bluuebunny/crossref_metadata_2025 huggingface dataset:
Game theory and risk‐based leveed river system planning with noncooperation
Authors: Hui Rui , Lund Jay R. , Madani Kaveh
Published: December 2015

Optimal risk‐based levee designs are usually developed for economic efficiency. However, in river systems with multiple levees, the planning and maintenance of different levees are controlled by different agencies or groups. For example, along many rivers, levees on opposite riverbanks constitute a simple leveed river system with each levee designed and controlled separately. Collaborative planning of the two levees can be economically optimal for the whole system. Independent and self‐interested landholders on opposite riversides often are willing to separately determine their individual optimal levee plans, resulting in a less efficient leveed river system from an overall society‐wide perspective (the tragedy of commons). We apply game theory to simple leveed river system planning where landholders on each riverside independently determine their optimal risk‐based levee plans. Outcomes from noncooperative games are analyzed and compared with the overall economically optimal outcome, which minimizes net flood cost system‐wide. The system‐wide economically optimal solution generally transfers residual flood risk to the lower‐valued side of the river, but is often impractical without compensating for flood risk transfer to improve outcomes for all individuals involved. Such compensation can be determined and implemented with landholders' agreements on collaboration to develop an economically optimal plan. By examining iterative multiple‐shot noncooperative games with reversible and irreversible decisions, the costs of myopia for the future in making levee planning decisions show the significance of considering the externalities and evolution path of dynamic water resource problems to improve decision‐making.
Transition of dominant peak flow source from snowmelt to rainfall along the Colorado Front Range: Historical patterns, trends, and lessons from the 2013 Colorado Front Range floods
Authors: Kampf Stephanie K. , Lefsky Michael A.
Published: December 2015

The Colorado Front Range has a large elevation gradient with deep seasonal snowpack in the mountains and limited snow accumulation in the foothills and plains. This study examines how the sources of annual peak flows (snowmelt, rainfall, mixed) change with the fraction of time snow persists on the ground, snow persistence (SP), and whether these sources have changed over time. Sources of peak flows for 20 gaging stations are estimated using a gridded rain and snow model forced with PRISM daily precipitation and both PRISM and TopoWx temperature. The mean snowmelt contribution to peak flow is highly correlated with SP (r2 = 0.86–0.90). Watersheds with SP < 0.3 (low snow, elevation <2000 m) are rainfall‐dominated, and watersheds with SP > 0.7 (persistent snow, elevation >3100 m) are mostly snowmelt‐dominated, with mixed sources between these thresholds. Rainfall runoff peak flows are possible at all elevations, but their likelihood declines with increasing SP. Rainfall runoff from an extreme storm in September 2013 produced the highest annual peaks at many stations, including some snowmelt‐dominated watersheds. Regional Kendall trend tests indicate that the contributions of snowmelt to peak flows and total annual inputs have declined in the mixed source zone. These changes may affect hydrographs, as analyses confirm that snowmelt runoff generally produces more attenuated peaks than rainfall runoff. Discrimination of peak flow source is sensitive to input data and model structure for mixed rain and snowmelt events, and both observation and modeling research are needed to help understand potential runoff changes in these conditions.
Methane occurrence is associated with sodium‐rich valley waters in domestic wells overlying the Marcellus shale in New York State
Authors: Christian Kayla M. , Lautz Laura K. , Hoke Gregory D. , Siegel Donald I. , Lu Zunli , Kessler John
Published: December 2015

Prior work suggests spatial parameters (e.g., landscape position, distance to nearest gas well) can be used to estimate the amount of dissolved methane in domestic drinking water wells overlying the deep Marcellus Shale. New York (NY) provides an opportunity to investigate methane occurrence prior to expansion of high‐volume hydraulic fracturing because unconventional gas production is currently banned in the state. We sampled domestic groundwater wells for methane in 2013 (n = 137) across five counties of NY bordering Pennsylvania, and then resampled a subset of those wells in 2014 for methane concentrations and δ13C‐CH4 and δD‐CH4. The majority of waters from wells sampled (77%) had low concentrations of methane (<0.1 mg/L), and only 5% (n = 7) had actionable levels of methane (>10 mg/L). Dissolved methane concentrations did not change as a function of proximity to existing vertical gas wells, nor other parameters indicating subsurface planes of weakness (i.e., faults or lineaments). Methane levels were significantly higher in wells closer to hydrography flow lines, and most strongly correlated to Na‐HCO3 water type. The distribution of methane between Ca‐HCO3 (n = 76) and Na‐HCO3 (n = 23) water types significantly differed (p < 0.01), with median methane concentrations of 0.002 and 0.78 mg/L, respectively. Combined classification of sampled waters based on the dominant water cation, well topographic position, and geologic unit of well completion effectively identified wells with a greater than 50% probability of having methane concentrations exceeding 1 mg/L. Such classification schemes may be useful as a screening tool to assess natural versus gas production‐related sources of methane in domestic wells.
Vocabulary Guessing Strategies
Authors: Gu Yongqi
Published: December 2015

Vocabulary guessing strategies (VGS) refer to the plans and procedures people use to guess the contextual meaning of words, during reading or listening, for the main purpose of comprehension. Guessing is needed when we encounter an unknown word in reading or listening in a second language (L2). In fact, even experienced readers and listeners in their first language (L1) use the guessing strategy all the time. Since many words are homonyms or homographs, part of the comprehension process depends on inferring the correct and appropriate meaning in context.
Grammatical Differences Between
B
ritish and
A
merican
E
nglish
Authors: Jäger Verena , Mondorf Britta
Published: December 2015

