bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel mutation in the NAGLU gene associated with Sanfilippo syndrome type B (mucopolysaccharidosis III B)
Authors: Hettiarachchi Dineshani , Nethikumara Nilaksha , Pathirana Bamunu Arachchi Pathiranage Sajeewani , Weththasigha Kalum , Dissanayake Weerabaddana Dilshani Niluka , Dissanayake Vajira H. W.
Published: April 2018

Key Clinical Message

Homozygous or compound heterozygous mutation in the gene encoding N‐alpha‐acetylglucosaminidase (NAGLU) on chromosome 17q21 results in Sanfilippo B, resulting in excess accumulation of intralysosomal glycosaminoglycans (mucopolysaccharides) in various tissues. We wish to report a novel homozygous variant in a child with features of Sanfilippo syndrome B.
A case of extreme weight loss due to mesenteric ischemia and antiphospholipid syndrome
Authors: Melas Nikolaos , Haji Younes Amil , Lindberg Robert , Magnusson Peter
Published: April 2018

Key Clinical Message

Mesenteric ischemia and antiphospholipid syndrome is a rare combination but should be suspected as a differential diagnosis. This may be presented as diffuse abdominal pain typically after food intake, diarrhea, and weight loss. Early recognition is warranted, and nutrition, stenting, and anticoagulant treatments are indicated.
Cor triatriatum dexter
Authors: Zoltowska Dominika , Kalavakunta Jagadeesh K
Published: April 2018

Key Clinical Message

Cor triatriatum dexter (CTD) is an extremely rare finding (<0.01%), resulting from the persistence of the right valve of sinus venosus. Echocardiography with color Doppler is the first‐line tool for diagnosis and decision making.
Photocatalytic Composite of a Floating BiOBr@Graphene Oxide@Melamine Foam for Efficient Removal of Organics
Authors: Liu Wenhua , Gao Yuan , Yang Yuping , Zou Quan , Yang Guoxiang , Zhang Ziping , Li Huifan , Miao Yingchun , Li Hexing , Huo Yuning
Published: April 2018

Hierarchical photocatalytic composite BiOBr@graphene oxide@melamine foam was developed by using a solvothermal process. In this composite, the graphene oxide‐wrapped melamine foam acted as the substrate for supporting the catalyst, and the BiOBr nanosheets stably combined with the graphene oxide surface in a uniform distribution. This composite could be floated on the solution surface to inhibit the light shielding effect of colorful organic pollutants. Furthermore, the graphene oxide‐wrapped melamine foam provided mass transfer channels for organics and enriched the organics in its 3D structure. BiOBr nanosheets presented efficient photodegradation of organics and solved the problem of adsorption saturation of graphene oxide@melamine foam. Graphene oxide could further improve the light utilization, inhibit the recombination of charges, and enrich the organics. In view of the synergistic effect of adsorption and photocatalysis, this catalyst system realized the efficient removal of the organic rhodamine B and presented the promoted amount of contaminant removal with increased rhodamine B concentration.
One‐step Synthesis of α‐Keto Acids from Racemic Amino Acids by A Versatile Immobilized Multienzyme Cell‐free System
Authors: Orrego Alejandro H. , López‐Gallego Fernando , Espaillat Akbar , Cava Felipe , Guisan José M. , Rocha‐Martin Javier
Published: April 2018

The elevated value of α‐keto acids has pushed scientists to explore more efficient and less expensive alternatives for their synthesis. In this work, an immobilized tri‐enzyme system that produced α‐keto acids in “one‐pot” from l‐ or racemic mixtures of diverse amino acids was presented. The system combined a broad‐spectrum amino acid racemase (BsrV), a d‐amino acid oxidase (DAAO) and catalase (CAT). BsrV racemized l‐amino acids into their d‐enantiomers, DAAO catalyzed the stereospecific oxidative deamination of the d‐amino acids into their corresponding α‐keto acids, ammonium ion, and H2O2. Finally, CAT converted the inactivating H2O2 into H2O and O2, which can be reused by the oxidase reaction. BsrV thermal stability was improved 3,300‐fold by immobilizing the enzyme on glyoxyl‐activated agarose beads. DAAO and CAT were co‐immobilized on agarose beads functionalized with glutaraldehyde groups for enhancing their stabilities and eliminating H2O2 in a much more effective way. To show the versatility of this system, racemic mixtures of amino acids were converted in their corresponding α‐keto acids. The coupling of the three immobilized enzymes permitted conversions of approximately 99 % through a dynamic kinetic resolution process. This system conserved 100 % of its initial effectiveness after 8 reaction cycles. Collectively, our innovative tri‐enzyme system for the synthesis of α‐keto acids opens the door for a cheapening in the production of many pharmaceutical and cosmetics.
Carbodicarbenes and their Captodative Behavior in Catalysis
Authors: Liu Shu‐kai , Shih Wei‐Chih , Chen Wen‐Ching , Ong Tiow‐Gan
Published: April 2018

The front cover artwork for issue 7/2018 is provided by Ong research group at Institute of Chemistry, Academia Sinica (Republic of China). The image shows a new family of ligands, that of carbodicarbenes. Because of their stronger σ‐donating capability, they have a huge potential to become a new class of scaffolds in organometallic chemistry and catalysis. See the Concept itself at https://doi.org/10.1002/cctc.201701577.
Nitrogenated Urchin‐like Nb2O5 Microspheres with Extraordinary Pseudocapacitive Properties for Lithium‐Ion Capacitors
Authors: Chen Zhijie , Li Hongsen , Lu Xiaoxia , Wu Langyuan , Jiang Jiangmin , Jiang Songbai , Wang Junjun , Dou Hui , Zhang Xiaogang
Published: April 2018

