bluuebunny/crossref_metadata_2025 huggingface dataset:
Bismuth‐Doped Ceria, Ce0.90Bi0.10O2: A Selective and Stable Catalyst for Clean Hydrogen Combustion
Authors: Beckers Jurriaan , Lee Adam F. , Rothenberg Gadi
Published: July 2009

Bismuth‐doped cerias are successfully applied as solid “oxygen reservoirs” in the oxidative dehydrogenation of propane. The lattice oxygen of the ceria is used to selectively combust hydrogen from the dehydrogenation mixture at 550 °C. This process has three key advantages: it shifts the dehydrogenation equilibrium to the desired products side, generates heat, aiding the endothermic dehydrogenation, and simplifies product separation (water vs. hydrogen). Furthermore, the process is safer, since it uses the catalyst’s lattice oxygen instead of gaseous oxygen. We show here that bismuth‐doped cerias are highly active and stable towards hydrogen combustion, and explore four different approaches for optimising their application in the oxidative dehydrogenation of propane: first, the addition of extra hydrogen which lowers hydrocarbon conversion by suppressing both combustion and coking; second, the addition of tin which completely inhibits coking; third, the addition of platinum which increases selectivity, but at the expense of lower activity. The best results are obtained through tuning the reaction temperature. At 400 °C, high activity and selectivity were obtained for the bismuth‐doped ceria Ce0.90Bi0.10O2. Here, 90% of the hydrogen feed is converted at 98% selectivity. This optimal reaction temperature can be rationalised from the hydrogen and propene temperature‐programmed reduction (TPR) profiles: 400 °C lies above the reduction maximum of hydrogen, yet below that of propene. That is, this temperature is sufficiently high to facilitate rapid hydrogen combustion, but low enough to prevent hydrocarbon conversion.
A synonymous mutation in TCOF1 causes Treacher Collins syndrome due to mis‐splicing of a constitutive exon
Authors: Macaya D. , Katsanis S.H. , Hefferon T.W. , Audlin S. , Mendelsohn N.J. , Roggenbuck J. , Cutting G.R.
Published: July 2009

Interpretation of the pathogenicity of sequence alterations in disease‐associated genes is challenging. This is especially true for novel alterations that lack obvious functional consequences. We report here on a patient with Treacher Collins syndrome (TCS) found to carry a previously reported mutation, c.122C > T, which predicts p.A41V, and a novel synonymous mutation, c.3612A > C. Pedigree analysis showed that the c.122C > T mutation segregated with normal phenotypes in multiple family members while the c.3612A  >  C was de novo in the patient. Analysis of TCOF1 RNA in lymphocytes showed a transcript missing exon 22. These results show that TCS in the patient is due to haploinsufficiency of TCOF1 caused by the synonymous de novo c.3612A > C mutation. This study highlights the importance of clinical and pedigree evaluation in the interpretation of known and novel sequence alterations. © 2009 Wiley‐Liss, Inc.
Epoxidöffnungskaskaden zur Synthese polycyclischer Polyether‐Naturstoffe
Authors: Vilotijevic Ivan , Jamison Timothy F.
Published: July 2009

Die polycyclischen Strukturelementevon Polyether‐Naturstoffen können in einigen Fällen bis auf ihren Ursprung in der Biosynthese zurückverfolgt werden, in anderen, weniger gut verstandenen Fällen jedoch nur auf vorgeschlagene Biosynthesewege, die spekulative Epoxidöffnungskaskaden vorsehen. In diesem Aufsatz wird zusammengefasst, wie solche Reaktionskaskaden zur Synthese polycyclischer Polyether und verwandter Naturstoffe genutzt wurden.

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Polycyclische Polyether‐Naturstoffe sind wegen ihrer faszinierenden Struktur und ihrer biologischen Eigenschaften von besonderem Interesse. Letztere umfassen potenziell therapeutische antibiotische und fungizide Wirkungen sowie Antikrebswirkungen und außerdem eine starke Giftwirkung bis hin zur Letalität. Die polycyclischen Strukturelemente dieser Verbindungsklasse können in einigen Fällen bis auf ihren Ursprung in der Biosynthese zurückverfolgt werden, in anderen, weniger gut verstandenen Fällen jedoch nur auf vorgeschlagene Biosynthesewege, die spekulative Epoxidöffnungskaskaden vorsehen. In diesem Aufsatz wird zusammengefasst, wie solche Reaktionskaskaden zur Synthese polycyclischer Polyether und verwandter Naturstoffe genutzt wurden.
Reviving the Living.Meaning Making in Living Systems. Von Yair Neuman.
Authors: Prinz Robert
Published: July 2009

Elsevier Science, 2008. 320 S., geb., 185.00 $.—ISBN 978‐0444530332

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A Persistent α‐Fluorocarbanion and Its Analogues: Preparation, Characterization, and Computational Study
Authors: Prakash G. K. Surya , Wang Fang , Shao Nan , Mathew Thomas , Rasul Golam , Haiges Ralf , Stewart Timothy , Olah George A.
Published: July 2009

Starkes Fluor: In Einklang mit theoretischen Studien zu α‐Fluorcarbanionen ergab eine Röntgenstrukturanalyse für das α‐Fluorbis(phenylsulfonyl)methid‐Anion eine pyramidale Konfiguration (siehe Bild). Anspruchsvolle Rechnungen und NMR‐spektroskopische Studien zeigten, dass elektronenziehende Substituenten die Eigenschaften von Bis(phenylsulfonyl)methid‐Anionen entscheidend beeinflussen.

