bluuebunny/crossref_metadata_2025 huggingface dataset:
Dependence of the relationship between the tropical cyclone track and western Pacific subtropical high intensity on initial storm size: A numerical investigation
Authors: Sun Yuan , Zhong Zhong , Yi Lan , Li Tim , Chen Ming , Wan Hongchao , Wang Yuxing , Zhong Kai
Published: October 2015

A suite of numerical experiments were conducted to investigate the sensitivity of the tropical cyclone (TC) motion—western Pacific subtropical high (WPSH) intensity relationship to initial storm size. Two TC cases, Songda (2004) and Megi (2010), were studied. It was found that with the increase of initial storm size, the main body of the WPSH tends to withdraw eastward and the TC tends to turn northward earlier. The involved physical mechanism was investigated. Rather than the change of the beta effect due to storm size change, it is the change of the geopotential height in the TC outer region that is critical for the different TC tracks between the sensitivity experiments. Due to increase of the initial storm size, the inflow mass flux entering the TC region increases, leading to a significant decrease in 500 hPa geopotential height in the TC outer region after 2–3 day integration. As a result, the simulated intensity of the WPSH over its fringe close to the TC decreases notably when the WPSH edge is within the TC outer region. Such a decrease leads to a break of WPSH. Subsequently, the TC turns northward toward the break of the subtropical high. This further weakens the intensity of the WPSH over the region close to the TC. The result helps us better understand the relationship between the TC track and WPSH intensity. It also indicates that a proper representation of initial storm size is important for realistic prediction of TC track and the change of the WPSH.
UFCORIN: A fully automated predictor of solar flares in GOES X‐ray flux
Authors: Muranushi Takayuki , Shibayama Takuya , Muranushi Yuko Hada , Isobe Hiroaki , Nemoto Shigeru , Komazaki Kenji , Shibata Kazunari
Published: October 2015

We have developed UFCORIN, a platform for studying and automating space weather prediction. Using our system we have tested 6160 different combinations of Solar Dynamic Observatory/Helioseismic and Magnetic Imager data as input data, and simulated the prediction of GOES X‐ray flux for 2 years (2011–2012) with 1 h cadence. We have found that direct comparison of the true skill statistic (TSS) from small cross‐validation sets is ill posed and used the standard scores (z) of the TSS to compare the performance of the various prediction strategies. The z of a strategy is a stochastic variable of the stochastically chosen cross‐validation data set, and the z for the three strategies best at predicting X‐, ≥M‐, and ≥C‐class flares are better than the average z of the 6160 strategies by 2.3σ, 2.1σ, and 3.8σ confidence levels, respectively. The best three TSS values were 0.75 ± 0.07, 0.48 ± 0.02, and 0.56 ± 0.04, respectively.
Multiscale hyporheic exchange through strongly heterogeneous sediments
Authors: Pryshlak Timothy T. , Sawyer Audrey H. , Stonedahl Susa H. , Soltanian Mohamad Reza
Published: October 2015

Heterogeneity in hydraulic conductivity (K) and channel morphology both control surface water‐groundwater exchange (hyporheic exchange), which influences stream ecosystem processes and biogeochemical cycles. Here we show that heterogeneity in K is the dominant control on exchange rates, residence times, and patterns in hyporheic zones with abrupt lithologic contrasts. We simulated hyporheic exchange in a representative low‐gradient stream with 300 different bimodal K fields composed of sand and silt. Simulations span five sets of sand‐silt ratios and two sets of low and high K contrasts (1 and 3 orders of magnitude). Heterogeneity can increase interfacial flux by an order of magnitude relative to homogeneous cases, drastically changes the shape of residence time distributions, and tends to decrease median residence times. The positioning of highly permeable sand bodies controls patterns of interfacial flux and flow paths. These results are remarkably different from previous studies of smooth, continuous K fields that indicate only moderate effects on hyporheic exchange. Our results also show that hyporheic residence times are least predictable when sand body connectivity is low. As sand body connectivity increases, the expected residence time distribution (ensemble average for a given sand‐silt ratio) remains approximately constant, but the uncertainty around the expectation decreases. Including strong heterogeneity in hyporheic models is imperative for understanding hyporheic fluxes and solute transport. In streams with strongly heterogeneous sediments, characterizing lithologic structure is more critical for predicting hyporheic exchange metrics than characterizing channel morphology.
Recrystallization Behavior at Diffusion Bonding Interface of High Nb Containing TiAl Alloy
Authors: Tang Bin , Qi Xian Sheng , Kou Hong Chao , Li Jin Shan , Milenkovic Srdjan
Published: October 2015

A series of diffusion bonding tests are conducted on a high Nb containing TiAl alloy with full lamellar (FL) microstructure and the effect of interfacial recrystallization behavior on the shear strength is discussed. Microstructural observations reveal that bonding above 1 100 °C and 30 MPa results in recrystallization at the bonding interface flanked by FL microstructure, thus promoting the interface migration and leading to a sound joint. Based on the present results, the nucleation mechanism of recrystallization at the bonding interface is studied. Shear testing results show that recrystallization at the bonded zone improves the bonding quality of the joints by changing the failure mode. The shear strength of the joints attains 400 MPa when bonding at 1 150 °C/30 MPa/45 min and 1 100 °C/40 MPa/45 min.
Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures
Authors: Skaja Katharina , Bäumer Christoph , Peters Oliver , Menzel Stephan , Moors Marco , Du Hongchu , Bornhöfft Manuel , Schmitz Christoph , Feyer Vitaliy , Jia Chun‐Lin , Schneider Claus Michael , Mayer Joachim , Waser Rainer , Dittmann Regina
Published: October 2015

Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta2O5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta4+ and Ta5+, which takes place over the entire former Pt/Ta2O5‐x interface of the dendrite‐like structure.
Nanoarchitectures for Mesoporous Metals
Authors: Malgras Victor , Ataee‐Esfahani Hamed , Wang Hongjing , Jiang Bo , Li Cuiling , Wu Kevin C.‐W. , Kim Jung Ho , Yamauchi Yusuke
Published: October 2015

The field of mesoporous metal nanoarchitectonics offers several advantages which cannot be found elsewhere. These materials have been showcasing impressive enhancements of their electrochemical properties for further implementation, compared to their micro‐ and macroporous counterparts. Since the last few decades, various methods have been developed to achieve narrow pore size distribution with a tunable porosity and particle morphology. While hard templates offer a reliable and intuitive approach to synthesize mesoporous metals, the complexity of the technique and the use of harmful chemicals pushed several research groups to focus in other directions. For example, soft templates (e.g., lyotropic crystals, micelles assemblies) and solution phase methods (requiring to control reduction reactions) offer more and more possibilities in terms of available compositions and morphologies. Indeed, various metal (Pt, Pd, Au, Ru, etc.) can now be synthesized as dendritic, core@shell, hollow or polyhedral nanoparticles, with single‐ or multicomponents, alloyed or not, with unprecedented electrochemical activity.
Flexible Electrospun Carbon Nanofiber@NiS Core/Sheath Hybrid Membranes as Binder‐Free Anodes for Highly Reversible Lithium Storage
Authors: Zhang Longsheng , Huang Yunpeng , Zhang Youfang , Gu Huahao , Fan Wei , Liu Tianxi
Published: October 2015

The lithium storage performance of metal sulfides is restricted by their intrinsic poor conductivity, large volumetric expansion, and involvement of insulating polymer binders during the electrode preparation process, which can be solved by constructing binder‐free hybrid electrodes with nanostructured metal sulfides grown on self‐standing conductive templates. In this work, flexible hybrid membranes with nickel sulfide (NiS) nanoparticles uniformly anchored on electrospun carbon nanofibers (CNFs) have been prepared as binder‐free anodes for high‐performance lithium‐ion batteries. The hierarchical CNF@NiS core/sheath hybrid membranes with 3D macroporous architecture can provide open and continuous channels for rapid diffusion of lithium ions to access the electrochemically active NiS nanoparticles. Moreover, the CNF can act as both a conductive core to provide efficient transport of electrons for fast lithiation/delithiation of the NiS sheath, and as a buffering matrix to mitigate the local volumetric expansion/contraction upon long‐term cycling. As a consequence, the optimized CNF@NiS hybrid membranes exhibit a high reversible capacity of 1149.4 mA h g−1 with excellent cycling stability, and high rate capability of 664.3 mA h g−1 even at a high current density of 3 A g−1, making them promising flexible and binder‐free anode materials for highly reversible lithium storage.
Low‐Cost Hollow Mesoporous Polymer Spheres and All‐Solid‐State Lithium, Sodium Batteries
Authors: Zhou Weidong , Gao Hongcai , Goodenough John B.
Published: October 2015

A practical, low‐cost synthesis of hollow mesoporous organic polymer (HMOP) spheres is reported. The electrochemical properties of Li+/Na+‐electrolyte membranes with these spheres substituting for oxide filler particles in poly(ethylene oxide) (PEO)‐filler composite are explored. The electrolyte membranes are mechanically robust, thermally stable to over 250 °C, and block dendrites from a metallic‐lithium/sodium anode. The Li+/Na+ transfer impedance across the lithium/sodium–electrolyte interface is initially acceptable at 65 °C and scavenging of impurities by the porous‐spheres filler lowers this impedance relative to that with Al2O3. All‐solid‐state Li/LiFePO4 and Na/NaTi2(PO4)3 cells give stable discharge capacity of ≈130 and 80 mAh g−1, respectively, at 0.5 C and 65 °C for 100 cycles.
Synergetic effect of graphene sheet and three‐dimensional crumpled graphene on the performance of dye‐sensitized solar cells
Authors: Roh Ki‐Min , Kim Sun Kyung , Choi Ji‐Hyuk , Jo Eun‐Hee , Chang Hankwon , Jang Hee Dong
Published: October 2015

Herein, an improved structure of the dye‐sensitized solar cell (DSSC) is demonstrated which is composed of surface modified fluorine‐doped tin oxide (FTO) glass with graphene (GR) sheets and TiO2 films incorporated with three‐dimensional crumped graphene (3‐D CGR)/GR sheets. The morphologies of the as‐prepared GR sheets on FTO glasses and 3‐D CGR/GR sheets/TiO2 films were observed by field‐emission scanning electron microscopy. Light harvesting and charge recombination kinetics were investigated with a solar simulator and electrochemical impedance spectroscopy analysis. In addition to the reduced charge resistance by the GR modified FTO, the enhanced dye loading capability of the 3‐D CGR, and the rapid charge transport by the 2‐D GR sheets, the power conversion efficiency was 7.2%, which was an increase of 56% compared to a “conventional” structured DSSC. © 2015 American Institute of Chemical Engineers AIChE J, 62: 574–579, 2016
Antiquity and diversity of aboriginal Australian Y‐chromosomes
Authors: Nagle Nano , Ballantyne Kaye N. , van Oven Mannis , Tyler‐Smith Chris , Xue Yali , Taylor Duncan , Wilcox Stephen , Wilcox Leah , Turkalov Rust , van Oorschot Roland A.H. , McAllister Peter , Williams Lesley , Kayser Manfred , Mitchell Robert J. ,   The Genographic Consortium
Published: October 2015

Objective

Understanding the origins of Aboriginal Australians is crucial in reconstructing the evolution and spread of Homo sapiens as evidence suggests they represent the descendants of the earliest group to leave Africa. This study analyzed a large sample of Y‐chromosomes to answer questions relating to the migration routes of their ancestors, the age of Y‐haplogroups, date of colonization, as well as the extent of male‐specific variation.

