bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimentelle und numerische Untersuchungen zum Tragverhalten von Stahlbetondecken mit kugelförmigen Hohlkörpern
Authors: Abramski Marcin , Albert Andrej , Pfeffer Karsten , Schnell Jürgen 
Published: June 2010

AbstractMassive Flachdecken erweisen sich in Hoch‐ und Industriebau häufig als insgesamt überlegenes Deckensystem. Die hohe Eigenlast dieser Decken kann ihren Anwendungsbereich jedoch einschränken. Eine sinnvolle Abhilfe schafft dann die Integration von Hohlkörpern in der neutralen Zone, weil hierdurch eine spürbare Gewichtsreduktion eintritt. Neben der Eigenlast wird auch der Verbrauch der unter ökologischen Gesichtspunkten wesentlichen Ressourcen Betonstahl und Zement deutlich verringert. Die Hohlräume beeinflussen vor allem die Querkrafttragfähigkeit solcher Decken. Vier Versuchsserien, die mit kugelförmigen Hohlkörperdecken des Systems “cobiax” durchgeführt wurden, werden in diesem Beitrag beschrieben. Aus den Versuchen wird ein Abminderungsfaktor zur Beschreibung des Querkrafttragverhaltens abgeleitet, der auch in die kürzlich erteilte allgemeine bauaufsichtliche Zulassung des Deckensystems eingegangen ist. Die Nachrechnung der Versuche mit der Finite‐Elemente‐Methode zeigt eine gute Übereinstimmung von Numerik und Experiment, so dass in der Weiterentwicklung Parameterstudien auf dieser Grundlage zur Ergänzung von Versuchen hilfreich sein werden.Experimental and Numerical Investigation of the Bearing Behaviour of Hollow Core SlabsMassive flat slabs have proven to be the most appropriate ceiling system for structural and industrial engineering. However the high dead load of these slabs might reduce their field of application. This problem can be solved by void formers that are placed in the neutral zone. These block‐outs cause a noticeable reduction of weight. Furthermore, the masses of ecologically important resources like reinforcement steel and cement can be reduced as well.The shear bearing capacity is significantly influenced by these block‐outs. This article describes four test series with spherical void former floors of the system “cobiax”. A reduction factor for the shear bearing capacity is derived from these tests. That factor was also introduced in the technical approval for this slab system which has been issued recently. A comparison to a calculation with the finite element method shows that the numerical results and the results of the tests are quite similar. In future research, parameter studies based on the finite element method might be helpful additional to further tests.
Metabolic pathways and fermentative production of L‐aspartate family amino acids
Authors: Park Jin Hwan , Lee Sang Yup 
Published: June 2010

AbstractThe L‐aspartate family amino acids (AFAAs), L‐threonine, L‐lysine, L‐methionine and L‐isoleucine have recently been of much interest due to their wide spectrum of applications including food additives, components of cosmetics and therapeutic agents, and animal feed additives. Among them, L‐threonine, L‐lysine and L‐methionine are three major amino acids produced currently throughout the world. Recent advances in systems metabolic engineering, which combine various high‐throughput omics technologies and computational analysis, are now facilitating development of microbial strains efficiently producing AFAAs. Thus, a thorough understanding of the metabolic and regulatory mechanisms of the biosynthesis of these amino acids is urgently needed for designing system‐wide metabolic engineering strategies. Here we review the details of AFAA biosynthetic pathways, regulations involved, and export and transport systems, and provide general strategies for successful metabolic engineering along with relevant examples. Finally, perspectives of systems metabolic engineering for developing AFAA overproducers are suggested with selected exemplary studies.
Molecular modeling and NMR studies of benzyl substituted mannosyl trisaccharide binding to two mannose‐specific lectins: Allium sativam agglutinin I and Concanavalin A
Authors: Mazumder Parichita , Mukhopadhyay Chaitali 
Published: June 2010

AbstractThe interaction of trimannoside, α−benzyl 3, 6‐di‐O‐(α‐D‐mannopyranosyl)‐α‐D‐mannopyranoside, 1 with ASAI (Allium sativam agglutinin I, garlic lectin) was studied to reveal the conformational preferences of this ligand in bound‐state and detailed binding mode at atomic level. The binding phenomenon was then compared with another well‐known mannose‐binding lectin, ConA (Concanavalin A). Structural studies of the ligand in free state were done using NMR spectroscopy and Molecular Dynamics simulations. It is found that the substituted‐trimannoside can undergo conformational transitions in solution, with one major and one minor conformation per glycosidic linkage (α 1→3 and α 1→6). On the other hand in the bound‐state only one of the two major conformations was significantly populated. The role of phenyl ring in the binding process was explored. An extended binding site was observed for the trimannoside in ASAI utilizing the aromatic substituent, which is not seen in ConA. Binding data from difference absorption spectroscopy supported this fact that the binding of benzyl‐substituted ligand is tighter with ASAI than ConA. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 952–967, 2010.
Conformations of stevastelin C3 analogs: Computational deconvolution of NMR data reveals conformational heterogeneity and novel motifs
Authors: Jogalekar Ashutosh S. 
Published: June 2010

