bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution inCandida albicansPopulations During a Single Passage Through a Mouse Host
Authors: Forche Anja , Magee P T , Selmecki Anna , Berman Judith , May Georgiana
Published: May 2009

The mechanisms and rates by which genotypic and phenotypic variation is generated in opportunistic, eukaryotic pathogens during growth in hosts are not well understood. We evaluated genomewide genetic and phenotypic evolution in Candida albicans, an opportunistic fungal pathogen of humans, during passage through a mouse host (in vivo) and during propagation in liquid culture (in vitro). We found slower population growth and higher rates of chromosome-level genetic variation in populations passaged in vivo relative to those grown in vitro. Interestingly, the distribution of long-range loss of heterozygosity (LOH) and chromosome rearrangement events across the genome differed for the two growth environments, while rates of short-range LOH were comparable for in vivo and in vitro populations. Further, for the in vivo populations, there was a positive correlation of cells demonstrating genetic alterations and variation in colony growth and morphology. For in vitro populations, no variation in growth phenotypes was detected. Together, our results demonstrate that passage through a living host leads to slower growth and higher rates of genomic and phenotypic variation compared to in vitro populations. Results suggest that the dynamics of population growth and genomewide rearrangement contribute to the maintenance of a commensal and opportunistic life history of C. albicans.
On rational approximation to | x |
Authors: Alzer Horst
Published: May 2009

Let \documentclass{aastex}
\usepackage{amsbsy}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{mathrsfs}
\usepackage{pifont}
\usepackage{stmaryrd}
\usepackage{textcomp}
\usepackage{upgreek}
\usepackage{portland,xspace}
\usepackage{amsmath,amsxtra}
\usepackage{bbm}
\pagestyle{empty}
\DeclareMathSizes{10}{9}{7}{6}
\begin{document}
$$e_n (S;x) = |x| - x\frac{{p(x) - p( - x)}}
{{p(x) + p( - x)}},$$
\end{document} We prove: for all
n
≧ 1 and
x
∈ [−1, 1] we have \documentclass{aastex}
\usepackage{amsbsy}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{mathrsfs}
\usepackage{pifont}
\usepackage{stmaryrd}
\usepackage{textcomp}
\usepackage{upgreek}
\usepackage{portland,xspace}
\usepackage{amsmath,amsxtra}
\usepackage{bbm}
\pagestyle{empty}
\DeclareMathSizes{10}{9}{7}{6}
\begin{document}
$$|e_n (S;x)| \leqq \frac{1}{{n^2 }},$$
\end{document} where equality holds if and only if
n
=
x
= 1 or
n
= 1,
x
= −1. This refines a result of Brutman (1998), who showed that the inequality \documentclass{aastex}
\usepackage{amsbsy}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{bm}
\usepackage{mathrsfs}
\usepackage{pifont}
\usepackage{stmaryrd}
\usepackage{textcomp}
\usepackage{upgreek}
\usepackage{portland,xspace}
\usepackage{amsmath,amsxtra}
\usepackage{bbm}
\pagestyle{empty}
\DeclareMathSizes{10}{9}{7}{6}
\begin{document}
$$|e_n (S;x)| < \frac{8}
{{e^2 (n^2 - 1)}}$$
\end{document} is valid for all
n
≧ 2 and
x
∈ [−1, 1].
Multiplicative character sums with the Euler function
Authors: Balasuriya Sanka , Shparlinski Igor , Sutantyo Daniel
Published: May 2009

We give upper bounds for sums of multiplicative characters modulo an integerq≧ 2 with the Euler functionϕ(n) and with the shifted largest prime divisorP(n) +aof integersn≦x.
Approximation by generalized Meyer-König and Zeller type operators
Authors: Guo Shunsheng , Liu Lixia , Chen Hua
Published: May 2009

In this paper we give the direct, inverse and equivalence theorems for generalization Meyer-König and Zeller type operators in the space
Lp
(1 ≦
p
≦
∞
) with Ditzian-Totik modulus.
Simulation of wave fronts on dry beds using Lagrangian blocks
Authors: Tan L. W. , Chu V. H.
Published: May 2009

Simulations of wave fronts on a dry bed are conducted using blocks as the computational elements. The non-negativity of the blocks allows simulations of the wave fronts to be carried out without the oscillation problem that limits the applicability of many existing computational methods. At the leading edge of the advancing front, the velocity is maximum and friction dominates. Simulations of this dominant friction effect at the wave front are carried out for the release of water from a dam-break outflow, a levee overflow and a sump outflow. Despite geometric differences, the frontal dynamics of all three flows are similarly affected by friction.
Climate-change impacts on long-term performance of slopes
Authors: Kilsby C. , Glendinning S. , Hughes P. N. , Parkin G. , Bransby M. F.
Published: May 2009

The UK biological and engineering impacts of climate change on slopes (Bionics) project was funded to bring together key stakeholders and academics to research advanced procedures for maintaining serviceability and safety of strategic embankments and cuttings in addition to advancing the science base. This paper summarises some of the evidence that suggests climate change will have an effect on the behaviour of infrastructure slopes and their management, and provides an overview of future climate scenarios for the UK. It also shows how climate data have been used in numerical and physical models and full-scale tests within the Bionics project to begin to determine the magnitude and timing of the effects of climate change on infrastructure slopes.
Influence of ph on sediment-associated sorption reactions of benzidine
Authors: Chen Shihua , Nyman Marianne C.
Published: May 2009