Methods

Knowledge of Y‐chromosome variation among Aboriginal Australians is extremely limited. This study examined Y‐SNP and Y‐STR variation among 657 self‐declared Aboriginal males from locations across the continent. 17 Y‐STR loci and 47 Y‐SNPs spanning the Y‐chromosome phylogeny were typed in total.

Results

The proportion of non‐indigenous Y‐chromosomes of assumed Eurasian origin was high, at 56%. Y lineages of indigenous Sahul origin belonged to haplogroups C‐M130*(xM8,M38,M217,M347) (1%), C‐M347 (19%), K‐M526*(xM147,P308,P79,P261,P256,M231,M175,M45,P202) (12%), S‐P308 (12%), and M‐M186 (0.9%). Haplogroups C‐M347, K‐M526*, and S‐P308 are Aboriginal Australian‐specific. Dating of C‐M347, K‐M526*, and S‐P308 indicates that all are at least 40,000 years old, confirming their long‐term presence in Australia. Haplogroup C‐M347 comprised at least three sub‐haplogroups: C‐DYS390.1del, C‐M210, and the unresolved paragroup C‐M347*(xDYS390.1del,M210).

Conclusions

There was some geographic structure to the Y‐haplogroup variation, but most haplogroups were present throughout Australia. The age of the Australian‐specific Y‐haplogroups suggests New Guineans and Aboriginal Australians have been isolated for over 30,000 years, supporting findings based on mitochondrial DNA data. Our data support the hypothesis of more than one route (via New Guinea) for males entering Sahul some 50,000 years ago and give no support for colonization events during the Holocene, from either India or elsewhere. Am J Phys Anthropol 159:367–381, 2016. © 2015 Wiley Periodicals, Inc.
Environmental and individual determinants of parasite richness across seasons in a free‐ranging population of Mandrills (Mandrillus sphinx)
Authors: Poirotte Clémence , Basset Didier , Willaume Eric , Makaba Fred , Kappeler Peter M. , Charpentier Marie J.E.
Published: October 2015

Objectives

Parasites are ubiquitous and evolve fast. Therefore, they represent major selective forces acting on their hosts by influencing many aspects of their biology. Humans are no exception, as they share many parasites with animals and some of the most important outbreaks come from primates. While it appears important to understand the factors involved in parasite dynamics, we still lack a clear understanding of the determinants underlying parasitism. In this 2‐year study, we identified several factors that influence parasite patterns in a wild population of free‐ranging mandrills (Mandrillus sphinx).

Methods

We explored the potential impact of seasonal factors—rainfall and temperature—and host characteristics, including sex, age, rank, and reproductive status, on parasite richness. We analyzed 12 parasite taxa found in 870 fecal samples collected from 63 individuals. Because nematodes and protozoa have different life‐cycles, we analyzed these two types of parasites separately.

Results

Contrary to other studies where humid conditions seem favorable to parasite development, we report here that rainfall and high temperatures were associated with lower nematode richness and were not associated with lower protozoa richness. In contrast, female reproductive status seemed to reflect the seasonal patterns found for protozoa richness, as early gestating females harbored more protozoa than other females. Sex and dominance rank had no impact on overall parasite richness. However, age was associated with a specific decrease in nematode richness.

Conclusion

Our study emphasizes the need to consider the ecological context, such as climatic conditions and habitat type, as well as the biology of both parasite and host when analyzing determinants of parasite richness. Am J Phys Anthropol 159:442–456, 2016. © 2015 Wiley Periodicals, Inc.
Detecting Cytosolic Peptide Delivery with the GFP Complementation Assay in the Low Micromolar Range
Authors: Schmidt Samuel , Adjobo‐Hermans Merel J. W. , Wallbrecher Rike , Verdurmen Wouter P. R. , Bovée‐Geurts Petra H. M. , van Oostrum Jenny , Milletti Francesca , Enderle Thilo , Brock Roland
Published: October 2015

Transfection of cells with a plasmid encoding for the first ten strands of the GFP protein (GFP1‐10) provides the means to detect cytosolic peptide import at low micromolar concentrations. Cytosolic import of the eleventh strand of the GFP protein either by electroporation or by cell‐penetrating peptide‐mediated import leads to formation of the full‐length GFP protein and fluorescence. An increase in sensitivity is achieved through structural modifications of the peptide and the expression of GFP1‐10 as a fusion protein with mCherry.
Directed meta‐Selective Bromination of Arenes with Ruthenium Catalysts
Authors: Yu Qingzhen , Hu Le'an , Wang Yue , Zheng Shasha , Huang Jianhui
Published: October 2015