AbstractThe stevastelins are depsipeptide natural products that show valuable immunomodulatory and phosphatase inhibitory activity. A previous report described the synthesis, conformational analysis, and biological activity of modified diastereomeric C3 analogs (1) of these molecules and deduced a single dominant conformational scaffold for each of the six benzylated stevastelin diastereomers in solution. In this study, we report a combined computational and experimental approach (NAMFIS) of these analogs based on geometric variables from the NMR data and extensive conformational searching that suggests a more subtle and complex distribution of conformations in solution. Although the results indicate some conformations to be similar to those previously proposed, they include novel motifs not observed earlier such as gamma turns. In addition, the NAMFIS analysis confirms dramatic changes in conformations accompanying a chirality change at the C3 center and also establishes the conformational homogeneity of the D‐serine diastereomers. The NAMFIS analysis thus suggests the use of D‐serine as a possible constraining element in peptide design and derives a set of experimental solution conformers that could shed light on the bioactive conformation of the stevastelins. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 968–976, 2010.
High‐solids biphasic CO2–H2O pretreatment of lignocellulosic biomass
Authors: Luterbacher Jeremy S. , Tester Jefferson W. , Walker Larry P. 
Published: June 2010

AbstractA high pressure (200 bar) CO2–H2O process was developed for pretreating lignocellulosic biomass at high‐solid contents, while minimizing chemical inputs. Hardwood was pretreated at 20 and 40 (wt.%) solids. Switchgrass, corn stover, big bluestem, and mixed perennial grasses (a co‐culture of big bluestem and switchgrass) were pretreated at 40 (wt.%) solids. Operating temperatures ranged from 150 to 250°C, and residence times from 20 s to 60 min. At these conditions a biphasic mixture of an H2O‐rich liquid (hydrothermal) phase and a CO2‐rich supercritical phase coexist. Following pretreatment, samples were then enzymatically hydrolyzed. Total yields, defined as the fraction of the theoretical maximum, were determined for glucose, hemicellulose sugars, and two degradation products: furfural and 5‐hydroxymethylfurfural. Response surfaces of yield as a function of temperature and residence time were compared for different moisture contents and biomass species. Pretreatment at 170°C for 60 min gave glucose yields of 77%, 73%, and 68% for 20 and 40 (wt.%) solids mixed hardwood and mixed perennial grasses, respectively. Pretreatment at 160°C for 60 min gave glucan to glucose yields of 81% for switchgrass and 85% for corn stover. Biotechnol. Bioeng. 2010;107: 451–460. © 2010 Wiley Periodicals, Inc.
Measurement of S‐methylcysteine and S‐methyl‐mercapturic acid in human urine by alkyl‐chloroformate extractive derivatization and isotope‐dilution gas chromatography–mass spectrometry
Authors: Rubino Federico M , Pitton Marco , Di Fabio Daniela , Meroni Giuseppe , Santaniello Enzo , Caneva Enrico , Pappini Marco , Colombi Antonio 
Published: June 2010

AbstractS‐methylcysteine (SMC) is a minor amino acid naturally excreted in human urine, a protective agent against oxidative stress and a biotransformation product of the fumigant biocide methyl bromide and of nicotine. A metabolic source of SMC is catabolism of the repair catalytic protein MGMT (EC 2.1.1.37), which specifically removes the methyl group from the modified DNA nucleotide O‐6‐methyl‐guanine to revert the normal GC base pairing. To assess the value of SMC and of S‐methylmercapturic acid (SMMA) as candidate biomarkers of proliferative phenomena, a sensitive analytical method by GC‐MS was applied in a pilot study of healthy subjects to assess their urinary elimination and the intra‐ and inter‐individual variability. Extractive alkylation with butylchloroformate‐n‐butanol‐pyridine (Husek technique) was employed for sample derivatization and isotope dilution GC‐MS with S‐[CD3]‐SMC and ‐SMMA was applied for specific and sensitive detection. To resolve the target analytes from the main coeluting interferents in the derivatized urine extract a medium‐polarity stationary phase was employed. SMMA was not detected in the morning urine of three healthy fertile‐age women followed for one month above the minimum detectable level of approx. 500 µg/L while SMC concentrations were in the 0.02–0.7 µg/mL range (n = 61) with large inter‐day and inter‐individual variations. In a young healthy male urine samples taken throughout a few days yielded concentrations in the same 90–810 µg/L range (n = 11). These preliminary results points at SMC as a candidate biomarker for the study of methylation turnover in several biochemical processes. Copyright © 2010 John Wiley & Sons, Ltd.
Simultaneous determination of norisoboldine and its major metabolite in rat plasma by ultra‐performance liquid chromatography–mass spectrometry and its application in a pharmacokinetic study
Authors: Chen Jian‐Zhong , Xu Ying , Chou Gui‐Xin , Wang Chang‐Hong , Yang Li , Wang Zheng‐Tao 
Published: June 2010

