bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous field‐aligned currents at Swarm and Cluster satellites
Authors: Dunlop M. W. , Yang J.‐Y. , Yang Y.‐Y. , Xiong C. , Lühr H. , Bogdanova Y. V. , Shen C. , Olsen N. , Zhang Q.‐H. , Cao J.‐B. , Fu H.‐S. , Liu W.‐L. , Carr C. M. , Ritter P. , Masson A. , Haagmans R.
Published: April 2015

We show for the first time, with direct, multispacecraft calculations of electric current density, and other methods, matched signatures of field‐aligned currents (FACs) sampled simultaneously near the ionosphere at low (~500 km altitude) orbit and in the magnetosphere at medium (~2.5 RE altitude) orbits using a particular Swarm and Cluster conjunction. The Cluster signatures are interpreted and ordered through joint mapping of the ground/magnetospheric footprints and estimation of the auroral zone boundaries (taken as indication of the boundaries of Region 1 and Region 2 currents). We find clear evidence of both small‐scale and large‐scale FACs and clear matching of the behavior and structure of the large‐scale currents at both Cluster and Swarm. The methodology is made possible through the joint operations of Cluster and Swarm, which contain, in the first several months of Swarm operations, a number of close three‐spacecraft configurations.
Frictional wave dissipation on a remarkably rough reef
Authors: Monismith Stephen G. , Rogers Justin S. , Koweek David , Dunbar Robert B.
Published: April 2015

We present a week of observations of wave dissipation on the south forereef of Palmyra Atoll. Using wave measurements made in 6.2 m and 11.2 m of water offshore of the surf zone, we computed energy fluxes and near‐bottom velocity. Equating the divergence of the shoreward energy flux to its dissipation by bottom friction and parameterizating dissipation in terms of the root‐mean‐square velocity cubed, we find that the wave friction factor, fw, for this reef is 1.80 ± 0.07, nearly an order of magnitude larger than values previously found for reefs. We attribute this remarkably high value of fw to the complex canopy structure of the reef, which we believe may be characteristic of healthy reefs. This suggests that healthy reefs with high coral cover may provide greater coastal protection than do degraded reefs with low coral cover.
Time domain structures: What and where they are, what they do, and how they are made
Authors: Mozer F. S. , Agapitov O. V. , Artemyev A. , Drake J. F. , Krasnoselskikh V. , Lejosne S. , Vasko I.
Published: April 2015

Time domain structures (TDS) (electrostatic or electromagnetic electron holes, solitary waves, double layers, etc.) are ≥1 ms pulses having significant parallel (to the background magnetic field) electric fields. They are abundant through space and occur in packets of hundreds in the outer Van Allen radiation belts where they produce magnetic‐field‐aligned electron pitch angle distributions at energies up to a hundred keV. TDS can provide the seed electrons that are later accelerated to relativistic energies by whistlers and they also produce field‐aligned electrons that may be responsible for some types of auroras. These field‐aligned electron distributions result from at least three processes. The first process is parallel acceleration by Landau trapping in the TDS parallel electric field. The second process is Fermi acceleration due to reflection of electrons by the TDS. The third process is an effective and rapid pitch angle scattering resulting from electron interactions with the perpendicular and parallel electric and magnetic fields of many TDS. TDS are created by current‐driven and beam‐related instabilities and by whistler‐related processes such as parametric decay of whistlers and nonlinear evolution from oblique whistlers. New results on the temporal relationship of TDS and particle injections, types of field‐aligned electron pitch angle distributions produced by TDS, the mechanisms for generation of field‐aligned distributions by TDS, the maximum energies of field‐aligned electrons created by TDS in the absence of whistler mode waves, TDS generation by oblique whistlers and three‐wave‐parametric decay, and the correlation between TDS and auroral particle precipitation, are presented.
Enantioselective Bio‐Hydrolysis of Various Racemic and meso Aromatic Epoxides Using the Recombinant Epoxide Hydrolase Kau2
Authors: Zhao Wei , Kotik Michael , Iacazio Gilles , Archelas Alain
Published: April 2015

Epoxide hydrolase Kau2 overexpressed in Escherichia coli RE3 has been tested with ten different racemic and meso α,β‐disubstituted aromatic epoxides. Some of the tested substrates were bi‐functional, and most of them are very useful building blocks in synthetic chemistry applications. As a general trend Kau2 proved to be an extremely enantioselective biocatalyst, the diol products and remaining epoxides of the bioconversions being obtained – with two exceptions – in nearly enantiomerically pure form. Furthermore, the reaction times were usually very short (around 1 h, except when stilbene oxides were used), and the use of organic co‐solvents was well tolerated, enabling very high substrate concentrations (up to 75 g/L) to be reached. Even extremely sterically demanding epoxides such as cis‐ and trans‐stilbene oxides were transformed on a reasonable time scale. All reactions were successfully conducted on a 1 g preparative scale, generating diol‐ and epoxide‐based chiral synthons with very high enantiomeric excesses and isolated yields close to the theoretical maximum. Thus we have here demonstrated the usefulness and versatility of lyophilized Escherichia coli cells expressing Kau2 epoxide hydrolase as a highly enantioselective biocatalyst for accessing very valuable optically pure aromatic epoxides and diols through kinetic resolution of racemates or desymmetrization of meso epoxides.

