bluuebunny/crossref_metadata_2025 huggingface dataset:
A Combined Negative and Positive Enrichment Assay for Cancer Cells Isolation and Purification
Authors: Cheng Boran , Wang Shuyi , Chen Yuanyuan , Fang Yuan , Chen Fangfang , Wang Zhenmeng , Xiong Bin
Published: July 2014

Cancer cells that detach from solid tumor and circulate in the peripheral blood (CTCs) have been considered as a new “biomarker” for the detection and characterization of cancers. However, isolating and detecting cancer cells from the cancer patient peripheral blood have been technically challenging, owing to the small sub-population of CTCs (a few to hundreds per milliliter). Here we demonstrate a simple and efficient cancer cells isolation and purification method. A biocompatible and surface roughness controllable TiO2 nanofilm was deposited onto a glass slide to achieve enhanced topographic interactions with nanoscale cellular surface components, again, anti-CD45 (a leukocyte common antigen) and anti-EpCAM (epithelial cell adhesion molecule) were then coated onto the surface of the nanofilm for advance depletion of white blood cells (WBCs) and specific isolation of CTCs, respectively. Comparing to the conventional positive enrichment technology, this method exhibited excellent biocompatibility and equally high capture efficiency. Moreover, the maximum number of background cells (WBCs) was removed, and viable and functional cancer cells were isolated with high purity. Utilizing the horizontally packed TiO2 nanofilm improved pure CTC-capture through combining cell-capture-agent and cancer cell-preferred nanoscale topography, which represented a new method capable of obtaining biologically functional CTCs for subsequent molecular analysis.
Next‐Generation Sequencing Fragment Library Construction
Authors: Podnar Jessica , Deiderick Heather , Hunicke‐Smith Scott
Published: July 2014

All current next‐generation sequencing (NGS) platforms and applications require the sequencing library to have specific characteristics: in particular, size, size distribution, and 5′ and 3′ flanking sequences. This unit presents a robust protocol for converting a wide variety of input DNA samples into appropriate NGS libraries and discusses important considerations in experimental design, failure modes, and typical results. Curr. Protoc. Mol. Biol. 107:7.17.1‐7.17.16. © 2014 by John Wiley & Sons, Inc.
Attenuation of Replication Stress–Induced Premature Cellular Senescence to Assess Anti‐Aging Modalities
Authors: Zhao Hong , Darzynkiewicz Zbigniew
Published: July 2014

Described is an in vitro model of premature senescence in pulmonary adenocarcinoma A549 cells induced by persistent DNA replication stress in response to treatment with the DNA damaging drug mitoxantrone (Mxt). The degree of cellular senescence, based on characteristic changes in cell morphology, is measured by laser scanning cytometry. Specifically, the flattening of cells grown on slides (considered the hallmark of cellular senescence) is measured as the decline in local intensity of DNA‐associated DAPI fluorescence (represented by maximal pixels). This change is paralleled by an increase in nuclear area. Thus, the ratio of mean intensity of maximal pixels to nuclear area provides a very sensitive morphometric biomarker for the degree of senescence. This analysis is combined with immunocytochemical detection of senescence markers, such as overexpression of cyclin kinase inhibitors (e.g., p21WAF1) and phosphorylation of ribosomal protein S6 (rpS6), a key marker associated with aging/senescence that is detected using a phospho‐specific antibody. These biomarker indices are presented in quantitative terms defined as a senescence index (SI), which is the fraction of the marker in test cultures relative to the same marker in exponentially growing control cultures. This system can be used to evaluate the anti‐aging potential of test agents by assessing attenuation of maximal senescence. As an example, the inclusion of berberine, a natural alkaloid with reported anti‐aging properties and a long history of use in traditional Chinese medicine, is shown to markedly attenuate the Mxt‐induced SI and phosphorylation of rpS6. The multivariate analysis of senescence markers by laser scanning cytometry offers a promising tool to explore the potential anti‐aging properties of a variety agents.Curr. Protoc. Cytom. 69:9.47.1‐9.47.10. © 2014 by John Wiley & Sons, Inc.
Sustaining ecosystem services: Overcoming the dilemma posed by local actions and planetary boundaries
Authors: Jonas Matthias , Ometto Jean Pierre , Batistella Mateus , Franklin Oskar , Hall Marianne , Lapola David M. , Moran Emilio F. , Tramberend Sylvia , Queiroz Bernardo Lanza , Schaffartzik Anke , Shvidenko Anatoly , Nilsson Sten B. , Nobre Carlos A.
Published: July 2014

Resolving challenges related to the sustainability of natural capital and ecosystem services is an urgent issue. No roadmap on reaching sustainability exists; and the kind of sustainable land use required in a world that acknowledges both multiple environmental boundaries and local human well‐being presents a quandary. In this commentary, we argue that a new globally consistent and expandable systems‐analytical framework is needed to guide and facilitate decision making on sustainability from the planetary to the local level, and vice versa. This framework would strive to link a multitude of Earth system processes and targets; it would give preference to systemic insight over data complexity through being highly explicit in spatiotemporal terms. Its strength would lie in its ability to help scientists uncover and explore potential, and even unexpected, interactions between Earth's subsystems with planetary environmental boundaries and socioeconomic constraints coming into play. Equally importantly, such a framework would allow countries such as Brazil, a case study in this commentary, to understand domestic or even local sustainability measures within a global perspective and to optimize them accordingly.
Integrated mathematical modeling of hydrological and hydrodynamic response to rainfall events in rural lowland catchments
Authors: Viero D. P. , Peruzzo P. , Carniello L. , Defina A.
Published: July 2014