Laypersons can often name the odd British–American difference in pronunciation, orthography, or vocabulary, but they are hard put to name grammatical contrasts. Even in linguistics British–American contrasts on the levels of phonology, orthography, and the lexicon have been far more extensively studied than grammatical differences.
Role and Optimization of the Active Oxide Layer in TiO2‐Based RRAM
Authors: Regoutz Anna , Gupta Isha , Serb Alexantrou , Khiat Ali , Borgatti Francesco , Lee Tien‐Lin , Schlueter Christoph , Torelli Piero , Gobaut Benoit , Light Mark , Carta Daniela , Pearce Stuart , Panaccione Giancarlo , Prodromakis Themistoklis
Published: December 2015

TiO2 is commonly used as the active switching layer in resistive random access memory. The electrical characteristics of these devices are directly related to the fundamental conditions inside the TiO2 layer and at the interfaces between it and the surrounding electrodes. However, it is complex to disentangle the effects of film “bulk” properties and interface phenomena. The present work uses hard X‐ray photoemission spectroscopy (HAXPES) at different excitation energies to distinguish between these regimes. Changes are found to affect the entire thin film, but the most dramatic effects are confined to an interface. These changes are connected to oxygen ions moving and redistributing within the film. Based on the HAXPES results, post‐deposition annealing of the TiO2 thin film was investigated as an optimisation pathway in order to reach an ideal compromise between device resistivity and lifetime. The structural and chemical changes upon annealing are investigated using X‐ray absorption spectroscopy and are further supported by a range of bulk and surface sensitive characterisation methods. In summary, it is shown that the management of oxygen content and interface quality is intrinsically important to device behavior and that careful annealing procedures are a powerful device optimisation technique.
Reversible Nanopatterning on Polypyrrole Films by Atomic Force Microscope Electrochemical Lithography
Authors: Liu He , Hoeppener Stephanie , Schubert Ulrich S.
Published: December 2015

A reversible, erasable, and rewritable pattern at the nanoscale is inscribed on polypyrrole films doped with sodium dodecylbenzenesulfonate (PPy(DBS)) utilizing atomic force microscopy based electrochemical lithography. Nanopatterns are formed by applying a bias voltage between a conductive tip and the substrate. Afterward, the generated nanopatterns can be erased completely, followed by rewriting at the same location of the polymer film. Moreover, the alterations of PPy(DBS) during the lithography process are investigated by comparing the changes of the current intensity and surface potential depending on the lithography time.
Helical 3D‐Printed Metal Electrodes as Custom‐Shaped 3D Platform for Electrochemical Devices
Authors: Ambrosi Adriano , Moo James Guo Sheng , Pumera Martin
Published: December 2015

3D‐printing represents an emerging technology that can revolutionize the way object and functional devices are fabricated. Here the use of metal 3D printing is demonstrated to fabricate bespoke electrochemical stainless steel electrodes that can be used as platform for different electrochemical applications ranging from electrochemical capacitors, oxygen evolution catalyst, and pH sensor by means of an effective and controlled deposition of IrO2 films. The electrodes have been characterized by scanning electrode microscopy and energy dispersive X‐ray spectroscopy before the electrochemical testing. Excellent pseudocapacitive as well as catalytic properties have been achieved with these 3D printed steel‐IrO2 electrodes in alkaline solutions. These electrodes also demonstrate Nernstian behavior as pH sensor. This work represents a breakthrough in on‐site prototyping and fabrication of highly tailored electrochemical devices with complex 3D shapes which facilitate specific functions and properties.
Conductive Screen Printing Inks by Gelation of Graphene Dispersions
Authors: Arapov Kirill , Rubingh Eric , Abbel Robert , Laven Jozua , de With Gijsbertus , Friedrich Heiner
Published: December 2015

This paper describes the gelation of highly concentrated graphene/polymer dispersions triggered by mild heating. The gel formation is only dependent on the concentration of graphene with 3.25 mg mL−1 as the minimum value for graphene network formation. The graphene gel is then utilized for the preparation of colloidally stable and highly concentrated (52 mg mL−1) graphene pastes that demonstrate excellent performance in screen printing down to lines of 40 μm in width. Printed patterns dried at 100 °C for only 5 min exhibit sheet resistances of 30 Ω −1 at 25 μm thickness, thus, removing the need for long‐time high temperature annealing, doping, or other treatments. Such a low drying temperature, high printing definition, and compatibility with industrially relevant plastic and paper substrates brings high‐volume roll‐to‐roll application in printed flexible electronics within reach.
Biogenic Crystallographically Continuous Aragonite Helices: The Microstructure of the Planktonic Gastropod Cuvierina
Authors: Willinger Marc G. , Checa Antonio G. , Bonarski Jan T. , Faryna Marek , Berent Katarzyna
Published: December 2015

The pteropod Cuvierina constructs very lightweight, thin, flexible, and resistant shells with the most unusual microstructure: densely packed, continuous crystalline aragonite fibers that coil helically around axes perpendicular to the shell surface. The high degree of fiber intergrowth results in a particular interlocking structure. The shell is constructed by guided self‐assembly, outside the animal's soft body. A prerequisite to understand its formation is to resolve the underlying crystallographic building principle. This is basic in order to use this hierarchically structured and highly functional biomaterial as inspiration for the production of new materials. It teaches us about the optimization of structures over millions of years of evolution under strict consideration of energetic costs and efficient use of available resources and materials. We have described how helical coiling proceeds by using a combination of diffraction and imaging techniques, which complement at different levels of resolution. Despite their curling, the fibers are continuously crystalline and show a preferred crystallographic growth direction. When the latter can no more be maintained due to the imposed curving, abrupt changes across twins permit to continue growth in the desired direction. This is a nice example of how crystallographically continuous fibers can grow helically.
Enhanced Differentiation of Human Embryonic Stem Cells Toward Definitive Endoderm on Ultrahigh Aspect Ratio Nanopillars
Authors: Rasmussen Camilla Holzmann , Reynolds Paul M. , Petersen Dorthe Roenn , Hansson Mattias , McMeeking Robert M. , Dufva Martin , Gadegaard Nikolaj
Published: December 2015