AbstractNorisoboldine (NIB) is one of the main bioactive isoquinoline alkaloids in Linderae Radix. A rapid, selective and sensitive method using UPLC‐ESI/MS was first developed for simultaneous determination of NIB and norisoboldine‐9‐O‐α‐glucuronide (NIB‐Glu), its major metabolite in rat plasma. A one‐step protein precipitation with methanol was employed as sample preparation technique. Chromatographic separation was carried out on an Acquity UPLC BEH C18 column (50 × 2.1 mm, i.d. 1.7 µm) with a gradient mobile phase consisting of acetonitrile and water containing 0.1% formic acid. Detection and quantification were performed using a quadrupole mass spectrometer by selective ion reaction‐monitoring mode. Good linearity was achieved using weighted (1/x2) least squares linear regression over the concentration ranges 0.01–2 µg/mL for NIB and 0.025–25 µg/mL for NIB‐Glu. The lower limit of quantification of NIB and NIB‐Glu was 0.01 and 0.025 µg/mL, respectively. The intra‐ and inter‐day precisions (relative standard deviations) of the assay at all three quality control levels were 4.6–14.1% for NIB, and 5.0–12.2% for NIB‐Glu. The accuracies (relative error) were −13.5–8.1% for NIB and −12.8–7.6% for NIB‐Glu, respectively. This developed method was successfully applied to an in vivo pharmacokinetic study in rats after a single intravenous dose of 10 mg/kg NIB. Copyright © 2010 John Wiley & Sons, Ltd.
LPS removal from an E. coli fermentation broth using aqueous two‐phase micellar system
Authors: Lopes André M. , Magalhães Pérola O. , Mazzola Priscila G. , Rangel‐Yagui Carlota O. , de Carvalho João C. M. , Penna Thereza C.V. , Pessoa Adalberto 
Published: June 2010

AbstractIn biotechnology, endotoxin (LPS) removal from recombinant proteins is a critical and challenging step in the preparation of injectable therapeutics, as endotoxin is a natural component of bacterial expression systems widely used to manufacture therapeutic proteins. The viability of large‐scale industrial production of recombinant biomolecules of pharmaceutical interest significantly depends on the separation and purification techniques used. The aim of this work was to evaluate the use of aqueous two‐phase micellar system (ATPMS) for endotoxin removal from preparations containing recombinant proteins of pharmaceutical interest, such as green fluorescent protein (GFPuv). Partition assays were carried out initially using pure LPS, and afterwards in the presence of E. coli cell lysate. The ATPMS technology proved to be effective in GFPuv recovery, preferentially into the micelle‐poor phase (KGFPuv < 1.00), and LPS removal into the micelle‐rich phase (%REMLPS > 98.00%). Therefore, this system can be exploited as the first step for purification in biotechnology processes for removal of higher LPS concentrations. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Effect of temperature, pH, dissolved oxygen, and hydrolysate on the formation of triple light chain antibodies in cell culture
Authors: Gomez Natalia , Ouyang Jun , Nguyen Mary D. H. , Vinson Abigail R. , Lin Andy A. , Yuk Inn H. 
Published: June 2010