Benzidine has been marked as a priority chemical on the National Priorities List by the U.S. Environmental Protection Agency because of its carcinogenic nature. Benzidine sorbs to the sediment matrix after entering water-sediment ecosystems and undergoes at least three different fate processes, including cation exchange, hydrophobic partitioning, and covalent binding. Sediment samples taken from Lake Macatawa (MI, USA) were used after drying and grinding treatments in this study. Sorption experiments were conducted in the buffered deionized water-sediment slurries with a pH range of approximately 3 to 7. Experimental results indicated that low pH conditions (e.g., pH 3.2) favored sorption of benzidine onto sediment, where a large proportion of benzidine species protonated and sorbed predominantly through the fast cation exchange process. Sorption kinetics data suggested that reactions between protons and carbonate components residing in the sediment matrices led to a shift of sorption mechanisms from cation exchange to hydrophobic partitioning, covalent binding, or both when the slurry pH increased from 3 to 7. A sorption mechanism-based model is presented to describe benzidine sorption behavior in the sediment-water systems at different pH values. This model comprises three components mathematically: the linear hydrophobic partitioning, Langmuir-type covalent binding, and quadratic cation exchange. On the basis of nonlinear regression, this model fits the experimental data well. The organic carbon-normalized distribution coefficient value calculated from this model (1,914 L/kg at pH 6.9), and the available covalent binding sites in the sediment matrices were 27 to 52 mmol/kg organic carbon in the pH range of 5.0 to 6.9. The predicted model parameters are in good agreement with the reported literature values. By this model, the individual contribution from each sorption mechanism can be quantified with a wide pH range (e.g., from pH 3 to 7). This model strategy could provide an alternative way to predict the complex sorption processes of aromatic amines containing one or two amino groups in the aqueous-sediment environment.
On some hydrodynamical aspects of quantum mechanics
Authors: Spera Mauro
Published: May 2009

In this note we first set up an analogy between spin and vorticity of a perfect 2d-fluid flow, based on the complex polynomial (i.e. Borel-Weil) realization of the irreducible unitary representations of SU(2), and looking at the Madelung-Bohm velocity attached to the ensuing spin wave functions. We also show that, in the framework of finite dimensional geometric quantum mechanics, the Schrödinger velocity field on projective Hilbert space is divergence-free (being Killing with respect to the Fubini-Study metric) and fulfils the stationary Euler equation, with pressure proportional to the Hamiltonian uncertainty (squared). We explicitly determine the critical points of the pressure of this “Schrödinger fluid”, together with its vorticity, which turns out to depend on the spacings of the energy levels. These results follow from hydrodynamical properties of Killing vector fields valid in any (finite dimensional) Riemannian manifold, of possible independent interest.
The Fantasy of the Elite Force Aviator: On Dolls and Desire
Authors: Curtis Neal
Published: May 2009

This article explores the relationship between mimesis and fantasy. Taking as its starting point James DerDerian's claims regarding the changing face of the military-industrial complex and its increasing use of the entertainment and cultural industries, the article argues that this move can only be fully understood if it is viewed alongside a consideration of the ideological function of fantasy, especially as it is set out in the work of Slavoj Žižek. The article focuses on one particular piece of mimesis, namely the “Elite Force Aviator: George W. Bush 12-inch Action Figure” to explore the phantasmatic kernel of the war on terror. The article also considers how the global image sphere has become the site for a conflict between competing fantasies, and aims to show how certain examples of countermimesis might be used to break the hold of the fantasies that currently coordinate our reality.
Bolivianos en España
Authors: Fernández García Mercedes
Published: May 2009

El presente artículo tiene como objetivo analizar el comportamiento del colectivo boliviano en España, a partir de los microdatos de la Encuesta Nacional de Inmigrantes. Partiendo de los parámetros socioeconómicos de la integración y de los postulados teóricos del capital humano, del mercado de trabajo segmentado, y de la visión transnacional de las migraciones, y utilizando el análisis factorial de correspondencias múltiple se elabora un perfil de los bolivianos, que actualmente residen en España.
Holothuria (Cystipus) casoae a new species of sea cucumber (Echinodermata: Holothuroidea) from the central-eastern Pacific Ocean
Authors: Laguarda-Figueras Alfredo , Solís-Marín Francisco A.
Published: May 2009

Holothuria (Cystipus) casoae n. sp. is described from the central-eastern Pacific, from depths between 45 and 100 m. The main characters separating H. (C.) casoae from the rest of the species included in the subgenus Cystipus are the presence of a prominent fringe of 10 or more conical papillae along each side of the body and the presence of tables with a spinose rim, the pillars of the spire are short ending in a complex spiny crown with a small central circular opening. This new species is distinctive in the genus Holothuria, subgenus Cystipus, but shows some similarities to H. (C.) cubana Ludwig, 1875, H. (C.) inhabilis Selenka, 1867 and H. (C.) pseudofossor Deichmann, 1930.
The effects of ongoing activity on time estimation in prospective remembering
Authors: Occhionero Miranda , Esposito Maria José , Cicogna Pier Carla , Nigro Giovanna
Published: May 2009

Two experiments examined whether time‐based prospective memory performance is influenced by the continuous or discontinuous nature of an ongoing activity. The first experiment demonstrated that prospective memory performance was not influenced by the engagement in continuous or discontinuous ongoing activity. The second experiment demonstrated that a discontinuous ongoing activity negatively affected prospective memory performance when participants had to execute two time‐based tasks for which the retention intervals partially overlapped. The results suggest that when individuals are engaged in multiple time‐based tasks, a general timing disruption occurs, with a proactive interference effect resulting in costs that are detrimental to prospective timing. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of Fluorenes via the Palladium‐Catalyzed 5‐exo‐dig Annulation of o‐Alkynylbiaryls
Authors: Chernyak Natalia , Gevorgyan Vladimir
Published: May 2009