In rural lowland catchments, negligible topographic gradients and possible interactions between overland and channel flows complicate efforts to predict flood formation, propagation, and inundation. In this study, we demonstrate that an approach in which a two‐dimensional shallow water model is coupled with a two‐dimensional model for the saturated flow in the topsoil layer can accurately reproduce floods in such a lowland catchment. The topsoil porous layer is treated as a confined aquifer where water ponds on the ground surface and as an unconfined aquifer elsewhere. The model includes infiltration from the ground surface into the topsoil layer and downward percolation out of the topsoil layer. The equations of both surface and subsurface models are suitably averaged over a representative elementary area to yield a subgrid model for the coupled surface‐subsurface flow. Field data collected in two rural lowland catchments in the North‐East of Italy are used to evaluate the model performance. The good agreement between computed and measured discharge at the catchments' outlet and the agreement between predicted and surveyed spatial pattern of inundated areas indicate that the model effectively reproduces overland flow and efficiently accounts for the surface‐subsurface flow interaction and the relevant subsurface processes.
Conditions favorable to new central Alaskan permafrost will not last
Authors: Wendel JoAnna
Published: July 2014

Permafrost—ground that has been frozen for longer than 2 years—has been useful for tracking the effects of climate change because thawing permafrost has implications for greenhouse gas emissions and shifting ecosystems. In the last 30 years, shrinkage of Arctic and subarctic lakes has been tied to permafrost thaw. However, on the margins of recently receded lakes, scientists recently have witnessed permafrost growth, complicating how climate change may affect future Arctic lakes. Scientists question whether these new permafrost‐friendly conditions will continue into the future.
Recent Ice Ages on Mars: The role of radiatively active clouds and cloud microphysics
Authors: Madeleine J.‐B. , Head J. W. , Forget F. , Navarro T. , Millour E. , Spiga A. , Colaïtis A. , Määttänen A. , Montmessin F. , Dickson J. L.
Published: July 2014

Global climate models (GCMs) have been successfully employed to explain the origin of many glacial deposits on Mars. However, the latitude‐dependent mantle (LDM), a dust‐ice mantling deposit that is thought to represent a recent “Ice Age,” remains poorly explained by GCMs. We reexamine this question by considering the effect of radiatively active water‐ice clouds (RACs) and cloud microphysics. We find that when obliquity is set to 35°, as often occurred in the past 2 million years, warming of the atmosphere and polar caps by clouds modifies the water cycle and leads to the formation of a several centimeter‐thick ice mantle poleward of 30° in each hemisphere during winter. This mantle can be preserved over the summer if increased atmospheric dust content obscures the surface and provides dust nuclei to low‐altitude clouds. We outline a scenario for its deposition and preservation that compares favorably with the characteristics of the LDM.
Indonesian throughflow nutrient fluxes and their potential impact on Indian Ocean productivity
Authors: Ayers Jennifer M. , Strutton Peter G. , Coles Victoria J. , Hood Raleigh R. , Matear Richard J.
Published: July 2014

The Indonesian throughflow (ITF) is a chokepoint in the upper ocean thermohaline circulation, carrying Pacific waters through the strongly mixed Indonesian Seas and into the Indian Ocean. Yet the influence of the ITF on biogeochemical fluxes into the Indian Ocean is largely unknown. This study determines the first depth‐ and time‐resolved nitrate, phosphate, and silicate fluxes at the three main exit passages of the ITF: Lombok Strait, Ombai Strait, and Timor Passage. Nutrient flux as well as its variability with depth and time differs greatly between the passages. We estimate the effective flux of nutrients into the Indian Ocean by accounting for existing nutrients in the basin and find it largest in the upper 300–400 m. This suggests that the majority of ITF nutrient supply to the Indian Ocean is to thermocline waters, where it is likely to support new production and significantly impact Indian Ocean biogeochemical cycling.
Simulated effects of a snow layer on retrieval of CryoSat‐2 sea ice freeboard
Authors: Kwok R.
Published: July 2014

The impact of a snow layer on the location of the tracking point (RP) for ranging to the sea ice surface in CryoSat‐2 synthetic aperture interferometric radar altimeter waveforms is simulated. With a range resolution of ~47 cm, the response of the air‐snow (a‐s) interface broadens the response of the snow‐ice (s‐i) interface and displaces the RP toward the altimeter. This effect is largest when the strengths of their returns are comparable and when snow thicknesses are >20 cm. On the other hand, the RP is displaced away from the altimeter when the reduced propagation speed in the snow layer is not accounted for. This analysis examines the dependence of these competing corrections on snow thickness and the relative scattering strengths of the interfaces and the sensitivity of two different tracking approaches (leading edge and centroid) to these snow parameters. Expected errors depend on a better understanding of the relative scattering strengths of the interfaces and snow layer.
Adaptive control strategy‐based reference model for spacecraft motion trajectory
Authors: Samigulina Zarina , Shiryayeva Olga , Samigulina Galina , Fourati Hassen
Published: July 2014

In aerospace field, the economic realization of a spacecraft is one of the main objectives that should be accomplished by conceiving the optimal propulsion system and the best control algorithms. This paper focuses on the development of a viable adaptive control approach (ACA) for spacecraft motion trajectory (SMT). The proposed strategy involves the nonlinear mathematical model of SMT expressed in the central field, which is linearized by the Taylor expansion, and the second Lyapunov method to offer a high rate and unfailing performance in the functioning. The adaptive control system is composed of the cascade of adaptation loop and feedback control loop. When the spacecraft deviates from its reference trajectory model, the ACA acts on the control system to correct this deviation and follow the optimal reference trajectory. Therefore, when the states of the adjustable model are different from its reference values, then the error signal is provided as an input to the adaptation law, which contains the adaptation algorithm. The output will be the state variable feedback control matrix, which will be used to calculate the new control law vector. The efficiencies of the linearization procedure and the control approach are theoretically investigated through some realistic simulations and tests under MATLAB. The steady‐state errors of control between the reference model and the adjustable model of SMT converge to zero. Copyright © 2014 John Wiley & Sons, Ltd.
Drastic Change in Photoluminescence Properties of Graphene Quantum Dots by Chromatographic Separation
Authors: Fuyuno Naoto , Kozawa Daichi , Miyauchi Yuhei , Mouri Shinichiro , Kitaura Ryo , Shinohara Hisanori , Yasuda Toku , Komatsu Naoki , Matsuda Kazunari
Published: July 2014