A Ru‐catalyzed direct CH activation/meta‐bromination of arenes bearing pyridyl, pyrimidyl, and pyrazolyl directing groups has been developed. A series of bromo aryl pyridines and pyrimidines have been synthesized, and further coupling reactions have also been demonstrated for a number of representative functionalized arenes. Preliminary mechanistic studies have revealed that this reaction may proceed through radical‐mediated bromination when NBS is utilized as the bromine source. This type of transformation has opened up a new direction for the radical non‐ipso functionalization of metal with regard to future CH activation development that would allow the remote functionalization of aromatic systems.
Kinetic Resolution of Azomethine Imines by Brønsted Acid Catalyzed Enantioselective Reduction
Authors: Bongers Amanda , Moon Patrick J. , Beauchemin André M.
Published: October 2015

Azomethine imines are valuable substrates in asymmetric catalysis, and can be precursors to β‐amino carbonyl compounds and complex hydrazines. However, their utility is limited because complex and enantioenriched azomethine imines are often unavailable. Reported herein is a kinetic resolution of N,N′‐cyclic azomethine imines by enantioselective reduction (s=13–43). This resolution was accomplished using a Brønsted acid catalyst, and represents the first example of the asymmetric reduction of azomethine imines. The pyrazolidinone product (up to 86 % ee) and the recovered azomethine imine (up to 99 % ee) can both be used to access the opposite enantiomers of valuable products.
Hexaphyrin–Cyclodextrin Hybrids: A Nest for Switchable Aromaticity, Asymmetric Confinement, and Isomorphic Fluxionality
Authors: Ménand Mickaël , Sollogoub Matthieu , Boitrel Bernard , Le Gac Stéphane
Published: October 2015

Conformational control over the highly flexible π‐conjugated system of expanded porphyrins is a key step toward the fundamental understanding of aromaticity and for the development of molecular electronics. We have synthesized unprecedented hexaphyrin–cyclodextrin (HCD) capped hybrids in which the hexaphyrin part is constrained in a planar rectangular conformation in either a 26 or a 28 π‐electron oxidation state ([26]/[28]HCD). These structures display strong aromaticity and antiaromaticity, respectively, exhibit markedly different chiroptical properties, and are interconvertible upon the addition of DDQ or NaBH(OAc)3, thus affording a rare switchable aromatic–antiaromatic system with a free‐base expanded porphyrin. Conformational analysis revealed discrimination of the two coordination sites of the hexaphyrin, one of which was coupled to a confined asymmetric environment, and fluxional behavior consisting of apparent rotation of the hexaphyrin cap through a shape‐shifting mechanism.
Highly Enantioselective Aza‐Michael Reaction between Alkyl Amines and β‐Trifluoromethyl β‐Aryl Nitroolefins
Authors: Wang Leming , Chen Jiean , Huang Yong
Published: October 2015

The aza‐Michael addition reaction is a vital transformation for the synthesis of functionalized chiral amines. Despite intensive research, enantioselective aza‐Michael reactions with alkyl amines as the nitrogen donor have not been successful. We report the use of chiral N‐heterocyclic carbenes (NHCs) as noncovalent organocatalysts to promote a highly selective aza‐Michael reaction between primary alkyl amines and β‐trifluoromethyl β‐aryl nitroolefins. In contrast to classical conjugate‐addition reactions, a strategy of HOMO‐raising activation was used. Chiral trifluoromethylated amines were synthesized in high yield (up to 99 %) with excellent enantioselectivity (up to 98 % ee).
Flexible, Stretchable, and Rechargeable Fiber‐Shaped Zinc–Air Battery Based on Cross‐Stacked Carbon Nanotube Sheets
Authors: Xu Yifan , Zhang Ye , Guo Ziyang , Ren Jing , Wang Yonggang , Peng Huisheng
Published: October 2015

The fabrication of flexible, stretchable and rechargeable devices with a high energy density is critical for next‐generation electronics. Herein, fiber‐shaped Zn–air batteries, are realized for the first time by designing aligned, cross‐stacked and porous carbon nanotube sheets simultaneously that behave as a gas diffusion layer, a catalyst layer, and a current collector. The combined remarkable electronic and mechanical properties of the aligned carbon nanotube sheets endow good electrochemical properties. They display excellent discharge and charge performances at a high current density of 2 A g−1. They are also flexible and stretchable, which is particularly promising to power portable and wearable electronic devices.
Single Nanoparticle Voltammetry: Contact Modulation of the Mediated Current
Authors: Li Xiuting , Batchelor‐McAuley Christopher , Whitby Samuel A. I. , Tschulik Kristina , Shao Lidong , Compton Richard G.
Published: October 2015

The cyclic voltammetric responses of individual palladium‐coated carbon nanotubes are reported. Upon impact—from the solution phase—with the electrified interface, the nanoparticles act as individual nanoelectrodes catalyzing the hydrogen‐oxidation reaction. At high overpotentials the current is shown to reach a quasi‐steady‐state diffusion limit, allowing determination of the tube length. The electrochemical response of the individual nanotubes also reveals the system to be modulated by the electrical contact between the electrode and carbon nanotube. This modulation presents itself as fluctuations in the recorded Faradaic current.
Extending the Family of V4+S= Kagome Antiferromagnets
Authors: Clark Lucy , Aidoudi Farida H. , Black Cameron , Arachchige Kasun S. A. , Slawin Alexandra M. Z. , Morris Russell E. , Lightfoot Philip
Published: October 2015