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A Symmetry‐Based Concise Formal Synthesis of Platencin, a Novel Lead against “Superbugs”
Authors: Ghosh Arun K. , Xi Kai
Published: July 2009

Rascher Zugang: Eine knappe und effiziente formale Synthese von Platencin in neun Stufen nutzt kommerziell erhältliches Ausgangsmaterial und nur eine Schutzgruppe. Die basenkatalysierte Michael‐Cyclisierung der Vorstufe 1 lieferte das Schlüsseldiketon 2, das über die radikalische Zwischenstufe 3 in den gewünschten hydrophoben Strukturteil 4 überführt wurde.

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Innentitelbild: Charge‐Conversional Polyionic Complex Micelles—Efficient Nanocarriers for Protein Delivery into Cytoplasm (Angew. Chem. 29/2009)
Authors: Lee Yan , Ishii Takehiko , Cabral Horacio , Kim Hyun Jin , Seo Ji‐Hun , Nishiyama Nobuhiro , Oshima Hiroki , Osada Kensuke , Kataoka Kazunori
Published: July 2009

Sehr effizient verläuft der Proteintransport ins Cytoplasma, den K. Kataoka et al. auf S. 5413 ff. beschreiben. Die Stabilität der Micellen aus Protein und polyionischem Blockcopolymerkomplex (PIC) wurde durch eine Zunahme der Ladungsdichte des Proteins durch reversible Modifikation mithilfe von Citaconamid und cis‐Aconitamid erhöht. Die rasche Änderung der Proteinladung in Endosomen führte zur Dissoziation der PIC‐Micellen und zum effizienten Verlassen der Endosome.

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Reviving the Living.Meaning Making in Living Systems. By Yair Neuman.
Authors: Prinz Robert
Published: July 2009

Elsevier Science, 2008. 320 pp., hardcover $ 185.00.—ISBN 978‐0444530332

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A Persistent α‐Fluorocarbanion and Its Analogues: Preparation, Characterization, and Computational Study
Authors: Prakash G. K. Surya , Wang Fang , Shao Nan , Mathew Thomas , Rasul Golam , Haiges Ralf , Stewart Timothy , Olah George A.
Published: July 2009

Fluoro power: In agreement with theoretical studies on α‐fluorocarbanions an X‐ray crystal structure shows the α‐fluorobis(phenylsulfonyl)methide anion adopts a pyramidal configuration (see picture). High‐level calculations and NMR spectroscopy studies demonstrate that electron‐withdrawing substituents play a crucial role in modulating the properties of bis(phenylsulfonyl)methide anions.

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Structural Crystallography of Inorganic Oxysalts.IUCr Monographs on Crystallography No. 22. By Sergey V. Krivovichev.
Authors: Albrecht‐Schmitt Thomas
Published: July 2009

Oxford University Press, Oxford 2009. 320 pp., hardcover, $ 130.00.—ISBN 978‐0199213207

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A Symmetry‐Based Concise Formal Synthesis of Platencin, a Novel Lead against “Superbugs”
Authors: Ghosh Arun K. , Xi Kai
Published: July 2009

Quick access: A concise and efficient formal synthesis of platencin has been accomplished in nine steps from a commercially available starting material. The synthesis utilized only one protecting group. The base‐catalyzed Michael cyclization of precursor 1 afforded the key diketone 2, which was converted into the desired core structure 4 via the radical intermediate 3.

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Studies on the effect of pH, temperature and metal ions on the production of pectinase from tamarind kernel powder by submerged fermentation using Aspergillus foetidus (NCIM 505)
Authors: JagadeeshBabu P. E. , Viswanathan Renuka
Published: July 2009

Filamentous fungi Aspergillus foetidus NCIM 505 was studied for its capacity to produce exo‐pectinase in submerged fermentation (SMF) from a new substrate of tamarind kernel powder (TKP). The process was further studied to optimize the initial operating variables like pH, time and temperature. Maximum pectinolytic activity was reached at 72 h of growth and the best fungal strain was found to be A. foetidus NCIM 505. Further, to increase the production rate of pectinase, the effects of metal ions were studied. Metal ions like Cu++, Mg++, Fe++, Co++ and Zn++ at different concentrations were used. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Equilibrium and heat of adsorption of phosphine on CaCl2‐modified molecular sieve
Authors: Yu Qiongfen , Tang Xiaolong , Yi Honghong , Ning Ping , Yang Liping , Yang Lina , Yu Lili , Li Hua
Published: July 2009

Adsorption characteristics of the virgin and CaCl2‐immersed molecular sieves at 298 K were investigated to select the adsorbent with high adsorption capacity to phosphine. Adsorption isobars and adsorption isotherms over the phosphine partial pressure and temperature ranged 0 ∼ 1000 Pa and 298 ∼ 343 K were measured. The adsorption equilibrium data for phosphine at various temperatures were fitted to Langmuir and Freundlich isotherm models and their isosteric heats of adsorption were determined by the Clausius‐Clapeyron equation. It was found the Freundlich was more suitable for description of phosphine adsorption process through calculating average absolute relative error, and the fitted result about Langmuir model showed the heterogeneous characteristics of modified adsorbent. The isosteric heat of adsorption was about 15 kJ/mol, which indicated adsorptive phosphine removal performance may be a dominant of physical adsorption being easy for desorption. The isosteric heat of adsorption decreased with an increase of the surface loading on CaCl2/5A, which means that CaCl2/5A molecular sieve had an energetically heterogeneous surface. The present study confirmed that the CaCl2/5A molecular sieves would be one of the candidates for separation and recycle of phosphine. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of lanthanum stearate on the crystallization behavior of isotactic polypropylene
Authors: Guo Xiaojing , Zhao Shicheng , Xin Zhong
Published: July 2009