Graphene quantum dots (GQDs) have attracted a great deal of interest from the viewpoints of both fundamental studies and applications. Photoluminescence (PL) is one of the intriguing properties of GQDs, however, the mechanism of the PL in GQDs is not fully understood. In the present study, a drastic change in the PL from UV to red light region is reported among GQDs separated by size‐exclusion high performance liquid chromatography. It is confirmed by transmission electron microscopy images that the GQDs are separated by the difference in their overall sizes. Two‐dimensional PL excitation spectra of the chromatographically separated GQDs show four distinct emission peaks at ∼330, ∼440, ∼520, and ∼600 nm. The dominant luminescence features of the separated GQDs show discrete changes depending on the overall size of GQDs, indicating that the PL variation occurs because of differences in density, shape, and size of sp2 fragments available in the GQDs.
Selective hydrogenation of nitriles to imines over a multifunctional heterogeneous Pt catalyst
Authors: Long Jilan , Yin Biaolin , Li Yingwei , Zhang Lianjie
Published: July 2014

Imines and their derivatives are versatile synthetic intermediates for the industrial preparation of both bulk and fine chemicals and for pharmaceuticals, but preparing these compounds efficiently through direct hydrogenation of nitriles are hindered by overhydrogenation to secondary amines. Here we report a highly efficient multifunctional catalyst system for selective hydrogenation coupling of nitriles to secondary imines using a heterogeneous Pt catalyst that was deposited on a nickel‐based metal‐organic framework (MOF) containing DABCO. The catalyst showed excellent synergy in promoting the hydrogenation of a variety of nitriles, giving significantly improved activity and selectivity (up to >99% yield) even under atmospheric pressure of H2. It is suggested that the Lewis base (DABCO) sites on the Ni‐MOF inhibit further hydrogenation of the imines. The influence of H2 pressure, reactant concentration, stirring speed, and reaction temperature was investigated. The kinetics and mechanism of hydrogenation of benzonitrile (BN) by the Pt/Ni‐MOF catalyst has been studied. The reaction showed a first‐order dependence on both BN concentration and H2 pressure. A kinetic model was proposed based on the mechanism of nitriles hydrogenation and compared with experimental observations. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3565–3576, 2014
Gemtuzumab ozogamicin with fludarabine, cytarabine, and granulocyte colony stimulating factor (FLAG‐GO) as front‐line regimen in patients with core binding factor acute myelogenous leukemia
Authors: Borthakur Gautam , Cortes Jorge E. , Estey Elihu E. , Jabbour Elias , Faderl Stefan , O'Brien Susan , Garcia‐Manero Guillermo , Kadia Tapan Mahendra , Wang Xuemei , Patel Keyur , Luthra Rajyalakshmi , Koller Charles , Brandt Mark , Ravandi Farhad , Kantarjian Hagop
Published: July 2014

Despite being considered “good‐risk” acute myelogenous leukemia (AML), long term outcomes in core binding factor (CBF) AML suggest room for improvement. We report on a regimen consisting of fludarabine, cytarabine, granulocyte colony stimulating factor, and low dose gemtuzumab ozogamicin (FLAG‐GO) as front‐line therapy of patients with CBF AML. Forty‐five patients were enrolled (median age 48 years). Remission rate was 95% with 5% induction deaths. The overall survival (OS) and relapse free survival (RFS) probability at 3 years are 78% and 85%, respectively. FLAG‐GO regimen results in high rates of RFS and OS in CBF AML. Our data along with recent data from several large groups strongly argues in favor of incorporation of gemtuzumab ozogamicin in frontline regimens for CBF AML. Am. J. Hematol. 89:964–968, 2014. © 2014 Wiley Periodicals, Inc.
Characterizing runs of homozygosity and their impact on risk for psychosis in a population isolate
Authors: Melhem Nadine M. , Lu Cong , Dresbold Cara , Middleton Frank A. , Klei Lambertus , Wood Shawn , Faraone Stephen V. , Vinogradov Sophia , Tiobech Josepha , Yano Victor , Roeder Kathryn , Byerley William , Myles‐Worsley Marina , Devlin Bernie
Published: July 2014

An increased abundance of runs of homozygosity (ROH) has been associated with risk for various diseases, including schizophrenia. Here we investigate the characteristics of ROH in Palau, an Oceanic population, evaluating whether these characteristics are related to risk for psychotic disorders and the nature of this association. To accomplish these aims we evaluate a sample of 203 cases with schizophrenia and related psychotic disorders—representing almost complete ascertainment of affected individuals in the population—and contrast their ROH to that of 125 subjects chosen to function as controls. While Palauan diagnosed with psychotic disorders tend to have slightly more ROH regions than controls, the distinguishing features are that they have longer ROH regions, greater total length of ROH, and their ROH tends to co‐occur more often at the same locus. The nature of the sample allows us to investigate whether rare, highly penetrant recessive variants generate such case–control differences in ROH. Neither rare, highly penetrant recessive variants nor individual common variants of large effect account for a substantial proportion of risk for psychosis in Palau. These results suggest a more nuanced model for risk is required to explain patterns of ROH for this population. © 2014 Wiley Periodicals, Inc.
Effect of bite force and diet composition on craniofacial diversification of Southern South American human populations
Authors: Menéndez Lumila , Bernal Valeria , Novellino Paula , Perez S. Ivan
Published: July 2014