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The direct palladium‐catalyzed intramolecular hydroarylation of o‐alkynylbiaryls proceeded in a highly stereoselective manner producing fluorenes 2, the products of 5‐exo‐dig cyclization, in excellent yields. The cascade intermolecular arylation, incorporated in this transformation, allowed for the efficient synthesis of fully substituted fluorenes 12. These cyclizations proceed more rapidly with electron‐deficient benzene rings which, in combination with a substantial isotope effect observed, strongly supports a CH activation mechanism for the key annulation step.
A Lutidine‐Bridged Bis‐Perimidinium Salt: Synthesis and Application as a Precursor in Palladium‐Catalyzed Cross‐Coupling Reactions
Authors: Tu Tao , Malineni Jagadeesh , Bao Xiaoling , Dötz Karl Heinz
Published: May 2009

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A novel lutidine‐bridged bis‐perimidinium dibromide 3 was synthesized in quantitative yield from cheap commercial starting materials. The bisylidene prepared therefrom in situ upon deprotonation is a potent precatalyst in palladium‐catalyzed Heck and Suzuki cross‐coupling reactions under aerobic conditions, and is efficient even with a ppm scale catalyst loading. Its stronger σ‐donor character is held to be responsible for its superior catalytic performance compared with imidazole‐ and benzimidazole‐based analogues bearing the same skeleton precursors.
[1.1]Ferrocenophane‐1,12‐dione as a Precursor of 1,12‐Di(cyclopenta‐2,4‐dienylidene)‐[1.1]ferrocenophane, a Doubly Bridged Difulvene
Authors: Garabatos‐Perera José Ramon , Wartchow Rudolf , Butenschön Holger
Published: May 2009

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An improved synthesis of [1.1]ferrocenophane‐1,12‐dione (2) by oxidation of [1.1]ferrocenophane with 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone (DDQ) is presented. The syn conformer of dione 2 is structurally characterized. The compound undergoes various addition reactions at the bridging carbonyl groups. Attempts to add 1,1′‐dilithioferrocene result, however, in the diadduct 9, not in the symmetric trinuclear diol 8. Reaction of 2 with sodium cyclopentadienide in the presence of aluminium trichloride (AlCl3) gives the respective difulvene 11 in excellent yield. The dynamic behavior of 11 is investigated by variable temperature 1H NMR measurements (VT‐NMR). The cyclovoltammogram of 11 indicates two reversible oxidation steps. Reduction of difulvene 11 with lithium aluminium hydride (LiAlH4) results in the formation of [1.1]ferrocenophane 12 with cyclopentadienyl anion substituents at either one of the two bridges. While attempts to generate a third ferrocene moiety by reaction with iron(II) choride (FeCl2) have failed so far, the formation of 12 is established by protonolysis and methylation reactions.
Selective Oxidative Ligand Coupling of Organoborates Bearing an Alkynyl Group
Authors: Amaya Toru , Tsukamura Yusuke , Hirao Toshikazu
Published: May 2009

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Selective oxidative ligand coupling of alkynyl(triaryl)borates was achieved by treatment with ethoxyvanadyl dichloride [VO(OEt)Cl2] to form the spsp2 carbon‐carbon bond. A one‐pot procedure through the in situ preparation of the borate was demonstrated using triphenylborane and 1‐ethynyl‐4‐methoxybenzene.
Highly Functionalised Enantiopure 4‐Hydroxypyridine Derivatives by a Versatile Three‐Component Synthesis
Authors: Eidamshaus Christian , Reissig Hans‐Ulrich
Published: May 2009

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The scope of a novel alkoxyallene‐based pyridine synthesis was expanded to enantiopure carboxylic acids and nitriles as starting materials. The enantiomeric purity of the chiral α‐secondary carboxylic acids and nitriles was completely preserved during this reaction sequence thus allowing the one‐pot preparation of a whole range of 4‐hydroxypyridines or their 4‐pyridinone tautomers in good yields.
Use of the Chiral Pool – Practical Asymmetric Organocatalytic Strecker Reaction with Quinine
Authors: Reingruber Rüdiger , Baumann Thomas , Dahmen Stefan , Bräse Stefan
Published: May 2009

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An efficient, organocatalytic enantioselective synthesis of N‐arylsulfonyl α‐amino nitriles from the corresponding α‐amido sulfones has been developed. This quinine‐catalyzed Strecker reaction provides the corresponding cyanated products in good yields and enantioselectivities.
Enantioselective Copper‐Catalyzed Allylic Substitution Reaction with Aminohydroxyphosphine Ligand
Authors: Yoshikai Naohiko , Miura Kotaro , Nakamura Eiichi
Published: May 2009

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A proline‐derived aminohydroxyphosphine ligand induced excellent regio‐ and enantioselectivities (SN2′:SN2>94:6, 94–97% ee) in the copper‐catalyzed substitution reaction of cinnamyl phosphates with Et2Zn. A computational modelling study of the reaction pathway suggests that the displacement of the leaving group takes place in an ordered, anti‐fashion through simultaneous copper–olefin and zinc–oxygen interactions, which is critical for the enantioselection.
Terephthalic acid synthesis at higher concentrations in high‐temperature liquid water. 2. Eliminating undesired byproducts
Authors: Osada Mitsumasa , Savage Phillip E.
Published: May 2009