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Structure‐Guided Engineering of D‐Fructose‐6‐Phosphate Aldolase for Improved Acceptor Tolerance in Biocatalytic Aldol Additions
Authors: Soler Anna , Gutiérrez Mariana L. , Bujons Jordi , Parella Teodor , Minguillon Cristina , Joglar Jesús , Clapés Pere
Published: April 2015

A structure‐guided redesign of D‐fructose‐6‐phosphate aldolase from Escherichia coli (FSA) was devised for improving the acceptor tolerance towards α‐substituted and conformationally constrained aldehydes. FSA A129S/R134X/A165G/S166G and L107Y/A129G/R134X/A165G/S166G variants, where X was R, V, P, or S, were the most suited biocatalysts for dihydroxyacetone, hydroxyacetone and glycolaldehyde additions to 20 α‐substituted N‐Cbz‐aminoaldehydes (Cbz=benzyloxycarbonyl) including pyrrolidine and piperidine derivatives. Full kinetic stereocontrol for si‐si face addition of the aldolase‐bound nucleophile to the N‐Cbz‐aminoaldehyde carbonyl was observed, furnishing the corresponding D‐threo configured aldol adduct in >95:5 dr as assessed by NMR. After reductive amination, 47 different iminocyclitols were identified and characterized. In some examples partial racemization of the corresponding aldehyde was observed, which appears to be produced mostly during the aldol addition reactions.

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Finding the Selectivity Switch – A Rational Approach towards Stereocomplementary Variants of the Ene Reductase YqjM
Authors: Rüthlein Elisabeth , Classen Thomas , Dobnikar Lina , Schölzel Melanie , Pietruszka Jörg
Published: April 2015

Ene reductases from the Old Yellow Enzyme family are versatile biocatalysts useful for the synthesis of optically active compounds. One disadvantage of biocatalysts when compared to competing catalysts in chemical syntheses is that often only one stereoisomer of the product is available. Another drawback can be the lack of activity in certain enzyme–substrate combinations. We were able to approach both of these challenges rationally in the case of the enzymatic synthesis of methyl 3‐hydroxy‐2‐methylpropanoate (commonly denoted as the Roche ester) and derivatives thereof using the ene reductase YqjM. By a highly efficient, concept‐based approach of designing mutant variants of YqjM and engineering substrates we could alter both the rate constant and the enantioselectivity of the reaction. Preparative scale reactions have been performed with successful mutants. In addition, the iterative modification of the substrate gave experiment‐based insights into the binding mode of the Roche ester precursor and its derivatives.

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Gas‐solid catalytic reactions with an extendedDSMCmodel
Authors: Pesch Georg R. , Riefler Norbert , Fritsching Udo , Colombi Ciacchi Lucio , Mädler Lutz
Published: April 2015

An algorithm of diffusive gas transport in porous solids based on random collisions of molecules (DSMC) is extended to include basic heterogeneous reaction mechanisms (adsorption, coadsorption, desorption, and reaction of gas species on the surface of the solid). With this model, we study the catalytic oxidation of CO inside highly porous nanoparticle layers in the transition regime using kinetic parameters from Pd(111) surfaces at ultra high vacuum conditions. Investigation of the reaction at different temperatures reveals a clear transition between a kinetic limit (low temperatures) and a diffusion limit (high temperatures). At high temperatures and under steady‐state conditions, the porous layer shows three distinct regions with different reaction rates (reactor poisoning, an effective reaction region, and a region with CO depletion), whose extends are determined by CO concentration and mass‐transport limitation. We expect that similar investigations help optimizing the structure of gas sensor elements based on nanoparticle layers fabricated with flame spray pyrolysis. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2092–2103, 2015
The phenotype of multiple congenital anomalies‐hypotonia‐seizures syndrome 1: Report and review
Authors: Couser Natario L. , Masood Maheer M. , Strande Natasha T. , Foreman Ann Katherine M. , Crooks Kristy , Weck Karen E. , Lu Mei , Wilhelmsen Kirk C. , Roche Myra , Evans James P. , Berg Jonathan S. , Powell Cynthia M.
Published: April 2015

The Multiple Congenital Anomalies‐Hypotonia‐Seizures Syndrome 1 (MCAHS1) has been described in two families to date. We describe a 2‐year‐old Mexican American boy with the syndrome and additional manifestations not yet reported as part of the phenotype. The patient presented with severe hypotonia, microphallus and left cryptorchidism, and was later diagnosed with epilepsy and severe cortical visual impairment. He also had supernumerary nipples, pectus excavatum, a short upturned nose, fleshy ear lobes, and a right auricular pit. Massively parallel exome sequencing and analysis revealed two novel compound heterozygous missense (Trp136Gly and Ser859Thr) variants in the PIGN gene. This report extends and further defines the phenotype of this syndrome. © 2015 Wiley Periodicals, Inc.
An angiotensin‐converting enzyme (ACE) polymorphism may mitigate the effects of angiotensin‐pathway medications on posttraumatic stress symptoms
Authors: Nylocks K. M. , Michopoulos V. , Rothbaum A. O. , Almli L. , Gillespie C. F. , Wingo A. , Schwartz A. C. , Habib L. , Gamwell K. L. , Marvar P. J. , Bradley B. , Ressler K. J.
Published: April 2015

Angiotensin, which regulates blood pressure may also act within the brain to mediate stress and fear responses. Common antihypertensive medication classes of angiotensin‐converting enzyme inhibitors (ACE‐Is) and angiotensin receptor blockers (ARBs) have been associated with lower PTSD symptoms. Here we examine the rs4311 SNP in the ACE gene, previously implicated in panic attacks, in the relationship between ACE‐I/ARB medications and PTSD symptoms. Participants were recruited from outpatient wait rooms between 2006 and March 2014 (n = 3803). We examined the interaction between rs4311 genotype and the presence of blood pressure medication on PTSD symptoms and diagnosis. PTSD symptoms were lower in individuals taking ACE‐Is or ARBs (N = 776). The rs4311 was associated with PTSD symptoms and diagnosis (N = 3803), as the T‐carriers at the rs4311 SNP had significantly greater likelihood of a PTSD diagnosis. Lastly, the rs4311 genotype modified the effect of ACE‐Is or ARBs on PTSD symptoms (N = 443; F1,443 = 4.41, P < 0.05). Individuals with the CC rs4311 genotype showed lower PTSD symptoms in the presence of ACE‐Is or ARBs. In contrast, T‐ carriers showed the opposite, such that the presence of ACE‐Is or ARBs was associated with higher PTSD symptoms. These data suggest that the renin‐angiotensin system may be important in PTSD, as ACE‐I/ARB usage associates with lower symptoms. Furthermore, we provide genetic evidence that some individuals are comparatively more benefitted by ACE‐Is/ARBs in PTSD treatment. Future research should examine the mechanisms by which ACE‐Is/ARBs affect PTSD symptoms such that pharmaco‐genetically informed interventions may be used to treat PTSD. © 2015 Wiley Periodicals, Inc.
Detection of TDP‐43 oligomers in frontotemporal lobar degeneration–TDP
Authors: Kao Patricia F. , Chen Yun‐Ru , Liu Xiao‐Bo , DeCarli Charles , Seeley William W. , Jin Lee‐Way
Published: April 2015