Ecological factors can be important to shape the patterns of morphological variation among human populations. Particularly, diet plays a fundamental role in craniofacial variation due to both the effect of the nutritional status—mostly dependent on the type and amount of nutrients consumed—on skeletal growth and the localized effects of masticatory forces. We examine these two dimensions of diet and evaluate their influence on morphological diversification of human populations from southern South America during the late Holocene. Cranial morphology was measured as 3D coordinates defining the face, base and vault. Size, form, and shape variables were obtained for 474 adult individuals coming from 12 samples. Diet composition was inferred from carious lesions and δ13C data, whereas bite forces were estimated using traits of main jaw muscles. The spatial structure of the morphological and ecological variables was measured using correlograms. The influence of diet composition and bite force on morphometric variation was estimated by a spatial regression model. Cranial variation and diet composition display a geographical structure, while no geographical pattern was observed in bite forces. Cranial variation in size and form is significantly associated with diet composition, suggesting a strong effect of systemic factors on cranial growth. Conversely, bite forces do not contribute significantly to the pattern of morphological variation among the samples analyzed. Overall, these results show that an association between diet composition and hardness cannot be assumed, and highlight the complex relationship between morphological diversification and diet in human populations. Am J Phys Anthropol 155:114–127, 2014. © 2014 Wiley Periodicals, Inc.
Maintenance of Amyloid β Peptide Homeostasis by Artificial Chaperones Based on Mixed‐Shell Polymeric Micelles
Authors: Huang Fan , Wang Jianzu , Qu Aoting , Shen Liangliang , Liu Jinjian , Liu Jianfeng , Zhang Zhenkun , An Yingli , Shi Linqi
Published: July 2014

The disruption of Aβ homeostasis, which results in the accumulation of neurotoxic amyloids, is the fundamental cause of Alzheimer’s disease (AD). Molecular chaperones play a critical role in controlling undesired protein misfolding and maintaining intricate proteostasis in vivo. Inspired by a natural molecular chaperone, an artificial chaperone consisting of mixed‐shell polymeric micelles (MSPMs) has been devised with tunable surface properties, serving as a suppressor of AD. Taking advantage of biocompatibility, selectivity toward aberrant proteins, and long blood circulation, these MSPM‐based chaperones can maintain Aβ homeostasis by a combination of inhibiting Aβ fibrillation and facilitating Aβ aggregate clearance and simultaneously reducing Aβ‐mediated neurotoxicity. The balance of hydrophilic/hydrophobic moieties on the surface of MSPMs is important for their enhanced therapeutic effect.
Helixförmige Packung von Nanopartikeln, eingeschlossen in zylindrische Domänen einer selbstorganisierten Blockcopolymerstruktur
Authors: Sanwaria Sunita , Horechyy Andriy , Wolf Daniel , Chu Che‐Yi , Chen Hsin‐Lung , Formanek Petr , Stamm Manfred , Srivastava Rajiv , Nandan Bhanu
Published: July 2014

Anhand theoretischer Modelle lässt sich vorhersagen, dass eine Vielzahl von durch Selbstorganisation gebildeten Strukturen dicht gepackter kugelförmiger Partikel entstehen kann, wenn diese in zylindrischen Räumen eingeschlossen werden. In der vorliegenden Arbeit demonstrieren wir zum ersten Mal, dass polymerbeschichtete Nanopartikel, die in den selbstorganisierten zylindrischen Domänen eines Blockcopolymers eingeschlossen sind, sich in einer helixförmig gepackten Morphologie anordnen. Es gelang uns, einzelne mit helixförmig angeordneten Nanopartikeln gefüllte Fasern zu isolieren. Dieses Ergebnis eröffnet einzigartige Möglichkeiten sowohl für die Grundlagenforschung als auch für die anwendungsorientierte Forschung.
Flow‐Based Enzymatic Ligation by Sortase A
Authors: Policarpo Rocco L. , Kang Hansol , Liao Xiaoli , Rabideau Amy E. , Simon Mark D. , Pentelute Bradley L.
Published: July 2014

Sortase‐mediated ligation (sortagging) is a versatile, powerful strategy for protein modification. Because the sortase reaction reaches equilibrium, a large excess of polyglycine nucleophile is often employed to drive the reaction forward and suppress sortase‐mediated side reactions. A flow‐based sortagging platform employing immobilized sortase A within a microreactor was developed that permits efficient sortagging at low nucleophile concentrations. The platform was tested with several reaction partners and used to generate a protein bioconjugate inaccessible by solution‐phase batch sortagging.
Cyclisierende radikalische Carboiodierung, Carbotellurierung und Carboaminoxylierung von Arylaminen
Authors: Hartmann Marcel , Studer Armido
Published: July 2014

Die radikalische Carboiodierung verschiedener Arylamine wird vorgestellt. Aryldiazoniumsalze, in situ aus den entsprechenden Arylaminen erzeugt, reagieren dabei mit Bu4NI zu Arylradikalen, welche 5‐exo oder 6‐exo‐Cyclisierungen eingehen. Anschließende I‐Abstraktion liefert die carboiodierten Produkte in guten bis exzellenten Ausbeuten. Bei Zugabe von TEMPO führt die Kaskade zu den entsprechenden carboaminoxylierten Produkten. Läuft die Reaktion in Gegenwart von PhTeTePh ab, so resultieren carbotellurierte cyclische Verbindungen.
Entwicklung eines 18F‐markierten Tetrazins mit vorteilhaften pharmakokinetischen Eigenschaften für die bioorthogonale Positronenemissionstomographie
Authors: Denk Christoph , Svatunek Dennis , Filip Thomas , Wanek Thomas , Lumpi Daniel , Fröhlich Johannes , Kuntner Claudia , Mikula Hannes
Published: July 2014

