bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kontrolle der Molmassenverteilung durch Polymerisation in der analytischen Ultrazentrifuge
Authors: Spinnrock Andreas , Cölfen Helmut 
Published: February 2018

AbstractMolmassenverteilungen sind in der makromolekularen Chemie von großem Interesse. Ein Ansatz, um breite Molmassenverteilungen zu erhalten und ihre Form zu kontrollieren, ist es, die Initiatorkonzentration in freien radikalischen Polymerisationen einzustellen. Ein kontrolliert einstellbarer Gradient der Initiatorkonzentration führt potenziell zu maßgeschneiderten Molmassenverteilungen. Analytische Ultrazentrifugation (AUZ) wurde genutzt, um den Konzentrationsgradienten eines Makroinitiators einzustellen und zu detektieren. Über anschließende Photopolymerisation eines gleichmäßig verteilten Monomers werden die gewünschten Kettenlängenverteilungen erhalten. Die entstehenden Verteilungen werden durch einen Schulz‐Flory‐Ansatz beschrieben und berechnet. Die gewünschten Konzentrationsprofile werden im Voraus simuliert und können jederzeit durch die optischen Systeme der Zentrifuge detektiert werden. Durch Vorhersagen aus Simulationen, die mit der belastbaren Theorie der AUZ erstellt werden, können daher jetzt maßgeschneiderte Molmassenverteilungen hergestellt werden.
Benzylic Fluorination of Aza‐Heterocycles Induced by Single‐Electron Transfer to Selectfluor
Authors: Danahy Kelley E. , Cooper Julian C. , Van Humbeck Jeffrey F. 
Published: February 2018

AbstractA selective and mild method for the benzylic fluorination of aromatic azaheterocycles with Selectfluor is described. These reactions take place by a previously unreported mechanism, in which electron transfer from the heterocyclic substrate to the electrophilic fluorinating agent Selectfluor eventually yields a benzylic radical, thus leading to the desired C−F bond formation. This mechanism enables high intra‐ and intermolecular selectivity for aza‐heterocycles over other benzylic components with similar C−H bond‐dissociation energies.
Atomic Force Microscopy for Molecular Structure Elucidation
Authors: Gross Leo , Schuler Bruno , Pavliček Niko , Fatayer Shadi , Majzik Zsolt , Moll Nikolaj , Peña Diego , Meyer Gerhard 
Published: February 2018

AbstractUsing scanning probe microscopy techniques, at low temperatures and in ultrahigh vacuum, individual molecules adsorbed on surfaces can be probed with ultrahigh resolution to determine their structure and details of their conformation, configuration, charge states, aromaticity, and the contributions of resonance structures. Functionalizing the tip of an atomic force microscope with a CO molecule enabled atomic‐resolution imaging of single molecules, and measurement of their adsorption geometry and bond‐order relations. In addition, by using scanning tunneling microscopy and Kelvin probe force microscopy, the density of the molecular frontier orbitals and the electric charge distribution within molecules can be mapped. Combining these techniques yields a high‐resolution tool for the identification and characterization of individual molecules. The single‐molecule sensitivity and the possibility of atom manipulation to induce chemical reactions with the tip of the microscope open up unique applications in chemistry, and differentiate scanning probe microscopy from conventional methods for molecular structure elucidation. Besides being an aid for challenging cases in natural product identification, atomic force microscopy has been shown to be a powerful tool for the investigation of on‐surface reactions and the characterization of radicals and molecular mixtures. Herein we review the progress that high‐resolution scanning probe microscopy with functionalized tips has made for molecular structure identification and characterization, and discuss the challenges it will face in the years to come.
Preparation and coagulation performance of hybrid coagulant polyacrylamide–polymeric aluminum ferric chloride
Authors: Wang Xinlei , Jiang Shaojie , Tan Siying , Wang Xun , Wang Hongwu 
Published: February 2018

