bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eastern Olympus Mons Basal Scarp: Structural and mechanical evidence for large‐scale slope instability
Authors: Weller M. B. , McGovern P. J. , Fournier T. , Morgan J. K. 
Published: April 2014

AbstractThe expression of the Eastern Olympus Mons Basal Scarp (EOMBS) is seemingly unique along the edifice. It exhibits two slope‐parallel structures: a nearly 100 km long upslope extensional normal fault system and a downslope contractional wrinkle ridge network, a combination that is found nowhere else on Olympus Mons. Through structural mapping and numerical modeling of slope stability of the EOMBS, we show that these structures are consistent with landsliding processes and volcanic spreading. The EOMBS is conditionally stable when the edifice contains pore fluid, and critically stable, or in failure, when the edifice contains a dipping overpressured confined aquifer and mechanical sublayer at depth. Failure of the fault‐bounded portion of the flank results in estimated volumes of material ranging from 5600–6900 km3, or 32–39% of the estimated volume of the “East” Olympus Mons aureole lobe. We suggest that the EOMBS faults may be an expression of early stage flank collapse and aureole lobe formation. Ages of deformed volcano adjacent plains associated with the wrinkle ridges indicate that this portion of the edifice may have been tectonically active at < 50 Ma and may be coeval with estimated ages of adjacent outflow channels, 25–40 Ma. This observation suggests that conditions that favor flank failure, such as water at depth below the edifice, existed in the relatively recent past and potentially could drive deformation to the present day.
Numerical simulations of bedrock valley evolution by meandering rivers with variable bank material
Authors: Limaye Ajay B. S. , Lamb Michael P. 
Published: April 2014

AbstractBedrock river valleys are fundamental components of many landscapes, and their morphologies—from slot canyons with incised meanders to wide valleys with strath terraces—may record environmental history. Several formation mechanisms for particular valley types have been proposed that involve changes in climatic and tectonic forcing, but the uniqueness of valley evolution pathways and the long‐term stability of valley morphology under constant forcing are unknown and are not predicted in existing numerical models for vertically incising rivers. Because rivers often migrate more rapidly through alluvium than through bedrock, we explore the hypothesis that the distribution of bank materials strongly influences river meandering kinematics and can explain the diversity of bedrock river valley morphology. Simulations using a numerical model of river meandering with vector‐based bank‐material tracking indicate that channel lateral erosion rate in sediment and bedrock, vertical erosion rate, and initial alluvial‐belt width explain first‐order differences in bedrock valley type; that bedrock‐bound channels can evolve under steady forcing from alluvial states; and that weak bedrock and low vertical incision rates favor wide, shallow valleys, while resistant bedrock and high vertical incision rates favor narrow, deep valleys. During vertical incision, sustained planation of the valley floor is favored when bedrock boundaries restrict channel migration to a zone of thin sediment fill. The inherent unsteadiness of river meandering in space and time is enhanced by evolving spatial contrasts in bank strength between sediment and bedrock and can account for several valley features—including strath terraces and underfit valleys—commonly ascribed to external drivers.
Multidecadal modulations of the low‐frequency climate variability in the wintertime North Pacific since 1950
Authors: Miyasaka Takafumi , Nakamura Hisashi , Taguchi Bunmei , Nonaka Masami 
Published: April 2014

AbstractThe North Pacific decadal variability (PDV) is known to manifest itself as two distinct spatial patterns. Observations since 1950 reveal that the wintertime PDV underwent notable modulations of their dominance in sea surface temperature (SST) variability and accompanying atmospheric variability. Until the 1980s, decadal SST variability was strongest along the subarctic frontal zone (SAFZ), the boundary between the warm Kuroshio and cool Oyashio waters. The SAFZ variability was highly correlated with decadal variability of the surface Aleutian Low but not simultaneously with tropical SST variability. Since the 1990s, however, this extratropical ocean‐atmosphere variability has lost its predominance, taken over by SST variability in the subtropical frontal zone. It accompanies subtropical anticyclone variability, exhibiting significant anticorrelation with tropical SST variability. These long‐term PDV modulations have remotely modulated temperature variability over Canada and Alaska. Similar PDV modulations are simulated in a centennial integration of a global climate model.
Image processing of multiphase images obtained via X‐ray microtomography: A review
Authors: Schlüter Steffen , Sheppard Adrian , Brown Kendra , Wildenschild Dorthe 
Published: April 2014