The influence of a nucleating agent, lanthanum stearate (LaSt), on the crystallization behavior of isotactic polypropylene (iPP) was investigated using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide‐angle x‐ray scattering (WAXD). It was found that LaSt can act as a β‐nucleating agent and induce the formation of a high content of β‐form during the crystallization of iPP. The content of β‐form is greatly affected by crystallization temperature and cooling rate. High crystallization temperature and low cooling rate are favorable to the formation of β‐form. The results of isothermal crystallization kinetics show that LaSt shortens the crystallization half time (t1/2) and accelerates the crystallization of iPP. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Influence of the OMCs pore structures on the capacitive performances of supercapacitor
Authors: Nong Gu‐Zhen , Wang Hua , Li Wen‐Cui
Published: July 2009

In the present study, two mesoporous carbons OMC‐KIT‐6 and OMC‐SBA‐16 were nanocasted using mesoporous silica of KIT‐6 and SBA‐16 as templates and furfuryl alcohol as carbon precursor. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) characterizations confirmed that the resultant samples are mesoporous carbons, and the as‐prepared OMC‐KIT‐6 has an Ia3d ordered structure, whereas OMC‐SBA‐16 belongs to Im3m space group. The surface area and the average pore size are (1658 m2 g−1 and 3.4 nm) for OMC‐KIT‐6 and (1638 m2 g−1 and 2.9 nm) for OMC‐SBA‐16, respectively. The results of cyclic voltammograms and galvanostatic charge‐discharge tests show that these two mesoporous carbons have excellent capacitive performances. But the difference of capacitive behavior between OMC‐KIT‐6 and OMC‐SBA‐16 may be a result of the difference of pore geometries of these two carbons. In order to find out the function of mesopore in a supercapacitor, we compared the capacitive properties of mesoporous and microporous carbons; the experiment results indicated that these two kinds of carbon exhibit nearly ideal capacitive behavior at low scan rate. When the scan rate is enhanced up to 50 mV s−1 the performance of mesoporous carbon is more stable than microporous carbon. This outcome demonstrated that mesopore plays an important role in forming double layers in the electrode materials. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of carbon sources on fungal morphology and lovastatin biosynthesis by submerged cultivation of Aspergillus terreus
Authors: Jia Zhihua , Zhang Xiaoli , Cao Xuejun
Published: July 2009

The influences of various carbon sources on fungal morphological changes and lovastatin production were investigated in submerged cultivation of a mutant of Aspergillus terreus. Lactose produced the least biomass (2.3 ± 0.15 gDCW l−1); however, the highest maximal specific lovastatin productivity (ρmax) was obtained. Glycerol achieved the highest lovastatin titer (937.5 ± 12.5 mg l−1), while soluble starch resulted in the highest biomass (12.05 ± 0.05 gDCW l−1) and the second highest lovastatin titer (501.3 ± 23.4 mg l−1). With the carbon source turning to be more easily metabolized, the values of ρmax dropped gradually while the corresponding Dp and mean filament ratio rose tardily. The value of ρmax (19.8 mg gDCW−1 d−1) was obtained in the presence of lactose while glucose resulted in the least ρmax (3.0 mg gDCW−1 d−1). This led to a 6.6‐fold decrease. The corresponding Dp and mean filament ratios appeared to reverse the effects, thus producing 1.9 and 3.3‐fold increases, respectively. The slowly utilizable carbon sources regulated the lovastatin production through both the inducement of fungal morphology differentiation and the control of metabolic regulation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis of lauryl methacrylate star‐like polymers via ATRP
Authors: Qiu Lei , Wang Yufeng , Lin Qunfang , Zhou Xiaodong
Published: July 2009

Lauryl methacrylate (LMA) star‐like polymers were synthesized by atom transfer radical polymerization (ATRP) using the ‘arm‐first’ method. Linear poly lauryl methacrylate (PLMA) precursors were firstly prepared with ethyl α‐bromoisobutyrate (EBriB) as initiator and cuprous chloride (CuCl)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as catalyst in cyclohexanone via ATRP, and subsequently used as macromolecule initiator(MI) to synthesize star polymers in the presence of cross‐linker ethylene glycol dimethacrylate (EGDMA). Several experimental parameters, such as the PLMA arm length, the ratio of MI to cross‐linker, the addition amount and moment of cross‐linker and the reaction time for the star formation were systematically investigated. The samples were removed at regular intervals and analyzed by gel permeation chromatography (GPC) to track Mn and Mw/Mn of star‐like polymer, by which the influence of the experimental parameters on the structures of the star‐like polymers was studied. Employing shorter arm lengths and more cross‐linker could produce star‐like polymers with higher molecular weight and more arms per star. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Distribution of several microorganisms and activity of alkaline phosphatase in sediments from Baihua Lake
Authors: Deng Jia‐jun , Huang Xian‐fei , Hu Ji‐wei , Li Cun‐xiong , Yi Yin , Long Jian
Published: July 2009

The distribution characteristics of ammonifiers, ammonium‐oxidizing bacteria, nitrite‐oxidizing bacteria, and denitrifiers, and activities of alkaline phosphatase (ALP) in sediments from Baihua Lake (a man‐made deep plateau canyon reservoir in Guizhou Province, China) were studied. The results suggested that the population number of ammonifiers in the sediments was higher at sampling sites Pingpu, Laojiutu, Yapengzhai, and Jiangjiapu than at the other sites. Ammonium‐oxidizing bacteria had the highest population number at sampling site Meituwan. The population number of nitrite‐oxidizing bacteria in the upper and middle sections of the lake was higher than that in the lower section. The population of denitrifiers was the highest at sampling site Jiangjiapu, and all the other sampling sites gave lower population numbers.