Es wurde ein niedermolekulares 18F‐markiertes Tetrazin entwickelt, das im Bereich der bioorthogonalen Bildgebung mithilfe von PET verwendet werden kann. Durch 18F‐Fluorierung einer geeigneten Vorstufe konnten die Verwendung von prosthetischen Gruppen und die Notwendigkeit mehrerer radiochemischer Syntheseschritte vermieden werden. Die Reaktionskinetik der Cycloaddition mit trans‐Cyclooctenen wurde mithilfe quantenchemischer Rechungen und Stopped‐Flow‐Messungen in humanem Plasma untersucht. Eine hohe Stabilität konnte in vitro und in vivo nachgewiesen werden, während PET/MR‐Untersuchungen an Mäusen eine schnelle homogene Biodistribution offenbarten. Anhand eines In‐vivo‐Experiments konnte die Bioorthogonalität der neuartigen Tetrazinsonde bestätigt werden. Die hervorragenden Eigenschaften dieser bioorthogonalen Sonde zur Lokalisierung und Visualisierung von Dienophil‐markierten Molekülen bilden die Grundlage für viele Anwendungsmöglichkeiten im Bereich der molekularen Bildgebung.
Total Chemical Synthesis of Biologically Active Fluorescent Dye‐Labeled Ts1 Toxin
Authors: Dang Bobo , Kubota Tomoya , Correa Ana M. , Bezanilla Francisco , Kent Stephen B. H.
Published: July 2014

Ts1 toxin is a protein found in the venom of the Brazilian scorpion Tityus serrulatus. Ts1 binds to the domain II voltage sensor in the voltage‐gated sodium channel Nav and modifies its voltage dependence. In the work reported here, we established an efficient total chemical synthesis of the Ts1 protein using modern chemical ligation methods and demonstrated that it was fully active in modifying the voltage dependence of the rat skeletal muscle voltage‐gated sodium channel rNav1.4 expressed in oocytes. Total synthesis combined with click chemistry was used to label the Ts1 protein molecule with the fluorescent dyes Alexa‐Fluor 488 and Bodipy. Dye‐labeled Ts1 proteins retained their optical properties and bound to and modified the voltage dependence of the sodium channel Nav. Because of the highly specific binding of Ts1 toxin to Nav, successful chemical synthesis and labeling of Ts1 toxin provides an important tool for biophysical studies, histochemical studies, and opto‐pharmacological studies of the Nav protein.
Platinum‐Promoted Ga/Al2O3 as Highly Active, Selective, and Stable Catalyst for the Dehydrogenation of Propane
Authors: Sattler Jesper J. H. B. , Gonzalez‐Jimenez Ines D. , Luo Lin , Stears Brien A. , Malek Andrzej , Barton David G. , Kilos Beata A. , Kaminsky Mark P. , Verhoeven Tiny W. G. M. , Koers Eline J. , Baldus Marc , Weckhuysen Bert M.
Published: July 2014

A novel catalyst material for the selective dehydrogenation of propane is presented. The catalyst consists of 1000 ppm Pt, 3 wt % Ga, and 0.25 wt % K supported on alumina. We observed a synergy between Ga and Pt, resulting in a highly active and stable catalyst. Additionally, we propose a bifunctional active phase, in which coordinately unsaturated Ga3+ species are the active species and where Pt functions as a promoter.
Fluorogenic Probes with Substitutions at the 2 and 7 Positions of Cephalosporin are Highly BlaC‐Specific for Rapid Mycobacterium tuberculosis Detection
Authors: Cheng Yunfeng , Xie Hexin , Sule Preeti , Hassounah Hany , Graviss Edward A. , Kong Ying , Cirillo Jeffrey D. , Rao Jianghong
Published: July 2014

Current methods for the detection of Mycobacterium tuberculosis (Mtb) are either time consuming or require expensive instruments and are thus are not suitable for point‐of‐care diagnosis. The design, synthesis, and evaluation of fluorogenic probes with high specificity for BlaC, a biomarker expressed by Mtb, are described. The fluorogenic probe CDG‐3 is based on cephalosporin with substitutions at the 2 and 7 positions and it demonstrates over 120 000‐fold selectivity for BlaC over TEM‐1 Bla, the most common β‐lactamase. CDG‐3 can detect 10 colony‐forming units of the attenuated Mycobacterium bovis strain BCG in human sputum in the presence of high levels of contaminating β‐lactamases expressed by other clinically prevalent bacterial strains. In a trial with 50 clinical samples, CDG‐3 detected tuberculosis with 90 % sensitivity and 73 % specificity relative to Mtb culture within one hour, thus demonstrating its potential as a low‐cost point‐of‐care test for use in resource‐limited areas.
Copper‐Catalyzed Cyclization/aza‐Claisen Rearrangement Cascade Initiated by Ketenimine Formation: An Efficient Stereocontrolled Synthesis of α‐Allyl Cyclic Amidines
Authors: Xu Hua‐Dong , Jia Zhi‐Hong , Xu Ke , Han Mei , Jiang Sai‐Nan , Cao Jing , Wang Jia‐Cheng , Shen Mei‐Hua
Published: July 2014

An efficient and convenient synthesis of α‐allyl cyclic amidines has been achieved by applying a novel cascade reaction. Copper(I)‐mediated in situ N‐sulfonyl ketenimine formation from the reaction of a terminal alkyne with sulfonyl azide is followed by an intramolecular nucleophilic attack on the central carbon atom by an allylic tertiary amine, and then an aza‐Claisen rearrangement takes place through a chair transition state to furnish the titled amidines with complete stereocontrol.
Access to β‐Lactams by Enantioselective Palladium(0)‐Catalyzed C(sp3)H Alkylation
Authors: Pedroni Julia , Boghi Michele , Saget Tanguy , Cramer Nicolai
Published: July 2014