AbstractEasier access to X‐ray microtomography (μCT) facilities has provided much new insight from high‐resolution imaging for various problems in porous media research. Pore space analysis with respect to functional properties usually requires segmentation of the intensity data into different classes. Image segmentation is a nontrivial problem that may have a profound impact on all subsequent image analyses. This review deals with two issues that are neglected in most of the recent studies on image segmentation: (i) focus on multiclass segmentation and (ii) detailed descriptions as to why a specific method may fail together with strategies for preventing the failure by applying suitable image enhancement prior to segmentation. In this way, the presented algorithms become very robust and are less prone to operator bias. Three different test images are examined: a synthetic image with ground‐truth information, a synchrotron image of precision beads with three different fluids residing in the pore space, and a μCT image of a soil sample containing macropores, rocks, organic matter, and the soil matrix. Image blur is identified as the major cause for poor segmentation results. Other impairments of the raw data like noise, ring artifacts, and intensity variation can be removed with current image enhancement methods. Bayesian Markov random field segmentation, watershed segmentation, and converging active contours are well suited for multiclass segmentation, yet with different success to correct for partial volume effects and conserve small image features simultaneously.
Online concurrent reinforcement learning algorithm to solve two‐player zero‐sum games for partially unknown nonlinear continuous‐time systems
Authors: Yasini Sholeh , Karimpour Ali , Naghibi Sistani Mohammad‐Bagher , Modares Hamidreza 
Published: April 2014

SummaryOnline adaptive optimal control methods based on reinforcement learning algorithms typically need to check for the persistence of excitation condition, which is necessary to be known a priori for convergence of the algorithm. However, this condition is often infeasible to implement or monitor online. This paper proposes an online concurrent reinforcement learning algorithm (CRLA) based on neural networks (NNs) to solve the H ∞  control problem of partially unknown continuous‐time systems, in which the need for persistence of excitation condition is relaxed by using the idea of concurrent learning. First, H ∞  control problem is formulated as a two‐player zero‐sum game, and then, online CRLA is employed to obtain the approximation of the optimal value and the Nash equilibrium of the game. The proposed algorithm is implemented on actor–critic–disturbance NN approximator structure to obtain the solution of the Hamilton–Jacobi–Isaacs equation online forward in time. During the implementation of the algorithm, the control input that acts as one player attempts to make the optimal control while the other player, that is, disturbance, tries to make the worst‐case possible disturbance. Novel update laws are derived for adaptation of the critic and actor NN weights. The stability of the closed‐loop system is guaranteed using Lyapunov technique, and the convergence to the Nash solution of the game is obtained. Simulation results show the effectiveness of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.
A Flexible Solution to Anion Transport: Powerful Anionophores Based on a Cyclohexane Scaffold
Authors: Cooper James A. , Street Steven T. G. , Davis Anthony P. 
Published: April 2014

AbstractTransmembrane anion carriers (anionophores) have potential for biological activity, including the treatment of channelopathies such as cystic fibrosis. A new family of anionophores has been synthesized, in which three thiourea groups are mounted on a cyclohexane‐based scaffold. Though conceptually related to earlier polycyclic systems, these molecules are simpler and far more accessible. Preorganization is somewhat reduced compared to earlier systems, and anion affinities are correspondingly lower. However, transport activities set new records. This surprising performance suggests a role for controlled flexibility in the design of transmembrane anion carriers.
White‐Light‐Emitting Edge‐Functionalized Graphene Quantum Dots
Authors: Sekiya Ryo , Uemura Yuichiro , Murakami Hideki , Haino Takeharu 
Published: April 2014

AbstractGraphene quantum dots (GQDs) have received considerable attention for their potential applications in the development of novel optoelectronic materials. In the generation of optoelectronic devices, the development of GQDs that are regulated in terms of their size and dimensions and are unoxidized at the sp2 surfaces is desired. GQDs functionalized with bulky Fréchet’s dendritic wedges at the GQD periphery were synthesized. The single‐layered, size‐regulated structures of the dendronized GQDs were revealed by atomic force microscopy. The edge‐functionalization of the GQDs led to white‐light emission, which is an uncommon feature.
Trinuclear Pd3O2 Intermediate in Aerobic Oxidation Catalysis
Authors: Ingram Andrew J. , Solis‐Ibarra Diego , Zare Richard N. , Waymouth Robert M. 
Published: April 2014