Change in the activity of ALP was of a strong regularity, and the basic tendency was that the activity increased from the upper to the lower portion of the lake. Specifically, the activity at sampling site Yapengzhai was the strongest. The statistical analysis for four groups of bacteria, ALP, organic matter, and so on were carried out to shed more light on their correlativity. This research will likely provide relevant data useful for establishment of bacteriological and zymological indicator systems for environmental monitoring. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Effects of physical properties estimation on process design: a case study using AspenPlus
Authors: Cadoret Loic , Yu Cheng‐Ching , Huang Hsiao‐Ping , Lee Ming‐Jer
Published: July 2009

This study focuses on the physical property model parameters estimation in order to accurately simulate separation processes for a given set of components. The non‐random two‐liquid (NRTL) model was chosen and parameters were calculated using different methods: experimental data regression and UNIFAC and COSMO‐SAC (conductor‐like screening model, segment activity coefficient) predictive models. The vapor‐liquid equilibrium (VLE) obtained from these different models was compared and results showed that COSMO‐SAC can be a reliable tool when data or functional groups are missing. Results also showed that the use of UNIFAC to estimate activity coefficients at infinite dilution can, in some cases, leads to inaccurate results and strongly impact process simulation results. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
A relation between h‐index and impact factor in the power‐law model
Authors: Egghe Leo , Liang Liming , Rousseau Ronald
Published: July 2009

Using a power‐law model, the two best‐known topics in citation analysis, namely the impact factor and the Hirsch index, are unified into one relation (not a function). The validity of our model is, at least in a qualitative way, confirmed by real data.
Truxene‐Based Columnar Liquid Crystals: Self‐Assembled Structures and Electro‐Active Properties
Authors: Isoda Kyosuke , Yasuda Takuma , Kato Takashi
Published: July 2009

Columnar liquid‐crystalline (LC) truxene derivatives containing branched flexible alkyl chains have been designed and synthesized. The dicyanomethylene and dithiafulvene substituents have been introduced into the π‐conjugated truxene framework to tune their electronic and redox properties as well as the molecular assembled structures. The π‐conjugated cores of dicyanomethylene‐ and dithiafulvene‐appended truxenes adopt bowl‐shaped conformations, giving rise to a large intrinsic dipole moment perpendicular to the aromatic framework. These molecules form stable columnar LC structures through intermolecular dipole–dipole interactions. The redox properties of LC truxene derivatives have been examined by cyclic voltammetry. The dicyanomethylene‐appended truxene shows the reversible four‐step electrochemical reductions, whereas the dithiafulvene‐appended truxene undergoes three‐step oxidations.
On the robustness of description and experience based decision tasks to social desirability
Authors: Koritzky Gilly , Yechiam Eldad
Published: July 2009

We compared the sensitivity of two classes of decision tasks to social desirability: description‐based tasks and experience‐based tasks. Participants completed a battery of decision tasks in two conditions: a Control condition in which they were asked to perform their best, and an Impression condition in which they were required to impress judges in the context of hiring decisions. The Impression condition was predicted to elicit relatively lower levels of risk taking than the Control condition. This was confirmed for the description‐based tasks while the experience‐based tasks were fairly robust to the impression manipulation. This finding points to the potential of experience‐based tasks' for assessing individual differences, particularly in situations where social desirability is prevalent. A second finding is that risk taking levels showed consistency across the description‐experience divide, but in line with the different sensitivity of the tasks to social desirability, this was only observed in the Control condition. Copyright © 2009 John Wiley & Sons, Ltd.
Big risks in small groups: The difference between epidemiology and counselling
Authors: Friedman J. M.
Published: July 2009

Congenital anomalies do not occur in all babies born after a teratogenic exposure. Whether a given exposure is teratogenic depends on the chemical nature and physical properties of the agent, the dose and route of exposure, when in pregnancy the exposure occurs, and genetic and other factors that affect susceptibility. Teratogenic birth defects are inherently multifactorial. Absolute risk, relative risk, and population attributable risk provide useful but different information regarding teratogenic effects. Statistical significance and clinical significance also are important considerations, but they may not be concordant. Demonstrating a teratogenic effect is easier if it is sought in a subgroup of patients in whom the effect is likely to be particularly prominent. The ability to detect a significant risk is, therefore, generally increased by subgroup analysis of epidemiology studies, but the greater the number of analyses performed, the higher the probability of finding associations that reach nominal statistical significance by chance alone. This problem is well recognized, but it is difficult to solve. The only compelling evidence for the reality of an association between maternal exposure to an agent during pregnancy and teratogenic effects in the children is replication of the findings in independent studies, but this is hard to obtain. As a consequence, there are very few exposures for which the available information is sufficient to make evidence‐based recommendations regarding the clinical management of teratogenic risks. It is important to admit these limitations and to learn more about exposures that cause birth defects and how to prevent them. Birth Defects Research (Part A) 2009. © 2009 Wiley‐Liss, Inc.
Mitosis in diatoms: rediscovering an old model for cell division
Authors: De Martino Alessandra , Amato Alberto , Bowler Chris
Published: July 2009