Recently, lithium‐ion capacitors (LICs) combining the complementary characteristics of both lithium‐ion batteries (LIBs) and supercapacitors, have received exhaustive investigation to meet the increasing demands for clean energy. However, their commercial application has been limited by the mismatch of charge‐storage capacity and electrode kinetics between the capacitor‐type cathode and battery‐type anode. Thus, developing a novel high‐power insertion anode material is the key to realizing excellent energy and power densities for LICs. Here, 3D hierarchical Nb2O5 microspheres assembled by surface‐nitrogenated nanowires have been synthesized through a unique anti‐solvent precipitation‐assisted solvothermal route accompanied by a nitrogenization treatment, which can be successfully used for advanced LICs configuration. Owing to the high aspect ratio of ultrathin nanowires, unique pore structures caused by nitridation, improved electronic conductivity, and favorable kinetic stemming from pseudocapacitive behavior, the resultant nitrogenated Nb2O5 microspheres can deliver a high capacity of 205.3 mAh g−1 with remarkable rate capability and long lifespan. When constructed into a new LIC device with peanut‐shell derived carbon (PSC) cathode, an exceptionally high energy density of ∼83.5 Wh kg−1 and a high power density of 10 kW kg−1 with prominent cycling stability are realized. Significantly, the simultaneous manipulation of superstructure design and surface nitrogenization in novel anode material provides new opportunities to boost the energy and power densities for hybrid‐ion capacitors.
Nitrogen‐Doped Graphdiyne as High‐capacity Electrode Materials for Both Lithium‐ion and Sodium‐ion Capacitors
Authors: Shen Xiangyan , Yang Ze , Wang Kun , Wang Ning , He Jianjiang , Du Huiping , Huang Changshui
Published: April 2018

Nitrogen‐doped graphdiyne (N‐GDY) is prepared through the nitriding of graphdiyne (GDY) under ammonia. This material possesses excellent ability for the fast diffusion and storage of lithium and sodium ions due to its high conductivity, wide interlayer distance, unique three‐dimensional porous structure, and associated defects from nitrogen doping. The lithium‐ion capacitor (LIC) and sodium‐ion capacitor (SIC) fabricated with N‐GDY as the negative electrode show outstanding electrochemical performance, especially having both high power density and energy density. Besides exhibiting an energy density of 174 Wh kg−1, the N‐GDY‐based LIC can still offer an energy density of 107 Wh kg−1even at a power density of 11250 W kg−1, whereas the N‐GDY‐based SIC can retain an energy density of 119 Wh kg−1at a power density of 22500 W kg−1. The energy densities of N‐GDY‐based LIC and SIC are higher than those of pure GDY and many other carbon materials.
Substitution‐Inert Polynuclear Platinum Complexes as Metalloshielding Agents for Heparan Sulfate
Authors: Gorle Anil Kumar , Katner Samantha J. , Johnson Wyatt E. , Lee Daniel E. , Daniel A. Gerard , Ginsburg Eric P. , von Itzstein Mark , Berners‐Price Susan J. , Farrell Nicholas P.
Published: April 2018

Cleavage of heparan sulfate proteoglycans (HSPGs) by the enzyme heparanase modulates tumour‐related events including angiogenesis, cell invasion, and metastasis. Metalloshielding of heparan sulfate (HS) by positively charged polynuclear platinum complexes (PPCs) effectively inhibits physiologically critical HS functions. Studies using bacterial P. heparinus heparinase II showed that a library of Pt complexes varying in charge and nuclearity and the presence or absence of a dangling amine inhibits the cleavage activity of the enzyme on the synthetic pentasaccharide, Fondaparinux (FPX). Charge‐dependent affinity of PPC for FPX was seen in competition assays with methylene blue and ethidium bromide. The dissociation constant (Kd) of TriplatinNC for FPX was directly measured by isothermal titration calorimetry (ITC). The trend in DFT calculated interaction energies with heparin fragments is consistent with the spectroscopic studies. Competitive inhibition of TAMRA‐R9 internalization in human carcinoma (HCT116) cells along with studies in HCT116, wildtype CHO and mutant CHO‐pgsA745 (lacking HS/CS) cells confirm that HSPG‐mediated interactions play an important role in the cellular accumulation of PPCs.
A Computational Mechanistic Investigation into Reduction of Gold(III) Complexes by Amino Acid Glycine: A New Variant for Amine Oxidation
Authors: Chipman Antony , Gouranourimi Ali , Farshadfar Kaveh , Olding Angus , Yates Brian F. , Ariafard Alireza
Published: April 2018