The ionothermal synthesis, structure, and magnetic susceptibility of a novel inorganic–organic hybrid material, imidazolium vanadium(III,IV) oxyfluoride [C3H5N2][V9O6F24(H2O)2] (ImVOF) are presented. The structure consists of inorganic vanadium oxyfluoride slabs with kagome layers of V4+ S= ions separated by a mixed valence layer. These inorganic slabs are intercalated with imidazolium cations. Quinuclidinium (Q) and pyrazinium (Pyz) cations can also be incorporated into the hybrid structure type to give QVOF and PyzVOF analogues, respectively. The highly frustrated topology of the inorganic slabs, along with the quantum nature of the magnetism associated with V4+, means that these materials are excellent candidates to host exotic magnetic ground states, such as the highly sought quantum spin liquid. Magnetic susceptibility measurements of all samples suggest an absence of conventional long‐range magnetic order down to 2 K despite considerable antiferromagnetic exchange.
Overcoming Statistical Complexity: Selective Coordination of Three Different Metal Ions to a Ligand with Three Different Coordination Sites
Authors: Akine Shigehisa , Matsumoto Takashi , Nabeshima Tatsuya
Published: October 2015

In general, it is difficult to selectively introduce different metal ions at specific positions of a cluster‐like structure. This is mainly due to statistical problems as well as the reversibility of the formation of coordination bonds. To overcome this statistical problem, we used a carefully designed ligand, H6L, which can accommodate three different kinds of metal ions in three types of coordination sites. The complex [LNiZn2La]3+, which contains three different metals, was quantitatively obtained by a stepwise procedure, but different products were obtained when the metal ions were added in a different order. However, equilibration studies indicated that this complex was almost solely formed among 54 (=3×3×3H2) possible products upon heating; the formation efficiency (ca. 100 %) was significantly higher than the statistical probability (2.47 %). Such carefully designed ligands should be useful for the synthesis multimetallic systems, which are of interest because of the interplay between the different metals.
Copper‐Catalyzed Reaction of Trifluoromethylketones with Aldehydes via a Copper Difluoroenolate
Authors: Doi Ryohei , Ohashi Masato , Ogoshi Sensuke
Published: October 2015

A copper‐catalyzed reaction of easily accessible α,α,α‐trifluoromethylketones with various aldehydes affords difluoro‐methylene compounds in the presence of diboron and NaOtBu. The key process of the reaction is the formation of a copper difluoroenolate by 1,2‐addition of a borylcopper intermediate to α,α,α‐trifluoromethylketones and subsequent β‐fluoride elimination. Mechanistic studies including the isolation and characterization of a possible anionic copper alkoxide intermediate are also described.
Production of the Bengamide Class of Marine Natural Products in Myxobacteria: Biosynthesis and Structure–Activity Relationships
Authors: Wenzel Silke C. , Hoffmann Holger , Zhang Jidong , Debussche Laurent , Haag‐Richter Sabine , Kurz Michael , Nardi Frederico , Lukat Peer , Kochems Irene , Tietgen Heiko , Schummer Dietmar , Nicolas Jean‐Paul , Calvet Loreley , Czepczor Valerie , Vrignaud Patricia , Mühlenweg Agnes , Pelzer Stefan , Müller Rolf , Brönstrup Mark
Published: October 2015

The bengamides, sponge‐derived natural products that have been characterized as inhibitors of methionine aminopeptidases (MetAPs), have been intensively investigated as anticancer compounds. We embarked on a multidisciplinary project to supply bengamides by fermentation of the terrestrial myxobacterium M. virescens, decipher their biosynthesis, and optimize their properties as drug leads. The characterization of the biosynthetic pathway revealed that bacterial resistance to bengamides is conferred by Leu 154 of the myxobacterial MetAP protein, and enabled transfer of the entire gene cluster into the more suitable production host M. xanthus DK1622. A combination of semisynthesis of microbially derived bengamides and total synthesis resulted in an optimized derivative that combined high cellular potency in the nanomolar range with high metabolic stability, which translated to an improved half‐life in mice and antitumor efficacy in a melanoma mouse model.
Transfer function and working principle of a pressure/temperature sensor based on carbon black/silicone rubber composites
Authors: Liu Ping , Liu Caixia , Huang Ying , Wang Weihua , Fang Ding , Zhang Yugang , Ge Yunjian
Published: October 2015

Pressure/temperature sensitive silicon rubber (SR) filled with carbon black (CB) was prepared by a liquid mixing method. The transfer function of a pressure/temperature sensor based on CB/SR was derived by general effective media theory. The results show that the transfer functions coincided well with the experimental data, and the negative pressure coefficient of the resistance/positive temperature coefficient of resistance are shown. The working principles of these two kinds of sensors are different. The working principle of the pressure sensor based on CB/SR was related to the volume fraction of CB. With increasing volume fraction of CB, the working principle of this kind of pressure sensor varied from a piezo‐resistive effect to a strain effect. In addition, the working principle of the temperature sensor based on CB/SR was that the resistivity changed with temperature; this was not related to the volume fraction of CB. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 42979.
Effect of microcellular foaming on the fracture behavior of ABS polymer
Authors: Gómez‐Monterde Javier , Schulte Manfred , Ilijevic Stefan , Hain Jörg , Sánchez‐Soto Miguel , Santana Orlando O. , Maspoch Maria Lluisa
Published: October 2015