AbstractTHIOMABs are recombinant antibodies with reactive cysteine residues used for forming THIOMAB–drug conjugates (TDCs). We recently reported a new impurity associated with THIOMABs: one of the engineered cysteines forms a disulfide bond with an extra light chain (LC) to generate a triple light chain antibody (3LC). In our previous investigations, increased LC expression increased 3LC levels, whereas increased glutathione (GSH) production decreased 3LC levels. In this work, on three stably transfected CHO cell lines, we investigated the effects of temperature, pH, dissolved oxygen (DO), and hydrolysate on 3LC formation during THIOMAB fed‐batch cell culture production. Although pH between 6.8 and 7.0 had no significant impact on 3LC formation, temperature at 35°C instead of 33 or 31°C generated the lowest 3LC values for two cell lines. The decreased 3LC level correlated with increased GSH production. We implemented a 35°C temperature process for large‐scale (2,000 L) production of a THIOMAB. This process reduced 3LC levels by ∼50% compared with a 33°C temperature process. By contrast, DO and hydrolysate had modest effect on 3LC levels for the model cell line studied. Overall, we did not find significant changes in LC expression under the conditions tested, whereas changes in GSH production were more evident. By investigating the impact of bioreactor process and medium conditions on 3LC levels, we identified strategies that reduced 3LC levels. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Good outcome and valve function despite medtronic‐corevalve underexpansion
Authors: Jilaihawi Hasan , Asgar Anita , Bonan Raoul 
Published: June 2010

AbstractAn 80‐year old nun with severe calcific aortic stenosis and a bicuspid aortic valve was referred for transcatheter aortic valve implantation. She was declined for conventional surgery on the basis of poor left ventricular function, frailty, and a logistic EuroSCORE of 29.66. A 29‐mm Medtronic‐Corevalve bioprosthesis was implanted by transfemoral route. The inflow portion of the stent frame was grossly underexpanded. However, aortic valve area at 1.3 cm2 was more than satisfactory for a body surface area of 1.29 m2 (indexed area 1.0 cm2/m2, peak gradient 23, and mean 16 mmHg). There was an early sustained improvement in New York Heart Association (NYHA) status, and there was no change in valvular function at 2 year follow‐up. This case highlights that gross underexpansion of the Medtronic‐Corevalve stent frame is compatible with good bioprosthetic function and excellent symptomatic recovery. © 2010 Wiley‐Liss, Inc.
Revascularization of a central vein total occlusion via antegrade and retrograde approach in a patient with hemodialysis access
Authors: Fang Hsiu‐Yu , Hsieh Yuan‐Kai , Wu Chiung‐Jen 
Published: June 2010

AbstractThe occurrence of central vein total occlusion results in upper arm edema, pain, and hemodialysis access failure in uremic patient. Previous studies have proven the effectiveness of percutaneous balloon angioplasty for central vein total occlusion. Here, we report a rare case of successful revascularization of central vein total occlusion via antegrade and retrograde approach. © 2010 Wiley‐Liss, Inc.
Device closure of ventricular septal defects by hybrid procedures: A multicenter retrospective study
Authors: Michel‐Behnke Ina , Ewert Peter , Koch Andreas , Bertram Harald , Emmel Mathias , Fischer Gunther , Gitter Roland , Kozlik‐Feldman Rainer , Motz Reinald , Kitzmüller Erwin , Kretschmar Oliver ,   for the Investigators of the Working Group Interventional Cardiology of the German Association of Pediatric Cardiology
Published: June 2010

AbstractObjective: This study reports on the feasibility, efficacy, and outcome of hybrid procedures to close ventricular septal defects (VSD), reflecting the experience of 11 centers in Germany, Austria, and Switzerland. Background: Beating heart closure of VSD has attracted interest in small infants, complex anomalies and postinfarction scenarios where patients are at high risk during surgery. Perventricular or intraoperative device placement allows access to the lesions where percutaneous delivery is limited. Methods: Between December 2001 and April 2009, placement of Amplatzer septal occluders was attempted in 26 patients. The defects were located in the perimembranous (n = 5) and muscular septum (n = 21). In 20 patients, a perventricular approach was used, and, in six, the occluders were placed under direct visualization being part of a complex heart surgery. Results: In 23 of 26 procedures, device placement was successful (88.5%). The mean defect size was 7.8 mm (range, 3.5–20). The occluder types were perimembranous VSD occluder (n = 4), muscular VSD occluder (n = 20), postinfarct VSD occluder (n = 1), and ASD occluder (n = 1) with a ratio device/defect of 0.9–2.4 (median 1.15). Device removal was necessary in three due to arrhythmia, malpositioning, and additional defects. Pericardial effusion occurred once. In the remaining 22 patients, there were no procedure or device‐related complications. During mean follow up of 1.4 years (range, 1 day–3.9 years), a residual shunt that was more than trivial was observed in one patient out of 21 successful procedures. Conclusions: Perventricular and intraoperative device closure of VSD is as effective as a surgical patch and averts the increased morbidity of conventional surgical repair in a subgroup of high‐risk patients. © 2010 Wiley‐Liss, Inc.
Synthesis, Characterization, and In Vitro Bioactivity of Sol‐Gel‐Derived Zn, Mg, and Zn‐Mg Co‐Doped Bioactive Glasses
Authors: Erol M. , Özyuguran A. , Çelebican Ö. 
Published: June 2010