Density functional theory (DFT) was utilized to explore the reduction of gold(III) complexes by the amino acid glycine (Gly). Interestingly, when the nitrogen atom of Gly coordinates to the gold(III) center, its Cα‐hydrogen atom becomes so acidic that it can be easily deprotonated by a mild base like water. The deprotonation converts the amino acid into a potent reductant by which gold(III) is reduced to gold(I) with a moderate activation energy. To our knowledge, this is the first contribution suggesting that primary amines are oxidized to imines via direct α‐carbon deprotonation. This finding may provide new insights into the mechanistic interpretation of amine oxidations catalyzed/mediated by a center with high cathodic reduction potential. This work also provides a rationalization behind why gold(III) complexes with amine‐based polydentate ligands are reluctant to undergo a redox process. Gold(III) reduction occurs most efficiently if the Cα proton leaves in the plane of the Cα, N and Au atoms. Chelation prevents this alignment, resulting in the gold(III) complex being unreactive toward reduction. It has been experimentally found that gold(III) is capable of oxidizing Gly to glyoxylic acid (GA) as the initial product. The latter, in the presence of another gold(III) complex, has been reported to undergo oxidative decarboxylation to afford CO2 and HCOOH. This process is found to be mediated by formation of a geminal diol intermediate produced by reaction of water with the aldehyde functional group of the coordinated GA.
Enantiopure versus Racemic Mixture in Reversible, Two‐Step, Single‐Crystal‐to‐Single‐Crystal Transformations of Copper(II) Complexes
Authors: Ene Cristian D. , Maxim Catalin , Rouzières Mathieu , Clérac Rodolphe , Avarvari Narcis , Andruh Marius
Published: April 2018

The reaction of chiral sodium complexes, 1∞[Na(S‐valmetH)]⋅H2O (1‐S) and 1∞[Na(R‐valmetH)]⋅H2O (1‐R), with copper(II) acetate affords chiral one‐dimensional coordination polymers with the formulas 1∞[Cu(S‐valmet)(H2O)]⋅H2O (2‐S) and 1∞[Cu(R‐valmet)(H2O)]⋅H2O (2‐R) (R/S‐valmetH2 are Schiff base proligands resulting from the condensation reactions between o‐vanillin and R/S‐methionine). The copper ions are connected by the carboxylato groups belonging to the amino‐acid moieties, resulting in infinite chains showing syn‐anti out‐of‐plane bridging mode. The circular dichroism spectra of 1‐S, 1‐R, 2‐S, and 2‐R confirm their enantiomeric nature. Compounds 2‐S and 2‐R undergo a two‐step single‐crystal‐to‐single‐crystal transformation, with the elimination of the lattice and coordinated water molecules: 1∞[Cu(S‐valmet)(H2O)]⋅H2O (2‐S)→1∞[Cu(S‐valmet)]⋅H2O (3‐S⋅H2O)→1∞[Cu(S‐valmet)] (3‐S) and 1∞[Cu(R‐valmet)(H2O)]⋅H2O (2‐R)→1∞[Cu(R‐valmet)]⋅H2O (3‐R⋅H2O)→1∞[Cu(R‐valmet)] (3‐R), respectively. During these transformations, every pair of face‐to‐face chains present in 2‐S (or 2‐R) has been “zipped up” into a chiral double chain through the removal of the aqua ligands and their replacement by the carboxylato oxygen atoms from the neighboring chain. Consequently, each carboxylato group now bridges three copper ions. The conversion of the single chains, 2‐S and 2‐R, into the double chains, 3‐S and 3‐R, is accompanied by a change of the strength of the exchange interactions between the copper ions: weak antiferromagnetic couplings are observed in compound 2‐S (J/kB=−1.23(5) K, H=−2J ΣSiSi+1) and relatively strong in compound 3‐S (J/kB=−76.0(8) K). When the racemic mixture of the ligands, R,S‐valmetH2, is employed, in the same experimental conditions, a racemic mixture of mononuclear compounds, [Cu(R,S‐valmet)(H2O)2]⋅H2O (4‐RS), is obtained. Compound 4‐RS also undergoes a SCSC transformation with the elimination of the lattice and one of the coordinated water molecules, resulting in a racemic mixture of chiral chains, 1∞[Cu(R‐valmet)(H2O)]⋅1∞[Cu(S‐valmet)(H2O)] (5‐RS). In this compound, the coupling of the copper(II) ions within the chains is weak and ferromagnetic (J/kB=+0.10(2) K). These results prove that the chirality of the valmetH2 ligands (optically pure or racemic mixture) plays a key role in the self‐assembly process of the copper(II) complexes.
Porous Nanocomposite Comprising Ultralong Hydroxyapatite Nanowires Decorated with Zinc‐Containing Nanoparticles and Chitosan: Synthesis and Application in Bone Defect Repair
Authors: Sun Tuan‐Wei , Yu Wei‐Lin , Zhu Ying‐Jie , Chen Feng , Zhang Yong‐Gang , Jiang Ying‐Ying , He Yao‐Hua
Published: April 2018

Hydroxyapatite nanowires exhibit a great potential in biomedical applications owing to their high specific surface area, high flexibility, excellent mechanical properties, and similarity to mineralized collagen fibrils of natural bone. In this work, zinc‐containing nanoparticle‐decorated ultralong hydroxyapatite nanowires (Zn‐UHANWs) with a hierarchical nanostructure have been synthesized by a one‐step solvothermal method. The highly flexible Zn‐UHANWs exhibit a hierarchical rough surface and enhanced specific surface area as compared with ultralong hydroxyapatite nanowires (UHANWs). To evaluate the potential application of Zn‐UHANWs in bone regeneration, the biomimetic Zn‐UHANWs/chitosan (CS) (Zn‐UHANWs/CS) composite porous scaffold with 80 wt % Zn‐UHANWs was prepared by incorporating Zn‐UHANWs into the chitosan matrix by the freeze‐drying process. The as‐prepared Zn‐UHANWs/CS composite porous scaffold exhibits enhanced mechanical properties, highly porous structure, and excellent water retention capacity. In addition, the Zn‐UHANWs/CS porous scaffold has a good biodegradability with the sustainable release of Zn, Ca, and P elements in aqueous solution. More importantly, the Zn‐UHANWs/CS porous scaffold can promote the osteogenic differentiation of rat bone marrow derived mesenchymal stem cells and facilitate in vivo bone regeneration as compared with the pure CS porous scaffold or UHANWs/CS porous scaffold. Thus, both the Zn‐UHANWs and Zn‐UHANWs/CS porous scaffold developed in this work are promising for application in bone defect repair.
Facile Synthesis of Highly Efficient Amorphous Mn‐MIL‐100 Catalysts: Formation Mechanism and Structure Changes during Application in CO Oxidation
Authors: Zhang Xiaodong , Li Hongxin , Lv Xutian , Xu Jingcheng , Wang Yuxin , He Chi , Liu Ning , Yang Yiqiong , Wang Yin
Published: April 2018