Differentiation of human embryonic stem cells is widely studied as a potential unlimited source for cell replacement therapy to treat degenerative diseases such as diabetes. The directed differentiation of human embryonic stem cells relies mainly on soluble factors. Although, some studies have highlighted that the properties of the physical environment, such as substrate stiffness, affect cellular behavior. Here, mass‐produced, injection molded polycarbonate nanopillars are presented, where the surface mechanical properties, i.e., stiffness, can be controlled by the geometric design of the ultrahigh aspect ratio nanopillars (stiffness can be reduced by 25.0003). It is found that tall nanopillars, yielding softer surfaces, significantly enhance the induction of definitive endoderm cells from pluripotent human embryonic stem cells, resulting in more consistent differentiation of a pure population compared to planar control. By contrast, further differentiation toward the pancreatic ­endoderm is less successful on “soft” pillars when compared to “stiff” pillars or control, indicating differential cues during the different stages of differentiation. To accompany the mechanical properties of the nanopillars, the concept of surface shear modulus is introduced to describe the characteristics of engineered elastic surfaces through micro or nanopatterning. This provides a framework whereby comparisons can be drawn between such materials and bulk elastomeric materials.
Design and Response of High‐Efficiency, Planar, Doped Luminescent Solar Concentrators Using Organic–Inorganic Di‐Ureasil Waveguides
Authors: Kaniyoor Adarsh , McKenna Barry , Comby Steve , Evans Rachel C.
Published: December 2015

Luminescent solar concentrators (LSCs) offer significant potential for solar energy capture in the urban environment. Here, the first example of a planar, doped LSC using Lumogen Red (LR305) as the luminophore and a di‐ureasil organic–inorganic hybrid as the waveguide is reported. The di‐ureasil waveguide offers several advantages over organic polymer waveguides including facile solution‐processing from benign solvents and extension of the absorption window through energy transfer. Spectral evaluation using absorption and photoluminescence spectroscopies is used to optimize the LSC composition, yielding optical efficiencies as high as 14.5% (300–800 nm). A power conversion efficiency (PCE) of 0.54% is obtained for the champion LSC coupled to a c‐Si PV cell using the di‐ureasil precursor as an optical glue to minimize interfacial losses. Finally, a simple figure of merit to evaluate the performance of LSC‐solar cell composite systems is proposed that enables comparison of the actual improvement in the efficiency of solar cells due to the attachment of the LSC, irrespective of the LSC design, architecture or materials. A PCE of 17.4% for the solar cell in the emission region of the LSC is obtained, which is a remarkable improvement of ≈40% over its AM 1.5G value.
Copper(II)/Silver(I)‐Catalyzed Sequential Alkynylation and Annulation of Aliphatic Amides with Alkynyl Carboxylic Acids: Efficient Synthesis of Pyrrolidones
Authors: Zhang Jitan , Li Danyang , Chen Hui , Wang Binjie , Liu Zhanxiang , Zhang Yuhong
Published: December 2015

A highly efficient protocol for the synthesis of pyrrolidones by the copper‐catalyzed alkynylation/annulation of aliphatic amides with alkynyl carboxylic acids is discussed in this paper. A broad range of easily accessible alkynyl carboxylic acids were introduced at the β‐methyl group of aliphatic amides with the assistance of an 8‐aminoquinolyl auxiliary group via decarboxylation to achieve the subsequent cyclic CN bond formation within one hour. High selectivity of β‐methyl groups over methylene groups was observed, and the extension of this catalytic system to the activation of methylene CH bonds failed. The substrates with two different groups at the α‐position of the aliphatic amides lead to the formation of diastereoisomers which is determined by 1H NMR spectroscopy. The initially produced products with Z‐configurations can be easily transformed to the corresponding products with E‐configurations by the treatment with dilute p‐toluenesulfonic acid after the reaction. This catalytic tandem decarboxylative cyclization provides a new opportunity for the direct functionalization of sp3 CH bonds.

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Click Grafting of Chitosan onto PVC Surfaces for Biomedical Applications
Authors: Mohy Eldin M. S. , Tamer T. M. , Abu Saied M. A. , Soliman E. A. , Madi N. K. , Ragab I. , Fadel I.
Published: December 2015

In this study, polyvinyl chloride (PVC) has been modified through click grafting of chitosan onto its surface. This goal has been achieved using three consecutive steps involving amination, activation, and grafting. Both the amination and chitosan grafting steps were confirmed based on the determination of nitrogen content. The chemical structure of the modified PVC membranes was confirmed by FTIR spectroscopy and thermal analysis, and the morphological changes were monitored by scanning electron microscopy. In addition, the induced physicochemical characteristics were investigated by analyzing the water uptake, mechanical properties, surface roughness, and contact angle. Finally, an evaluation of blood compatibility and protein adsorption characteristics for the chitosan‐g‐PVC membranes is presented.
A New Strategy for Achieving a High Performance Anode for Lithium Ion Batteries—Encapsulating Germanium Nanoparticles in Carbon Nanoboxes
Authors: Li Dan , Wang Hongqiang , Liu Hua Kun , Guo Zaiping
Published: December 2015