We synthesized terephthalic acid (TPA) from p‐xylene at an initial concentration above its solubility limit in high‐temperature liquid water (HTW). The nominal p‐xylene loading at the reaction conditions was 0.4 mol L−1, which is the highest reported to date for generation of high TPA yields (>70 mol %) in HTW. The presence of two liquid phases during the reaction did not appear to accelerate the rate, unlike behavior reported for some other organic reactions done “on water” at lower temperatures. Adding oxygen gas in a large increment during synthesis produced a black liquid and a black solid byproduct, which is a previously undocumented problem. Adding oxygen in smaller increments prevented formation of the liquid and solid byproducts and also provided high selectivities (90 mol %) and yields (>70 mol %) of TPA. These results demonstrate the feasibility of HTW as a medium for TPA synthesis at p‐xylene concentrations even higher than its solubility limit. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Theoretical analysis of the effects of asymmetric membrane structure on fouling during microfiltration
Authors: Li Weiyi , Duclos‐Orsello Chase , Ho Chia‐Chi
Published: May 2009

There is a growing interest in the use of both asymmetric and composite membranes for microfiltration and ultrafiltration processes. This includes particle removal applications in the semiconductor industry and virus clearance in biopharmaceutical applications. Filter fouling plays an important role in these processes. Although flux decline models have been developed for homogeneous membranes, the effects of asymmetric membrane structure on flux decline behavior remain poorly understood on a fundamental level. Here, we develop a theoretical model to describe the effects of asymmetric membrane structure on flux decline. The asymmetric structure was described by the spatial variation in Darcy permeability in the directions normal to and parallel to the membrane surface. The velocity profile and flux decline because of pore blockage were described using Darcy's law and a pore blockage and cake filtration model. Flux decline data were obtained using pseudocomposite membranes with highly interconnected polyvinylidene fluoride membranes (PVDF) and straight through pore polycarbonate track‐etched membranes (PCTE). Model composite membranes were formed by layering PCTE or PVDF membranes with different pore sizes on top of each other. Flux decline data for the composite membrane were in good agreement with model calculations. The results provide important insights into the effects of asymmetric membrane pore structures on flux decline. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Description of the mutual solubilities of fatty acids and water with the CPA EoS
Authors: Oliveira M. B. , Pratas M. J. , Marrucho I. M. , Queimada A. J. , Coutinho J. A. P.
Published: May 2009

Data for the mutual solubilities of fatty acid + water mixtures are scarce and so measurements for seven fatty acid (C5‐C10, C12) + water systems were carried out. This new experimental data was successfully modelled with the cubic plus association EoS. Using data from C6 to C10 and the Elliot's cross‐associating combining rule a correlation for the kij binary interaction parameter, as a function of the acid chain length, is proposed. The mutual solubilities of water and fatty acids can be adequately described with average deviations inferior to 6% for the water rich phase and 30% for the acid rich phase. Furthermore, satisfactory predictions of solid‐liquid equilibria of seven fatty acids (C12‐C18) + water systems were achieved based only on the kij correlation obtained from liquid–liquid equilibria data. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Women's fertility and mortality in late mid life: A comparison of three contemporary populations
Authors: Grundy Emily
Published: May 2009

Evolutionary theory suggests a trade‐off between reproduction and somatic maintenance implying a negative relationship between parity and longevity, at least in natural fertility populations. In populations in which fertility control is usual, there are also a number of mechanisms that may link reproductive careers and later mortality, but evidence of associations between women's fertility patterns and their later life health has been judged inconclusive due to varying controls for socio‐economic characteristics and marital status. Here, we build on three recent studies that followed a common framework to investigate associations between women's parity and timing of first and last birth with mortality in late middle age in three contemporary developed counties, Norway, England and Wales, and the USA. Data were drawn from whole population registers (Norway); a large census‐based record linkage study (England and Wales), and a nationally representative survey linked to death records (USA). Results show that teenage childbirth was associated with higher mortality risks in late middle age in all three countries. Risks of death were significantly raised among nulliparous women in Norway and England and Wales, and also raised (although not significantly so) for childless US women. However, although higher parity was associated with a slight mortality disadvantage in England and Wales and the USA, the reverse seemed the case in Norway. These finding suggest that in populations in which fertility control is usual, contextual factors influencing the relative costs and benefits of childbearing may influence associations between fertility histories and later mortality. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
An fMRI study of working memory in persons with bipolar disorder or at genetic risk for bipolar disorder
Authors: Thermenos Heidi W. , Goldstein Jill M. , Milanovic Snezana M. , Whitfield‐Gabrieli Susan , Makris Nikos , LaViolette Peter , Koch Jennifer K. , Faraone Stephen V. , Tsuang Ming T. , Buka Stephen L. , Seidman Larry J.
Published: May 2009

First‐degree relatives of persons with bipolar disorders (BDs) carry elevated risk for the illness, and manifest deficits in attention and memory (possible “endophenotypes”). However, there is only one published functional magnetic resonance imaging (fMRI) study of candidate endophenotypes in BD. We used fMRI to examine brain function in BD and in first‐degree relatives performing a 2‐back working memory (WM) task, and correlated brain activity with mood measures taken at the scanning session. Subjects (age 32–46) were 19 persons with BD, 18 unmedicated, non‐psychotic first‐degree relatives (RELs) of persons with BD, and 19 matched controls, ascertained from a long‐term follow‐up of a prenatal cohort study in New England. fMRI signal during 2‐back and 0‐back WM tasks was measured on a Siemens 1.5T MR scanner. fMRI data were analyzed using SPM‐2. Persons with BD and RELs failed to suppress activation in the left anterior insula (BA 13) during WM, whereas controls suppressed activation. Compared to controls, RELs also failed to suppress activation in the orbitofrontal cortex (OFC) and superior parietal cortex. Controls and RELs exhibited greater activation than BD individuals in the left frontopolar cortex (BA 10) during WM. Results remained significant after controlling for confounders except for mild attenuation of OFC findings. Significant correlations between brain activity, mood, and WM suggest that activity in WM circuits is affected by activity in emotion‐regulatory circuits. Persons with BD and RELs exhibit altered activity in the frontopolar cortex and insula, which may represent biomarkers of genetic risk for BD. © 2009 Wiley‐Liss, Inc.
The dangers of multi‐male groupings: trauma and healing in cercopithecoid monkeys from Cameroon
Authors: Chapman Tara J. , Legge Scott S.
Published: May 2009