ABSTRACTIn this study, we synthesized a novel hybrid coagulant, polyacrylamide (PAM)–polymeric aluminum ferric chloride (PAFC), by the polymerization of acrylamide monomer with the redox system (NH4)2S2O8–NaHSO3. The factors affecting the PAM–PAFC hybrid coagulant were investigated in an orthogonal experiment. The maximum intrinsic viscosity was observed at an initiator mass fraction of 0.5%, a polymerization temperature of 50 °C, a monomer mass fraction of 20%, and a polymerization time of 4 h, which were the optimum synthesis parameters. The spatial network structure of the PAM–PAFC hybrid coagulant was graphically determined by scanning electron microscopy. Hybrid PAM–PAFC was adopted to treat the kaolin–humic acid suspension and the synthetic dye wastewater. The effect of the coagulant dosage and pH on the coagulant experiments were examined. The coagulant experiment on the kaolin–humic acid suspension showed that the optimum treatment efficiency was achieved at a coagulants dosage of 0.6 mg/L, at which level the turbidity reductions with the inorganic PAFC coagulant, PAM–PAFC composite, and PAM–PAFC hybrid were 95.30%, 95.84%, and 98.38%, respectively. Treatment with the PAM–PAFC hybrid coagulant was also effective in removing Congo Red and Direct Fast Turquoise Blue GL; the color‐removal efficiencies for these dyes were higher than 93% and 94%, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46355.
Gambusia holbrooki, the ‘tadpolefish’: The impact of its predatory behaviour on four protected species of European amphibians
Authors: Vannini Andrea , Bruni Giacomo , Ricciardi Giulia , Platania Leonardo , Mori Emiliano , Tricarico Elena 
Published: February 2018

Abstract

Biological invasions are widely regarded as the second major cause of the current global biodiversity crisis. Freshwater environments in particular include many habitats and species of conservation concern. Among those, amphibians are threatened worldwide by habitat loss and by the introduction of alien taxa, including pathogens and fish.
The North American mosquitofish Gambusia spp. have been introduced throughout the world for the biological control of mosquitoes, and have established alien populations in over 110 countries. Their impact on native freshwater vertebrates, especially in Europe, is still poorly known.
Here, the predatory impact of mosquitofish on the larval stages of four European amphibian species (Hyla intermedia, Triturus carnifex, Pelophylax kl. hispanicus, and Bufotes balearicus), locally abundant in Central Italy, has been investigated under laboratory conditions to assess whether any difference occurs in species vulnerability and interactions with the predator, as their breeding sites are often invaded by mosquitofish. Larval mortality and fish attacks, as well as observations on fish predatory behaviour, were recorded at four time intervals (10 min, 1 h, 6 h, and 24 h) and at three different prey abundances (with five, 10, and 20 larvae).
A significant difference in predation rate for species, exposure time, and larval abundance occurred, with H. intermedia being the most vulnerable species and B. balearicus being the least vulnerable species. An increase in exposure time increased the rate of predation, whereas small groups of larvae (i.e. <10 individuals) appeared to be far more vulnerable to fish attack compared with the larger groups.
Mosquitofish show considerable potential to prey upon the larvae of European amphibians, representing a serious threat for their conservation. Appropriate management and legislative strategies are thus necessary to prevent the further introduction and spread of this alien fish in natural environments.
Geophysical surveying of the ancient walls of the town of Cagliari, Italy, by means of refraction and up‐hole seismic tomography techniques
Authors: Balia Roberto , Pirinu Andrea 
Published: February 2018

AbstractThe ancient walls of Santa Croce in the town of Cagliari (Sardinia, Italy), date back to the Middle Age and have had, until the nineteenth century, several interventions with superpositions and modifications. Beyond the historical and archaeological interest, the study of the structure of the ancient walls became necessary in view of building an underground car parking just at the base of the walls itself. With this purpose, in addition to classical archaeological surveys a geophysical non‐destructive survey with seismic techniques has been carried out, namely two refraction tomographies aimed at characterizing the rocks at the base of the walls, and four up‐hole tomographies across the walls itself. These geophysical surveys provide good geotechnical information on the foundation condition, the problematic feasibility of the underground parking and, along with the archaeological procedures, on the heterogeneous structure of the walls.
Construction of a Triangle‐Shaped Trimer and a Tetrahedron Using an α‐Helix‐Inserted Circular Permutant of Cytochrome c555
Authors: Oda Akiya , Nagao Satoshi , Yamanaka Masaru , Ueda Ikki , Watanabe Hiroki , Uchihashi Takayuki , Shibata Naoki , Higuchi Yoshiki , Hirota Shun 
Published: February 2018