A novel strategy to improve the electrochemical performance of a germanium anode is proposed via encapsulating germanium nanoparticles in carbon nanoboxes by carbon coating the precursor, germanium dioxide cubes, and then subjecting them to a reduction treatment. The complete and robust carbon boxes are shown to not only provide extra void space for the expansion of germanium nanoparticles after lithium insertion but also offer a large reactive area and reduced distance for the lithium diffusion. Furthermore, the thus‐obtained composite, composed of densely stacked carbon nanoboxes encapsulating germanium nanoparticles (germanium@carbon cubes (Ge@CC)), exhibits a high tap density and improved electronic conductivity. Compared to carbon‐coated germanium bulks, the Ge@CC material shows excellent electrochemical properties in terms of both rate capability and cycling stability, due to the unique cubic core–shell structure and the effective carbon coating, so that the Ge@CC electrode delivers ≈497 mA h g−1 at a current rate of 30 C and shows excellent cycling stability of 1065.2 mA h g−1 at 0.5 C for over 500 cycles.
Green‐Solvent‐Processed All‐Polymer Solar Cells Containing a Perylene Diimide‐Based Acceptor with an Efficiency over 6.5%
Authors: Li Sunsun , Zhang Hao , Zhao Wenchao , Ye Long , Yao Huifeng , Yang Bei , Zhang Shaoqing , Hou Jianhui
Published: December 2015

To realize high power conversion efficiencies (PCEs) in green‐solvent‐processed all‐polymer solar cells (All‐PSCs), a long alkyl chain modified perylene diimide (PDI)‐based polymer acceptor PPDIODT with superior solubility in nonhalogenated solvents is synthesized. A properly matched PBDT‐TS1 is selected as the polymer donor due to the red‐shifted light absorption and low‐lying energy level in order to achieve the complementary absorption spectrum and matched energy level between polymer donor and polymer acceptor. By utilizing anisole as the processing solvent, an optimal efficiency of 5.43% is realized in PBDT‐TS1/PPDIODT‐based All‐PSC with conventional configuration, which is comparable with that of All‐PSCs processed by the widely used binary solvent. Due to the utilization of an inverted device configuration, the PCE is further increased to over 6.5% efficiency. Notably, the best‐performing PCE of 6.58% is the highest value for All‐PSCs employing PDI‐based polymer acceptors and green‐solvent‐processed All‐PSCs. The excellent photovoltaic performance is mainly attributed to a favorable vertical phase distribution, a higher exciton dissociation efficiency (Pdiss) in the blend film, and a higher electrode carrier collection efficiency. Overall, the combination of rational molecular designing, material selection, and device engineering will motivate the efficiency breakthrough in green‐solvent‐processed All‐PSCs.
Semiconducting Group 15 Monolayers: A Broad Range of Band Gaps and High Carrier Mobilities
Authors: Zhang Shengli , Xie Meiqiu , Li Fengyu , Yan Zhong , Li Yafei , Kan Erjun , Liu Wei , Chen Zhongfang , Zeng Haibo
Published: December 2015

Optoelectronic applications require materials both responsive to objective photons and able to transfer carriers, so new two‐dimensional (2D) semiconductors with appropriate band gaps and high mobilities are highly desired. A broad range of band gaps and high mobilities of a 2D semiconductor family, composed of monolayer of Group 15 elements (phosphorene, arsenene, antimonene, bismuthene) is presented. The calculated binding energies and phonon band dispersions of 2D Group 15 allotropes exhibit thermodynamic stability. The energy band gaps of 2D semiconducting Group 15 monolayers cover a wide range from 0.36 to 2.62 eV, which are crucial for broadband photoresponse. Significantly, phosphorene, arsenene, and bismuthene possess carrier mobilities as high as several thousand cm2 V−1 s−1. Combining such broad band gaps and superior carrier mobilities, 2D Group 15 monolayers are promising candidates for nanoelectronics and optoelectronics.
Activating a Low Overpotential CO2 Reduction Mechanism by a Strategic Ligand Modification on a Ruthenium Polypyridyl Catalyst
Authors: Johnson Ben A. , Maji Somnath , Agarwala Hemlata , White Travis A. , Mijangos Edgar , Ott Sascha
Published: December 2015

The introduction of a simple methyl substituent on the bipyridine ligand of [Ru(tBu3tpy)(bpy)(NCCH3)]2+ (tBu3tpy=4,4′,4′′‐tri‐tert‐butyl‐2,2′:6′,2′′‐terpyridine; bpy=2,2′‐bipyridine) gives rise to a highly active electrocatalyst for the reduction of CO2 to CO. The methyl group enables CO2 binding already at the one‐electron reduced state of the complex to enter a previously not accessible catalytic cycle that operates at the potential of the first reduction. The complex turns over with a Faradaic efficiency close to unity and at an overpotential that is amongst the lowest ever reported for homogenous CO2 reduction catalysts.
Molekulare Polyarsenide der Seltenerdelemente
Authors: Arleth Nicholas , Gamer Michael T. , Köppe Ralf , Konchenko Sergey N. , Fleischmann Martin , Scheer Manfred , Roesky Peter W.
Published: December 2015

Die Reduktion von [Cp*Fe(η5‐As5)] mit [Cp′′2Sm(thf)] (Cp′′=η5‐1,3‐(tBu)2C5H3) führt unter verschiedenen Reaktionsbedingungen zu [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] und [(Cp′′2Sm)2As7(Cp*Fe)]. Bei beiden Verbindungen handelt es sich um die ersten Polyarsenide der Seltenerdmetalle. [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] ist zudem der erste d/f‐Tripeldeckersandwichkomplex mit einem planaren rein anorganischen Mitteldeck. Die zentrale As42−‐Einheit ist isolobal zum 6π‐aromatischen Cyclobutadiendianion (CH)42−. [(Cp′′2Sm)2As7(Cp*Fe)] enthält einen As73−‐Käfig, der eine norbornadienartige Struktur mit zwei kurzen As‐As‐Bindungen hat. DFT‐Rechnungen bestätigen die strukturellen Beobachtungen. Abschätzungen ergaben, dass die As‐As‐Bindungsordnung innerhalb des cyclo‐As4‐Liganden in [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] zwischen einer As‐As‐Einfachbindung und der eines formal aromatischen As42−‐Systems liegt.
Interface Engineering in Two‐Dimensional Heterostructures: Towards an Advanced Catalyst for Ullmann Couplings
Authors: Sun Xu , Deng Haitao , Zhu Wenguang , Yu Zhi , Wu Changzheng , Xie Yi
Published: December 2015