Objective

The proteinaceous inclusions in TDP‐43 proteinopathies such as frontotemporal lobar degeneration (FTLD)‐TDP are made of high–molecular‐weight aggregates of TDP‐43. These aggregates have not been classified as amyloids, as prior amyloid staining results were not conclusive. Here we used a specific TDP‐43 amyloid oligomer antibody called TDP‐O to determine the presence and abundance of TDP‐43 oligomers among different subtypes of FTLD‐TDP as well as in hippocampal sclerosis (HS), which represents a non‐FTLD pathology with TDP‐43 inclusions.

Methods

Postmortem tissue from the hippocampus and anterior orbital gyrus from 54 prospectively assessed and diagnosed subjects was used for immunostaining with TDP‐O. Electron microscopy was used to assess the subcellular locations of TDP‐O–decorated structures.

Results

TDP‐43 inclusions staining with TDP‐O were present in FTLD‐TDP and were most conspicuous for FTLD‐TDP type C, the subtype seen in most patients with semantic variant primary progressive aphasia. TDP‐O immunoreactivity was absent in the hippocampus of HS patients despite abundant TDP‐43 inclusions. Ultrastructurally, TDP‐43 oligomers resided in granular or tubular structures, frequently in close proximity to, but not within, neuronal lysosomes.

Interpretation

TDP‐43 forms amyloid oligomers in the human brain, which may cause neurotoxicity in a manner similar to other amyloid oligomers. Oligomer formation may contribute to the conformational heterogeneity of TDP‐43 aggregates and mark the different properties of TDP‐43 inclusions between FTLD‐TDP and HS. Ann Neurol 2015;78:211–221
Polarizing neutron by light‐irradiated graphene
Authors: Peng Feng
Published: April 2015

We study the spin orientation of the neutron scattered by light‐irradiated graphene and calculate the average value of spin z‐component of the neutron in terms of a generating functional technique. Our calculation results indicate that there is a remarkable neutron polarization effect when a neutron penetrates graphene irradiated by a circularly polarized light. We analyse the dynamical source of generating this effect from the aspect of photon‐mediated interaction between the neutron spin and valley pseudospin. By comparing with the polarization induced by a magnetic field, we find that this polarization may be equivalent to the one led by a magnetic field of several hundred Teslas if the photon frequency is in the X‐ray frequency range. This provides an approach of polarizing neutrons.

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Die Entfaltung der C‐terminalen α‐Helix des Neuropeptids Y ist entscheidend für die Bindung und Aktivierung des Y2‐Rezeptors
Authors: Kaiser Anette , Müller Paul , Zellmann Tristan , Scheidt Holger A. , Thomas Lars , Bosse Mathias , Meier Rene , Meiler Jens , Huster Daniel , Beck‐Sickinger Annette G. , Schmidt Peter
Published: April 2015

Trotz jüngster Fortschritte in der Strukturbestimmung von G‐Protein‐gekoppelten Rezeptoren (GPCR) gibt es nur wenige Daten zur Interaktion von GPCRs mit größeren Peptidliganden. In dieser Arbeit kombinieren wir Methoden der NMR‐Spektroskopie, der molekularen Modellierung und der ortsgerichteten komplementären Mutagenese und präsentieren ein Strukturmodell des Peptidhormons Neuropeptid Y (NPY) im Komplex mit seinem humanen G‐Protein‐gekoppelten Y2‐Rezeptor (Y2R). Festkörper‐NMR‐Messungen von spezifisch isotopenmarkiertem NPY im Komplex mit in vitro gefaltetem und in Phospholipid‐Bizellen rekonstituiertem Y2R liefern Daten zur bioaktiven Peptidstruktur. Unterstützt von Lösungs‐NMR‐Studien konnten Interaktionen des Liganden mit dem zweiten extrazellulären Loop des Rezeptors über hydrophobe Kontakte nachgewiesen werden. Die C‐terminale α‐Helix von NPY, die sich in einer Membranumgebung in Abwesenheit des Rezeptors bildet, entfaltet sich ab T 32, um einen optimalen Kontakt tief in der Bindungstasche des transmembranen Bereichs des Y2R zu ermöglichen.
Tailoring Supramolecular Nanotubes by Bile Salt Based Surfactant Mixtures
Authors: Gubitosi Marta , Travaglini Leana , di Gregorio Maria Chiara , Pavel Nicolae V. , Vázquez Tato José , Sennato Simona , Olsson Ulf , Schillén Karin , Galantini Luciano
Published: April 2015

An approach for tailoring self‐assembled tubular structures is described. By controlling the relative composition of a two‐component surfactant mixture comprising the natural bile salt lithocholate and its bolamphiphilic derivative, it was possible to finely tune the nanotube cross‐section of the mixed tubular aggregates that self‐associated spontaneously in aqueous solution at pH 12. The diameter was found to vary up to 50 % when the stoichiometric ratio of the two bile salts was changed. The tuning of supramolecular nanochannels with such remarkable precision is of significant interest for technological applications of these materials.
Reversible Hydrophobic–Hydrophilic Transition of Ionic Liquids Driven by Carbon Dioxide
Authors: Xiong Dazhen , Cui Guokai , Wang Jianji , Wang Huiyong , Li Zhiyong , Yao Kaisheng , Zhang Suojiang
Published: April 2015

