bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated, spatio‐temporally controlled cell microprinting with polymeric aqueous biphasic system
Authors: Petrak David , Atefi Ehsan , Yin Liya , Chilian William , Tavana Hossein 
Published: August 2013

ABSTRACTCell printing is a promising approach to create organized constructs for tissue engineering applications. We present an automated cell printing microtechnology based on the use of an aqueous two‐phase system (ATPS) interfaced with a three‐axis motorized system. Cells suspended in the denser aqueous dextran (DEX) phase are loaded into printing tips, which are placed onto the cartridge of the motorized system. Using a computer interface, tips are lowered in the vicinity of a biological surface maintained in the immersion, aqueous polyethylene glycol (PEG) phase to perform a horizontal motion, autonomously dispense their contents onto the surface, and retracted out of the PEG phase. The motorized ATPS technology allows precise spatial and temporal control of the printing process and supports printing fully viable cells. We conduct a systematic study and show that the resolution of ATPS‐mediated cellular patterns depends on several factors including the dimensions of the printing tips, lateral speed of tips during horizontal motion, and the loaded volume of the DEX phase in the tips. The finest resolution is ∼300 µm obtained with a tip diameter of 200 µm at a printing tip speed of 16.5 mm/s. Higher speeds result in unstable DEX patterns that break into drops due to capillary instability, and thus are avoided. We also test a number of printing substrates and find that in addition to a cell monolayer, decellularized matrices can serve as a substrate for cell printing with ATPS. Using the principles from the characterization studies, we create duplex prints of cells to demonstrate the potential of this approach for spatio‐temporally controlled cell placement. The ATPS printing microtechnology will be a step forward toward developing well‐organized, three‐dimensional tissue constructs. Biotechnol. Bioeng. 2014;111: 404–412. © 2013 Wiley Periodicals, Inc.
Dynamic model‐based analysis of furfural and HMF detoxification by pure and mixed batch cultures of S. cerevisiae and S. stipitis
Authors: Hanly Timothy J. , Henson Michael A. 
Published: August 2013

ABSTRACTInhibitory compounds that result from biomass hydrolysis are an obstacle to the efficient production of second‐generation biofuels. Fermentative microorganisms can reduce compounds such as furfural and 5‐hydroxymethyl furfural (HMF), but detoxification is accompanied by reduced growth rates and ethanol yields. In this study, we assess the effects of these furan aldehydes on pure and mixed yeast cultures consisting of a respiratory deficient mutant of Saccharomyces cerevisiae and wild‐type Scheffersomyces stipitis using dynamic flux balance analysis. Uptake kinetics and stoichiometric equations for the intracellular reduction reactions associated with each inhibitor were added to genome‐scale metabolic reconstructions of the two yeasts. Further modification of the S. cerevisiae metabolic network was necessary to satisfactorily predict the amount of acetate synthesized during HMF reduction. Inhibitory terms that captured the adverse effects of the furan aldehydes and their corresponding alcohols on cell growth and ethanol production were added to attain qualitative agreement with batch experiments conducted for model development and validation. When the two yeasts were co‐cultured in the presence of the furan aldehydes, inoculums that reduced the synthesis of highly toxic acetate produced by S. cerevisiae yielded the highest ethanol productivities. The model described here can be used to generate optimal fermentation strategies for the simultaneous detoxification and fermentation of lignocellulosic hydrolysates by S. cerevisiae and/or S. stipitis. Biotechnol. Bioeng. 2014;111: 272–284. © 2013 Wiley Periodicals, Inc.
Laser Welding of Multilayer Stacks Made of Thin‐Sheet Material for the Manufacture of Microstructured Devices for Process Engineering
Authors: Gietzelt Thomas , Eichhorn Lutz , Wunsch Torsten , Schorle Cornelia , Kraut Manfred , Dittmeyer Roland 
Published: August 2013