The design of advanced catalysts for organic reactions is of profound significance. During such processes, electrophilicity and nucleophilicity play vital roles in the activation of chemical bonds and ultimately speed up organic reactions. Herein, we demonstrate a new way to regulate the electro‐ and nucleophilicity of catalysts for organic transformations. Interface engineering in two‐dimensional heteronanostructures triggered electron transfer across the interface. The catalyst was thus rendered more electropositive, which led to superior performance in Ullmann reactions. In the presence of the engineered 2D Cu2S/MoS2 heteronanostructure, the coupling of iodobenzene and para‐chlorophenol gave the desired product in 92 % yield under mild conditions (100 °C). Furthermore, the catalyst exhibited excellent stability as well as high recyclability with a yield of 89 % after five cycles. We propose that interface engineering could be widely employed for the development of new catalysts for organic reactions.
Visible‐Light‐Induced Hydrodifluoromethylation of Alkenes with a Bromodifluoromethylphosphonium Bromide
Authors: Lin Qing‐Yu , Xu Xiu‐Hua , Zhang Ke , Qing Feng‐Ling
Published: December 2015

Bromodifluoromethylphosphonium bromide was solely used as the precursor of difluorocarbene. Herein, an unprecedented visible‐light‐induced hydrodifluoromethylation of alkenes with bromodifluoromethylphosphonium bromide using H2O and THF as hydrogen sources for the synthesis of difluoromethylated alkanes is described. This difluoromethylation is characterized by mild reaction conditions, ready availability of reagents, and excellent functional‐group tolerance.
Palladium‐Catalyzed C(sp2)−H Alkylation of Aldehyde‐Derived Hydrazones with Functionalized Difluoromethyl Bromides
Authors: Prieto Alexis , Melot Romain , Bouyssi Didier , Monteiro Nuno
Published: December 2015

A palladium‐catalyzed C(sp2)−H difluoromethylation of aldehyde‐derived hydrazones using bromodifluoromethylated compounds to afford the corresponding functionalized difluoromethylketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a difluoroalkyl radical may be involved in the catalytic cycle. Applications of the methodology to the synthesis of α,α‐difluoro‐β‐ketoesters and α,α‐difluoroketones (RCOCF2H) have been illustrated.
Precision Synchronization Motion Trajectory Tracking Control of Multiple Pneumatic Cylinders
Authors: Meng Deyuan , Tao Guoliang , Li Aimin , Li Wei
Published: December 2015

This paper deals with the synchronized motion trajectory tracking control problem of multiple pneumatic cylinders. An adaptive robust synchronization controller is developed by incorporating the cross‐coupling technology into the integrated direct/indirect adaptive robust control (DIARC) architecture. The position synchronization error and the trajectory tracking error of each cylinder are combined to construct the so‐called coupled position error. The proposed adaptive robust synchronization controller is designed with the feedback of this coupled position error and is composed of two parts: an on‐line parameter estimation algorithm and a robust control law. The former is employed to obtain accurate estimates of model parameters for reducing the extent of parametric uncertainties, while the latter is utilized to attenuate the effects of parameter estimation errors, unmodelled dynamics, and external disturbances. Theoretically, both the position synchronization and trajectory tracking errors will achieve asymptotic convergence simultaneously. Moreover, the effectiveness of the proposed controller is verified by the extensive experimental results performed on a two‐cylinder pneumatic system.
Effects of the Dielectric Constant on the Association Equilibria of Aliphatic Monocarboxylic Acids in Solution
Authors: Conti Filippo , Franconi Cafiero
Published: December 2015

Measurements of shifts of the resonance of the hydroxylic protons of aliphatic monocarboxylic acids in binary and ternary mixtures with aprotic solvents made at a given concentration of acid show a linear dependence of the shift on the reciprocal of the dielectric constant of the medium.

Furthermore, interesting regularities in the paramagnetic dilution shifts of the pure acids are evidenced. These shifts are interpreted as an effect of the law of mass action on the complex equilibria in solution. It is shown that the equilibrium between the open and cyclic dimers might be the predominant equilibrium down to low concentrations.
Wasserstoffbrückenassoziation und Exzeßfunktionen von Mischungen aliphatischer Amine mit Kohlenwasserstoffen oder Tetrachlorkohlenstoff
Authors: Wolff H. , Höpfner A. , Höppel H.‐E.
Published: December 2015

Aus den Aktivitätskoeffizienten von Mischungen aliphatischer Amine mit Kohlenwasserstoffen oder Tetrachlorkohlenstoff werden die freie Exzeßenthalpie GE, die Mischungsenthalpie HE und das Entropieglied T · SE für Temperaturen zwischen + 20 und ‐ 30 °C berechnet. Dabei zeigt sich bei den Amin‐Kohlenwasserstoff‐Systemen:

Mit fallender Temperatur nimmt GE zu und nehmen HE sowie T. SE ab, bei gleichzeitiger Wanderung ihres Maximums zu kleineren Aminmolenbrüchen; mit wachsender Kettenlange des Amins nehmen die Exzeßfunktionen sämtlich ab, mit wachsender Kettenlange des Kohlenwasserstoffs aber sämtlich zu;

die Funktionen zweier Mischungen, die denselben Kohlenwasserstoff und im einen Fall das normale, im anderen aber das am N‐ oder C‐Atom deuterierte Amin enthalten, unterscheiden sich nur innerhalb der Fehlergrenzen; (HE/x1)x1→0, die integrale Lösungswärme der Amine bis zu unendlicher Verdünnung, liegt bei etwa 2000 cal/mol.