Diatoms are important protists that generate one fifth of the oxygen produced annually on earth. These aquatic organisms likely derived from a secondary endosymbiosis event, and they display peculiar genomic and structural features that reflect their chimeric origin. Diatoms were one of the first models of cell division and these early studies revealed a range of interesting features including a unique acentriolar microtubule‐organising centre. Unfortunately, almost nothing is known at the molecular level, in contrast to the advances in other experimental organisms. Recently the full genome sequences of two diatoms have been annotated and molecular tools have been developed. These resources offer new possibilities to re‐investigate the mechanisms of cell division in diatoms by recruiting information from more intensively studied organisms. A renaissance of the topic is further justified by the current interest in diatoms as a source of biofuels and for understanding massive diatom proliferation events in response to environmental stimuli.
Comparing Accuracy in an Unpaired Post‐market Device Study with Incomplete Disease Assessment
Authors: Alonzo Todd A.
Published: July 2009

The sensitivity and specificity of a new medical device are often compared relative to that of an existing device by calculating ratios of sensitivities and specificities. Although it would be ideal for all study subjects to receive the gold standard so true disease status was known for all subjects, it is often not feasible or ethical to obtain disease status for everyone. This paper proposes two unpaired designs where each subject is only administered one of the devices and device results dictate which subjects are to receive disease verification. Estimators of the ratio of accuracy and corresponding confidence intervals are proposed for these designs as well as sample size formulae. Simulation studies are performed to investigate the small sample bias of the estimators and the performance of the variance estimators and sample size formulae. The sample size formulae are applied to the design of a cervical cancer study to compare the accuracy of a new device with the conventional Pap smear.
Resonance light scattering study on the interaction between quinidine sulfate and congo red and its analytical application
Authors: Zeng Yanbo , Cai Liling , Wang Haidong , Li Lei , You Weijing , Guo Longhua , Chen Guonan
Published: July 2009

The interaction between quinidine sulfate (QDS) and congo red (CR) was studied using resonance light scattering (RLS) technique, ultraviolet–visual spectrophotometry and fluorimetry. In weak acidic medium, QDS reacts with CR to form a supermolecular complex which results in the enhanced RLS intensity. Some important interacting parameters, such as the solution acidity and CR concentration, salt effect and addition order of the reagents, were investigated and optimized. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of QDS in the range 0.2–8.4 µg mL−1. The corresponding detection limit was 12.0 ng mL−1. The results showed that this new method enabled simple, sensitive and rapid determination of QDS and was used for the determination of QDS in urine and simulated huamn serum samples. Copyright © 2009 John Wiley & Sons, Ltd.
Life‐cycle kinetic model for endospore‐forming bacteria, including germination and sporulation
Authors: Park Seongjun , Rittmann Bruce E. , Bae Wookeun
Published: July 2009

We develop a mechanistic life‐cycle model for endospore‐forming bacteria (EFB) and test the model with experiments with a Bacillus mixed culture. The model integrates and quantifies how sporulation and germination are triggered by depletion or presence of a limiting substrate, while both substrates affect the rate of vegetative growth by a multiplicative model. Kinetic experiments show the accumulation of small spherical spores after the triggering substrate is depleted, substantially more rapid decay during sporulation than for normal decay of vegetative cells, and a higher specific substrate utilization rate for the germinating cells than that for growth of vegetative cells. Model simulations capture all of these experimental trends. According to model predictions, when a batch reactor is started, seeding with EFB spores instead of active EFB delays the onset of rapid chemical oxygen demand (COD) utilization and biomass growth, but the end points are the same. Simulated results with low aeration intensity show that germination can consume some substrate without dissolved oxygen (DO) depletion. Biotechnol. Bioeng. 2009; 104: 1012–1024. © 2009 Wiley Periodicals, Inc.
A new metabolite of nodakenetin by rat liver microsomes and its quantification by RP‐HPLC method
Authors: Zhang Peng , Yang Xiu‐Wei
Published: July 2009

The biotransformation of nodakenetin (NANI) by rat liver microsomes in vitro was investigated. Two major polar metabolites were produced by liver microsomes from phenobarbital‐pretreated rats and detected by reversed‐phase high‐performance liquid chromatography (RP‐HPLC) analysis. The chemical structures of two metabolites were firmly identified as 3′(R)‐hydroxy‐nodakenetin‐3′‐ol and 3′(S)‐hydroxy‐nodakenetin‐3′‐ol, respectively, on the basis of their 1H‐NMR, MS and optical rotation analysis. The latter was a new compound. A sensitive, selective and simple RP‐HPLC method has been developed for the simultaneous determination of NANI and its two major metabolites in rat liver microsomes. Chromatographic conditions comprise a C18 column, a mobile phase with MeOH‐H2O (40 : 60, v/v), a total run time of 40 min, and ultraviolet absorbance detection at 330 nm. In the rat heat‐inactivated liver microsomal supernatant, the lower limits of detection and quantification of metabolite I, metabolite II and NANI were 5.0, 2.0, 10.0 ng/mL and 20.0, 5.0, 50.0 ng/mL, respectively, and their calibration curves were linear over the concentration range 50–400, 20–120 and 150–24000 ng/mL, respectively. The results provided a firm basis for further evaluating the pharmacokinetics and clinical efficacy of NANI. Copyright © 2009 John Wiley & Sons, Ltd.
Pellet culture elicits superior chondrogenic redifferentiation than alginate‐based systems
Authors: Bernstein Peter , Dong Meng , Corbeil Denis , Gelinsky Michael , Günther Klaus‐Peter , Fickert Stefan
Published: July 2009