A comprehensive study was carried out on amorphous metal‐organic frameworks Mn‐MIL‐100 as efficient catalysts for CO oxidation. This study focused on explaining the crystalline–amorphous–crystalline transformations during thermolysis of Mn‐MIL‐100 and studying the structure changes during the CO oxidation reaction. A possible formation mechanism of amorphous Mn‐MIL‐100 was proposed. Amorphous Mn‐MIL‐100 obtained by calcination at 250 °C (a‐Mn‐250) showed a smaller specific surface area (4 m2 g−1) but high catalytic activity. Furthermore, the structure of amorphous Mn‐MIL‐100 was labile during the reaction. When a‐Mn‐250 was treated with reaction atmosphere at high temperature (giving used‐a‐Mn‐250‐S), the amorphous catalysts transformed into Mn2O3. Meanwhile, the BET surface area (164 m2 g−1) and catalytic performance both sharply increased. In addition, used‐a‐Mn‐250‐S catalyst transformed from Mn2O3 into Mn3O4, and this resulted in a slight decrease of catalytic activity in the presence of 1 vol % water vapor in the feed stream. A schematic mechanism of the structure changes during the reaction process was proposed. The success of the synthesis relies on the increase in BET surface area by using CO as retreatment atmosphere, and the enhanced catalytic activity was attributed to the unique structure, a large quantity of surface active oxygen species, oxygen vacancies, and good low‐temperature reduction behavior.
Acquiring High‐Performance Deep‐Blue OLED Emitters through an Unexpected Blueshift Color‐Tuning Effect Induced by Electron‐Donating ‐OMe Substituents
Authors: Peng Song , Zhao Yihuan , Fu Caixia , Pu Xuemei , Zhou Liang , Huang Yan , Lu Zhiyun
Published: April 2018

A series of blue‐emissive 7‐(diphenylamino)‐4‐phenoxycoumarin derivatives bearing ‐CF3, ‐OMe, or ‐N(Me)2 substituents on the phenoxy subunit were synthesized. Although both the ‐CF3 and ‐N(Me)2 modifications were found to trigger redshifted fluorescence, the ‐OMe substitution was demonstrated to exert an unexpected blueshift color‐tuning effect toward the deep‐blue region. The reason is that the moderate electron‐donating ‐OMe group can endow coumarins with unaltered HOMO but elevated LUMO energy levels. Moreover, the ‐OMe substitution was found to be beneficial to the thermal stability of these coumarins. Therefore, the trimethoxy‐substituted objective compound can act as a high‐performance deep‐blue organic light‐emitting diode (OLED) emitter, and OLED based on it emits deep‐blue light with CIE coordinates of (0.148, 0.084), maximum luminance of 7800 cd m−2, and maximum external quantum efficiency of 5.1 %. These results not only shed light on the molecular design strategy for high‐performance deep‐blue OLED emitters through color‐tuning, but also show the perspective of coumarin derivatives as deep‐blue OLED emitters.
Real‐Space In Situ Bond Energies: Toward A Consistent Energetic Definition of Bond Strength
Authors: Menéndez‐Crespo Daniel , Costales Aurora , Francisco Evelio , Martín Pendás Ángel
Published: April 2018

A rigorous definition of intrinsic bond strength based on the partitioning of a molecule into real‐space fragments is presented. Using the domains provided by the quantum theory of atoms‐in‐molecules (QTAIM) together with the interacting quantum atoms (IQA) energetic decomposition, we show how an in situ bond strength, matching all the requirements of an intrinsic bond energy, can be defined between each pair of fragments. Total atomization or fragmentation energies are shown to be equal to the sum of these in situ bond energies (ISBEs) if the energies of the fragments are measured with respect to their in‐the‐molecule state. These energies usually lie above the ground state of the isolated fragments by quantities identified with the standard fragment relaxation or deformation energies, which are also provided by the protocol. Deformation energies bridge dissociation energies with ISBEs, and can be dissected by using well‐known tools of real‐space theories of chemical bonding. Similarly, ISBEs can be partitioned into ionic and covalent contributions, and this feature adds to the chemical appeal of the procedure. All the energetic quantities examined are observable and amenable, in principle, to experimental determination. Several systems, exemplifying the role of each energetic term presented herein, are used to show the power of the approach.
A Pseudo‐Octahedral Cobalt(II) Complex with Bispyrazolylpyridine Ligands Acting as a Zero‐Field Single‐Molecule Magnet with Easy Axis Anisotropy
Authors: Rigamonti Luca , Bridonneau Nathalie , Poneti Giordano , Tesi Lorenzo , Sorace Lorenzo , Pinkowicz Dawid , Jover Jesus , Ruiz Eliseo , Sessoli Roberta , Cornia Andrea
Published: April 2018