In this work, the properties of microcellular ABS were studied. Foamed samples exhibited a solid skin/foamed core structure, with some elongated cells in the flow direction, while spherical cells were mostly observed in the transversal direction. The flexural modulus, flexural strength, and fracture toughness KIc decreased with the density. However, the Crack Tip Opening Displacement (CTOD) was found to increase with the foaming ratio. The evolution of the mechanical properties and fracture toughness was well described by prediction models considering the skin/core morphology of these microcellular materials. Foaming increased the anisotropic behavior of the material, due to the cell elongation caused by the fountain flow during injection. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43010.
Scatheless active functionalized poly(p‐phenylene terephthalamide) fibres and their outstanding potential in enhancing interface adhesion with polymer matrix
Authors: Yuan Ye , Song Shaokun , Deng Sufen , Wang Qin , Feng Qisong , Xiong Chuanxi , Dong Lijie
Published: October 2015

Exploration of new functionalization approaches to inert rigid fiber, activation inert surface, and enhancing interface adhesion is urgently required for fiber‐based multiphase materials. In this paper, we developed a simple yet efficient method towards active functionalized poly(p‐phenylene terephthalamide) fiber through mussel‐adhesive, self‐polymerization, and successive dipping–drying procedure based on as‐designed detachable equipment. In comparison with current acid etching and high energy radiation methods, the active functional strategy achieves scatheless functional modification to inert rigid fiber. Attribute to π–π conjugation effect, the new active nanolayers integrate rigid fiber and polymer matrix into homogeneous‐like structure. Consequently, the functionalized fiber‐based composites exhibit great mechanical property and desirable field‐responsive ability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43018.
Isothermal emulsion polymerization of n‐butyl methacrylate with KPS and redox initiators: Kinetic study at different surfactant/initiator concentrations and reaction temperature
Authors: Wang Shi , Daniels Eric S. , Sudol E. David , Klein Andrew , El‐Aasser Mohamed S.
Published: October 2015

Thermal initiators, although widely used in emulsion polymerization, are limited to high reaction temperatures due to their high activation energy. Redox initiators have low activation energies indicating that emulsion polymerization could be conducted at lower temperatures to save energy. In the present study, a redox initiator system comprised of hydrogen peroxide (H2O2) and ascorbic acid (AA) in conjunction with a Fe2+ ion catalyst is compared with a potassium persulfate (KPS) thermal initiator in an emulsion polymerization system consisting of n‐butyl methacrylate (BMA), sodium lauryl sulfate (SLS) and water. The dependence of particle number on surfactant and initiator concentrations shows that redox‐ and KPS‐initiated systems both follow the Smith‐Ewart theory. However, the high radical flux generated from the redox initiator results in the formation of much smaller latex particles and higher reaction rate with lower molecular weights. Latex particle size and molecular weight could also be influenced by reaction temperature. By using redox initiator, small monodisperse particles (diameter < 50 nm) can be achieved without using a large amount of surfactant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43037.
Study on the microstructure and properties of bromobutyl rubber (BIIR)/polyamide‐12 (PA12) thermoplastic vulcanizates (TPVs)
Authors: Ning Nanying , Hu Linjia , Yao Pengjun , Wu Hanguang , Han Jibin , Zhang Liqun , Tian Hongchi , Tian Ming
Published: October 2015

In this study, polyamide‐12 (PA12)/brominated isobutylene‐isoprene (BIIR) TPVs with good mechanical properties and low gas permeability were prepared by dynamic vulcanization in a twin‐screw extruder. The effects of three kinds of compatibilizers on the microstructure and properties of BIIR/PA12 TPV were studied. The compatibility between BIIR and PA12 was improved when maleated hydrocarbon polymeric compatibilizer is added. The reaction between maleic anhydride and amine in polyamide leads to the in situ formation of hydrocarbon polymer grafted polyamide which subsequently can be used to lower the interfacial tension between BIIR and polyamide. The compatibilizing effect of maleic anhydride modified polypropylene (PP‐g‐MAH) on BIIR/PA12 blends is the best among these compatibilizers because the surface energy of PP‐g‐MAH is very close to that of BIIR. The dispersed rubber phase of the blend compatibilized by PP‐g‐MAH shows the smallest size and more uniform size distribution, and the resulting TPVs show the best mechanical properties. The effects of fillers on the properties of BIIR/PA12 TPV were also investigated. The size of the BIIR phase increases with the increase in the content of CaCO3. The modulus and tensile strength of TPVs increased with the increase in the content of CaCO3 because of the reinforcing effect of CaCO3 on TPVs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43043.
Acceptance of clickers in a large multimodal biochemistry class as determined by student evaluations of teaching: Are they just an annoying distraction for distance students?
Authors: Miles Nathan. G. , Soares da Costa Tatiana P.
Published: October 2015

A student response system (clickers) was introduced into a second year introductory biochemistry class to improve student engagement and performance. The class was delivered in both internal and distance education (DE) modes, with the DE students receiving recordings of the lectures (including clicker activities). However, there was concern over the use of clickers in internal classes as it may be alienating or distracting to DE students while reviewing the recordings of these lectures. In order to examine students' attitudes toward clickers, closed‐ and open‐ended questions were examined in the student evaluations of teaching (SET). Understanding attitudes of internal and DE students is especially important as differences may exist between these groups due to the different learning environments they experience. Approximately 45% of students completed the surveys, of which 88%–91% provided written comments. Of the written comments, 18% of DE students and 22% of internal students provided unsolicited comments about clickers. Interestingly, no difference was observed in the themes identified in the comments between cohorts. The key themes included 1) clickers were beneficial for learning (and increased knowledge), 2) clickers were engaging/fun, and 3) clickers could have been used more widely. Overall, based on this study, it was believed that clicker usage was not seen as negative activity by DE students and it was worth continuing to use clickers in teaching the large multimodal class studied here. However, there is a need to investigate the potential of new and emerging technologies to provide more interactive experiences for DE students. © 2015 by The International Union of Biochemistry and Molecular Biology, 44:99–108, 2016.
Increased expression of transient receptor potential canonical 6 (TRPC6) in differentiating human megakaryocytes
Authors: Ramanathan Gajalakshmi , Mannhalter Christine
Published: October 2015