β‐Lactams are very important structural motifs because of their broad biological activities as well as their propensity to engage in ring‐opening reactions. Transition‐metal‐catalyzed CH functionalizations have emerged as strategy enabling yet uncommon highly efficient disconnections. In contrast to the significant progress of Pd0‐catalyzed CH functionalization for aryl–aryl couplings, related reactions involving the formation of saturated C(sp3)C(sp3) bonds are elusive. Reported here is an asymmetric CH functionalization approach to β‐lactams using readily accessible chloroacetamide substrates. Important aspects of this transformation are challenging C(sp3)C(sp3) and strain‐building reductive eliminations to for the four‐membered ring. In general, the β‐lactams are formed in excellent yields and enantioselectivities using a bulky taddol phosphoramidite ligand in combination with adamantyl carboxylic acid as cocatalyst.
The Evolving Role of Chemical Synthesis in Antibacterial Drug Discovery
Authors: Wright Peter M. , Seiple Ian B. , Myers Andrew G.
Published: July 2014

The discovery and implementation of antibiotics in the early twentieth century transformed human health and wellbeing. Chemical synthesis enabled the development of the first antibacterial substances, organoarsenicals and sulfa drugs, but these were soon outshone by a host of more powerful and vastly more complex antibiotics from nature: penicillin, streptomycin, tetracycline, and erythromycin, among others. These primary defences are now significantly less effective as an unavoidable consequence of rapid evolution of resistance within pathogenic bacteria, made worse by widespread misuse of antibiotics. For decades medicinal chemists replenished the arsenal of antibiotics by semisynthetic and to a lesser degree fully synthetic routes, but economic factors have led to a subsidence of this effort, which places society on the precipice of a disaster. We believe that the strategic application of modern chemical synthesis to antibacterial drug discovery must play a critical role if a crisis of global proportions is to be averted.
Coupling of Titanacyclopentadienes with a Cp Ligand and Elimination of One Substituent
Authors: Mizukami Yuki , Li Haijun , Nakajima Kiyohiko , Song Zhiyi , Takahashi Tamotsu
Published: July 2014

Titanacyclopentadienes, prepared from [Cp2TiBu2] and either two equivalents of an alkyne or a diyne, were treated with PMe3 (3 equiv) at 50 °C for 3 h and then with azobenzene at room temperature for 12 h to give 4,5,6‐trisubstituted indene derivatives with the loss of one substituent in good yields. This reaction contrasts sharply with our previously reported reaction for the formation of 4,5,6,7‐tetrasubstituted indene derivatives without the loss of substituents by the treatment of titanacyclopentadienes with azobenzene without PMe3. 13C NMR spectroscopy of the product derived from a 13C‐enriched complex revealed that the five carbon atoms originating from a Cp ligand were arranged linearly in the trisubstituted indene derivatives, in contrast to the 4,5,6,7‐tetrasubsituted indene derivatives, in which the corresponding five carbon atoms are arranged in a ring.
Development of a 18F‐Labeled Tetrazine with Favorable Pharmacokinetics for Bioorthogonal PET Imaging
Authors: Denk Christoph , Svatunek Dennis , Filip Thomas , Wanek Thomas , Lumpi Daniel , Fröhlich Johannes , Kuntner Claudia , Mikula Hannes
Published: July 2014

A low‐molecular‐weight 18F‐labeled tetrazine derivative was developed as a highly versatile tool for bioorthogonal PET imaging. Prosthetic groups and undesired carrying of 18F through additional steps were evaded by direct 18F‐fluorination of an appropriate tetrazine precursor. Reaction kinetics of the cycloaddition with trans‐cyclooctenes were investigated by applying quantum chemical calculations and stopped‐flow measurements in human plasma; the results indicated that the labeled tetrazine is suitable as a bioorthogonal probe for the imaging of dienophile‐tagged (bio)molecules. In vitro and in vivo investigations revealed high stability and PET/MRI in mice showed fast homogeneous biodistribution of the 18F‐labeled tetrazine that also passes the blood–brain barrier. An in vivo click experiment confirmed the bioorthogonal behavior of this novel tetrazine probe. Due to favorable chemical and pharmacokinetic properties this bioorthogonal agent should find application in bioimaging and biomedical research.
BiZn Bond Formation in Liquid Ammonia Solution: [BiZnBi]4−, a Linear Polyanion that is Iso(valence)‐electronic to CO2
Authors: Benda Christian B. , Köchner Tobias , Schäper Raphaela , Schulz Stephan , Fässler Thomas F.
Published: July 2014

Reactions of the zinc(I) complex [Zn2(Mesnacnac)2] (Mesnacnac=[(2,4,6‐Me3C6H2)NC(Me)]2CH) with solid K3Bi2 dissolved in liquid ammonia yield crystals of the compound K4[ZnBi2]⋅(NH3)12 (1), which contains the molecular, linear heteroatomic [BiZnBi]4− polyanion (1 a). This anion represents the first example of a three‐atomic molecular ion of metal atoms being iso(valence)‐electronic to CO2 and being synthesized in solution. The analogy of the discrete [BiZnBi]4− anion and the polymeric ${{{\hfill 1\atop \hfill \infty }}}$[(ZnBi4/2)4−] unit to monomeric CO2 and polymeric SiS2 is rationalized.
Synthesis of Two‐Dimensional Transition‐Metal Phosphates with Highly Ordered Mesoporous Structures for Lithium‐Ion Battery Applications
Authors: Yang Dan , Lu Ziyang , Rui Xianhong , Huang Xiao , Li Hai , Zhu Jixin , Zhang Wenyu , Lam Yeng Ming , Hng Huey Hoon , Zhang Hua , Yan Qingyu
Published: July 2014