The homoleptic mononuclear compound [Co(bpp‐COOMe)2](ClO4)2 (1) (bpp‐COOMe=methyl 2,6‐di(pyrazol‐1‐yl)pyridine‐4‐carboxylate) crystallizes in the monoclinic C2/c space group, and the cobalt(II) ion possesses a pseudo‐octahedral environment given by the two mer‐coordinated tridentate ligands. Direct‐current magnetic data, single‐crystal torque magnetometry, and EPR measurements disclosed the easy‐axis nature of this cobalt(II) complex, which shows single‐molecule magnet behavior when a static field is applied in alternating‐current susceptibility measurements. Diamagnetic dilution in the zinc(II) analogue [Zn(bpp‐COOMe)2](ClO4)2 (2) afforded the derivative [Zn0.95Co0.05(bpp‐COOMe)2](ClO4)2 (3), which exhibits slow relaxation of magnetization even in zero field thanks to the reduction of dipolar interactions. Theoretical calculations confirmed the overall electronic structure and the magnetic scenario of the compound as drawn by experimental data, thus confirming the spin‐phonon Raman relaxation mechanism, and a direct quantum tunneling in the ground state as the most plausible relaxation pathway in zero field.
Hypervalent Iodine Reagents by Anodic Oxidation: A Powerful Green Synthesis
Authors: Elsherbini Mohamed , Wirth Thomas
Published: April 2018

The anodic oxidation of aryl iodides is a powerful method for the synthesis of hypervalent iodine reagents, which eliminates the necessity to use expensive or hazardous chemical oxidizing reagents. The hypervalent iodine reagents generated at the anode are successfully used as either in‐cell or ex‐cell mediators for different valuable chemical transformations such as fluorinations and oxidative cyclizations. More recently, recyclable mediators and catalytic protocols have been developed.
Transformation of Perovskite BaBiO3 into Layered BaBiO2.5 Crystals Featuring Unusual Chemical Bonding and Luminescence
Authors: Li Hong , Zhao Qing , Liu Bo‐Mei , Zhang Jun‐Ying , Li Zhi‐Yong , Guo Shao‐Qiang , Ma Ju‐Ping , Kuroiwa Yoshihiro , Moriyoshi Chikako , Zheng Li‐Rong , Sun Hong‐Tao
Published: April 2018

Engineering oxygen coordination environments of cations in oxides has received intense interest thanks to the opportunities for the discovery of novel oxides with unusual properties. Herein, the synthesis of stoichiometric layered BaBiO2.5 by a nontopotactic phase transformation of perovskite BaBiO3 is presented. By analyzing the synchrotron X‐ray diffraction data by the maximum‐entropy method/Rietveld technique, it was found that Bi is involved in an unusual chemical bonding situation with four oxygen atoms featuring one ionic bond and three covalent bonds, which results in an asymmetric coordination geometry. Photophysical characterization revealed that this peculiar structure shows near‐infrared luminescence differing from that of conventional Bi‐containing compounds. Experimental and theoretical results led to the proposal of an excitonic nature of the luminescence. This work highlights that synthesizing materials with uncommon Bi−O bonding and Bi coordination geometry provides a pathway to the discovery of systems with new functionalities. This could inspire interest in the exploration of a range of materials containing heavier p‐block elements with prospects for finding systems with unusual properties.
Reductive Elimination Leading to C−C Bond Formation in Gold(III) Complexes: A Mechanistic and Computational Study
Authors: Rocchigiani Luca , Fernandez‐Cestau Julio , Budzelaar Peter H. M. , Bochmann Manfred
Published: April 2018

The factors affecting the rates of reductive C−C cross‐coupling reactions in gold(III) aryls were studied by using complexes that allow easy access to a series of electronically modified aryl ligands, as well as to gold methyl and vinyl complexes, by using the pincer compounds [(C^N^C)AuR] (R=C6F5, CH=CMe2, Me and p‐C6H4X, where X=OMe, F, H, tBu, Cl, CF3, or NO2) as starting materials (C^N^C=2,6‐(4′‐tBuC6H3)2pyridine dianion). Protodeauration followed by addition of one equivalent SMe2 leads to the quantitative generation of the thioether complexes [(C^N‐CH)AuR(SMe2)]+. Upon addition of a second SMe2 pyridine is displaced, which triggers the reductive aryl−R elimination. The rates for these cross‐couplings increase in the sequence k(vinyl)>k(aryl)≫k(C6F5)>k(Me). Vinyl−aryl coupling is particularly fast, 1.15×10−3 L mol−1 s−1 at 221 K, whereas both C6F5 and Me couplings encountered higher barriers for the C−C bond forming step. The use of P(p‐tol)3 in place of SMe2 greatly accelerates the C−C couplings. Computational modelling shows that in the C^N‐bonded compounds displacement of N by a donor L is required before the aryl ligands can adopt a conformation suitable for C−C bond formation, so that elimination takes place from a four‐coordinate intermediate. The C−C bond formation is the rate‐limiting step. In the non‐chelating case, reductive C(sp2)−C(sp2) elimination from three‐coordinate ions [(Ar1)(Ar2)AuL]+ is almost barrier‐free, particularly if L=phosphine.
13C Kinetic Isotope Effects as a Quantitative Probe To Distinguish between Enol and Enamine Mechanisms in Aminocatalysis
Authors: Roytman Vladislav A. , Karugu Rachael W. , Hong Yun , Hirschi Jennifer S. , Vetticatt Mathew J.
Published: April 2018