Die aufgezählten Beobachtungen lassen sich aus den bei der Verdünnung erfolgenden Änderungen der Wasserstoff‐ oder Deuteriumbrückenassoziation zwanglos deuten. Dabei belegt die Übereinstimmung, die die Funktionen der Systeme mit dem normalen und mit dem am N‐Atom deuterierten Amin innerhalb der Fehlergrenzen erkennen lassen, daß Wasserstoff‐ und Deuteriumbrückenassoziation sich höchstens geringfügig unterscheiden können. Der Wert von annähernd 2000 cal/mol für die integrale Lösungswärme bis zu unendlicher Verdünnung belegt, in Einklang mit früheren Berechnungen unmittelbar aus den Aktivitätskoeffizienten, daß die Assoziationsenergie der Aminmolekeln von ähnlicher Größe ist. Bei den nur für Dimethylamin berechneten Funktionen der Mischungen mit Tetrachlorkohlenstoff ist lediglich die Aussage möglich, daß GE nahezu 0 ist und HE sowie T · SE

wesentlich kleiner als bei Dimethylamin‐n‐Hexan sind. Dies entspricht der Deutung, daß in den Tetrachlorkohlenstofflösungen nicht nur zwischen den Aminmolekeln, sondern auch zwischen den Amin‐ und den Tetrachlorkohlenstoffmolekeln eine spezifische Wechselwirkung besteht.
Spektroskopische Untersuchungen an Chalkogenometallaten: Elektronenabsorptionsspektren von VS43−, MoO222−, WO2S22 und ReO3S−. Schwingungsspektren, Kraftkonstanten und mittlere Schwingungsamplituden von VO43−, VS43−, MoS42−, WS42− und ReO3S−
Authors: Müller A. , Krebs B. , Rittner W. , Stockburger M.
Published: December 2015

Die Elektronenabsorptionsspektren der Ionen VS43−, MoO222−, WO2S22 und ReO3S− in wäßriger Lösung werden mitgeteilt und diskutiert. Das Raman‐Spektrum des VO43− Ions in Lösung und das IR‐Spektrum von (NH4)3VS4 wurden gemessen. Mit Hilfe der Lasertechnik konnten die Raman‐Spektren der farbigen kristallinen Salze Cs2MoS4 (rot) und Cs2WS4 (gelb) aufgenommen werden. Kraftkonstanten eines allgemeinen und eines modifizierten Valenzkraftfeldes sowie des Urey‐Bradley‐Kraftmodells sind für VO43−, VS43−, MoS42− und WS42− angegeben. Nach der L‐Matrix‐Methode von Morino wurden mittlere Schwingungsamplituden bei 298 °K für diese lonen berechnet. Für ReO3S− werden Kraftkonstanten unter Annahme einer diagonalen F‐Matrix mitgeteilt. Die Valenzkraftkonstanten aller Ionen werden im Zusammenhang mit den Bindungsverhältnissen diskutiert.
Zur elektrischen Leitfähigkeit in nematischen Lösungen
Authors: Heppke G. , Schneider F.
Published: December 2015

Es wird die äquivalentleitfähigkeit von Tetrapropylammoniumpikrat (TPAP) in N‐(p‐Methoxybenzyliden)‐p‐n‐butylanilin (MBBA) in Abhängigkeit von der Konzentration (7 ± 10−6 bis 5 ± 10−3 mol/l) und der Temperatur (16 bis 65°C) bestimmt. Die Meßwerte werden mit einem von Fuoss und Kraus angegebenen Verfahren auf unendliche Verdünnung extrapoliert.

Die Abhängigkeit der Leitfähigkeit vom Winkel zwischen dem Magnetfeld, das zur Ausrichtung der nematischen Phase dient, und dem elektrischen Feld wird untersucht. Das Verhältnis der Extremwerte der Leitfähigkeit bleibt bei Konzentrationen unterhalb von 10−3 mol/l konstant. Die änderung dieses Anisotropieverhältnisses mit der Temperatur läßt sich, wie ein Vergleich mit bekannten Werten der Brechungsindizes zeigt, auf die Temperaturabhängigkeit des Ordnungsgrades zurückführen.
Einflüsse der Gasadsorption auf die Feldionisation an Eisen‐und Platinoberflächen
Authors: Schmidt W. A. , Frank O. , Block J. H.
Published: December 2015

Es werden Einsatzspannungen der Feldionisation an Fe‐und Pt‐Emittern für die Edelgase Ar, Kr und Xe und für O2, CO, N2 und H2 massenspektrometrisch gemessen. Für die Edelgase erfolgt der Ionisationseinsatz an gereinigten Emitteroberflächen nach dem von der Theorie geforderten Zusammenhang zwischen Ionisierungsspannung des Gases und Austrittsarbeit des Metalles. Für die übrigen Gase werden erniedrigte oder erhöhte Einsatzspannungen gefunden, die durch adsorptionsbedingte Austrittsarbeitsänderungen nicht erklärt werden können.