AbstractHighly‐ordered protein structures have gained interest for future uses for biomaterials. Herein, we constructed a building block protein (BBP) by the circular permutation of the hyperthermostable Aquifex aeolicus cytochrome (cyt) c555, and assembled BBP into a triangle‐shaped trimer and a tetrahedron. The angle of the intermolecular interactions of BBP was controlled by cleaving the domain‐swapping hinge loop of cyt c555 and connecting the original N‐ and C‐terminal α‐helices with an α‐helical linker. We obtained BBP oligomers up to ≈40 mers, with a relatively large amount of trimers. According to the X‐ray crystallographic analysis of the BBP trimer, the N‐terminal region of one BBP molecule interacted intermolecularly with the C‐terminal region of another BBP molecule, resulting in a triangle‐shaped structure with an edge length of 68 Å. Additionally, four trimers assembled into a unique tetrahedron in the crystal. These results demonstrate that the circular permutation connecting the original N‐ and C‐terminal α‐helices with an α‐helical linker may be useful for constructing organized protein structures.
Lipophilicity evaluation of some thiazolyl‐1,3,4‐oxadiazole derivatives with antifungal activity
Authors: Stoica Cristina Ioana , Ionuț Ioana , Vlase Laurian , Tiperciuc Brîndușa , Marc Gabriel , Oniga Smaranda , Araniciu Cătălin , Oniga Ovidiu 
Published: February 2018

AbstractThe chromatographic behavior of a series of thiazolyl‐1,3,4‐oxadiazoles with antifungal activity was studied by reverse‐phase thin‐layer chromatography (RP‐TLC). The lipophilicity parameters derived from RP‐TLC were correlated with the data derived from liquid‐chromatography mass‐spectrometry. Good linear relationships were observed between the chromatographic lipophilicity parameters and the theoretical lipophilicity descriptors (logP) generated by various computer software and internet modules. Principal component analysis, applied on the experimental chromatographic lipophilicity indices and the theoretically calculated logP, enabled us to obtain a lipophilicity chart for better vizualization of the similarities and differences of the investigated compounds, which were grouped by k‐means clustering in two congeneric classes.
Motivations of sustainable entrepreneurship and their impact of enterprise performance in Gauteng Province, South Africa
Authors: Nhemachena Charles , Murimbika McEdward 
Published: February 2018

AbstractThe paper discussed motivations of sustainable entrepreneurship in Gauteng Province, South Africa, and estimated relationships between these motivations and enterprise performance. Despite the growing field of sustainable entrepreneurship, most of the available literature has been mainly theoretical and qualitative or has focused on developed countries. This paper contributes to addressing this gap through empirical analysis based on primary survey data from 91 sustainable entrepreneurs. Reliability of the performance and motivation scales were subjected to the Cronbach's alpha coefficient test, and the results were acceptable. The exploratory factor analysis indicated that the motivations of sustainable entrepreneurship factored into 4 dimensions: extrinsic, intrinsic, income security and financial independence, and necessity motivations. Regression analysis revealed that extrinsic and intrinsic motivations are important determinants of enterprise performance. These motivations can be targeted to promote sustainable entrepreneurship in addition to complementary support such as improving business management skills and competencies of sustainable entrepreneurs.
A simulation tool to promote active learning of controlled rectifiers
Authors: Chibante Rui , Vaz De Carvalho Carlos , Ferreira Paulo 
Published: February 2018

AbstractThe use of interactive simulation tools can effectively support the adoption of active learning methodologies in Engineering Education therefore increasing the motivation of the students and improving their knowledge acquisition. This paper presents the design and development of a pedagogical simulation tool for the teaching and self‐studying of thyristor controlled rectifiers. The application enables the user to vary the thyristors firing angle and to analyze its influence on the rectifier output voltage. Waveforms are plotted using specific heuristics instead of solving the system of equations that governs the circuit's operation which makes the application extremely fast. The software is also independent of the operating system and does not require any kind of installation. In comparison with other existing tools, the proposed system provides a much simpler approach, user‐friendlier, and with an easier learning curve. Evaluation results showed that students reported a positive feedback from the use of the simulation tool.
A Cytidine Phosphoramidite with Protected Nitroxide Spin Label: Synthesis of a Full‐Length TAR RNA and Investigation by In‐Line Probing and EPR Spectroscopy
Authors: Weinrich Timo , Jaumann Eva A. , Scheffer Ute , Prisner Thomas F. , Göbel Michael W. 
Published: February 2018