Materials with ordered mesoporous structures have shown great potential in a wide range of applications. In particular, the combination of mesoporosity, low dimensionality, and well‐defined morphology in nanostructures may exhibit even more attractive features. However, the synthesis of such structures is still challenging in polar solvents. Herein, we report the preparation of ultrathin two‐dimensional (2D) nanoflakes of transition‐metal phosphates, including FePO4, Mn3(PO4)2, and Co3(PO4)2, with highly ordered mesoporous structures in a nonpolar solvent. The as‐obtained nanoflakes with thicknesses of about 3.7 nm are constructed from a single layer of parallel‐packed pore channels. These uniquely ordered mesoporous 2D nanostructures may originate from the 2D assembly of cylindrical micelles formed by the amphiphilic precursors in the nonpolar solvent. The 2D mesoporous FePO4 nanoflakes were used as the cathode for a lithium‐ion battery, which exhibits excellent stability and high rate capabilities.
Synthesis, Structure, and Reactivity of a Gold Carbenoid Complex That Lacks Heteroatom Stabilization
Authors: Harris Robert J. , Widenhoefer Ross A.
Published: July 2014

Hydride abstraction from the neutral gold cycloheptatrienyl complex [(P)Au(η1‐C7H7)] (P=P(tBu)2(o‐biphenyl)) with triphenylcarbenium tetrafluoroborate at −80 °C led to the isolation of the cationic gold cycloheptatrienylidene complex [(P)Au(η1‐C7H6)]+ BF4− in 52 % yield, which was characterized in solution and by single‐crystal X‐ray diffraction. This cycloheptatrienylidene complex represents the first example of a gold carbenoid complex that lacks conjugated heteroatom stabilization of the electron‐deficient C1 carbon atom. The cycloheptatrienylidene ligand of this complex is reactive; it can be reduced by mild hydride donors, and converted to tropone in the presence of pyridine N‐oxide.
Aerogels with 3D Ordered Nanofiber Skeletons of Liquid‐Crystalline Nanocellulose Derivatives as Tough and Transparent Insulators
Authors: Kobayashi Yuri , Saito Tsuguyuki , Isogai Akira
Published: July 2014

Aerogels of high porosity and with a large internal surface area exhibit outstanding performances as thermal, acoustic, or electrical insulators. However, most aerogels are mechanically brittle and optically opaque, and the structural and physical properties of aerogels strongly depend on their densities. The unfavorable characteristics of aerogels are intrinsic to their skeletal structures consisting of randomly interconnected spherical nanoparticles. A structurally new type of aerogel with a three‐dimensionally ordered nanofiber skeleton of liquid‐crystalline nanocellulose (LC‐NCell) is now reported. This LC‐NCell material is composed of mechanically strong, surface‐carboxylated cellulose nanofibers dispersed in a nematic LC order. The LC‐NCell aerogels are transparent and combine mechanical toughness and good insulation properties. These properties of the LC‐NCell aerogels could also be readily controlled.
Nitrite‐Templated Synthesis of Lanthanide‐Containing [2]Rotaxanes for Anion Sensing
Authors: Langton Matthew J. , Blackburn Octavia A. , Lang Thomas , Faulkner Stephen , Beer Paul D.
Published: July 2014

The first anion‐templated synthesis of a lanthanide‐containing interlocked molecule is demonstrated by utilizing a nitrite anion to template initial pseudorotaxane formation. Subsequent stoppering of the interpenetrated assembly allows for the preparation of a lanthanide‐functionalized [2]rotaxane in high yield. Following removal of the nitrite anion template, the europium [2]rotaxane host is demonstrated to recognize and sense fluoride selectively.
Regiocontrolled Gold‐Catalyzed [2+2+2] Cycloadditions of Ynamides with Two Discrete Nitriles to Construct 4‐Aminopyrimidine Cores
Authors: Karad Somnath Narayan , Liu Rai‐Shung
Published: July 2014

Reported herein is the novel gold‐catalyzed intermolecular [2+2+2] cycloaddition of ynamides with two discrete nitriles to form monomeric 4‐aminopyrimidines, which are pharmaceutically important structural motifs. The utility of this new cycloaddition is demonstrated by the excellent regioselectivity obtained using a variety of ynamides and nitriles.
Predicting the electrospinnability of polymer solutions with electromechanical simulation
Authors: Sidaravicius Jonas , Rinkūnas Ringaudas , Jurksus Justinas , Lozovski Tadeus , Heiskanen Isto , Backfolk Kaj
Published: July 2014

The number of polymers successfully electrospun is increasing, and methods are needed predict the electrospinnability of polymers. With such methods, researchers should consider the polymer solution parameters and perform measurements in conditions that mimic the electrospinning process. A novel test method based on the electromechanical simulation of the fiber formation was developed. We formed fibers by mechanically dragging a conductive ball from the solution at an applied voltage and measuring the electrical current. The changes in the time of the electrical current (the ball current) reflect the fiber‐formation process, which depended on certain polymer solution properties (e.g., viscosity, surface tension, liquid flow) and on the influence of charges on the fiber surface. The data obtained with the proposed method was compared with experimental data from electrospinning trials with the spinneret and bubble electrospinning. The results demonstrate that the ball‐current method made it possible to predict the polymer solution behavior in the electrospinning process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41091.
Polyaniline salts as polymer‐based solid acid catalyst for low molecular weight poly(lactic acid)
Authors: Rajender Boddula , Palaniappan Srinivasan
Published: July 2014