A combination of experimental 13C kinetic isotope effects (KIEs) and high‐level density functional theory (DFT) calculations is used to distinguish between “enamine” and “enol” mechanisms in the Michael addition of acetone to trans‐β‐nitrostyrene catalyzed by Jacobsen's primary amine thiourea catalyst. In light of the recent findings that the widely used 18O‐incorporation probe for these mechanisms is flawed, the results described in this communication demonstrate an alternative probe to distinguish between these pathways. A key advantage of this probe is that quantitative mechanistic information is obtained without modifying experimental conditions. This approach is expected to find application in resolving mechanistic debates, while providing valuable information about the key transition state of organocatalyzed reactions involving the α‐functionalization of carbonyls.
Turning Off Transcription with Bacterial RNA Polymerase through CuAAC Click Reactions of DNA Containing 5‐Ethynyluracil
Authors: Slavíčková Michaela , Janoušková Martina , Šimonová Anna , Cahová Hana , Kambová Milada , Šanderová Hana , Krásný Libor , Hocek Michal
Published: April 2018

Copper(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) click reaction in the major groove of DNA containing 5‐ethynyluracil (UE) with azides was used for turning off sequence‐specific protein–DNA interactions. The concept was first demonstrated on switching off cleavage of short modified DNA by restriction endonuclease BamHI‐HF. Finally, DNA template containing UE was used for in vitro transcription with E. coli RNA polymerase and the transcription was turned off by CuAAC with 3‐azidopropane‐1,2‐diol or 3‐azido‐7‐hydroxycoumarin.
Potent Inhibitors of Plasmodial Serine Hydroxymethyltransferase (SHMT) Featuring a Spirocyclic Scaffold
Authors: Schwertz Geoffrey , Witschel Matthias C. , Rottmann Matthias , Leartsakulpanich Ubolsree , Chitnumsub Penchit , Jaruwat Aritsara , Amornwatcharapong Watcharee , Ittarat Wanwipa , Schäfer Anja , Aponte Raphael A. , Trapp Nils , Chaiyen Pimchai , Diederich François
Published: April 2018

With the discovery that serine hydroxymethyltransferase (SHMT) is a druggable target for antimalarials, the aim of this study was to design novel inhibitors of this key enzyme in the folate biosynthesis cycle. Herein, 19 novel spirocyclic ligands based on either 2‐indolinone or dihydroindene scaffolds and featuring a pyrazolopyran core are reported. Strong target affinities for Plasmodium falciparum (Pf) SHMT (14–76 nm) and cellular potencies in the low nanomolar range (165–334 nm) were measured together with interesting selectivity against human cytosolic SHMT1 (hSHMT1). Four co‐crystal structures with Plasmodium vivax (Pv) SHMT solved at 2.2–2.4 Å resolution revealed the key role of the vinylogous cyanamide for anchoring ligands within the active site. The spirocyclic motif in the molecules enforces the pyrazolopyran core to adopt a substantially more curved conformation than that of previous non‐spirocyclic analogues. Finally, solvation of the spirocyclic lactam ring of the receptor‐bound ligands is discussed.
Stepwise Hierarchical Self‐Assembly of Supramolecular Amphiphiles into Higher‐Order Three‐Dimensional Nanostructures
Authors: della Sala Flavio , Verbeet Wessel , Silvestrini Simone , Fortunati Ilaria , Ferrante Camilla , Prins Leonard J.
Published: April 2018

Hierarchical self‐assembly describes the spontaneous formation of large well‐defined molecular structures through a sequence of spontaneous processes driven by noncovalent interactions between molecules and intermediate structures. The chemical information embedded in the initial molecules determines the structural outcome of the overall assembly process. This is clearly advantageous in terms of product accessibility, but poses limits to the extent of control that can be exerted over the process. Here we report the stepwise hierarchical self‐assembly of well‐defined three‐dimensional organic nanostructures with dimensions of over 100 nm in each single xyz‐direction and a total volume of up to 1.5×10−2 μm3. These structures are formed through three consecutive processes that rely exclusively on the establishment of noncovalent interactions between the components: (1) complex formation between Zn2+ and a macrocyclic ligand, (2) association of the amphiphiles in disk‐like micellar structures and, finally, (3) ATP‐induced stacking of the disks into large hexagonal prisms. The top and bottom surface of these structures are flat multivalent cationic surfaces covered with ATP with dimensions in the order of 2×105 nm2 onto which nanometer‐sized gold nanoparticles can be deposited through a final self‐assembly process. The stepwise hierarchical process bears a close analogy with a multistep covalent synthetic pathway with the difference that all steps rely exclusively on noncovalent interactions.
Dynamic Modulation of Circularly Polarized Luminescence in Photoresponsive Assemblies
Authors: Hashimoto Yuichiro , Nakashima Takuya , Kuno Jumpei , Yamada Miku , Kawai Tsuyoshi
Published: April 2018