AbstractLasermaterialbearbeitung ist eine stark wachsende Technologie, die ständig neue Anwendungsfelder erschließt. Aufgrund der konzentrierten Wärmeeinbringung und der dadurch erzielbaren hohen Geschwindigkeiten bleibt die Wärmeeinflusszone an den Bauteilen eng begrenzt, so dass unerwünschte Materialveränderungen weitgehend vermieden werden. Selbst Stapel dünner Bleche, wie z. B. für Brennstoffzellen oder mikroverfahrenstechnische Apparate erforderlich, können mit dem Laser prozesssicher und verzugsarm verschweißt werden. Hier wird über das Fügen eines Multilagen‐Blechstapels aus mikrostrukturierten Blechen mit Blechdicken von 0,63 und 1 mm mittels Laserschweißen berichtet. Einige unerwartete Effekte, die dabei auftraten, werden diskutiert.
Oncogenic mutations in cervical cancer
Authors: Wright Alexi A. , Howitt Brooke E. , Myers Andrea P. , Dahlberg Suzanne E. , Palescandolo Emanuele , Van Hummelen Paul , MacConaill Laura E. , Shoni Melina , Wagle Nikhil , Jones Robert T. , Quick Charles M. , Laury Anna , Katz Ingrid T. , Hahn William C. , Matulonis Ursula A. , Hirsch Michelle S. 
Published: August 2013

BACKGROUNDCervical cancer is the second leading cause of cancer deaths among women worldwide. The objective of this study was to describe the most common oncogenic mutations in cervical cancers and to explore genomic differences between the 2 most common histologic subtypes: adenocarcinoma and squamous cell carcinoma.METHODSA high‐throughput genotyping platform, termed Oncomap, was used to interrogate 80 cervical tumors for 1250 known mutations in 139 cancer genes. Samples were analyzed using a mass spectrometry‐based genotyping platform and were validated using orthogonal chemistry. Epidermal growth factor receptor (EGFR) mutations were further validated by massive parallel sequencing. Human papilloma virus (HPV) genotyping also was performed.RESULTSValidated mutations were detected in 48 of 80 tumors (60%) examined. The highest mutation rates were in the genes phosphatidylinositol 3‐kinase, catalytic subunit α (PIK3CA) (31.3%); Kirsten rat sarcoma viral oncogene homolog (KRAS) (8.8%); and EGFR (3.8%). PIK3CA mutation rates did not differ significantly between adenocarcinomas and squamous cell carcinomas (25% vs 37.5%, respectively; P = .33). In contrast, KRAS mutations were identified only in adenocarcinomas (17.5% vs 0%; P = .01), and a novel EGFR mutation was detected only in squamous cell carcinomas (0% vs 7.5%; P = .24). There were no associations between HPV‐16 or HPV‐18 and somatic mutations or overall survival. In adjusted analyses, PIK3CA mutations were associated with shorter survival (67.1 months vs 90.3 months; hazard ratio, 9.1; 95% confidence interval, 2.8‐29.5 months; P < .001).CONCLUSIONSCervical cancers harbor high rates of potentially targetable oncogenic mutations. In addition, cervical squamous cell carcinoma and adenocarcinoma have distinct molecular profiles, suggesting that clinical outcomes may be improved with the use of more tailored treatment strategies, including PI3K and MEK inhibitors. Cancer 2013;119:3776–3783. © 2013 American Cancer Society.
Efficient collection of sensor data via a new accelerated random walk
Authors: Angelopoulos C. M. , Nikoletseas S. , Patroumpa D. , Raptopoulos C. 
Published: August 2013

SummaryMotivated by the problem of efficiently collecting data from wireless sensor networks via a mobile sink, we present an accelerated random walk on random geometric graphs (RGG). Random walks in wireless sensor networks can serve as fully local, lightweight strategies for sink motion that significantly reduce energy dissipation but introduce higher latency in the data collection process. In most cases, random walks are studied on graphs like Gn,p and grid. Instead, we here choose the RGG model, which abstracts more accurately spatial proximity in a wireless sensor network. We first evaluate an adaptive walk (the random walk with inertia) on the RGG model; its performance proved to be poor and led us to define and experimentally evaluate a novel random walk that we call γ‐stretched random walk. Its basic idea is to favour visiting distant neighbours of the current node towards reducing node overlap and accelerate the cover time. We also define a new performance metric called proximity cover time that, along with other metrics such as visit overlap statistics and proximity variation, we use to evaluate the performance properties and features of the various walks. Copyright © 2013 John Wiley & Sons, Ltd.
Toward energy efficiency in heterogeneous processors: findings on virtual screening methods
Authors: Guerrero Ginés D. , Cebrián Juan M. , Pérez‐Sánchez Horacio , García José M. , Ujaldón Manuel , Cecilia José M. 
Published: August 2013