AbstractEPR studies on RNA are complicated by three major obstacles related to the chemical nature of nitroxide spin labels: Decomposition while oligonucleotides are chemically synthesized, further decay during enzymatic strand ligation, and undetected changes in conformational equilibria due to the steric demand of the label. Herein possible solutions for all three problems are presented: A 2‐nitrobenzyloxymethyl protective group for nitroxides that is stable under all conditions of chemical RNA synthesis and can be removed photochemically. By careful selection of ligation sites and splint oligonucleotides, high yields were achieved in the assembly of a full‐length HIV‐1 TAR RNA labeled with two protected nitroxide groups. PELDOR measurements on spin‐labeled TAR in the absence and presence of arginine amide indicated arrest of interhelical motions on ligand binding. Finally, even minor changes in conformation due to the presence of spin labels are detected with high sensitivity by in‐line probing.
The Gold(I)‐Mediated Domino Reaction to Fused Diphenyl Phosphoniumfluorenes: Mechanistic Consequences for Gold‐Catalyzed Hydroarylations and Application in Solar Cells
Authors: Arndt Sebastian , Borstelmann Jan , Eshagh Saatlo Rebeka , Antoni Patrick W. , Rominger Frank , Rudolph Matthias , An Qingzhi , Vaynzof Yana , Hashmi A. Stephen K. 
Published: February 2018

AbstractA domino sequence, involving a phosphinoauration and a gold‐catalyzed 6‐endo‐dig cyclization step, was developed. Starting from modular and simple‐to‐prepare phosphadiynes, π‐extended phosphoniumfluorenes were synthesized. The mechanistic proposal was supported by kinetic measurements and by the trapping of key intermediates. These led to important conclusions for the gold‐catalyzed hydroarylation mechanism. Cyclic voltammetry (CV) and UV/Vis spectroscopy measurements indicated interesting properties for materials science. The phosphoniumfluorene structure was tested as a hole‐blocking layer in perovskite solar cells of inverted architecture. Devices with the phosphoniumfluorene exhibited an efficiency of 14.2 %, which was much higher than that of devices without (10.7 %).
Production of Multilayer Graphene in a Vibratory Disk Mill
Authors: Trüe Michael , Aman Sergej , Müller Peter , Hintz Werner , Hirsch Sören 
Published: February 2018

AbstractOptimale Prozessbedingungen für das mikromechanische Abblättern von mehrschichtigem Graphen werden mit einer Scheibenschwingmühle realisiert, in der eine hochviskose Flüssigkeit bestehend aus Zucker und Graphitpartikeln zerkleinert wird. Die Bedingungen, bei denen die Scherkräfte im Prozess in der Scheibenschwingmühle entstehen, werden untersucht. Graphenblätter mit Schichtdicken von 2 – 10 Schichten werden gewonnen. Das erhaltene mehrschichtige Graphen kann bei der Herstellung von Lithium‐Ionen‐Akkumulatoren eingesetzt werden.
Scripting as an Approach to Automated CFD Simulation for Packed Bed Catalytic Reactor Modeling
Authors: Fernengel Johanna , Habla Florian , Hinrichsen Olaf 
Published: February 2018

AbstractIn recent years computational fluid dynamics (CFD) has become a widely applied tool for the simulation of catalytic fixed‐bed reactors and numerous authors have contributed towards methods for random packed bed generation and flow simulation. The presented approach focuses on an automated simulation routine realized through bash and python scripting covering multiple entire simulation runs including preprocessing, simulation as well as post‐processing based on open‐source software. As an example, the routine is demonstrated with a case study on catalytic fixed‐bed reactors.
Discovery of Molidustat (BAY 85‐3934): A Small‐Molecule Oral HIF‐Prolyl Hydroxylase (HIF‐PH) Inhibitor for the Treatment of Renal Anemia
Authors: Beck Hartmut , Jeske Mario , Thede Kai , Stoll Friederike , Flamme Ingo , Akbaba Metin , Ergüden Jens‐Kerim , Karig Gunter , Keldenich Jörg , Oehme Felix , Militzer Hans‐Christian , Hartung Ingo V. , Thuss Uwe 
Published: February 2018

AbstractSmall‐molecule inhibitors of hypoxia‐inducible factor prolyl hydroxylases (HIF‐PHs) are currently under clinical development as novel treatment options for chronic kidney disease (CKD) associated anemia. Inhibition of HIF‐PH mimics hypoxia and leads to increased erythropoietin (EPO) expression and subsequently increased erythropoiesis. Herein we describe the discovery, synthesis, structure–activity relationship (SAR), and proposed binding mode of novel 2,4‐diheteroaryl‐1,2‐dihydro‐3H‐pyrazol‐3‐ones as orally bioavailable HIF‐PH inhibitors for the treatment of anemia. High‐throughput screening of our corporate compound library identified BAY‐908 as a promising hit. The lead optimization program then resulted in the identification of molidustat (BAY 85‐3934), a novel small‐molecule oral HIF‐PH inhibitor. Molidustat is currently being investigated in clinical phase III trials as molidustat sodium for the treatment of anemia in patients with CKD.
Precision in the reproduction of colored coatings
Authors: Meichsner Georg , Hiesgen Renate , Etzl Thomas , Vanderhoeven Marcel , Brinz Thomas 
Published: February 2018

