by using ESR spectrometry. Unexpectedly, it was found that the primary oxidized product of vitamin C, dehydroascorbic acid (DHA), efficiently consumes nitric oxide. Since ESR spectrometry further revealed that ascorbyl radical anions are also generated during the spontaneous decay of DHA, the DHA–nitric oxide reaction is related to recombination of .NO with the thus formed ascorbyl radical anions. A conclusively established mechanism of the NANT–ascorbate reaction is presented, with O‐nitrosoascorbate as a key intermediate, as additionally supported by CBS‐QB3 calculations. The present study suggests that vitamin C and its oxidation products can chemically counterbalance endogenous nitric oxide levels.
Catalytic PH Activation by Ti and Zr Catalysts
Authors: Masuda Jason D. , Hoskin Aaron J. , Graham Todd W. , Beddie Chad , Fermin Maria C. , Etkin Nola , Stephan Douglas W.
Published: September 2006

Catalytic dehydrocoupling of phosphines was investigated using the anionic zirconocene trihydride salts [Cp*2Zr(μ‐H)3Li]3 (1 a) or [Cp*2Zr(μ‐H)3K(thf)4] (1 b), and the metallocycles [CpTi(NPtBu3)(CH2)4] (6) and [Cp*M(NPtBu3)(CH2)4] (M=Ti 20, Zr 21) as catalyst precursors. Dehydrocoupling of primary phosphines RPH2 (R=Ph, C6H2Me3, Cy, C10H7) gave both dehydrocoupled dimers RP(H)P(H)R or cyclic oligophosphines (RP)n (n=4, 5) while reaction of tBu3C6H2PH2 gave the phosphaindoline tBu2(Me2CCH2)C6H2PH (9). Stoichiometric reactions of these catalyst precursors with primary phosphines afforded [Cp*2Zr((PR)2)H][K(thf)4] (R=Ph 2, Cy 3, C6H2Me3 4), [Cp*2Zr((PPh)3)H][K(thf)4] (5), [CpTi(NPtBu3)(PPh)3] (7) and [CpTi(NPtBu3)(μ‐PHPh)]2 (8), while reaction of 6 with (C6H2tBu3)PH2 in the presence of PMe3 afforded [CpTi(NPtBu3)(PMe3)(P(C6H2tBu3)] (10). The secondary phosphines Ph2PH and (PhHPCH2)2CH2 also undergo dehydrocoupling affording (Ph2P)2 and (PhPCH2)2CH2. The bisphosphines (CH2PH2)2 and C6H4(PH2)2 are dehydrocoupled to give (PCH2CH2PH)2 (12) and (C6H4P(PH))2 (13) while prolonged reaction of 13 gave (C6H4P2)8 (14). The analogous bisphosphine Me2C6H4(PH)2 (17) was prepared and dehydrocoupling catalysis afforded (Me2C6H2P(PH))2 (18) and subsequently [(Me2C6H2P2)2(μ‐Me2C6H2P2)]2 (19). Stoichiometric reactions with these bisphosphines gave [Cp*2Zr(H)(PH)2C6H4][Li(thf)4] (22), [CpTi(NPtBu3)(PH)2C6H4]2 (23) and [Cp*Ti(NPtBu3)(PH)2C6H4] (24). Mechanistic implications are discussed.
Probing Structural Effects on Replication Efficiency through Comparative Analyses of Families of Potential Self‐Replicators
Authors: Kassianidis Eleftherios , Pearson Russell J. , Philp Douglas
Published: September 2006

A formidable synthetic apparatus for the creation of nanoscale molecular structures and supramolecular assemblies through molecular structures can potentially be created from systems that are capable of parallel automultiplication (self‐replication). In order to achieve this goal, a detailed understanding of the relationship between molecular structure and replication efficiency is necessary. Diastereoisomeric templates that are capable of specific and simultaneous autocatalysis have been synthesised. A systematic experimental and theoretical evaluation of their behaviour and that of structurally‐related systems reveals the key determinants that dictate the emergence of self‐replicative function and defines the structural space within which this behaviour is observed.
Local Aromaticity in Polycyclic Aromatic Hydrocarbons: Electron Delocalization versus Magnetic Indices
Authors: Bultinck Patrick , Fias Stijn , Ponec Robert
Published: September 2006

The local aromaticity of benzenoid rings is examined by means of the Polansky index (P) and generalized population analysis (GPA). The results are found to agree very well with recently published circuit‐condensed ring currents and magnetic‐energetic aromaticity indices, but no correlation is found with nucleus independent chemical shifts (NICS). This is usually seen as a manifestation of the more general multidimensional nature of aromaticity. This paper examines the sources for the observed correlations, showing that some indices give conflicting results because they inherently reflect different phenomena.
Mechanism of the Condensation of Homocysteine Thiolactone with Aldehydes
Authors: Jakubowski Hieronim
Published: September 2006