AbstractThe activation of O2 is a key step in selective catalytic aerobic oxidation reactions mediated by transition metals. The bridging trinuclear palladium species, [(LPdII)3(μ3‐O)2]2+ (L=2,9‐dimethylphenanthroline), was identified during the [LPd(OAc)]2(OTf)2‐catalyzed aerobic oxidation of 1,2‐propanediol. Independent synthesis, structural characterization, and catalytic studies of the trinuclear compound show that it is a product of oxygen activation by reduced palladium species and is a competent intermediate in the catalytic aerobic oxidation of alcohols. The formation and catalytic activity of the trinuclear Pd3O2 species illuminates a multinuclear pathway for aerobic oxidation reactions catalyzed by Pd complexes.
Supramolecular Polymerization Promoted and Controlled through Self‐Sorting
Authors: Huang Zehuan , Yang Liulin , Liu Yiliu , Wang Zhiqiang , Scherman Oren A. , Zhang Xi 
Published: April 2014

AbstractA new method in which supramolecular polymerization is promoted and controlled through self‐sorting is reported. The bifunctional monomer containing p‐phenylene and naphthalene moieties was prepared. Supramolecular polymerization is promoted by selective recognition between the p‐phenylene group and cucurbit[7]uril (CB[7]), and 2:1 complexation of the naphthalene groups with cucurbit[8]uril (CB[8]). The process can be controlled by tuning the CB[7] content. This development will enrich the field of supramolecular polymers with important advances towards the realization of molecular‐weight and structural control.
Magnesiacyclopentadienes as Alkaline‐Earth Metallacyclopentadienes: Facile Synthesis, Structural Characterization, and Synthetic Application
Authors: Wei Junnian , Liu Liang , Zhan Ming , Xu Ling , Zhang Wen‐Xiong , Xi Zhenfeng 
Published: April 2014

AbstractMetallacyclopentadienes have attracted much attention as building blocks for synthetic chemistry as well as key intermediates in many metal‐mediated or metal‐catalyzed reactions. However, metallacyclopentadienes of the alkaline‐earth metals have not been reported, to say nothing of their structures, reaction chemistry, and synthetic applications. In this work, the first series of magnesiacyclopentadienes, spiro‐dilithio magnesiacyclopentadienes, and dimagnesiabutadiene were synthesized from 1,4‐dilithio 1,3‐butadienes. Single‐crystal X‐ray structural analysis of these magnesiacycles revealed unique structural characteristics and bonding modes. Their reaction chemistry and synthetic application were preliminarily studied and efficient access to amino cyclopentadienes was established through their reaction with thioformamides. Experimental and DFT calculations demonstrated that these magnesiacyclopentadienes could be regarded as bis(Grignard) reagents wherein the two MgC(sp2) bonds have a synergetic effect when reacting with substrates.
Pressure‐Induced Bond Rearrangement and Reversible Phase Transformation in a Metal–Organic Framework
Authors: Spencer Elinor C. , Kiran Mangalampalli S. R. N. , Li Wei , Ramamurty Upadrasta , Ross Nancy L. , Cheetham Anthony K. 
Published: April 2014

AbstractPressure‐induced phase transformations (PIPTs) occur in a wide range of materials. In general, the bonding characteristics, before and after the PIPT, remain invariant in most materials, and the bond rearrangement is usually irreversible due to the strain induced under pressure. A reversible PIPT associated with a substantial bond rearrangement has been found in a metal–organic framework material, namely [tmenH2][Er(HCOO)4]2 (tmenH22+=N,N,N′,N′‐tetramethylethylenediammonium). The transition is first‐order and is accompanied by a unit cell volume change of about 10 %. High‐pressure single‐crystal X‐ray diffraction studies reveal the complex bond rearrangement through the transition. The reversible nature of the transition is confirmed by means of independent nanoindentation measurements on single crystals.
Heterocycle Synthesis Based on Allylic Alcohol Transposition Using Traceless Trapping Groups
Authors: Xie Youwei , Floreancig Paul E. 
Published: April 2014