Ionic liquids (ILs) with a reversible hydrophobic–hydrophilic transition were developed, and they exhibited unique phase behavior with H2O: monophase in the presence of CO2, but biphase upon removal of CO2 at room temperature and atmospheric pressure. Thus, coupling of reaction, separation, and recovery steps in sustainable chemical processes could be realized by a reversible liquid–liquid phase transition of such IL‐H2O mixtures. Spectroscopic investigations and DFT calculations showed that the mechanism behind hydrophobic–hydrophilic transition involved reversible reaction of CO2 with anion of the ILs and formation of hydrophilic ammonium salts. These unique IL‐H2O systems were successfully utilized for facile one‐step synthesis of Au porous films by bubbling CO2 under ambient conditions. The Au porous films and the ILs were then separated simultaneously from aqueous solutions by bubbling N2, and recovered ILs could be directly reused in the next process.
Bright Fluorescence and Host–Guest Sensing with a Nanoscale M4L6 Tetrahedron Accessed by Self‐Assembly of Zinc–Imine Chelate Vertices and Perylene Bisimide Edges
Authors: Frischmann Peter D. , Kunz Valentin , Würthner Frank
Published: April 2015

A highly luminescent Zn4L6 tetrahedron is reported with 3.8 nm perylene bisimide edges and hexadentate ZnII–imine chelate vertices. Replacing FeII and monoamines commonly utilized in subcomponent self‐assembly with ZnII and tris(2‐aminoethyl)amine provides access to a metallosupramolecular host with the rare combination of structural integrity at concentrations <10−7 mol L−1 and an exceptionally high fluorescence quantum yield of Φem=0.67. Encapsulation of multiple perylene or coronene guest molecules is accompanied by strong luminescence quenching. We anticipate this self‐assembly strategy may be generalized to improve access to brightly fluorescent coordination cages tailored for host–guest light‐harvesting, photocatalysis, and sensing.
Wie der [NiFe4S4]‐Cluster der CO‐Dehydrogenase CO2 und NCO− aktiviert
Authors: Fesseler Jochen , Jeoung Jae‐Hun , Dobbek Holger
Published: April 2015

Ni,Fe‐haltige CO‐Dehydrogenasen (CODHs) nutzen einen [NiFe4S4]‐Cluster, auch C‐Cluster genannt, um CO2 mit hohen Umsatzzahlen reversibel zu CO zu reduzieren. Die Bindung an Ni und Fe aktiviert CO2, jedoch sind aktuelle Kristallstrukturen unzureichend aufgelöst, um die Geometrie des gebundenen CO2 zu analysieren und den Grad seiner Aktivierung zu enthüllen. Wir berichten hier über die Kristallstruktur von CODH im Komplex mit CO2 und dem zu CO2 isoelektronischen Inhibitor NCO− bei atomarer Auflösung (dmin≤1.1 Å). NCO− ist, wie CO2, ein μ2‐η2‐Ligand des Clusters und wirkt als Mechanismus‐abhängiger Inhibitor. Während gebundenes CO2 die Struktur einer Carboxylatgruppe besitzt, wird NCO− zu einer Carbamoylgruppe umgesetzt. Beide Moleküle durchlaufen damit eine formale Zweielektronenreduktion nach der Bindung und werden durch starke π‐Rückbindungen stabilisiert. Die Strukturen zeigen, dass der Umsatz von CO2 und die Inhibition durch NCO− auf der Kombination einer stabilen μ2‐η2‐Koordination zwischen Ni und Fe2 mit einer reduktiven Aktivierung beruhen.
Magnetic Assembly and Field‐Tuning of Ellipsoidal‐Nanoparticle‐Based Colloidal Photonic Crystals
Authors: Wang Mingsheng , He Le , Xu Wenjing , Wang Xin , Yin Yadong
Published: April 2015

Anisotropic nanostructures provide an additional degree of freedom for tailoring the collective properties of their ensembles. Using Fe@SiO2 nanoellipsoids as anisotropic building blocks, herein we demonstrate a new class of magnetically responsive photonic structures whose photonic properties can be dynamically tuned by controlling the direction of the magnetic fields they are exposed to. These novel photonic structures diffract at a minimum wavelength when the field direction is perpendicular to the incident angle, and a maximum wavelength when the field is switched to parallel direction; and the diffraction intensity reaches maximum values when the fields are either parallel or perpendicular to the incident light, and decreases when the field direction is moved off‐angle.
Self‐Assembly of Disorazole C1 through a One‐Pot Alkyne Metathesis Homodimerization Strategy
Authors: Ralston Kevin J. , Ramstadius H. Clinton , Brewster Richard C. , Niblock Helen S. , Hulme Alison N.
Published: April 2015

Alkyne metathesis is increasingly explored as a reliable method to close macrocyclic rings, but there are no prior examples of an alkyne‐metathesis‐based homodimerization approach to natural products. In this approach to the cytotoxic C2‐symmetric marine‐derived bis(lactone) disorazole C1, a highly convergent, modular strategy is employed featuring cyclization through an ambitious one‐pot alkyne cross‐metathesis/ring‐closing metathesis self‐assembly process.
White‐Light Emission Strategy of a Single Organic Compound with Aggregation‐Induced Emission and Delayed Fluorescence Properties
Authors: Xie Zongliang , Chen Chengjian , Xu Shidang , Li Jun , Zhang Yi , Liu Siwei , Xu Jiarui , Chi Zhenguo
Published: April 2015