Chemical reactivity of homocysteine thiolactone (HTL) has been implicated in cardiovascular disease. Owing to its aminoacyl‐thioester character, HTL undergoes facile electrophilic and nucleophilic reactions at its amino and activated‐carboxyl group, respectively. To gain insight into the mechanism of the reactions involving its amino group, the kinetics of the condensation of homocysteine thiolactone with formaldehyde, acetaldehyde, and pyridoxal phosphate, were analyzed in the pH range from 5 to 10. The reactions were first order with respect to HTL, aldehyde, and hydroxide ion concentrations. Of the two ionic species of HTL (pKa=6.67±0.05), the acid form HTL+ was ∼100‐fold more reactive than the base form HTL0. The reactions of HTL with aldehydes involve intermediate adducts. The conversion of the intermediate carbinolamine to a product, 1,3‐tetrahydrothiazine‐4‐carboxylic acid or its 2‐substituted analogue, occurs in a two‐step reaction. The first step involves hydrolysis of the thioester bond in the intermediate, facilitated by anchimeric assistance by the oxygen of the carbinolamine group of the intermediate. The second step involves an attack of the liberated thiolate on the aldehyde‐derived carbon of the intermediate, affording 1,3‐tetrahydrothiazine‐4‐carboxylic acid or its 2‐substituted analogue. An unusual feature of these reactions is that the formation of the carbinolamine group increases the reactivity of the thioester bond of HTL ∼104‐fold. The facile formation of tetrahydrothiazines may contribute to HTL elimination from the human body.
Structure–Activity Relationship Studies of 3‐Aroylindoles as Potent Antimitotic Agents
Authors: Liou Jing‐Ping , Mahindroo Neeraj , Chang Chun‐Wei , Guo Fu‐Ming , Lee Sandy Wen‐Hsing , Tan Uan‐Kang , Yeh Teng‐Kuang , Kuo Ching‐Chuan , Chang Yi‐Wei , Lu Ping‐Hsun , Tung Yen‐Shih , Lin Ke‐Ta , Chang Jang‐Yang , Hsieh Hsing‐Pang
Published: September 2006

The concise synthesis and structure–activity relationship (SAR) studies of 3‐aroylindoles were carried out in an effort to improve the potency and solubility of anticancer drug candidate BPR0L075 (8) by exploring structure modifications through three regimens: substitution of the B ring, at the N1 position, and of the 3‐carbonyl linker. The SAR information revealed that the methoxy group of the B ring could be replaced with an electron‐donating group such as methyl (in compound 9) or N,N‐dimethylamino (in compound 13) while retaining both strong cytotoxic and antitubulin activities. The introduction of amide (compounds 30–33) and carbamate (compounds 34–37) functionalities at the N1 position of 8 gave analogues with potent antiproliferative activities. The cytotoxic potency of 8 was improved by replacing the carbonyl group with sulfide (compound 41) or oxygen (compound 43), indicating that the carbonyl moiety is important but not essential. The N,N‐dimethylamino derivative 13 not only displayed potent cytotoxicity and antitubulin activity, but also showed a markedly improved physicochemical profile relative to the parent compound.
Prediction of ADMET Properties
Authors: Norinder Ulf , Bergström Christel A. S.
Published: September 2006

This Review describes some of the approaches and techniques used today to derive in silico models for the prediction of ADMET properties. The article also discusses some of the fundamental requirements for deriving statistically sound and predictive ADMET relationships as well as some of the pitfalls and problems encountered during these investigations. It is the intension of the authors to make the reader aware of some of the challenges involved in deriving useful in silico ADMET models for drug development.
Cover Picture: Synthesis and Biological Evaluation of a Multiantigenic Tn/TF‐Containing Glycopeptide Mimic of the Tumor‐Related MUC1 Glycoprotein (ChemMedChem 9/2006)
Authors: Cremer Gaëlle‐Anne , Bureaud Nicole , Piller Véronique , Kunz Horst , Piller Friedrich , Delmas Agnès F.
Published: September 2006

The cover picture shows human MCF7 mammary adenocarcinoma cells, a cell line which has been used extensively to characterize tumor‐associated MUC1 glycoprotein. Cells were analysed by fluorescence‐activated cell sorting after being labelled with antibodies induced in mice by a synthetic glycopeptide construct (structure shown) in association with a mild adjuvant suitable for human therapy. This construct, composed of a universal T‐helper and three diversely glycosylated tumor‐related epitopes, was assembled using a convergent strategy based on two successive oxime ligations. It is the most immunogenic synthetic construct reported to date and is able to elicit antibodies that recognize tumor‐related MUC1 on MCF7 cells. (Thanks to T. Cantalupo for the image.) For more details, see the Communication by A. F. Delmas et al. on p. 965 ff.
Effect of Architecture on the Tensile Properties of Triblock Copolymers in a Lamellar Phase
Authors: Huang Rui , Jiang Ying , Liang Haojun
Published: September 2006

We have used self‐consistent field theory to calculate the tensile moduli of triblock copolymers in lamellar microstructures prepared from linear and star architectures. The extensional moduli K33 are the main contributors to the tensile moduli, and the contribution of ${{\rm{K}}{}_{33}^{{\rm{U}}\,} }$ (the internal energy contribution to K33) is the main component of the value of K33. We find that the tensile moduli of ABC three‐miktoarm star terpolymers are smaller than those of ABC linear triblock copolymers having identical components, presumably for two main reasons. First, for the ABC three‐miktoarm star terpolymers, the contributions of ${{\rm{K}}{}_{33}^{{\rm{U}}\,} }$ are larger than those of the linear triblock copolymers; we attribute this phenomenon to the star terpolymers having smaller lamellar domain sizes at equilibrium relative to those of the linear triblock copolymers. Second, conformational entropies play an important role in affecting the tensile moduli, mainly because of the different degrees of freedom of the various chains. In contrast, the shear moduli contribute negligibly to the tensile moduli.