ABSTRACTThe integration of the latest breakthroughs in computational modeling and high performance computing (HPC) has leveraged advances in the fields of healthcare and drug discovery, among others. By integrating all these developments together, scientists are creating new exciting personal therapeutic strategies for living longer that were unimaginable not that long ago. However, we are witnessing the biggest revolution in HPC in the last decade. Several graphics processing unit architectures have established their niche in the HPC arena but at the expense of an excessive power and heat. A solution for this important problem is based on heterogeneity. In this paper, we analyze power consumption on heterogeneous systems, benchmarking a bioinformatics kernel within the framework of virtual screening methods. Cores and frequencies are tuned to further improve the performance or energy efficiency on those architectures. Our experimental results show that targeted low‐cost systems are the lowest power consumption platforms, although the most energy efficient platform and the best suited for performance improvement is the Kepler GK110 graphics processing unit from Nvidia by using compute unified device architecture. Finally, the open computing language version of virtual screening shows a remarkable performance penalty compared with its compute unified device architecture counterpart. Copyright © 2013 John Wiley & Sons, Ltd.
Heterogeneous Catalytic Hydrogenation of Biobased Levulinic and Succinic Acids in Aqueous Solutions
Authors: Corbel‐Demailly Louis , Ly Bao‐Khanh , Minh Doan‐Pham , Tapin Benoit , Especel Catherine , Epron Florence , Cabiac Amandine , Guillon Emmanuelle , Besson Michèle , Pinel Catherine 
Published: August 2013

AbstractSupported noble‐metal catalysts (Ru, Pd or Pt) and the corresponding Re‐promoted catalysts exhibit a high activity for the hydrogenation of biobased carboxylic acids. Levulinic acid and succinic acid are converted into the lactones or the diols depending on the nature of the catalyst and the reaction conditions. The highest selectivity to 1,4‐pentanediol of 82 % is achieved at 140 °C in the presence of the 1.9 % Ru–3.6 % Re/C catalyst.
A generalized geometrical piecewise‐affine model of DC‐DC power electronic converters
Authors: Siewniak Piotr , Grzesik Bogusław 
Published: August 2013

AbstractA generalized model of the dynamics (GMD) of DC‐DC power electronic converters (PECs) is discussed in this paper. It is a geometrical piecewise‐affine continuous‐time model. The general idea of the GMD is to determine the local dynamic behavior of trajectories on the faces of the PEC commutation structure, which is a geometrical model of its commutation. This allows us to establish the direction of PEC dynamics on these faces. It can be either ‘entering’ into specific regions in state space or ‘exiting’ from them. Therefore, the local PEC dynamics can be treated as logical (two‐state). In practice, the GMD can be used for the analysis of PEC practical stability, which is a completely different concept from the concept of PEC stability in the classical Lyapunov sense. An outline of the design‐oriented approach to PEC practical stability analysis, which is based on the GMD, has also been presented.As illustrative examples, the GMD of a boost converter under peak current‐mode control and its application are presented. These examples show that the Lyapunov stability of a given PEC does not imply its practical stability, and that the results of PEC Lyapunov stability analysis and practical stability analysis are complementary to each other. Copyright © 2013 John Wiley & Sons, Ltd.
Climate change, species distribution models, and physiological performance metrics: predicting when biogeographic models are likely to fail
Authors: Woodin Sarah A. , Hilbish Thomas J. , Helmuth Brian , Jones Sierra J. , Wethey David S. 
Published: August 2013

AbstractModeling the biogeographic consequences of climate change requires confidence in model predictions under novel conditions. However, models often fail when extended to new locales, and such instances have been used as evidence of a change in physiological tolerance, that is, a fundamental niche shift. We explore an alternative explanation and propose a method for predicting the likelihood of failure based on physiological performance curves and environmental variance in the original and new environments. We define the transient event margin (TEM) as the gap between energetic performance failure, defined as CTmax, and the upper lethal limit, defined as LTmax. If TEM is large relative to environmental fluctuations, models will likely fail in new locales. If TEM is small relative to environmental fluctuations, models are likely to be robust for new locales, even when mechanism is unknown. Using temperature, we predict when biogeographic models are likely to fail and illustrate this with a case study. We suggest that failure is predictable from an understanding of how climate drives nonlethal physiological responses, but for many species such data have not been collected. Successful biogeographic forecasting thus depends on understanding when the mechanisms limiting distribution of a species will differ among geographic regions, or at different times, resulting in realized niche shifts. TEM allows prediction of the likelihood of such model failure.
Less can be more: loss of MHC functional diversity can reflect adaptation to novel conditions during fish invasions
Authors: Monzón‐Argüello Catalina , Garcia de Leaniz Carlos , Gajardo Gonzalo , Consuegra Sofia 
Published: August 2013