AbstractBioactive glasses in the systems CaO‐SiO2‐P2O5‐ZnO, CaO‐SiO2‐P2O5‐MgO, and CaO‐SiO2‐P2O5‐MgO‐ZnO were prepared and characterized. Bioactive glass powders were produced by the sol‐gel method. The prepared bioactive glass powders were immersed in a simulated body fluid (SBF) for periods of up to 28 days at 310 K to investigate the bioactivity of the produced samples. Inductively coupled plasma (ICP) and ultraviolet (UV) spectroscopic techniques were used to detect changes in the SBF composition. X‐Ray diffraction (XRD) was utilized to recognize and confirm the formation of a hydroxyapatite (HA) layer on the bioactive glass powders. Microstructural characterizations of the bioactive glass samples were investigated by scanning electron microscopy (SEM) techniques. Density, porosity, and surface area values of bioactive glass powders were also determined in order to characterize the textural properties of the samples. The results revealed the growth of an HA layer on the surface of the bioactive glass samples. MgO in the glass sample increases the rate of formation of an HA layer while ZnO in the glass slows it down.
Modeling of the Adsorptive Desulfurization of Diesel Fuel in a Fixed‐Bed Column
Authors: Muzic M. , Gomzi Z. , Sertic‐Bionda K. 
Published: June 2010

AbstractAdsorptive desulfurization enables the attainment of ultra‐low sulfur content in hydrocarbon fuels by removing the refractory sulfur compounds, which are difficult to remove in hydrodesulferization (HDS) processing when sulfur concentrations below 10 mg kg–1 must be attained. In this work, diesel fuel was desulfurized by adsorption using activated carbon as an adsorbent and the adsorption was carried out in a fixed‐bed column. The output sulfur content of less then 0.7 mg kg–1 was achieved for the lowest flow rate of 1.0 cm3min–1 and the highest bed depth of 28.4 cm at 50 °C. In all the experiments, at least one output sample contained less then 10.0 mg kg–1 of sulfur with a longest achieved breakthrough time of 11.8 h. A mathematical model of the fixed‐bed adsorber was applied to describe the kinetics and to estimate the breakthrough curves. The model equations included a differential material balance for a liquid phase and a mass transfer rate expression. The ability of the model to fit the experimental data was shown to be satisfactory.
Anilinic N‐Oxides Support Cytochrome P450‐Mediated N‐Dealkylation through Hydrogen‐Atom Transfer
Authors: Roberts Kenneth M. , Jones Jeffery P. 
Published: June 2010

AbstractThe mechanism of N‐dealkylation mediated by cytochrome P450 (P450) has long been studied and argued as either a single electron transfer (SET) or a hydrogen atom transfer (HAT) from the amine to the oxidant of the P450, the reputed iron–oxene. In our study, tertiary anilinic N‐oxides were used as oxygen surrogates to directly generate a P450‐mediated oxidant that is capable of N‐dealkylating the dimethylaniline derived from oxygen donation. These surrogates were employed to probe the generated reactive oxygen species and the subsequent mechanism of N‐dealkylation to distinguish between the HAT and SET mechanisms. In addition to the expected N‐demethylation of the product aniline, 2,3,4,5,6‐pentafluoro‐N,N‐dimethylanilineN‐oxide (PFDMAO) was found to be capable of N‐dealkylating bothN,N‐dimethylaniline (DMA) andN‐cyclopropyl‐N‐methylaniline (CPMA). Rate comparisons of the N‐demethylation of DMA supported by PFDMAO show a 27‐fold faster rate than when supported byN,N‐dimethylanilineN‐oxide (DMAO). Whereas intermolecular kinetic isotope effects were masked, intramolecular measurements showed values reflective of those seen previously in DMAO‐ and the native NADPH/O2‐supported systems (2.33 and 2.8 for the N‐demethylation of PFDMA and DMA from the PFDMAO system, respectively). PFDMAO‐supported N‐dealkylation of CPMA led to the ring‐intact productN‐cyclopropylaniline (CPA), similar to that seen with the native system. The formation of CPA argues against a SET mechanism in favor of a P450‐like HAT mechanism. We suggest that the similarity of KIEs, in addition to the formation of the ring‐intact CPA, argues for a similar mechanism of Compound I (Cpd I) formation followed by HAT for N‐dealkylation by the native and N‐oxide‐supported systems and demonstrate the ability of the N‐oxide‐generated oxidant to act as an accurate mimic of the native P450 oxidant.