Although pellet culture and encapsulation of chondrocytes into gel‐like biomaterials have lead to major advances in cartilage tissue engineering, a quantitative comparative characterization of cellular differentiation behavior during those cultivation procedures has not yet been performed. Our study therefore aimed at answering the following question: is the redifferentiation pathway of chondrocytes altered by slight changes in the type of alginate biomaterial (pure alginate, alginate‐fibrin, alginate‐chitosan) and how do the cells behave in comparison to biomaterial‐free (pellet) three‐dimensional culturing? Monolayer‐expanded chondrocytes from healthy adult porcine knee joints were cultivated in alginate, alginate‐chitosan, alginate‐fibrin beads and as pellets up to 4 weeks. Quantitative PCR and Immunohistology were used to assess chondrogenic markers. Alginate‐fibrin—encapsulated chondrocytes behaved almost like monolayer chondrocytes. Alginate‐ and alginate‐chitosan encapsulation lead to a low chondrogenic marker gene expression. Although all 3D‐cultured chondrocytes showed a considerable amount of Sox9 expression, only pellet cultivation lead to a sufficient Collagen II expression. This puts the usage of alginate‐cultivated cartilage tissue engineering constructs under question. Fibrin addition is not beneficial for chondrogenic differentiation. Sox9 and Collagen II behave differently, depending upon the surrounding 3D‐environment. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Promoting α‐secretase cleavage of beta‐amyloid with engineered proteolytic antibody fragments
Authors: Kasturirangan Srinath , Brune Dan , Sierks Michael
Published: July 2009

Deposition of beta‐amyloid (Aβ) is considered as an important early event in the pathogenesis of Alzheimer's Disease (AD), and reduction of Aβ levels by various therapeutic approaches is actively being pursued. A potentially non‐inflammatory approach to facilitate clearance and reduce toxicity is to hydrolyze Aβ at its α‐secretase site. We have previously identified a light chain fragment, mk18, with α‐secretase‐like catalytic activity, producing the 1–16 and 17–40 amino acid fragments of Aβ40 as primary products, although hydrolysis is also observed following other lysine and arginine residues. To improve the specific activity of the recombinant antibody by affinity maturation, we constructed a single chain variable fragment (scFv) library containing a randomized CDR3 heavy chain region. A biotinylated covalently reactive analog mimicking α‐secretase site cleavage was synthesized, immobilized on streptavidin beads, and used to select yeast surface expressed scFvs with increased specificity for Aβ. After two rounds of selection against the analog, yeast cells were individually screened for proteolytic activity towards an internally quenched fluorogenic substrate that contains the α‐secretase site of Aβ. From 750 clones screened, the two clones with the highest increase in proteolytic activity compared to the parent mk18 were selected for further study. Kinetic analyses using purified soluble scFvs showed a 3‐ and 6‐fold increase in catalytic activity (kcat/KM) toward the synthetic Aβ substrate compared to the original scFv primarily due to an expected decrease in KM rather than an increase in kcat. This affinity maturation strategy can be used to select for scFvs with increased catalytic specificity for Aβ. These proteolytic scFvs have potential therapeutic applications for AD by decreasing soluble Aβ levels in vivo. © 2009 American Institute of Chemical Engineers. Biotechnol. Prog., 2009
Time‐lapsed imaging for in‐process evaluation of supercritical fluid processing of tissue engineering scaffolds
Authors: Mather Melissa L. , Brion Michael , White Lisa J. , Shakesheff Kevin M. , Howdle Steven M. , Morgan Stephen P. , Crowe John A.
Published: July 2009

This article demonstrates the application of time‐lapsed imaging and image processing to inform the supercritical processing of tissue scaffolds that are integral to many regenerative therapies. The methodology presented provides online quantitative evaluation of the complex process of scaffold formation in supercritical environments. The capabilities of the developed system are demonstrated through comparison of scaffolds formed from polymers with different molecular weight and with different venting times. Visual monitoring of scaffold fabrication enabled key events in the supercritical processing of the scaffolds to be identified including the onset of polymer plasticization, supercritical points and foam formation. Image processing of images acquired during the foaming process enabled quantitative tracking of the growing scaffold boundary that provided new insight into the nature of scaffold foaming. Further, this quantitative approach assisted in the comparison of different scaffold fabrication protocols. Observed differences in scaffold formation were found to persist, post‐fabrication as evidenced by micro x‐ray computed tomography (μ x‐ray CT) images. It is concluded that time‐lapsed imaging in combination with image processing is a convenient and powerful tool to provide insight into the scaffold fabrication process. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Biochemical, mechanical, and spectroscopic analyses of genetically engineered flax fibers producing bioplastic (poly‐β‐hydroxybutyrate)
Authors: Wróbel‐Kwiatkowska Magdalena , Skórkowska‐Telichowska Katarzyna , Dymińska Lucyna , Mączka Mirosław , Hanuza Jerzy , Szopa Jan
Published: July 2009