AbstractThe ability of invasive species to adapt to novel conditions depends on population size and environmental mismatch, but also on genetic variation. Away from their native range, invasive species confronted with novel selective pressures may display different levels of neutral versus functional genetic variation. However, the majority of invasion studies have only examined genetic variation at neutral markers, which may reveal little about how invaders adapt to novel environments. Salmonids are good model systems to examine adaptation to novel pressures because they have been translocated all over the world and represent major threats to freshwater biodiversity in the Southern Hemisphere, where they have become invasive. We examined patterns of genetic differentiation at seven putatively neutral (microsatellites) loci and one immune‐related major histocompatibility complex (MHC class II‐β) locus among introduced rainbow trout living in captivity (farmed) or under natural conditions (naturalized) in Chilean Patagonia. A significant positive association was found between differentiation at neutral and functional markers, highlighting the role of neutral evolutionary forces in shaping genetic variation at immune‐related genes in salmonids. However, functional (MHC) genetic diversity (but not microsatellite diversity) decreased with time spent in the wild since introduction, suggesting that there was selection against alleles associated with captive rearing of donor populations that do not provide an advantage in the wild. Thus, although high genetic diversity may initially enhance fitness in translocated populations, it does not necessarily reflect invasion success, as adaptation to novel conditions may result in rapid loss of functional MHC diversity.
Experimental demonstration of accelerated extinction in source‐sink metapopulations
Authors: Drake John M. , Griffen Blaine D. 
Published: August 2013

AbstractPopulation extinction is a fundamental ecological process which may be aggravated by the exchange of organisms between productive (source) and unproductive (sink) habitat patches. The extent to which such source‐sink exchange affects extinction rates is unknown. We conducted an experiment in which metapopulation effects could be distinguished from source‐sink effects in laboratory populations of Daphnia magna. Time‐to‐extinction in this experiment was maximized at intermediate levels of habitat fragmentation, which is consistent with a minority of theoretical models. These results provided a baseline for comparison with experimental treatments designed to detect effects of concentrating resources in source patches. These treatments showed that source‐sink configurations increased population variability (the coefficient of variation in abundance) and extinction hazard compared with homogeneous environments. These results suggest that where environments are spatially heterogeneous, accurate assessments of extinction risk will require understanding the exchange of organisms among population sources and sinks. Such heterogeneity may be the norm rather than the exception because of both the intrinsic heterogeneity naturally exhibited by ecosystems and increasing habitat fragmentation by human activity.
Mixed asexual and sexual reproduction in the Indo‐Pacific reef coral Pocillopora damicornis
Authors: Combosch David J. , Vollmer Steven V. 
Published: August 2013

AbstractPocillopora damicornis is one of the best studied reef‐building corals, yet it's somewhat unique reproductive strategy remains poorly understood. Genetic studies indicate that P. damicornis larvae are produced almost exclusively parthenogenetically, and yet population genetic surveys suggest frequent sexual reproduction. Using microsatellite data from over 580 larvae from 13 colonies, we demonstrate that P. damicornis displays a mixed reproductive strategy where sexual and asexual larvae are produced simultaneously within the same colony. The majority of larvae were parthenogenetic (94%), but most colonies (10 of the 13) produced a subset of their larvae sexually. Logistic regression indicates that the proportion of sexual larvae varied significantly with colony size, cycle day, and calendar day. In particular, the decrease in sexual larvae with colony size suggests that the mixed reproductive strategy changes across the life of the coral. This unique shift in reproductive strategy leads to increasingly asexual replications of successful genotypes, which (in contrast to exclusive parthenogens) have already contributed to the recombinant gene pool.
Synthesis and Characterization of Carbazole Dendrimers as Solution‐Processed High Tg Amorphous Hole‐Transporting Materials for Electroluminescent Devices
Authors: Prachumrak Narid , Pansay Sukrawee , Namuangruk Supawadee , Kaewin Tinnagon , Jungsuttiwong Siriporn , Sudyoadsuk Taweesak , Promarak Vinich 
Published: August 2013