A novel white‐light‐emitting organic molecule, which consists of carbazolyl‐ and phenothiazinyl‐substituted benzophenone (OPC) and exhibits aggregation‐induced emission‐delayed fluorescence (AIE‐DF) and mechanofluorochromic properties was synthesized. The CIE color coordinates of OPC were directly measured with a non‐doped powder, which presented white‐emission coordinates (0.33, 0.33) at 244 K to 252 K and (0.35, 0.35) at 298 K. The asymmetric donor–acceptor–donor′ (D‐A‐D′) type of OPC exhibits an accurate inherited relationship from dicarbazolyl‐substituted benzophenone (O2C, D‐A‐D) and diphenothiazinyl‐substituted benzophenone (O2P, D′‐A‐D′). By purposefully selecting the two parent molecules, that is, O2C (blue) and O2P (yellow), the white‐light emission of OPC can be achieved in a single molecule. This finding provides a feasible molecular strategy to design new AIE‐DF white‐light‐emitting organic molecules.
Scalable Synthesis of the Potent HIV Inhibitor BMS‐986001 by Non‐Enzymatic Dynamic Kinetic Asymmetric Transformation (DYKAT)
Authors: Ortiz Adrian , Benkovics Tamas , Beutner Gregory L. , Shi Zhongping , Bultman Michael , Nye Jeffrey , Sfouggatakis Chris , Kronenthal David R.
Published: April 2015

Described herein is the synthesis of BMS‐986001 by employing two novel organocatalytic transformations: 1) a highly selective pyranose to furanose ring tautomerization to access an advanced intermediate, and 2) an unprecedented small‐molecule‐mediated dynamic kinetic resolution to access a variety of enantiopure pyranones, one of which served as a versatile building block for the multigram, stereoselective, and chromatography‐free synthesis of BMS‐986001. The synthesis required five chemical transformations and resulted in a 44 % overall yield.
Ring Tension Applied to Thiol‐Mediated Cellular Uptake
Authors: Gasparini Giulio , Sargsyan Gevorg , Bang Eun‐Kyoung , Sakai Naomi , Matile Stefan
Published: April 2015

The objective of the study was to explore the potential of ring tension in cyclic disulfides for thiol‐mediated cellular uptake. Fluorescent probes that cannot enter cells were equipped with cyclic disulfides of gradually increasing ring tension. As demonstrated by flow cytometry experiments, uptake into HeLa Kyoto cells increased with increasing tension. Differences in carbon‐sulfur‐sulfur‐carbon (CSSC) dihedral angles as small as 8° caused significant changes in uptake efficiency. Uptake with high ring tension was better than with inactivated or activated linear disulfides or with thiols. Conversion of thiols on the cell surface into sulfides and disulfides decreased the uptake. Reduction of exofacial disulfides into thiols increased the uptake of transporters with disulfides and inactivated controls with thiols. These results confirm the occurrence of dynamic covalent disulfide‐exchange chemistry on cell surfaces. Mechanistic and colocalization studies indicate that endocytosis does not fully account for this cellular uptake with ring tension.
Epitope Targeting of Tertiary Protein Structure Enables Target‐Guided Synthesis of a Potent In‐Cell Inhibitor of Botulinum Neurotoxin
Authors: Farrow Blake , Wong Michelle , Malette Jacquie , Lai Bert , Deyle Kaycie M. , Das Samir , Nag Arundhati , Agnew Heather D. , Heath James R.
Published: April 2015

Botulinum neurotoxin (BoNT) serotype A is the most lethal known toxin and has an occluded structure, which prevents direct inhibition of its active site before it enters the cytosol. Target‐guided synthesis by in situ click chemistry is combined with synthetic epitope targeting to exploit the tertiary structure of the BoNT protein as a landscape for assembling a competitive inhibitor. A substrate‐mimicking peptide macrocycle is used as a direct inhibitor of BoNT. An epitope‐targeting in situ click screen is utilized to identify a second peptide macrocycle ligand that binds to an epitope that, in the folded BoNT structure, is active‐site‐adjacent. A second in situ click screen identifies a molecular bridge between the two macrocycles. The resulting divalent inhibitor exhibits an in vitro inhibition constant of 165 pM against the BoNT/A catalytic chain. The inhibitor is carried into cells by the intact holotoxin, and demonstrates protection and rescue of BoNT intoxication in a human neuron model.
Unwinding of the C‐Terminal Residues of Neuropeptide Y is critical for Y2 Receptor Binding and Activation
Authors: Kaiser Anette , Müller Paul , Zellmann Tristan , Scheidt Holger A. , Thomas Lars , Bosse Mathias , Meier Rene , Meiler Jens , Huster Daniel , Beck‐Sickinger Annette G. , Schmidt Peter
Published: April 2015

Despite recent breakthroughs in the structural characterization of G‐protein‐coupled receptors (GPCRs), there is only sparse data on how GPCRs recognize larger peptide ligands. NMR spectroscopy, molecular modeling, and double‐cycle mutagenesis studies were integrated to obtain a structural model of the peptide hormone neuropeptide Y (NPY) bound to its human G‐protein‐coupled Y2 receptor (Y2R). Solid‐state NMR measurements of specific isotope‐labeled NPY in complex with in vitro folded Y2R reconstituted into phospholipid bicelles provided the bioactive structure of the peptide. Guided by solution NMR experiments, it could be shown that the ligand is tethered to the second extracellular loop by hydrophobic contacts. The C‐terminal α‐helix of NPY, which is formed in a membrane environment in the absence of the receptor, is unwound starting at T32 to provide optimal contacts in a deep binding pocket within the transmembrane bundle of the Y2R.
Cationic Titanocene(III) Complexes for Catalysis in Single‐Electron Steps
Authors: Gansäuer Andreas , Hildebrandt Sven , Michelmann Antonius , Dahmen Tobias , von Laufenberg Daniel , Kube Christian , Fianu Godfred D. , Flowers Robert A.
Published: April 2015