SummaryThe objective of this study was to apply Hotelling's T2‐statistics to color measurement data of colored coatings. It is described, how outliers can be detected by comparing T2 with an appropriate statistical distribution function. As an example, the precision in the reproduction of colored coatings produced in laboratory and prepared by a robot for high‐throughput experimentation was investigated on a turquoise coating. After elimination of outliers the precision of reproduction of the coatings color was determined by the sample color differences to the average color coordinates in CIELAB and DIN99 color spaces as well as with CIEDE2000 color differences. As expected, laboratory experimentation (reproducibility conditions) showed a lower precision of color reproduction as samples prepared with the high‐throughput experimentation device (repeatability conditions).
On the design of secure user authenticated key management scheme for multigateway‐based wireless sensor networks using ECC
Authors: Sutrala Anil Kumar , Das Ashok Kumar , Kumar Neeraj , Reddy Alavalapati Goutham , Vasilakos Athanasios V. , Rodrigues Joel J. P. C. 
Published: February 2018

SummaryIn wireless sensor networks (WSNs), there are many critical applications (for example, healthcare, vehicle tracking, and battlefield), where the online streaming data generated from different sensor nodes need to be analyzed with respect to quick control decisions. However, as the data generated by these sensor nodes usually flow through open channel, so there are higher chances of various types of attacks either on the nodes or on to the data captured by these nodes. In this paper, we aim to design a new elliptic curve cryptography–based user authenticated key agreement protocol in a hierarchical WSN so that a legal user can only access the streaming data from generated from different sensor nodes. The proposed scheme is based upon 3‐factor authentication, as it applies smart card, password, and personal biometrics of a user (for ticket generation). The proposed scheme maintains low computation cost for resource‐constrained sensor nodes, as it uses efficient 1‐way cryptographic hash function and bitwise exclusive‐OR operations for secure key establishment between different sensor nodes. The security analysis using the broadly accepted Burrows‐Abadi‐Needham logic, formal security verification using the popular simulation tool (automated validation of Internet security protocols and applications), and informal security show that the proposed scheme is resilient against several well‐known attacks needed for a user authentication scheme in WSNs. The comparison of security and functionality requirements, communication and computation costs of the proposed scheme, and other related existing user authentication schemes shows the superior performance of the proposed scheme.
Preparing for an uncertain future: migrating shorebird response to past climatic fluctuations in the Prairie Potholes
Authors: Steen Valerie , Skagen Susan K. , Noon Barry R. 
Published: February 2018

AbstractThe Prairie Pothole Region, situated in the northern Great Plains, provides important stopover habitat for migratory shorebirds. During spring migration in the U.S. Prairie Potholes, 7.3 million shorebirds refuel in the region's myriad small, freshwater wetlands. Shorebirds use mudflats, shorelines, and ephemeral wetlands that are far more abundant in wet years than dry years. Generally, climate change is expected to bring warmer temperatures, seasonality shifts, more extreme events, and changes to precipitation. The impacts to wetland habitats are uncertain. In the Prairie Potholes, earlier spring onset and warmer temperatures may advance drying of wetlands or, alternately, increased spring precipitation may produce abundant shallow‐water habitats. To look at the availability of habitats for migratory shorebirds under different climate regimes, we compared habitat selection between a historic wet year and a dry year using binomial random‐effects models to describe local and landscape patterns. We found that in the dry year shorebirds were distributed more northerly and among more permanent wetlands, whereas in the wet year shorebirds were distributed more southerly and among more temporary wetlands. However, landscape‐scale variation played a larger role in the dry year. At the local wetland scale, shorebirds selected similarly between years—for shallower wetlands and wetlands in croplands. Overall, while shorebirds were sensitive to local habitat conditions, they exhibited a degree of adaptive capacity to climate change impacts by their ability to shift on the landscape. This indicates an avenue through which management decisions can enhance climate change resilience for these species given an uncertain future—by preserving shallow‐water wetlands in croplands throughout the landscape.