Es werden Einflüsse auf den Feldionisationsprozeß diskutiert, wobei chemische Wechselwirkungen und geänderte Elektronendichteverteilungen an der Emitteroberfläche in Betracht gezogen werden.
Substitution reactions of beryllium(II) ion in mixed solvents IV. Beryllium sulphate complexes in water‐hexamethylphosphoric triamide mixtures
Authors: Strehlow H. , Devia D. H. , Dagnall S. , Busse G.
Published: December 2015

Using conductivity and pressure jump relaxation measurements the complex formation of BeSO4 has been studied in mixtures of water and hexamethylphosphoric triamide (HMPT). The rate of substitution of a solvent molecule in the inner solvation sheath of the beryllium ion by a sulphate ion depends on the composition of the solvate species Be(HMPT)i(H2O)4‐i and on the type of solvent molecule being replaced by the sulphate ion. Above a mole fraction xHMPT ≥ 0.2 six relaxation processes have been observed. From the conductivity and the kinetic measurements the existence of a Be(SO4)22− complex was inferred in the mixed solvents. Measurements of the densities, dielectric constants and viscosities of the solvent mixtures are reported.
Interaction of carbon monoxide and hydrogen with metal films of Fe, Co, Ni, and FeCo‐alloy
Authors: Dittrich Th. , Buschmann H. W. , Vielstich W.
Published: December 2015

The interaction of carbon monoxide and hydrogen with metal films of Fe, Co, Ni, and FeCo‐alloy has been investigated by means of thermal desorption mass spectrometry. ‐ Since no exchange was observed between different CO‐isotopes adsorbed, desorption of CO can be treated as a first order reaction. At low coverages, the activation energies of desorption have been measured as 83,133,116, and 67 kJ/mol for Fe, Co, Ni, and FeCo‐alloy respectively. ‐ Hydrogen is adsorbed dissociatively. At low coverages the activation energies of desorption have been found to be 65, 110, 82, and 60 kJ/mol resp. ‐ The rate constants for desorption of both, CO and H2, strongly increase with increasing coverage. At saturation coverage, a dynamic equilibrium between the gas phase and the adsorbed molecules is established. ‐ CO inhibits the adsorption of H2 and displaces preadsorbed H2 in part. No reaction products have been observed following the coadsorption or the consecutive adsorption of CO and H2. ‐ The kinetics of the systems can be described by a system of coupled differential equations. The according solutions show that the pressure should exceed 0.1 Torr in order to observe CH‐reaction products, provided that the rate determining step of hydrocarbon formation is the hydrogenation of carbidic C‐atoms.
Two are Better Than One: The Link Between Management Systems and Business Performance
Authors: Ferrón Vílchez Vera , Darnall Nicole
Published: December 2015

Little is known about the complementary performance benefits associated with facilities’ combined use of both quality management systems (QMSs) and environmental management systems (EMSs), and how these performance benefits might differ from those associated with facilities’ use of only one of these management systems (or neither). We suggest that complementarities arise because each management system fosters the development of internal capabilities that facilitates the adoption and routine operationalization of the other, while maintaining differentiated goals that enhance strategic value. We examine these relationships using a sample of 2619 manufacturing facilities operating within six OECD countries, while controlling for self‐selection issues. Our findings support the idea of complementarity, in that facilities that adopt both QMS and EMS are more associated with positive business performance than facilities that adopt either a QMS or an EMS on its own, or no management system. Copyright © 2014 John Wiley & Sons, Ltd and ERP Environment
Numerical Study of Natural Convection in a Porous Cavity with Sinusoidal Thermal Boundary Condition
Authors: Wu Feng , Wang Gang , Zhou Wenjing
Published: December 2015

The steady natural convection in a rectangular cavity filled with a heat‐generating porous medium was numerically investigated using a thermal non‐equilibrium model for the heat transfer between the fluid and solid phases. All of the walls of the enclosure are adiabatic, except for the left wall, which is partially heated and cooled by a spatial sinusoidal temperature profile. The results show that the temperature fields near the left wall and the local Nusselt number of the left wall vary periodically because of the sinusoidal boundary condition. There exists an optimal fluctuant parameter of N (N = 3) to maximize the heat transfer rate of the fluid phase in the square enclosure. The periodicity parameter N has a significant influence on the value of the average Nusselt number of the fluid phase when the Darcy and Rayleigh numbers increase.
Foam Formation in Biogas Plants – A Survey on Causes and Control Strategies
Authors: Lindorfer Harald , Demmig Claudia
Published: December 2015

Experiences of numerous full‐scale biogas plants on spontaneous foam formation were evaluated. Focus was laid on the feedstock mix, the causes of foaming, and control strategies. Mostly, the main digester was affected, but excessive foam formation in the post digester was found as well. The feedstock mix was stated as the main cause of foam formation followed by process troubles, abrupt degassing, temperature changes, and changes in viscosity. In the feedstock of plants affected by foaming, manure, cereals, sugar beets, and cosubstrates were used most often. Successful control strategies were gathered and categorized into seven groups: emergency measures, application of antifoam additives, avoidance of foam‐forming substrates, prevention of process upsets, changes of physicochemical conditions, optimization of mixing, and installation of technical equipment against foam formation.
Planarized Intramolecular Charge Transfer: A Concept for Fluorophores with both Large Stokes Shifts and High Fluorescence Quantum Yields
Authors: Haberhauer Gebhard , Gleiter Rolf , Burkhart Christoph
Published: December 2015

Fluorophores were successfully used in several areas of chemistry and biochemistry. For many purposes, however, it is necessary that the fluorescence compound features a high fluorescence quantum yield as well as a large Stokes shift. The latter is, for example, achieved by the use of a twisted intramolecular charge‐transfer (TICT) compound, which shows a twisted geometry in the excited state. However, the higher the twisting is, the lower becomes in general the fluorescence quantum yield as the resulting emission from the twisted state is forbidden. In order to escape this dilemma, we propose the model of planarized intramolecular charge‐transfer (PLICT) states. These compounds are completely twisted in the ground states and planar in the excited states. By means of quantum chemical calculations (time‐dependent (TD)‐B3LYP and CC2) and experimental studies, we could demonstrate that 1‐aminoindole and its derivatives form photoinduced PLICT states. They show both very large Stokes shifts (
=9000–13 500 cm−1, i.e., λ=100–150 nm) and high fluorescence quantum yields. These characteristics and their easy availability starting from the corresponding indoles, make them very attractive for the use as optical switches in various fields of chemistry as well as biological probes.
A Hexameric Cationic Copper(II) Metallacrown as a Pertechnetate and Perrhenate Scavenger
Authors: Rodríguez‐Hermida Sabina , Lago Ana Belén , Pino‐Cuevas Arantxa , Hagenbach Adelheid , Cañadillas‐Delgado Laura , Carballo Rosa , Abram Ulrich , Vázquez‐López Ezequiel M.
Published: December 2015