AbstractWe report on an efficient and facile synthesis of up to 4th generation carbazole dendrons by using a mild Ullmann coupling reaction. The dendrimers, namely GnC (n = 1–4), are thermally stable amorphous materials with high glass transition temperatures (Tg) up to 347 °C and exhibit chemically stable redox properties. The compounds show great potential to work as solution‐processed hole‐transporting materials for electroluminescent devices. Double‐layer Alq3‐based organic light‐emitting diodes employing these dendrimers as the hole‐transporting layers with the device configuration of ITO/PEDOT: PSS/GnC(spin‐coating)(40 nm)/Alq3(50 nm)/LiF(0.5 nm):Al(150 nm) emit a bright green color (λem = 514 nm) from the Alq3 layer, with maximum luminance, maximum current efficiency, and turn‐on voltage of 29,262 cd m–2, 5.11 cd A–1, and 3.0 V, respectively. The abilities of GnC to act as hole‐transporting materials in terms of thermal property and device performance are superior to common hole‐transporters, N,N′‐diphenyl‐N,N′‐bis(1‐naphthyl)‐(1,1′‐biphenyl)‐4,4′‐diamine (NPB) and N,N′‐bis(3‐methylphenyl)‐N,N′‐bis(phenyl)benzidine (TPD).
From Aspartic Acid to Dihydropyridone‐2‐carboxylates: Access to Enantiopure 6‐Substituted 4‐Oxo‐ and 4‐Hydroxypipecolic Acid Derivatives
Authors: Vu Huy‐Dinh , Renault Jacques , Toupet Loïc , Uriac Philippe , Gouault Nicolas 
Published: August 2013

AbstractWe describe a method that starts from a protected (S)‐aspartic acid and employs a gold‐catalyzed cyclization to give enantiopure dihydropyridone 2‐carboxylates, which are then converted into 6‐substituted 4‐oxo‐ and 4‐hydroxypipecolic acid derivatives. Thus, the lateral chain carboxylic acid of a commercially available, protected (S)‐aspartic acid forms a Weinreb amide, which is then converted into an ynone followed by a gold‐catalyzed cyclization to furnish enantiopure enaminones in high yields. The steric hindrance from the protecting group was revealed as an efficient guide for the selectivity of the reduction reactions. Thus, classical methods that use palladium or sodium borohydride afford various enantiopure 6‐substituted 4‐oxo‐ and 4‐hydroxypipecolic acid derivatives. In these cases, the substituents have an all‐cis configuration, whereas a Luche reduction furnishes the 2,4‐trans analogues. In the case of the 6‐unsubstituted enaminone, the 1,4‐addition of a Grignard reagent furnishes the 2,6‐trans compound. All 6‐substituted 4‐hydroxy‐ and 4‐oxopipecolic derivatives were obtained in good yields. The diastereoselectivity for most of the reactions and the ease of separation of the diastereomers, in a few cases, render this method applicable for gram‐scale synthesis.
One‐Pot Synthesis of 4‐Substituted 1H‐[1,2,3]triazolo[4,5‐c]quinolines Through CuO‐Promoted Tandem Cyclization Reactions of (E)‐3‐(2‐Bromoaryl)‐1‐arylprop‐2‐en‐1‐ones with Sodium Azide
Authors: Li Kangning , Chen Jinying , Li Jihui , Chen Yongxin , Qu Jinpeng , Guo Xin , Chen Chunxia , Chen Baohua 
Published: August 2013

AbstractA facile and efficient protocol for the synthesis of 4‐substituted‐1H‐[1,2,3]triazolo[4,5‐c]quinolines through a CuO‐promoted tandem cyclization reaction has been developed. This method allows for the construction of two heterocyclic rings in a one‐pot reaction of readily available (E)‐3‐(2‐bromoaryl)‐1‐arylprop‐2‐en‐1‐ones and sodium azide without the addition of any additive. A series of triazole‐fused N‐heterocyclic compounds could be prepared in moderate to good yields.
Total Synthesis of the Antifungal Natural Product Mollisin
Authors: Schwolow Sonja , Kunz Horst , Rheinheimer Joachim , Opatz Till 
Published: August 2013

AbstractMollisin, a bioactive polyketide secondary metabolite of the fungus Mollisia caesia, was synthesized in nine linear steps from commercially available 2,6‐dimethyl‐γ‐pyrone. A key transformation in this first total synthesis of mollisin was the ipso substitution of an arylstannane, which permitted the otherwise cumbersome introduction of the characteristic dichloroacetyl moiety. The fungal fungicide was obtained in an overall yield of 9 %.