By exploiting solvent and anion effects, [Cp2Ti]+complexes for atom‐economical catalysis in single‐electron steps were developed and applied for the first time. These complexes constitute remarkably stable and active catalysts for radical arylations. The reaction kinetics and catalyst composition were studied by cyclic voltammetry and in situ IR spectroscopy.
A Small Molecule Walks Along a Surface Between Porphyrin Fences That Are Assembled In Situ
Authors: Haq Sam , Wit Bareld , Sang Hongqian , Floris Andrea , Wang Yu , Wang Jianbo , Pérez‐García Lluïsa , Kantorovitch Lev , Amabilino David B. , Raval Rasmita
Published: April 2015

An on‐surface bimolecular system is described, comprising a simple divalent bis(imidazolyl) molecule that is shown to “walk” at room temperature via an inchworm mechanism along a specific pathway terminated at each end by oligomeric “fences” constructed on a monocrystalline copper surface. Scanning tunneling microscopy shows that the motion of the walker occurs along the [1$\bar 1$0] direction of the Cu surface with remarkably high selectivity and is effectively confined by the orthogonal construction of covalent porphyrin oligomers along the [001] surface direction, which serve as barriers. Density functional theory shows that the mobile molecule walks by attaching and detaching the nitrogen atoms in its imidazolyl “legs” to and from the protruding close‐packed rows of the metal surface and that it can transit between two energetically equivalent extended and contracted conformations by overcoming a small energy barrier.
Unsaturated polyester resins for thermoset applications using renewable isosorbide as a component for property improvement
Authors: Sadler Joshua M. , Toulan Faye R. , Palmese Giuseppe R. , La Scala John J.
Published: April 2015

Unsaturated polyester (UPE) resins are used in a variety of thermosetting applications due to the reduced cost when compared to epoxy resins; however, UPE resins also have reduced thermomechanical performance. Investigating avenues to improve the performance of UPEs has led to the use of bio‐based starting materials as structural components of the synthesized prepolymers as a result of their advantageous structural features. Isosorbide, a compound derived from renewable feedstocks, has been utilized to provide additional stiffness from the diol component for novel unsaturated polyesters resins. These resins have been shown to possess Tg's (32−72°C) and storage moduli (540−2200 MPa) that are in the desired range for composite materials with viscosities (1.2−25 Pa s) amenable to a variety of liquid molding techniques. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42315.
Facebook apps and tagging: The trade‐off between personal privacy and engaging with friends
Authors: Wisniewski Pamela , Xu Heng , Lipford Heather , Bello‐Ogunu Emmanuel
Published: April 2015

The use of social network sites offers many potential social benefits, but also raises privacy concerns and challenges for users. The trade‐off users have to make between using sites such as Facebook to connect with their friends versus protecting their personal privacy is not well understood. Furthermore, very little behavioral research has focused on how personal privacy concerns are related to information disclosures made by one's friends. Our survey study of 116 Facebook users shows that engaging with friends through tagging activity and third‐party application use is associated with higher levels of personal Facebook usage and a stronger emotional attachment to Facebook. However, users who have high levels of personal privacy concern and perceive a lack of effectiveness in Facebook's privacy policies tend to engage less frequently in tagging and app activities with friends, respectively. Our model and results explore illustrate the complexity of the trade‐off between privacy concerns, engaging with friends through tagging and apps, and Facebook usage.
What is behind the curtain of the Leiden Ranking?
Authors: Mutz Rüdiger , Daniel Hans‐Dieter
Published: April 2015

Even with very well‐documented rankings of universities, it is difficult for an individual university to reconstruct its position in the ranking. What is the reason behind whether a university places higher or lower in the ranking? Taking the example of ETH Zurich, the aim of this communication is to reconstruct how the high position of ETHZ (in Europe rank no. 1 in PP[top 10%]) in the Centre for Science and Technology Studies (CWTS) Leiden Ranking 2013 in the field “social sciences, arts and humanities” came about. According to our analyses, the bibliometric indicator values of a university depend very strongly on weights that result in differing estimates of both the total number of a university's publications and the number of publications with a citation impact in the 90th percentile, or PP(top 10%). In addition, we examine the effect of weights at the level of individual publications. Based on the results, we offer recommendations for improving the Leiden Ranking (for example, publication of sample calculations to increase transparency).
An alternative approach in regulation of expression of a transgene by endogenous miR‐145 in carcinoma and normal breast cell lines
Authors: Ghanbari Safari Maryam , Baesi Kazem , Hosseinkhani Saman
Published: April 2015

MicroRNAs are small noncoding RNAs that regulate gene expression by repressing translation of target cellular transcripts. Increasing evidences indicate that miRNAs have different expression profiles and play crucial roles in numerous cellular processes. Delivery and expression of transgenes for cancer therapy must be specific for tumors to avoid killing of healthy tissues. Many investigators have shown that transgene expression can be suppressed in normal cells using vectors that are responsive to microRNA regulation. To overcome this problem, miR‐145 that exhibits downregulation in many types of cancer cells was chosen for posttranscriptional regulatory systems mediated by microRNAs. In this study, a psiCHECK‐145T vector carrying four tandem copies of target sequences of miR‐145 into 3’‐UTR of the Renilla luciferase gene was constructed. Renilla luciferase activity from the psiCHECK‐145T vector was 57% lower in MCF10A cells with high miR‐145 expression as compared to a control condition. Additionally, overexpression of miR‐145 in MCF‐7 cells with low expression level of miR‐145 showed more than 76% reduction in the Renilla luciferase activity from the psiCHECK‐145T vector. Inclusion of miR‐145 target sequences into the 3′‐UTR of the Renilla luciferase gene is a feasible strategy for restricting transgene expression in a breast cancer cell line while sparing a breast normal cell line.
Fluorescence spectroscopy and docking study in two flavonoids, isolated tectoridin and its aglycone tectorigenin, interacting with human serum albumin: a comparison study
Authors: Li Yuanzhi , Wang Qing , He Jiawei , Yan Jin , Li Hui
Published: April 2015