Members of the transient receptor potential (TRP) family of cation conducting channels are found in several tissues and cell types where they have different physiological functions. The canonical TRP channel 6 (TRPC6) is present on the platelet membrane and appears to participate in calcium influx during platelet activation. However, limited information is available on the importance of TRPC channels in megakaryocytes (MKs), the precursor cells of platelets. We determined the mRNA and protein expression of TRPC family members and investigated the role of TRPC6 for proliferation and differentiation of human MKs derived from CD34+ progenitor cells. TRPC6 transcripts were highly expressed during the differentiation of MKs and TRPC6 protein was detectable in MK cytoplasm by confocal staining. TRPC6 channel activity was modulated by pharmacological approaches using flufenamic acid (FFA) for activation and SKF96365 for inhibition. Upon FFA stimulation in MKs, an increase in intracellular calcium was observed, which was blocked by SKF96365 at 10 µM concentration. Incubation of MKs with SKF96365 resulted in a reduction in thrombopoietin‐stimulated cell proliferation. Our results suggest a role of TRPC6 in calcium homeostasis during MK development, particularly for cell proliferation.
Synthesis of Enamides by Ruthenium‐Catalyzed Reaction of Alkyl Azides with Acid Anhydrides in Ionic Liquid
Authors: Pak Han Kyu , Han Junghoon , Jeon Mina , Kim Yongjin , Kwon Yearang , Park Jin Yong , Rhee Young Ho , Park Jaiwook
Published: October 2015

Enamides were synthesized by a ruthenium‐catalyzed one‐pot, one‐step procedure from alkyl azides and acid anhydrides. The substrate scope includes not only secondary azides, but also primary aliphatic ones to give a wide range of enamides containing various functional groups. This one‐step procedure was based on the newly discovered activity of Severin's diruthenium complex ([Cp^RuCl2]2: Cp^=η5‐1‐methoxy‐2,4‐di‐tert‐butyl‐3‐neopentylcyclopentadienyl) for the transformation of alkyl azides into the corresponding N−H imine intermediates in ionic liquids. The formation of ruthenium tetrazene complexes was observed in the stoichiometric reaction of Severin's complex with alkyl azides, which acted as the catalyst for the formation of N−H imine intermediates.
Selective Probing of Gaseous Ammonia Using Red‐Emitting Carbon Dots Based on an Interfacial Response Mechanism
Authors: Jiang Bang‐Ping , Zhou Bo , Shen Xing‐Can , Yu Yun‐Xiang , Ji Shi‐Chen , Wen Chang‐Chun , Liang Hong
Published: October 2015

Solid‐state fluorescence sensing is one of the most appealing detection techniques because of its simplicity and convenience in practical operation. Herein, we report the development of a red‐emitting carbon dots (RCDs)‐based material as a solid‐state fluorescence sensor for the selective probing of gaseous ammonia. The RCDs were prepared by a low‐cost, one‐step carbonization method using sugar cane bagasse as the carbon precursor. The pristine RCDs were then directly coated on polyvinylidene fluoride membrane to produce a new fluorescence sensor capable of selectively distinguishing toxic gaseous ammonia from other analyte vapors through sensitive fluorescence quenching with a low detection limit. More importantly, the interfacial response mechanism occurring on the surface of the RCDs has been studied by X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, and Raman measurements. The results indicate that fluorescence quenching in the RCDs might result from ammonia‐induced Michael addition through insertion of N into the CC group and deprotonation of the carboxyl group. To the best of our knowledge, this is the first report that provides clear insight into the mechanism of surface chemistry on CDs in the solid state.
Activation of CH Bonds through Oxidant‐Free Photoredox Catalysis: Cross‐Coupling Hydrogen‐Evolution Transformation of Isochromans and β‐Keto Esters
Authors: Xiang Ming , Meng Qing‐Yuan , Li Jia‐Xin , Zheng Yi‐Wen , Ye Chen , Li Zhi‐Jun , Chen Bin , Tung Chen‐Ho , Wu Li‐Zhu
Published: October 2015

The direct and controlled activation of a C(sp3)H bond adjacent to an O atom is of particular synthetic value for the conventional derivatization of ethers or alcohols. In general, stoichiometric amounts of an oxidant are required to remove an electron and a hydrogen atom of the ether for subsequent transformations. Herein, we demonstrate that the activation of a CH bond next to an O atom could be achieved under oxidant‐free conditions through photoredox‐neutral catalysis. By using a commercial dyad photosensitizer (Acr+‐Mes ClO4−, 9‐mesityl‐10‐methylacridinium perchlorate) and an easily available cobaloxime complex (Co(dmgBF2)2⋅2 MeCN, dmg=dimethylglyoxime), the nucleophilic addition of β‐keto esters to oxonium species, which is rarely observed in photocatalysis, leads to the corresponding coupling products and H2 in moderate to good yields under visible‐light irradiation. Mechanistic studies suggest that both isochroman and the cobaloxime complex quench the electron‐transfer state of this dyad photosensitizer and that benzylic CH bond cleavage is probably the rate‐determining step of this cross‐coupling hydrogen‐evolution transformation.
Evidence of CuI/CuII Redox Process by X‐ray Absorption and EPR Spectroscopy: Direct Synthesis of Dihydrofurans from β‐Ketocarbonyl Derivatives and Olefins
Authors: Yi Hong , Liao Zhixiong , Zhang Guanghui , Zhang Guoting , Fan Chao , Zhang Xu , Bunel Emilio E. , Pao Chih‐Wen , Lee Jyh‐Fu , Lei Aiwen
Published: October 2015