Polymer‐based solid acid catalyst, polyaniline (PANI) salt, is used for the first time to synthesize polymer. In continuation of our work to synthesize organic chemicals using PANI‐based solid acid catalyst, in this work, polylactic acid is synthesized by the condensation polymerization of lactic acid using PANI salts. PANI salts are characterized by FTIR, FE‐SEM, and TGA analyses. Polymerization of lactic acid in xylene solvent at 140°C for 24 h with the use of very low amount of PANI catalysts gave polylactic acid (PLLA) in the order: PANI‐MSA (46%) > PANI‐TFA (33%) > PANI‐Bi(OTf)3 (27%) > PANI‐Cu(OTf)2 (20%) > PANI‐Yb(OTf)3 (15%). Molecular weights of PLLA synthesized using PANI‐MSA and PANI‐TFA are found to be 4385 and 4830, respectively. This methodology gives highly crystalline polymer with mushroom cap‐like morphology. Advantage of this methodology is the use of easily synthesizable, recyclable, easily handlable, cheaper, and eco‐friendly nature of the catalyst. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41147.
Competitive adsorption of acid dyes from aqueous solution on diethylenetriamine‐modified chitosan beads
Authors: Yan Yikai , Xiang Bo , Yi Xiaowei , Li Yijiu , Jia Qian
Published: July 2014

The interaction between two dyes (AO7 and AG25) during adsorption was studied in detail with diethylenetriamine‐modified chitosan beads (CTSN‐beads) as the adsorbent. Results indicate that the adsorption capacities and rates were directly related to the molecular size of the dye. The adsorption capacity and rate of AO7 could be greatly weakened by interaction with AG 25 during adsorption, which has a larger molecular size. The adsorption followed the pseudo‐second‐order kinetic equation and Freundlich model gave a satisfying correlation with the equilibrium data both in the single and binary component system. Adsorption could be divided into three stages, each controlled by different mechanisms. Temperature experiments showed high temperature was beneficial to the mass transfer of dyes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41168.
Signal crayfish (Pacifastacus leniusculus) predation upon Atlantic salmon (Salmo salar) eggs
Authors: Findlay John D. S. , Riley William D. , Lucas Martyn C.
Published: July 2014

The signal crayfish (Pacifastacus leniusculus) is a large, polytrophic crustacean which has invaded waterways across much of Europe. Crayfish prey on the eggs of several fish species and egg predation, especially by invasive crayfish, is cited as a likely cause of population decline and a serious concern for the conservation of some fish species including at least one salmonid.

Numerically, crayfish populations may be dominated by small individuals, but most studies have investigated egg predation by large crayfish. Evidence for crayfish gaining access to buried fish eggs is equivocal.

The ability of signal crayfish of a range of age groups (and hence, sizes) to prey on unburied and buried Atlantic salmon (Salmo salar) eggs was investigated in laboratory experiments.

Only Age 2+ and older crayfish (24–43 mm carapace length (CL)) significantly reduced egg survival in unburied egg experiments, although some evidence of egg predation was observed with Age 1+ crayfish (16–22 mm CL). Age 0+ crayfish (8–14 mm CL) did not prey on salmon eggs. No evidence of substantial excavations or predation upon buried eggs by crayfish of any size class was observed. Binomial logistic regression of egg survival against crayfish CL indicated that mean egg recovery fell below control levels when CL exceeded 16.3 mm.

These results suggest that large signal crayfish are likely to pose the greatest threat to salmonid eggs, but that crayfish larger than 16.3 mm CL have the potential to prey on eggs.

Further research is needed before manual removal or harvesting of signal crayfish are used as conservation measures for Atlantic salmon spawning areas in which signal crayfish occur. Restoration of high‐quality salmonid spawning habitat might, however, help to prevent signal crayfish predation of salmonid eggs in addition to broader benefits for salmonid conservation.

© 2014 Crown copyright. Aquatic Conservation: Marine and Freshwater Ecosystems © 2014 John Wiley & Sons, Ltd.
Projections of the impacts of gear‐modification on the recovery of fish catches and ecosystem function in an impoverished fishery
Authors: Condy Michelle , Cinner Joshua E. , McClanahan Tim R. , Bellwood David R.
Published: July 2014

The regulation of fishing gear is a widely accepted fisheries management solution that requires further research to improve the chances of achieving sustainable yields, maintaining ecological integrity, and assisting fishers to escape from poverty. Fishing traps are a good candidate for modification because they are used widely, represent one of the most profitable gears, and often catch key species known to promote ecological resilience.

The ecological and economic implications of modifying fishing traps with escape slots were examined in a heavily fished and poor artisanal Kenyan fishery. Catches of fish from traps with four escape slot sizes (2, 4, 6, and 8 cm,) were examined for differences in the catch rates and composition and to calibrate a simulation model. The simulation model was used to predict how the ecological and economic outcomes will change as the standing stock responds to the new size selectivity of the fishing traps.

The results suggest a fishery's wide implementation of the 2 cm escape slots could provide an immediate benefit to the ecosystem by reducing the catch of juvenile fishes and algal browsers, which could help avoid or reverse coral–macroalgal phase shifts that can reduce reef biodiversity. However, the model predicts a decline in per trap profits in the first year that the 2 cm escape slot is implemented. This period would be followed by profitability increasing by a factor of 1.6 and 2.2 in the second year for the 2 cm and 4 cm escape slots respectively.

Sequential implementation of 2 cm slots followed by 4 cm slots in the fourth year reduces the total economic cost of implementing the 4 cm slots by 34%. Consequently, sequential implementation of these traps is suggested as a potential way to simultaneously conserve key ecosystem functions and reduce poverty.

Copyright © 2014 John Wiley & Sons, Ltd.