This study examines the potential linkage between social organization and trauma in a sample of cercopithecids from Cameroon. Skeletal trauma is described in a museum collection of eight sympatric monkey species. Macroscopic analysis was carried out on a total of 139 complete skeletons of mangabeys, colobines and guenons. Species in multi‐male groups were found to have higher fracture frequencies than those in uni‐male groups. These higher frequencies may be related to intra‐specific male–male aggression; however, similarities in fracture patterning between males and females in multi‐male groups suggest that other factors may be involved. Although fracture etiology may not be identified with certainty, this study suggests that predation may indirectly be a cause of traumatic injuries in those species of cercopithecid monkeys displaying multi‐male social organizations. The data presented also highlight the utility of museum collections as an additional resource in analyses of primate behavior, demonstrating that behavioral information does not die when the animal does. Am. J. Primatol. 71:567–573, 2009. © 2009 Wiley‐Liss, Inc.
Molecular Photoacoustic Tomography with Colloidal Nanobeacons
Authors: Pan Dipanjan , Pramanik Manojit , Senpan Angana , Yang Xinmai , Song Kwang H. , Scott Mike J. , Zhang Huiying , Gaffney Patrick J. , Wickline Samuel A. , Wang Lihong V. , Lanza Gregory M.
Published: May 2009

Erkennung von Engpässen: Goldhaltige Kolloidpartikel wie die abgebildeten GNBs („gold nanobeacons“) eignen sich als exogene Kontrastmittel zur Erkennung von Fibrin, einem biochemischen Anzeiger der Thrombenbildung. Fibrinbindende GNBs ergaben eine zehnfache Signalverstärkung bei der photoakustischen Tomographie im Nah‐IR‐Bereich und könnten daher für diagnostische Bildgebungsverfahren interessant sein.

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Linearer Aufbau eines reinen Glykoenzyms
Authors: Davis Benjamin G.
Published: May 2009

Aus Liebe zur Sache: Die Synthese der aktiven reinen Glykoform eines Enzyms (RNase) durch native chemische Ligation eines (Glyko)Peptids mit Peptidthioester‐Fragmenten erforderte eine Reihe mühsamer Schritte: Optimierung der Strategie, Gewinnung aktiver Inteine, Feinabstimmung von Redoxbedingungen und die Synthese der Glykoaminosäuren‐Bausteine.

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A Microreactor with Thousands of Subcompartments: Enzyme‐Loaded Liposomes within Polymer Capsules
Authors: Städler Brigitte , Chandrawati Rona , Price Andrew D. , Chong Siow‐Feng , Breheney Kerry , Postma Almar , Connal Luke A. , Zelikin Alexander N. , Caruso Frank
Published: May 2009

Vollgeladen: Durch nichtkovalente Verankerung von Liposomen auf mehrschichtigen Polymerfilmen mit Cholesterin‐modifizierten Polymeren gelingt die Herstellung von Kapsosomen – Polymerkapseln mit Liposom‐Kompartimenten (siehe Bild). Eine quantitative enzymatische Reaktion bestätigte das Vorliegen einer aktiven eingelagerten Spezies in den Kapsosomen und diente zur Bestimmung der Zahl an Kompartimenten im neuen biomedizinischen Trägersystem.

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Molecular Photoacoustic Tomography with Colloidal Nanobeacons
Authors: Pan Dipanjan , Pramanik Manojit , Senpan Angana , Yang Xinmai , Song Kwang H. , Scott Mike J. , Zhang Huiying , Gaffney Patrick J. , Wickline Samuel A. , Wang Lihong V. , Lanza Gregory M.
Published: May 2009

Spotting clots: Vascularly constrained colloidal gold nanobeacons (GNBs; see picture) can be used as exogenous photoacoustic contrast agents for the targeted detection of fibrin, a major biochemical feature of thrombus. Fibrin‐targeted GNBs provide a more than tenfold signal enhancement in photoacoustic tomography in the near‐IR wavelength window, indicating their potential for diagnostic imaging.

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The Linear Assembly of a Pure Glycoenzyme
Authors: Davis Benjamin G.
Published: May 2009

A labor of love: The synthesis of an active pure enzyme (RNase) glycoform by the native chemical ligation of a (glyco)peptide and peptide thioester fragments required numerous painstaking steps: the strategy was optimized, active inteins accessed, redox conditions fine‐tuned, and glycoamino acid building blocks synthesized.

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A Microreactor with Thousands of Subcompartments: Enzyme‐Loaded Liposomes within Polymer Capsules
Authors: Städler Brigitte , Chandrawati Rona , Price Andrew D. , Chong Siow‐Feng , Breheney Kerry , Postma Almar , Connal Luke A. , Zelikin Alexander N. , Caruso Frank
Published: May 2009

Fully loaded: Noncovalent anchoring of liposomes into polymer multilayered films with cholesterol‐modified polymers allows the preparation of capsosomes—liposome‐compartmentalized polymer capsules (see picture). A quantitative enzymatic reaction confirmed the presence of active cargo within the capsosomes and was used to determine the number of subcompartments within this novel biomedical carrier system.