The CuI/CuII and CuI/CuIII catalytic cycles have been subject to intense debate in the field of copper‐catalyzed oxidative coupling reactions. A mechanistic study on the CuI/CuII redox process, by X‐ray absorption (XAS) and electron paramagnetic resonance (EPR) spectroscopies, has elucidated the reduction mechanism of CuII to CuI by 1,3‐diketone and detailed investigation revealed that the halide ion is important for the reduction process. The oxidative nature of the thereby‐formed CuI has also been studied by XAS and EPR spectroscopy. This mechanistic information is applicable to the copper‐catalyzed oxidative cyclization of β‐ketocarbonyl derivatives to dihydrofurans. This protocol provides an ideal route to highly substituted dihydrofuran rings from easily available 1,3‐dicarbonyls and olefins.
Selektive Abtrennung von Indium und Germanium aus Laugungslösungen mit Membranverfahren
Authors: Werner Arite , Mosch Maria , Haseneder Roland , Repke Jens‐Uwe
Published: October 2015

Die steigende Nachfrage nach den strategischen Elementen Indium und Germanium erfordert die Entwicklung neuer Gewinnungsverfahren. Ziel der vorgestellten Forschungsarbeit ist die selektive Gewinnung von Indium und Germanium aus Laugungslösungen eines In‐situ‐Bioleaching‐Prozesses. Anstelle der herkömmlich verwendeten Solvent‐Extraktion wird die Eignung von Membranverfahren, insbesondere Nanofiltration und membrangestützte Extraktion, überprüft. Indium und Germanium zeigen ein pH‐abhängiges Trennverhalten bei der Nanofiltration und können selektiv getrennt werden. Die Abtrennung von Indium aus einer konzentrierten Lösung aus Zn, Cu, Fe und As mittels membrangestützter Extraktion war erfolgreich und vielversprechend für weitere Untersuchungen.
Exploring the Photodeactivation Pathways of Pt[O^N^C^N] Complexes: A Theoretical Perspective
Authors: Luo Yafei , Xu Yanyan , Zhang Wenting , Li Ming , He Rongxing , Shen Wei
Published: October 2015

In this article, the influence of the tert‐butyl unit on the photodeactivation pathways of Pt[O^N^C^N] (O^N^C^N=2‐(4‐(3,5‐di‐tert‐butylphenyl)‐6‐(3‐(pyridin‐2‐l)phenyl) pyridin‐2‐yl)phenolate) is investigated by DFT/TDDFT calculations. To further explore the factors that determine the radiative processes, the transition dipole moments of the singlet excited states, spin–orbit coupling (SOC) matrix elements, and energy gaps between the lowest triplet excited states and singlet excited states are calculated. As demonstrated by the results, compared with Pt‐3, Pt‐1 and Pt‐2 have larger SOC matrix elements between the lowest triplet excited states and singlet excited states, an indicator that they have faster radiative decay processes. In addition, the SOC matrix elements between the lowest triplet excited states and ground states are also computed to elucidate the temperature‐independent non‐radiative decay processes. Moreover, the temperature‐dependent non‐radiative decay mechanisms are also explored via the potential energy profiles.
Anxious Children and Adolescents Non‐responding to CBT: Clinical Predictors and Families' Experiences of Therapy
Authors: Lundkvist‐Houndoumadi Irene , Thastum Mikael
Published: October 2015

The purpose of the study was to examine clinical predictors of non‐response to manualized cognitive behaviour therapy (CBT) among youths (children and adolescents) with anxiety disorders, and to explore families' perspective on therapy, using a mixed methods approach. Non‐response to manualized group CBT was determined among 106 youths of Danish ethnicity (7–17 years old) with a primary anxiety disorder, identified with the Clinical Global Impression of Improvement Scale at the 3‐month follow‐up. Twenty‐four youths (22.6 %) had not responded to treatment, and a logistic regression analysis revealed that youths with a primary diagnosis of social phobia were seven times more likely not to respond, whereas youths with a comorbid mood disorder were almost four times more likely. Families of non‐responding youths with primary social phobia and/or a comorbid mood disorder (n = 15) were interviewed, and data were analysed through interpretative phenomenological analysis. Two superordinate themes emerged: youths were not involved in therapy work, and manualized group format posed challenges to families. The mixed methods approach provided new perspectives on the difficulties that may be encountered by families of non‐responding youths with a primary social phobia diagnosis and youths with a comorbid mood disorder during manualized group CBT. Clinical implications related to youths' clinical characteristics, and families' experience and suggestions are drawn. Copyright © 2015 John Wiley & Sons, Ltd.

Key Practitioner Messages

Youths with an anxiety disorder, who had a primary social phobia diagnosis and those, who had a comorbid mood disorder, were more likely not to respond to manualized group CBT.

Parents of those non‐responding youths often considered them as motivated to overcome their difficulties, but due to their symptomatology, they were unreceptive, reluctant and ambivalent and therefore not actively involved in therapy.

The non‐responding youths with social phobia felt evaluated and nervous of what others thought of them in the group.

The parents of the non‐responding youths with a comorbid mood disorder felt the group format placed restraints on therapists' ability to focus on their individual needs.