A photochromic molecule composed of a helical tetrathiazole framework and two pyrene units bridged by amino acid spacers exhibited on‐off photoswitching of circularly polarized luminescence (CPL) of a pyrene‐excimer‐like state in a molecularly dispersed state. The pyrene‐modified chiral tetrathiazole is employed as a building unit of supramolecular aggregates and self‐assembled into spherical nanoparticles in a methylcyclohexane‐based mixed solvent system. The spherical assemblies showed an enhancement of CPL activity compared to that of the molecularly dispersed state. UV light irradiation of the self‐assembled state gave rise to a 6π‐electrocyclization reaction in the photoresponsive tetrathiazole framework. The photoreaction of the self‐assembly component led to efficient emission quenching via energy transfer from the pyrene unit to the colored photochrome center in the aggregates. The CPL activity was diminished along with this emission quenching. The photoreaction also brought about the clouding of the solution due to a secondary aggregation of spherical assemblies. The CPL activity as well as the secondary aggregation were reversibly modulated by successive photoirradiation using UV and visible (>440 nm) light.
Development of theoretical framework and measures for the role of social media in realizing corporate social responsibility through native and non‐native communication modes: Moderating effects of cross‐cultural management
Authors: Hao Yunhong , Farooq Qamar , Sun Yuan
Published: April 2018

Businesses have recognized the importance of corporate social responsibility (CSR) for overall fulfillment of strategic prerequisites. Long‐term success for any business enterprise is not possible without giving due attention to CSR. This paper aims to ascertain the unfamiliar communication links that can influence realization of CSR. It also discusses the possible mediating effects of two basic communication modes on CSR when used through social media. It is of further interest for future researchers due to the study of the moderator cross‐cultural management, which can strengthen the relationship between usage of social media and CSR realization. By exploring the utilization of social media for communication of CSR, this report is an important step towards empirical research to produce a concrete theory based on the methodology, tests and measures prescribed herein.
Characterizing BJTs using the Early voltage in the forward active mode
Authors: Costa Luciano da F. , Silva Filipi Nascimento , Comin Cesar H.
Published: April 2018

Bipolar junction transistors (BJTs) have been at the core of linear electronics from its beginnings. Here, we suggest an Early‐based inspired geometric model of BJT devices and its application to derive models of related electronic circuits (more specifically a common‐emitter configuration). The approach involves using a beam of isolines converging at the Early voltage as the model of a BJT. The angles of the isolines are experimentally verified often to vary almost linearly with the base current. A numerical methodology is suggested for the Early voltage estimation and applied to 12 real‐world small signal NPN BJTs. Interesting results are obtained, including the identification of diverse Early voltage values for different BJT types and estimation of transfer functions.
Improvement of high‐voltage impulses in track circuits with Kasami and LS codes
Authors: Yuan Lei , Yang Yuan , Hernández Álvaro
Published: April 2018

Track circuit systems based on high‐voltage impulses (HVI) have already been used in China to detect the state of track sections. With the demand for more reliable intelligent transportation systems in recent years, new advances, improvements, and innovations are being applied to their development. This work defines a HVI track circuit based on the encoding of the transmitted signal. Not only 15‐bit and 63‐bit Kasami sequences but also 19‐bit and 71‐bit loosely synchronized codes are applied to encode simultaneous HVI transmissions from 2 emitters. Train occupancy in different parts of the track section is also considered. The quality of the detection is evaluated by means of the correlation bounds. Furthermore, a simulation model for double‐track railways has been developed, which can be dedicated to the evaluation of a suitable signal processing in the track circuit under study. Compared to previous HVI track circuits, as a novelty, this work proposes the use of encoded transmissions to these track circuits, to improve their performance in terms of scanned distance and detection accuracy. The correlation properties of the sequences involved also make feasible to avoid any synchronization link between emitters and receivers, thus providing a significant advantage for later deployment.
Determination of partial factor for model uncertainty for unreinforced masonry shear walls
Authors: Salehi Hamidreza
Published: April 2018

Experiments in structural engineering can play an important role in the prediction and characterization of the material properties and behaviour of structural components. In order to cover all aspects in tests and use the results for design purposes, several methods have been included in EN 1990 Annex D for design based on test data. The calculation of characteristic values and design values for material resistance are the main aspects. In this study, the recommended methods in Annex D of EN 1990 for resistance of the material will be used to extract the partial safety factors for masonry structures based on the formulation of design and characteristic values. A database including more than 100 tests on unreinforced masonry shear walls will be used to evaluate the results. The resistance model for shear walls based on the recommendation in the Eurocode will be compared with the test results. The main aim will be to compare the model prediction and the test results. Deviation of the prediction from the test is caused by model error or model uncertainty. The test database includes results for three types of masonry units – fired clay, calcium silicate and autoclaved aerated concrete. The evaluation of partial factors for masonry shear models will be undertaken based on the scatter and the model bias for the whole database. Further analysis will also be performed for each type of masonry unit for classification of the outcome.
Deflection limitation of beam‐type reinforced masonry constructions – proposals for future requirements
Authors: Gunkler Erhard
Published: April 2018

Deflection limitation of reinforced masonry building elements under bending is undertaken according in DIN EN 1996‐1‐1:2013‐02, Section 5.5.2.6, Table 5.2 [N 4], by limiting the span l ef or the ratio of lef to the effective depth d, for example lef/d ≤ 20 for simply supported beams. A further requirement in DIN EN 1996‐1‐1:2013‐02, Section 7.3, states that reinforced masonry elements should not deflect excessively under serviceability loading conditions. For reinforced masonry with dimensions, which are within the limits stated in clause 5.5.2.6 [N 4], acceptable vertical deflection of a beam can normally be assumed.