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Implementation of Design of Experiments projects in industry
Authors: Tanco Martín , Viles Elisabeth , Ilzarbe Laura , Alvarez María Jesus
Published: May 2009

Although design of experiments (DoE) is a common feature of statistics and quality literature, it is insufficiently used in industry. Surveys and numerous articles alike have verified that a gap exists between theoretical development and its effective application in industry. Therefore, we have developed a complete, friendly and easy‐to use methodology, from an engineering point of view, to ease the implementation of DoE in companies. Our approach presents a framework for the experimentation process that follows the traditional DMAIC steps of ‘Six Sigma’ as a generic problem solving methodology. We aim to present a complete overview of the experimentation process useful for those engineers, statisticians and scientists who are not experts in DoE. Copyright © 2009 John Wiley & Sons, Ltd.
Leukocyte depletion for safe blood transfusion
Authors: Singh Shikha , Kumar Ashok
Published: May 2009

Leukocytes have ability to distinguish between self cells (body own cells) and foreign (allogenic) cells on the basis of human leukocyte antigen (HLA) proteins that are present on the cell membrane and are effectively unique to a person. During allogenic blood transfusion a person receives large number of allogenic donor leukocytes and these are recognized as foreign cells by the recipient immune system which leads to several adverse reactions. To avoid such leukocyte‐mediated adverse reactions leukodepleted blood transfusion is required. Leukocytes can be separated on the basis of size, dielectric properties, by affinity separation, freeze‐thawing and centrifugation but all these methods are time consuming and costly. Filtration is another method for leukocyte depletion that is comparatively less expensive and more efficient as it gives more than 90% leukodepletion of blood along with minimal cell loss. However, present filtration procedures also have some limitations as they work efficiently with blood components but not with whole blood and show non‐specific adhesion of large number of platelets and red blood cells along with leukocytes. All the currently available filters are costly, which has been a major reason for their limited application. Therefore, demand for a more efficient and cost‐effective filter is high in medical community and scientists are attenpting to improve the efficiency of currently available filters. The present review gives an overview of the significance of leukodepleted blood transfusion and focuses on different methods for leukocyte depletion and challenges involved in all these technologies.
Substrate and water adsorption phenomena in a gas/solid enzymatic reactor
Authors: Dimoula Kerasina , Pohl Martina , Büchs Jochen , Spiess Antje C.
Published: May 2009

The adsorption of water and substrates to dry deposited alcohol dehydrogenase from Lactobacillus brevis (LBADH) is studied in a continuous enzymatic gas/solid reactor. This work is aiming at obtaining a deeper and more thorough understanding of the enzyme microenvironment in the gas/solid system of acetophenone reduction with concomitant oxidation of 2‐propanol. Extensive water adsorption studies showed that the effect of sucrose in the enzyme preparation on the water adsorption isotherm is significant for water activities exceeding 0.5 and reaches a factor 2 with respect to bead mass at water activity of 0.9. Significant hysteresis during water desorption is identified, resulting in up to 0.6 mgwater/mgprotein, for lyophilized enzyme preparation and up to 10 mgwater/mgprotein for deposited enzyme preparation. The adsorption of the substrates is quantified here for the first time. Whereas the adsorption of the main substrate, acetophenone, may reach a significant level of up to 6 mg/mgprotein, at an acetophenone activity of 0.32, the secondary substrate, 2‐propanol is not adsorbed at a detectable degree. The presence of water leads to a decrease of the adsorbed amount of acetophenone, by approximately 25%, at a water activity of 0.54.
Synthesis of alkyl esters by cutinase in miniemulsion and organic solvent media
Authors: de Barros Dragana P. C. , Fonseca Luís P. , Cabral Joaquim M. S. , Weiss Clemens K. , Landfester Katharina
Published: May 2009

The main objective of this work was studying and testing the nature and influence of reaction media (organic solvent vs. miniemulsion system) on the synthesis of alkyl esters catalyzed by Fusarium solani pisi cutinase. Ester synthesis and cutinase selectivity for different chain length of acids and alcohols (ethyl and hexyl) were evaluated. In iso‐octane, after 1 h of reaction, cutinase exhibits rates of esterification between 0.24 μmol x mg–1 x min–1 for ethyl oleate and 1.15 μmol x mg–1 x min–1 for ethyl butyrate, while in a miniemulsion system the rates were from 0.05 for ethyl heptanoate to 0.76 μmol x mg–1 x min–1 for ethyl decanoate. The reaction rate for the synthesis of hexyl esters in a miniemulsion system was from 0.19 for hexyl heptanoate to 1.07 μmol x mg–1 x min–1 for hexyl decanoate. High conversion yields of 95% at equilibrium after 8 h of reaction in iso‐octane for pentanoic acid (C5) with ethanol at equimolar concentration (0.1 M) was achieved. Additionally, this work showed that a significant and unexpected shift in cutinase selectivity occurred towards longer chain length carboxylic acids (C8–C10) in miniemulsion system as compared to organic solvent (iso‐octane) and previous studies in reverse micellar systems. The possibility of working with higher concentration of substrates, without inhibitory effect on the enzyme, was another advantage of the miniemulsion system.
Visualization of biomass solubilization and cellulose regeneration during ionic liquid pretreatment of switchgrass
Authors: Singh Seema , Simmons Blake A. , Vogel Kenneth P.
Published: May 2009