Materials based on the cationic copper(II) hexanuclear 18‐membered metallacrown [18‐MC
‐6]6+ (2phH=2‐piconyl hydrazide) and tetrafluoroborate, perchlorate, nitrate, sulfate, and perrhenate anions were prepared by an easy method in aqueous medium. Single‐crystal X‐ray characterization of six members of this new family of complexes showed that the anions are attached to the metallacrown by direct coordination to a copper cation or by hydrogen‐bonding interaction with the center of the hexamer. The stable cationic nature of the complexes and their ability to bind different anions allows them to adsorb and immobilize environmentally relevant anions such as MO4− (M=Tc, Re). The MO4− trapping capacities suggest that these materials would be useful in the treatment of oxoanionic contaminants in water.
N‐Alkyl Ammonium Resorcinarene Salts as High‐Affinity Tetravalent Chloride Receptors
Authors: Beyeh N. Kodiah , Pan Fangfang , Bhowmik Sandip , Mäkelä Toni , Ras Robin H. A. , Rissanen Kari
Published: December 2015

N‐Alkyl ammonium resorcinarene salts (NARYs, Y=triflate, picrate, nitrate, trifluoroacetates and NARBr) as tetravalent receptors, are shown to have a strong affinity for chlorides. The high affinity for chlorides was confirmed from a multitude of exchange experiments in solution (NMR and UV/Vis), gas phase (mass spectrometry), and solid‐state (X‐ray crystallography). A new tetra‐iodide resorcinarene salt (NARI) was isolated and fully characterized from exchange experiments in the solid‐state. Competition experiments with a known monovalent bis‐urea receptor (5) with strong affinity for chloride, reveals these receptors to have a much higher affinity for the first two chlorides, a similar affinity as 5 for the third chloride, and lower affinity for the fourth chloride. The receptors affinity toward chloride follows the trend K1≫K2≫K3≈5>K4, with Ka=5011 m−1 for 5 in 9:1 CDCl3/[D6]DMSO.
Ruthenium‐Catalyzed Multicomponent Reactions: Access to α‐Silyl‐β‐Hydroxy Vinylsilanes, Stereodefined 1,3‐Dienes, and Cyclohexenes
Authors: Trost Barry M. , Koester Dennis C. , Sharif Ehesan U.
Published: December 2015

The synthesis of densly functionized α‐silyl‐β‐hydroxyl vinylsilanes via ruthenium‐catalyzed multicomponent reaction (MCR) is reported herein. Exceptionally high regio‐ and diastereoselectivity was achieved by employing an unprecedented hydrosilylation of bifunctional silyl‐propargyl boronates. The simple protocol, mild reaction conditions, and unique tolerability of this method make it a valuable tool for the synthesis of highly elaborated building blocks. The one‐pot synthesis of stereodefined olefins, the generation of a valuable cyclohexene building block through a four‐component MCR, and further functionalization in an abundance of diastereoselective reactions is disclosed herein.
How To Design a Successful p53–MDM2/X Interaction Inhibitor: A Thorough Overview Based on Crystal Structures
Authors: Estrada‐Ortiz Natalia , Neochoritis Constantinos G. , Dömling Alexander
Published: December 2015

A recent therapeutic strategy in oncology is based on blocking the protein–protein interaction between the murine double minute (MDM) homologues MDM2/X and the tumor‐suppressor protein p53. Inhibiting the binding between wild‐type (WT) p53 and its negative regulators MDM2 and/or MDMX has become an important target in oncology to restore the antitumor activity of p53, the so‐called guardian of our genome. Interestingly, based on the multiple disclosed compound classes and structural analysis of small‐molecule–MDM2 adducts, the p53–MDM2 complex is perhaps the best studied and most targeted protein–protein interaction. Several classes of small molecules have been identified as potent, selective, and efficient inhibitors of the p53–MDM2/X interaction, and many co‐crystal structures with the protein are available. Herein we review the properties as well as preclinical and clinical studies of these small molecules and peptides, categorized by scaffold type. A particular emphasis is made on crystallographic structures and the observed binding modes of these compounds, including conserved water molecules present.
Little Thermodynamic Penalty for the Synthesis of Ultraporous Metal Organic Frameworks
Authors: Akimbekov Zamirbek , Navrotsky Alexandra
Published: December 2015

Many metal–organic frameworks (MOFs) of ultrahigh porosity (with molar volumes more than ten times greater than those of the corresponding dense phases) have been synthesized. However, the number of possible structures far exceeds those that have been made. It is logical to ask if there are energetic barriers to the stability of ultraporous MOFs or whether there is little thermodynamic penalty to their formation. Herein, we show that although the molar volumes of MOF‐177 and UMCM‐1 reach ultrahigh values, their energetic metastability is in the same range (of 7–36 kJ mol−1) as that seen previously for other porous materials. These findings suggest that there is little thermodynamic penalty for the synthesis of structures with varying porosity, and hence, ultraporous frameworks are energetically accessible. Therefore, innovative synthesis methods have the possibility to overcome the drawbacks of conventional approaches and greatly extend the number, porosity, and properties of new framework materials.