AbstractAllylic alcohols undergo transposition reactions in the presence of Re2O7 whereby the equilibrium can be dictated by trapping one isomer with a pendent electrophile. Additional ionization can occur when the trapping group is an aldehyde or ketone, thus leading to cyclic oxocarbenium ion formation. Terminating the process through bimolecular nucleophilic addition into the intermediate provides a versatile method for the synthesis of diverse oxygen‐containing heterocycles. Understanding the relative rates of the steps in the sequence leads to the design of reactions which create multiple stereocenters with good to excellent levels of control.
Programmable Polymer‐Based Supramolecular Temperature Sensor with a Memory Function
Authors: Sambe Léna , de La Rosa Victor R. , Belal Khaled , Stoffelbach François , Lyskawa Joel , Delattre François , Bria Marc , Cooke Graeme , Hoogenboom Richard , Woisel Patrice 
Published: April 2014

AbstractA new class of polymeric thermometers with a memory function is reported that is based on the supramolecular host–guest interactions of poly(N‐isopropylacrylamide) (PNIPAM) with side‐chain naphthalene guest moieties and the tetracationic macrocycle cyclobis(paraquat‐p‐phenylene) (CBPQT4+) as the host. This supramolecular thermometer exhibits a memory function for the thermal history of the solution, which arises from the large hysteresis of the thermoresponsive LCST phase transition (LCST=lower critical solution temperature). This hysteresis is based on the formation of a metastable soluble state that consists of the PNIPAM–CBPQT4+ host–guest complex. When heated above the transition temperature, the polymer collapses, and the host–guest interactions are disrupted, making the polymer more hydrophobic and less soluble in water. Aside from providing fundamental insights into the kinetic control of supramolecular assemblies, the developed thermometer with a memory function might find use in applications spanning the physical and biological sciences.
A Rapid Synthesis of 4‐Oxazolidinones: Total Synthesis of Synoxazolidinones A and B
Authors: Shymanska Nataliia V. , An Il Hwan , Pierce Joshua G. 
Published: April 2014

AbstractA five‐step total synthesis of the marine natural product synoxazolidinone A was achieved through a diastereoselective imine acylation/cyclization cascade. Synoxazolidinone B and a series of analogues were also prepared to explore the potential of these 4‐oxazolidinone natural products as antimicrobial agents. These studies confirmed the importance of the chlorine substituent for antimicrobial activity and revealed simplified dichloro derivatives that are equally potent against several bacterial strains.
Altering associations of doxorubicin‐loaded alginate esters micelles in presence of β‐cyclodextrin
Authors: Zhou Qiquan , Yang Jisheng 
Published: April 2014

ABSTRACTThe aim of this article was to evaluate the effects of β‐cyclodextrin (β‐CD) on doxorubicin (DOX)‐loaded alginate esters (SA‐C16) micelles (DOX/SA‐C16) in aqueous solution. DOX was physically loaded into SA‐C16 micelles by an o/w emulsion method with a substantial encapsulation efficiency (EE) level (36.12%), and DOX/SA‐C16 was distributed in size diameters of approximately 254 nm. SA‐C16 as carriers for the DOX can lead to the formation of associative networks in aqueous solutions between the hydrophobic tails of SA‐C16 and DOX, and the dried morphology of DOX/SA‐C16 aggregate was spherical shape. Addition of β‐CD to the system of DOX/SA‐C16 facilitated decoupling of these associations via inclusion complex formation between β‐CD cavities and the polymer hydrophobic tails that produced the release of DOX immediately, and the EE level was dropped to 0.08%, and at the same time the size distribution of aggregate was increased to about 413 nm, moreover, the aggregate was relatively large and becoming irregular spherical shape. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40702.
Alkaline fungal degradation of oxidized polyethylene in black liquor: Studies on the effect of lignin peroxidases and manganese peroxidases
Authors: Mukherjee Shritama , Kundu Patit P. 
Published: April 2014