Two flavonoids, tectoridin (TD) isolated from rhizomes of Iris tectorum and hydrolyzed aglycone tectorigenin (TG) were prepared and characterized to compare their different interaction ability with human serum albumin (HSA). Based on the results, the affinity of TG–HSA was stronger than that of TD–HAS, and TG combined more closely with HSA than did TD. HSA fluorescence was quenched by TD/TG. The interactions between TD/TG and HSA involved static quenching. The thermodynamic parameters indicated that both binding processes were spontaneous; hydrogen binding and van der Waals force were the main forces between TD and HSA, whereas a hydrophobic interaction was the main binding force between TG and HSA. Synchronous and 3D fluorescence spectra showed that the binding of TD/TG to HSA induced conformational changes. Moreover, a docking study confirmed the experimental results. Copyright © 2015 John Wiley & Sons, Ltd.
Realistic and stable animation of cloth
Authors: Yao Junfeng , Lan Lei , Lin Wenlin , She Yingying , Zhang Binbin
Published: April 2015

Researchers have proposed various techniques for cloth simulation in the last decades. The crucial problem in interactive animation for cloth is how to speed up simulation with a stable system. In this paper, we describe a realistic and stable scheme for cloth simulation based on mass‐spring system. This scheme modifies semi‐implicit integration used in cloth simulation system with an efficient damping method. Semi‐implicit integration methods have been widely used in dynamic simulation because of acceptable speed and stability. However, internal damping forces are generated with respect to rotational rigid motions, which are only depending on relative velocities. Undesirable change in global movement of dynamic cloth could result in damping artifact. We replace the internal damping forces with an optimal damping method which is based on iterative spring damping but the limit can be computed directly. The method provides simple damping parameter estimation and guarantees conservation of global movement. As a result, complex clothes can be realistically and stably simulated in real time. Copyright © 2015 John Wiley & Sons, Ltd.
PCMD: personality‐characterized mood dynamics model toward personalized virtual characters
Authors: Zhang Juzheng , Zheng Jianmin , Magnenat‐Thalmann Nadia
Published: April 2015

How to endow the virtual characters with personalized behavior patterns remains a challenging problem. Instead of heuristically designing behaviors for certain personalities, this paper bridges the gap between personalities and behaviors using a medium concept, mood, to make the behaviors of the characters consistent enough to convey their personalities, while flexible enough to make appropriate response in various situations. We propose a personality‐characterized mood dynamics model, in which the emotion weights are computed as a solution of a convex optimization problem that is constructed to make the overall mood approaches the personality after sufficient interactions. The convergence of the algorithm is demonstrated by numerical simulations. The implementation of the personality‐characterized mood dynamics model enables an emotion‐oriented virtual human, Sophie, to show personalized behaviors in the emotional interactions with users. Copyright © 2015 John Wiley & Sons, Ltd.
Snapshot quiz – recurrent right iliac fossa pain in the patient with a previous history of appendicitis
Authors: Aris Chandran Johan , Cobb Will A. , Keeler Barrie D. , Soin Bob
Published: April 2015

Key Clinical Message

A low threshold for computed tomography (CT) scanning in patients with previous appendicectomy and right iliac fossa pain helps facilitate timely diagnosis and exclusion of other differential diagnoses. Here, we present a rare cause which has significant medicolegal ramifications and is accurately diagnosed with CT.
Continuous Transfer Hydrogenation of Sugars to Alditols with Bioderived Donors over Cu–Ni–Al Catalysts
Authors: Scholz David , Aellig Christof , Mondelli Cecilia , Pérez‐Ramírez Javier
Published: April 2015

The transfer hydrogenation of sugars to alditols with biobased alcohol donors was studied over hydrotalcite‐derived Cu6−xNixAl2 catalysts prepared by coprecipitation at different pH and featuring variable Cu/Ni ratios. Their evaluation, after in situ activation in pure H2 at 773 K, in the ethanol‐assisted upgrading of glucose in a continuous‐flow fixed‐bed reactor identified the solid synthesized at pH 9–10 and with Cu/Ni=1 as the best performer. Based on textural, structural, and redox analyses, this is related to an enhanced intermetallic interaction. Upon screening alternative donors, a sorbitol yield as high as 67 % was achieved with 1,4‐butanediol. The catalytic system displayed a stable behavior during 48 h on stream and proved suitable to hydrogenate also fructose, mannose, xylose, and arabinose to the corresponding polyols (yields up to 65 %), thus standing as a more sustainable and economical alternative to Ru‐based catalysts for sugar reductive upgrading.
Thermally Induced Strains on the Catalytic Activity and Stability of Pt–M2O3/C (M=Y or Gd) Catalysts towards Oxygen Reduction Reaction
Authors: Luo Yun , Habrioux Aurélien , Calvillo Laura , Granozzi Gaetano , Alonso‐Vante Nicolas
Published: April 2015