The interest in biofibers has grown in recent years due to their expanding range of applications in fields as diverse as biomedical science and the automotive industry. Their low production costs, biodegradability, physical properties, and perceived eco‐friendliness allow for their extensive use as composite components, a role in which they could replace petroleum‐based synthetic polymers. We performed biochemical, mechanical, and structural analyses of flax stems and fibers derived from field‐grown transgenic flax enriched with PHB (poly‐β‐hydroxybutyrate). The analyses of the plant stems revealed an increase in the cellulose content and a decrease in the lignin and pectin contents relative to the control plants. However, the contents of the fibers' major components (cellulose, lignin, pectin) remain unchanged. An FT‐IR study confirmed the results of the biochemical analyses of the flax fibers. However, the arrangement of the cellulose polymer in the transgenic fibers differed from that in the control, and a significant increase in the number of hydrogen bonds was detected. The mechanical properties of the transgenic flax stems were significantly improved, reflecting the cellulose content increase. However, the mechanical properties of the fibers did not change in comparison with the control, with the exception of the fibers from transgenic line M13. The generated transgenic flax plants, which produce both components of the flax/PHB composites (i.e., fibers and thermoplastic matrix in the same plant organ) are a source of an attractive and ecologically safe material for industry and medicine. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Effects of citraconylation on enzymatic modification of human proinsulin using trypsin and carboxypeptidase B
Authors: Son Young‐Jin , Kim Chang‐Kyu , Kim Young Bong , Kweon Dae‐Hyuk , Park Yong‐Cheol , Seo Jin‐Ho
Published: July 2009

Insulin is a polypeptide hormone which is produced by the β‐cell of pancreas and controls the blood glucose level in the human body. Enzymatic modification of human proinsulin using trypsin and carboxypeptidase B generally causes high accumulation of insulin derivatives, leading to more complicated purification processes. A simple method including citraconylation and decitraconylation in the enzymatic modification process was developed for the reduction of a major derivative, des‐threonine human insulin. Addition of 3.0 g citraconic anhydride per g protein into the reaction solution led to the citraconylation of lysine residues in human proinsulin and reduction of relative des‐threonine insulin content from 13.5 to 1.0%. After the enzymatic hydrolysis of the citraconylated proinsulin, 100% of lysine residues can be decitraconylated and restored by adjusting pH to 2–3 at 25 °C. Combination of hydrogen peroxide addition and citraconylation of proinsulin expressed in recombinant Escherichia coli remarkably improved the conversion yield of insulin from 52.7 to 77.7%. Consequently, citraconylation of lysine residues blocked the unexpected cleavage of human proinsulin by trypsin, minimized the formation of des‐threonine insulin and hence increased the production yield of active insulin. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Spreadsheets: The ideal tool for distance learning in engineering education
Authors: Kanyarusoke Kant E. , Uziak Jacek
Published: July 2009

Formal Engineering Education has traditionally been delivered using the low technology—high touch lecturing method, in which the lecturer and student meet face to face. Distance education in this field has been quite slow to develop primarily because of difficulty in delivery of practical based instructions and problems on integrity of assessments. Developments in information technology and the increased demand for further education by people already in employment have however changed this even in developing countries. It puts extra demand on Lecturers to guide distance learners in handling numerical computations so prevalent in Engineering. At the campuses, computer based methods are available in the high touch—high tech lecture method. High level and efficient computer software is used to help the student to simulate and solve some problems. However, such software is expensive—and therefore—not readily available to the distant learner. Spreadsheets on the other hand are almost universal on today's computers and they bridge the gap between hand calculations and high level programme computations. This paper therefore makes a case for the use of spreadsheets in Distance Engineering Education. An example in Spring Design, Selection and Adaptation is used to illustrate the simplification and other advantages of their use by practicing distance learners. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 216–223, 2011
A software based on MATLAB for teaching substation lightning protection design to undergraduate students with emphasize on different striking distance models
Authors: Vahidi B. , Aliabad A. A. Damaki
Published: July 2009

Everyday experience and scientific observations, including those made as far back as the 18th century, indicate that lightning most often strikes individual structures elevated above the earth, these may high voltage substations. The lightning conductors as a means of protection from direct lightning strokes were used much before the beginning of the present era, but they acquired wide recognition only in the middle of 18th century as a result of the work of Benjamin Franklin. The paper presents an approach to teaching high voltage course using specially designed exercises that can be done using MATLAB. This paper present MATLAB based software to design substation lightning protection. Evaluation of the simulation with 40 students is very positive in terms of their developing confidence in and understanding of this simulation. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 256–267, 2011
Design of Crystalline Solids
Authors: Jones M. J. , Szepes A. , Ulrich J.
Published: July 2009

Product design is an active area of research. In a top‐down approach to product design, the required product properties dictate product development from the very basic choice of the functional material to use for a defined task up to the processing required to render the material in a suitable form. This article focuses on processing crystalline solids with a particular field of application in mind and shows how process conditions can be used both to generate a material with particular properties and to tailor these properties. The examples selected are biased towards novel pharmaceutical applications; the principles of the processes and the resulting product properties discussed can, however, be transferred to other areas where materials with similar functions are required. The case studies presented pertain to in situ coating of solid particles (cases 1 and 2) with a crystalline coating of a different chemical nature, to freeze casting for generating porous particles and, finally, to the potential for exploiting phase transformations to generate tubular crystalline solids that can function as micro‐delivery devices for other materials. Potential advantages of all four processing techniques are the delivery of well‐defined products with tailored properties that can be controlled by judicious choice of the process conditions.
Confocal Raman Microscopy as a Tool to Investigate Concentration Profiles of Melt Crystallized Ibuprofen/Carnauba Wax
Authors: Qu H. , Römbach E. , Louhi‐Kultanen M. , Jones M. J. , Ulrich J.
Published: July 2009