ABSTRACTHigh‐molecular‐weight polyethylene is resistant to natural environmental degradation for its crystalline, hydrophobic structure. In this study, waste polyethylene bags are chemically oxidized at 80°C for 5 days by potassium dichromate solutions of various concentrations along with sulfuric acid. Absorbance peaks of carbonyl and carboxylate ions in the Fourier transform infrared spectroscopy spectra and formation of amorphous phase from crystalline one as indicated in X ray diffraction studies of oxidized polyethylenes indicate the formation of a polar hydrophilic and low‐molecular‐weight material after oxidation. From the scanning electron microscopy studies, it is observed that reacted polyethylene surface is disintegrated and numerous fissures are formed throughout the surface. The respective weight loss of incubated oxidized polyethylene with Phanerochaete chrysosporium (MTCC‐787) after 15 days of incubation is 70%, respectively, in black liquor–glucose–malt extract medium. As both lignin peroxidase (LiP) and manganese peroxidase (MnP) were detected in this media, further degradation of oxidized polyethylene is carried out in four different media with varying amount of N and Mn. The weight loss is observed only in media with excess nitrogen (N) and limited manganese (Mn), the condition which enhances the presence of LiP and MnP. This indicates that these enzymes are essential for degradation of lignin as well as oxidized polyethylene. UV spectroscopic studies indicate 40% decrease in the lignin concentration. This process of fungal degradation of chemically oxidized polyethylene using black liquor is very quick compared to the other related studies, leading to the simultaneous degradation of two waste materials, polyethylene and black liquor. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40738.
Nonsyndromic cleft lip with or without cleft palate: Increased burden of rare variants withinGremlin‐1, a component of the bone morphogenetic protein 4 pathway
Authors: Al Chawa Taofik , Ludwig Kerstin U. , Fier Heide , Pötzsch Bernd , Reich Rudolf H. , Schmidt Gül , Braumann Bert , Daratsianos Nikolaos , Böhmer Anne C. , Schuencke Hannah , Alblas Margrieta , Fricker Nadine , Hoffmann Per , Knapp Michael , Lange Christoph , Nöthen Markus M. , Mangold Elisabeth 
Published: April 2014

BackgroundThe genes Gremlin‐1 (GREM1) and Noggin (NOG) are components of the bone morphogenetic protein 4 pathway, which has been implicated in craniofacial development. Both genes map to recently identified susceptibility loci (chromosomal region 15q13, 17q22) for nonsyndromic cleft lip with or without cleft palate (nsCL/P). The aim of the present study was to determine whether rare variants in either gene are implicated in nsCL/P etiology.MethodsThe complete coding regions, untranslated regions, and splice sites of GREM1 and NOG were sequenced in 96 nsCL/P patients and 96 controls of Central European ethnicity. Three burden and four nonburden tests were performed. Statistically significant results were followed up in a second case‐control sample (n = 96, respectively). For rare variants observed in cases, segregation analyses were performed.ResultsIn NOG, four rare sequence variants (minor allele frequency < 1%) were identified. Here, burden and nonburden analyses generated nonsignificant results. InGREM1, 33 variants were identified, 15 of which were rare. Of these, five were novel. Significantp‐values were generated in three nonburden analyses. Segregation analyses revealed incomplete penetrance for all variants investigated.ConclusionOur study did not provide support for NOG being the causal gene at 17q22. However, the observation of a significant excess of rare variants inGREM1supports the hypothesis that this is the causal gene at chr. 15q13. Because no single causal variant was identified, future sequencing analyses ofGREM1should involve larger samples and the investigation of regulatory elements.Birth Defects Research (Part A) 100:493–498, 2014. © 2014 Wiley Periodicals, Inc.
Development and thermodynamic evaluation of novel lipid raft stationary phase chromatography for screening potential antitumor agents
Authors: Tong Shanshan , Sun Chaonan , Cao Xia , Zheng Qianfeng , Zhang Huiyun , Firempong Caleb Kesse , Feng Yingshu , Yang Yan , Yu Jiangnan , Xu Ximing 
Published: April 2014

ABSTRACTNovel lipid raft stationary phase chromatography (LRSC), with lipid rafts that contain abundant tropomyosin‐related tyrosine kinase A receptors immobilized on the stationary phase, was developed for a high‐throughput screening of potentially active antitumor agents. Lestaurtinib was used as a model compound to determine the operational parameters of the LRSC. Of all the factors considered, the particle size of column packing, the column temperature and the flow rate were of immense importance in determining the performance of the established LRSC system. In order to profoundly comprehend the binding interaction between the model drug and the receptors on the column, thermodynamic studies were employed. The results revealed that the interaction was spontaneous and exothermic, a typical enthalpy‐driven process. Additionally, the primary forces were hydrogen bonding and van der Waals forces. In evaluating the applicability of the method, active extracts from Albizziae Cortex were screened out using the LRSC system under the optimized conditions. The bioactive components were successfully confirmed by the MTT assay. In conclusion, it could be said that the LRSC is a good model for screening potential antitumor agents because of its viability, rapid response and scalable features. Copyright © 2014 John Wiley & Sons, Ltd.