Yttrium oxide and gadolinium oxide modified platinum nanoparticles supported on carbon (Vulcan XC‐72), noted as Pt–M2O3/C (M=Y and Gd), were synthesized by water‐in‐oil nanoemulsion chemical route, followed by heat treatment at 100 and 300 °C under hydrogen/nitrogen (H2/N2) atmosphere and tested as electrocatalysts for the oxygen reduction reaction (ORR). As revealed by powder X‐ray diffraction analysis, all obtained catalysts showed solely Pt face‐centered‐cubic structure, and absence of a secondary phase before and after heat treatments, indicating that Y2O3 and Gd2O3 are highly disordered (amorphous) and dispersed clusters. The surface Pt:M ratio (M=Y and Gd), as revealed by X‐ray photoelectron spectroscopy, increased after heat treatment with respect to the value of as‐prepared samples, for which the ratio was 1:1. Microstrain data extracted from Williamson–Hall plots for Pt–M2O3/C (M=Y and Gd) catalysts surprisingly increased after heat treatment at 100 °C, remaining nearly constant after heat treatment at 300 °C, whereas the value of pure Pt nanoparticles, noted as Pt/C, decreased after heat treatments. The mean particle size derived from TEM images for Pt–M2O3/C (M=Y and Gd) was almost unchanged after heat treatments, at variance with the Pt/C case where a clear increase is observed. Surface specific activity and mass activity towards ORR obtained with as‐prepared Pt–M2O3/C (M=Y and Gd) catalysts were higher than those of as‐prepared Pt/C catalyst. After heat treatment, the ORR activity of Pt–M2O3/C (M=Y and Gd) augmented, whereas that of Pt/C diminished. Moreover, after 6000 cycles between 0.5 and 0.95 V versus reversible hydrogen electrode (vs. RHE), Pt–M2O3/C (M=Y and Gd) catalysts retained a large active surface area and a high kinetic current density at 0.9 V vs. RHE in comparison with Pt/C samples. These facts assess a positive effect of the interaction between M2O3 (M=Y and Gd) and Pt catalytic centers both on the catalytic activity of the material towards ORR and on its durability.
Suppressing Vertical Displacement of Lithiated Silicon Particles in High Volumetric Capacity Battery Electrodes
Authors: Yu Denis Y. W. , Zhao Ming , Hoster Harry E.
Published: April 2015

Silicon is a potential high‐capacity anode material for lithium‐ion batteries. However, large volume changes in the material remains a bottleneck to its commercialization. Many works have been devoted to nanostructured composites with voids to accommodate the volume expansion. Yet, the full capability of silicon cannot be utilized, because these nanostructured electrodes have low volumetric capacities. Herein, we redesign dense silicon electrodes with three times the volumetric capacity of graphite. In situ electrochemical dilatometry reveals that the electrode thickness change is nonlinear as a function of state of charge and highly affected by the electrode composition. One key problem is the large vertical displacement of the silicon particles during lithiation, which leads to irreversible particle detachment and electrode porosity increase. Better reversibility in electrode thickness changes can be achieved by using polyimide, with a higher modulus and larger ultimate elongation, as the binder, leading to better cycle stability.
Nitrate Anion Recognition in Organic–Aqueous Solvent Mixtures by a Bis(triazolium)acridine‐Containing [2]Rotaxane
Authors: Martí‐Centelles Vicente , Beer Paul D.
Published: April 2015

The synthesis of a novel [2]rotaxane host system containing a bis(triazolium)acridine‐based axle component is reported. 1H NMR anion‐binding titrations reveal that the rotaxane is able to recognise selectively the NO3− anion over a range of more basic oxoanions (AcO−, HCO3− and H2PO4−) in a competitive organic–aqueous solvent mixture.
Structural and Solubility Parameter Correlations of Gelation Abilities for Dihydroxylated Derivatives of Long‐Chain, Naturally Occurring Fatty Acids
Authors: Zhang Mohan , Selvakumar Sermadurai , Zhang Xinran , Sibi Mukund P. , Weiss Richard G.
Published: April 2015

Creating structure–property correlations at different distance scales is one of the important challenges to the rational design of molecular gelators. Here, a series of dihydroxylated derivatives of long‐chain fatty acids, derived from three naturally occurring molecules—oleic, erucic and ricinoleic acids—are investigated as gelators of a wide variety of liquids. Conclusions about what constitutes a more (or less!) efficient gelator are based upon analyses of a variety of thermal, structural, molecular modeling, and rheological results. Correlations between the manner of molecular packing in the neat solid or gel states of the gelators and Hansen solubility data from the liquids leads to the conclusion that diol stereochemistry, the number of carbon atoms separating the two hydroxyl groups, and the length of the alkanoic chains are the most important structural parameters controlling efficiency of gel formation for these gelators. Some of the diol gelators are as efficient or even more efficient than the well‐known, excellent gelator, (R)‐12‐hydroxystearic acid; others are much worse. The ability to form extensive intermolecular H‐bonding networks along the alkyl chains appears to play a key role in promoting fiber growth and, thus, gelation. In toto, the results demonstrate how the efficiency of gelation can be modulated by very small structural changes and also suggest how other structural modifications may be exploited to create efficient gelators.
Hierarchical Assembly of Plasmonic Nanoparticles
Authors: Hamon Cyrille , Liz‐Marzán Luis M.
Published: April 2015

In this Minireview, we summarize recent advances in the ordering of plasmonic nanoparticles over extended areas on solid substrates. The spotlight is thus focused on examples showing one‐, two‐, and three‐dimensional assemblies, with a particular attention on assemblies displaying hierarchical order. Throughout the manuscript we identify the main parameters and methods that can be tuned to achieve long range organization.
Chiral Iminophosphoranes—An Emerging Class of Superbase Organocatalysts
Authors: Krawczyk Henryk , Dzięgielewski Marek , Deredas Dariusz , Albrecht Anna , Albrecht Łukasz
Published: April 2015

Chiral Brønsted base catalysis is a fascinating and highly explored field of research. For many years catalysts based on chincona alkaloid chiral scaffolds have constituted privileged systems widely employed in numerous base‐promoted organic transformations. Recently, a novel group of chiral base catalysts has been successfully introduced. The application of organosuperbases, namely cyclopropenimines, guanidines, and iminophosphoranes, as chiral catalysts is receiving increasing attention. The aim of this Concept article is to summarize recent progress in the field of chiral iminophosphorane superbase organocatalysis. Catalysts design, different approaches to their synthesis, and applications in asymmetric synthesis are outlined and discussed in detail.