Coatings are of great significance for pharmaceutical solid dosage forms. They fulfil a number of functions and are often necessary to control drug delivery, to mask bitter taste, or to protect the active pharmaceutical ingredient from detrimental environmental factors. The process of self‐coating by melt crystallization of a suitable binary mixture eliminates the need for an additional process step in the manufacture of a solid drug. Self‐coating relies upon the physical and spatial separation of individual components in a melt during solidification. This paper focuses on the use of confocal Raman microscopy as a nondestructive technique for quantifying the spatial distribution of the components in self‐coated pastilles manufactured from the binary system ibuprofen/carnauba wax. Pastilles are produced from the melt. Raman spectroscopy allows the direct analysis of concentration profiles across the surface of the pastille. Here, the samples are cleaved and the cleaved surface is investigated in order to establish the distribution of the components in the interior of the solid. A univariate calibration model was developed and statistically validated with standard mixtures of ibuprofen and carnauba wax. Different regression models (linear or polynomial, using different significant peaks for the respective compounds) were assessed and a linear model was found to be adequate to determine the concentration gradient in the pastilles.
Drop Size Distribution in a Standard Twin‐Impeller Batch Mixer at High Dispersed‐Phase Volume Fraction
Authors: EL‐Hamouz A.
Published: July 2009

The preparation of concentrated aqueous silicone oil emulsions has been investigated with particular attention to the effect of the dispersed‐phase volume fraction ϕ from 0.01 to 0.5 for a wide range of oil viscosities (50 to 1000 cSt). Oil was added on the top surface of a 6‐L vessel. Drop size distribution and Sauter mean diameter, d32, measurements were carried out over 24 h mixing time. Emulsification was found to be relatively sensitive to the oil phase viscosity, μd, for the same ϕ yielding a narrower drop size distribution for low oil viscosity (50 cSt) and a wider drop size distribution for the highly viscous oil (1000 cSt). For the same ϕ, increasing μd resulted in increasing d32. The equilibrium d32 was found to be well correlated to the viscosity number by $ {d_{32} \over D} = 0.026\, \ast \;{V_{\rm i}^{0.204}} $ for ϕ = 0.5. For the same oil viscosity, d32 was found to increase with increasing ϕ. A multiregression of d32 with both ϕ and Vi for various silicone oil viscosity grades was successfully correlated by $ d_{32} = 9.6\, \phi^{0.069} V_{\rm i}^{0.216} $ with a regression coefficient (R2) of 0.975. This shows a very weak dependence of the equilibrium d32 on ϕ.
Miniaturization of Pressure Filtration Processes for Lean Development
Authors: Jermann S. , Schreiner A. , Schneeberger R.
Published: July 2009

As a basic operation of mechanical process engineering, pressure filtration and its scale‐up has been described in detail in the literature. But, the pharmaceutical development of active substances, in particular, calls for a scale‐up of relatively small quantities to execute downstream processes in a lean and reliable manner. Therefore, development depends on conclusions from smaller filter equipment. In this study, results from laboratory nutsche filters with filter surface areas of 1.4 cm2 and 9.6 cm2 were compared with results from a 20 cm2 nutsche. It has been shown that no reproducible and reliable data could be generated using the 1.4‐cm2 nutsche. While this was possible using the 9.6 cm2 nutsche, the permeability was greater than with the recommended 20 cm2 nutsche so that a correction factor has to be introduced.
Particle Characterization by X‐Ray Powder Diffraction
Authors: Herrmann M. , Förter‐Barth U. , Kempa P. B. , Kröber H.
Published: July 2009

Two examples demonstrate how X‐ray diffraction can be used to characterize internal particle parameters including crystal structure, crystallite size and microstrain. After cocrystallization of pharmaceutical ingredients by ball milling and supercritical processes new phases and strained crystal lattices were found with crystallite sizes in the submicro to nanometer range. For two energetic materials the crystal to microstructure relation and the influence of comminution techniques on domain size and microstrain were investigated. Both examples focused on advanced particle engineering by understanding the function and design of crystalline constituents.
Computational Approach to Characterize the Mass Transfer between the Counter‐Current Gas‐Liquid Flow
Authors: Xu Y. Y. , Paschke S. , Repke J.‐U. , Yuan J. Q. , Wozny G.
Published: July 2009

Structured packed columns are widely used in the chemical industry for distillation and absorption. However, the understanding of the transfer mechanism behind the counter‐current gas‐liquid flow in structured packed columns is still limited. In this work, a three‐dimensional CFD model that considers the local absorption and the local momentum transfer mechanism is developed for a film flow on a small plate with a counter‐current gas flow. The model, based on the Volume of Fluid (VOF) method, is built up on the basis of a pressure drop model and the penetration theory to quantitatively investigate the instantaneous hydrodynamics and mass transfer characteristics of the liquid phase. Simulations and experiments are carried out for a system consisting of propane and toluene. A comparison of the simulation results with the experimental data for the outlet concentrations shows good agreement.