Auto‐fluorescent mapping of plant cell walls was used to visualize cellulose and lignin in pristine switchgrass (Panicum virgatum) stems to determine the mechanisms of biomass dissolution during ionic liquid pretreatment. The addition of ground switchgrass to the ionic liquid 1‐n‐ethyl‐3‐methylimidazolium acetate resulted in the disruption and solubilization of the plant cell wall at mild temperatures. Swelling of the plant cell wall, attributed to disruption of inter‐ and intramolecular hydrogen bonding between cellulose fibrils and lignin, followed by complete dissolution of biomass, was observed without using imaging techniques that require staining, embedding, and processing of biomass. Subsequent cellulose regeneration via the addition of an anti‐solvent, such as water, was observed in situ and provided direct evidence of significant rejection of lignin from the recovered polysaccharides. This observation was confirmed by chemical analysis of the regenerated cellulose. In comparison to untreated biomass, ionic liquid pretreated biomass produces cellulose that is efficiently hydrolyzed with commercial cellulase cocktail with high sugar yields over a relatively short time interval. Biotechnol. Bioeng. 2009; 104: 68–75 Published 2009 Wiley Periodicals, Inc.
Metabolomics for biotransformations: Intracellular redox cofactor analysis and enzyme kinetics offer insight into whole cell processes
Authors: Schroer Kirsten , Zelic Bruno , Oldiges Marco , Lütz Stephan
Published: May 2009

For redox reactions catalyzed by microbial cells the analysis of involved cofactors is of special interest since the availability of cofactors such as NADH or NADPH is often limiting and crucial for the biotransformation efficiency. The measurement of these cofactors has usually been carried out using spectrophotometric cycling assays. Today LC‐MS/MS methods have become a valuable tool for the identification and quantification of intracellular metabolites. This technology has been adapted to measure all four nicotinamide cofactors (NAD, NADP, NADH, and NADPH) during a whole cell biotransformation process catalyzed by recombinant Escherichia coli cells. The cells overexpressing an alcohol dehydrogenase from Lactobacillus brevis were used for the reduction of methyl acetoacetate (MAA) with substrate‐coupled cofactor regeneration by oxidation of 2‐propanol. To test the reliability of the measurement the data were evaluated using a process model. This model was derived using the measured concentrations of reactants and cofactors for initiation as well as the kinetic constants from in vitro measurements of the isolated enzyme. This model proves to be highly effective in the process development for a whole cell redox biotransformation in predicting both the right concentrations of cofactors and reactants in a batch and in a CSTR process as well as the right in vivo expression level of the enzyme. Moreover, a sensitivity analysis identifies the cofactor regeneration reaction as the limiting step in case for the reduction of MAA to the corresponding product (R)‐methyl 3‐hydroxybutyrate. Using the combination of in vitro enzyme kinetic measurements, measurements of cofactors and reactants and an adequate model initiated by intracellular concentrations of all involved reactants and cofactors the whole cell biotransformation process can be understood quantitatively. Biotechnol. Bioeng. 2009; 104: 251–260 © 2009 Wiley Periodicals, Inc.
Location and incidence of the zygomaticofacial foramen: An anatomic study
Authors: Aksu Funda , Ceri Nazli Gulriz , Arman Candan , Zeybek Fatma Gulşah , Tetik Suleyman
Published: May 2009

The location and incidence of the zygomaticofacial foramen (ZFF) was studied in 80 dry skulls (160 sides) of unsexed adult skulls of West Anatolian people. The average distances from the ZFF to the frontozygomatic suture, to the zygomaticomaxillary suture, and to the inferior orbital rim were found to be 26.2 ± 3.2 mm, 18.6 ± 3.14 mm, and 5.94 ± 1.43 mm, respectively. The zygomas were evaluated for the number of foramina on their facial aspects. There was none in 25 (15.6%), one in 71 (44.4%), two in 45 (28.1%), three in 10 (6.3%), four in seven (4.4%), and five in two (1.3%) sides. The ZFF was also studied for its distribution around the zygoma by dividing the surface into four anatomical areas. There was no statistical difference between the morphometrical results on both sides. Data regarding the location and variation in the number of the ZFF is important in avoiding zygomatic nerve and vessel injury during surgery, but by virtue of the great variability found, ZFF is an unreliable landmark for maxillofacial surgery. Clin. Anat. 22:559–562, 2009. © 2009 Wiley‐Liss, Inc.
Chemical kinetics‐assisted, path‐based smoke simulation
Authors: Jang Yoojin , Ihm Insung
Published: May 2009

Despite recent successes in physics‐based fluid animation, generating desired fluid flow with intuitive control of its motion still remains a challenging problem in the special effects industry. In this paper, we propose a novel approach for path‐based smoke simulation that explores the theory of chemical kinetics in an aim to provide a useful animation tool. By describing intended smoke effects through chemical reaction equations and adjusting their parameters, our method allows to easily create various interesting smoke effects that were often hard to get with previous techniques. To demonstrate the effectiveness of the presented animation framework, we describe several examples of path‐based smoke animations, generated with easily understandable reaction equations and control parameters. Copyright © 2009 John Wiley & Sons, Ltd.
Fireworks controller
Authors: Zhao Hanli , Fan Ran , Wang Charlie C. L. , Jin Xiaogang , Meng Yuwei
Published: May 2009

This paper presents the fireworks controller, a novel real‐time shape‐constrained fireworks animation system. We depict the shape of a firework by a 3D mesh. In order to approximate the mesh using evenly distributed points, we propose a fast point sampling method by extending the dual depth peeling algorithm. The samples are then taken as input to shape‐constrained fireworks whose physically plausible animations are based on inverse dynamics. We present a highly parallel iterative clustering algorithm to support multi‐level fireworks explosion. In order to simulate natural fuzzy fireworks, we impose extra random particles with a parallel random number generator. Several novel intuitive user interfaces are introduced to improve the usability of the system. Experimental results demonstrate the prettiness and efficiency of the proposed approach. Copyright © 2009 John Wiley & Sons, Ltd.
Time‐critical collision handling for deformable modeling
Authors: Gissler Marc , Schmedding Ruediger , Teschner Matthias
Published: May 2009

Collision handling is a comparatively time‐consuming task in dynamic simulations and the computational efficiency of collision handling techniques can vary significantly dependent on the spatial configuration of the environment. These issues have to be addressed in interactive simulations such as games or surgical simulators, where a pre‐defined response time should be guaranteed for each simulation step. We present a time‐critical collision handling approach for deformable objects. The technique employs spatial subdivision for the detection of collisions and penetration depth information is computed to estimate penalty forces. Detection, penetration depth estimation, and response are divided into atomic tasks. In case of an interruption, the algorithm basically resumes in the next time step. If collisions are not completely handled in one simulation step, the algorithm ensures that persistent collisions are handled in a subsequent simulation step. If an exact response cannot be computed in a given time frame, the algorithm efficiently approximates penalty forces for colliding points. Experiments indicate that the proposed technique provides a physically plausible collision handling in the case of incomplete or inconsistent collision information. User‐defined limits for the computation time can be guaranteed with an efficiency gain of up to factor three. Copyright © 2009 John Wiley & Sons, Ltd.
Real‐time fluid simulation with adaptive SPH
Authors: Yan He , Wang Zhangye , He Jian , Chen Xi , Wang Changbo , Peng Qunsheng
Published: May 2009

We present a new adaptive model for real‐time fluid simulation based on Smoothed Particle Hydrodynamics (SPH) framework. Unlike traditional time‐consuming SPH methods, our model can simulate fluid at a considerably faster speed without losing realism. In our model, we first introduce the non‐uniform particle system and propose a generalized distance field function which considers not only geometrical complexity but also physical complexity of fluid body. And the new sampling rules for splitting and merging of particles are also presented. This can greatly reduce the computation time of the dynamic fluid simulation. Then, a new pressure state equation and an adaptive surface tension model are proposed to enhance the stability of the system and to make the free surface more realistic. To further accelerate the computation, a special fluid solver is designed and implemented using GPU. Various fluid phenomena like breaking wave and flood are simulated at real‐time. Experiments demonstrate that our new adaptive model can greatly enhance the computation efficiency of fluid simulation compared with previous adaptive methods. Copyright © 2009 John Wiley & Sons, Ltd.
Are nociceptin(1‐13)NH2and its structural analogue [ORN9]nociceptin(1‐13)NH2able to affect brain antioxidant status in control and kainic acid‐treated rats?
Authors: Tzvetanova Elina , Pavlova Almira , Alexandrova Albena , Nenkova Galina , Petrov Lubomir , Kirkova Margarita , Girchev Radoslav , Naydenova Emilia
Published: May 2009

In‐vivoeffects of nociceptin (N/OFQ(1‐13)NH2) on the levels of lipid peroxidation and cell enzyme (superoxide dismutase, glutathione peroxidase and glutathione reductase) and non‐enzyme (glutathione) antioxidants in brain of control and kainic acid‐treated rats were studied. N/OFQ(1‐13)NH2effects were compared with those of its structural analogue [Orn9]N/OFQ(1‐13)NH2. Kainic acid (25 µg, i.c.v) increased the lipid peroxidation (4 and 24 h after kainic acid treatment) and decreased the glutathione level (1 h after kainic acid injection). We failed to find, any changes in antioxidant enzyme activities, independently of the time of kainic acid treatment. At the background of kainic acid‐effects, N/OFQ(1‐13)NH2and [Orn9] N/OFQ(1‐13)NH2, injected 30 min before kainic acid, had no effects on all parameters, tested in brain. In addition, the neuropeptides did not change the antioxidant status in brain of control animals. It might be concluded that N/OFQ(1‐13)NH2and [Orn9]N/OFQ(1‐13)NH2have neither pro‐ nor anti‐oxidant activity. Copyright © 2009 John Wiley & Sons, Ltd.
Fluorescent Probes to Characterise FK506‐Binding Proteins
Authors: Kozany Christian , März Andreas , Kress Christoph , Hausch Felix
Published: May 2009

Talented all‐rounders: Fluorescence polarisation assays were developed for members of the FK506‐binding protein family by using fluorescent rapamycin analogues (demonstrated in the figure). These tracers retain medium to high affinity to all tested proteins (FKBP12, ‐12.6, ‐13, ‐25, ‐51, ‐52). They can be used for active‐site titrations, competition assays with unlabelled ligands and enable a robust, miniaturized assay adequate for high‐throughput screening.

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FK506‐binding proteins (FKBPs) convey the immunosuppressive action of FK506 and rapamycin and mediate the neuroprotective properties of these compounds, and participate in the regulation of calcium channels. In addition, the larger homologues FKBP51 and FKBP52 act as cochaperones for Hsp90 and regulate the transactivational activity of steroid hormone receptors. To further characterize these FKBPs, we have synthesized fluorescein‐coupled rapamycin analogues. In fluorescence polarization assays one of these compounds retained high affinity to all tested proteins (Kd: 0.1–20 nM) and could be used for active‐site titrations. To adapt the fluorescence polarization assay for high‐throughput purposes, a simplified rapamycin derivative was synthesized and labelled with fluorescein. This probe showed moderate affinity for the FK1 domains of FKBP51 (177 nM) and FKBP52 (469 nM) and allowed a highly robust, optimized, miniaturized assay (Z′>0.7) sufficient for high‐throughput screening of large compound libraries.