In this scientific paper, the figures stated in [N 4] for the limitation of the bending slenderness l ef/d of reinforced masonry beams like masonry or prefabricated lintels are checked by calculation with the ”ζ procedure“ from reinforced concrete theory. The suitability of this procedure was first demonstrated by comparing calculated and experimentally obtained values.

It was determined that maintenance of the bending slenderness ratio lef/d ≤ 20 for the tested calcium silicate masonry lintels does not always lead to deflection values w/lef ≤ 1/250. For prefabricated straight (flat arch) calcium silicate lintels and horizontal aerated concrete lintels with limit slendernesses of lef/d ≤ 15 and calcium silicate masonry lintels with lef/d ≤ 10, w/lef ≤ 1/250 was fulfilled.

With regard to future requirements for the tested reinforced masonry constructions, a method is proposed for the calculation of the limit slenderness ratio lef/d, which leads to maintenance of w/lef ≤ 1/250. Furthermore, the presented ”ζ procedure“ enables reliable calculation of deflection figures at the serviceability limit state considering long‐term effects.
Prediction of stiffness, force and drift capacity of modern in‐plane loaded URM walls
Authors: Wilding Bastian Valentin , Beyer Katrin
Published: April 2018

Unreinforced masonry (URM) walls show a limited horizontal in‐plane deformation capacity, which can lead to an unfavorable seismic response. To predict this response, the walls' effective stiffness, shear force and drift capacity are required. While mechanics‐based models for the force capacity are well established, such approaches are largely lacking for the effective stiffness and the drift capacity. The mostly empirical code equations for the two latter parameters lead to often unsatisfactory and, in the case of drift capacities, sometimes unconservative predictions when compared to test results. This article summarises recently developed simple closed‐form equations for the effective stiffness, the shear force and the drift capacity. Furthermore, it compares said formulations and currently used code equations to a database of shear compression tests. It shows that the novel models capture the effective stiffness and the drift capacity more accurately than current code equations. The shear force capacity is predicted with a similar reliability, yet using a very simple formulation.
Innovative insulation technology for the reduction of thermal transmission losses in cavity walls
Authors: Alkhateeb Eyas , Youssef Hassan
Published: April 2018

The German energy‐saving regulations (EnEV) are continuously revised to make the statutory requirements for thermal insulation of new buildings more stringent, which results in an increased need for highly effective insulation systems.

The objective of a research project being carried out at the TU Dresden, Faculty of Architecture, Chair of Structural Design is to solve the problem of reducing thermal losses from masonry buildings through the development of an innovative insulation and fixing system for cavity wall building. The newly developed insulation system should fulfil the essential requirements regarding geometry, loadbearing capacity, flexibility, lifetime and capability of dismantling as well as current requirements for energy saving to ensure the zero energy standard. The research project is mainly based on the use of vacuum panels (VIP vacuum insulated panels) as the central insulation layer in cavity masonry walls and the development of a linear tie system [1], [2].
Differentiation between the terms ”confined masonry“ and ”infill masonry“
Authors: Graubner Carl‐Alexander
Published: April 2018

This publication concerns the differentiation between the terms ”confined masonry“ and ”infill masonry“ using the example of the national technical approval Z‐17.1‐1145 – POROTON S9 MW –vertically perforated clay units with integrated thermal insulation using thin layer mortar [1].
Book Review
Authors: Haden N. Karl , Jenkins Rob
Published: April 2018

The 9 Virtues of Exceptional Leaders: Unlocking Your Leadership Potential
Difference in plasticity of resting metabolic rate – the proximate explanation to different niche breadth in sympatricFicedulaflycatchers
Authors: McFarlane S. Eryn , Ålund Murielle , Sirkiä Päivi M. , Qvarnström Anna
Published: April 2018

Variation in relative fitness of competing recently formed species across heterogeneous environments promotes coexistence. However, the physiological traits mediating such variation in relative fitness have rarely been identified. Resting metabolic rate (RMR) is tightly associated with life history strategies, thermoregulation, diet use, and inhabited latitude and could therefore moderate differences in fitness responses to fluctuations in local environments, particularly when species have adapted to different climates in allopatry. We work in a long‐term study of collared (Ficedula albicollis)and pied flycatchers (Ficedula hypoleuca) in a recent hybrid zone located on the Swedish island of Öland in the Baltic Sea. Here, we explore whether differences inRMRmatch changes in relative performance of growing flycatcher nestlings across environmental conditions using an experimental approach. The fitness of pied flycatchers has previously been shown to be less sensitive to the mismatch between the peak in food abundance and nestling growth among late breeders. Here, we find that pied flycatcher nestlings have lowerRMRin response to higher ambient temperatures (associated with low food availability). We also find that experimentally relaxed nestling competition is associated with an increasedRMRin this species. In contrast, collared flycatcher nestlings did not vary theirRMRin response to these environmental factors. Our results suggest that a more flexible nestlingRMRin pied flycatchers is responsible for the better adaptation of pied flycatchers to the typical seasonal changes in food availability experienced in this hybrid zone. Generally, subtle physiological differences that have evolved when species were in allopatry may play an important role to patterns of competition, coexistence, or displacements between closely related species in secondary contact.
Plant community responses to increased precipitation and belowground litter addition: Evidence from a 5‐year semiarid grassland experiment
Authors: Chen Hongxia , Ma Linna , Xin Xiaoping , Liu Junyao , Wang Renzhong
Published: April 2018

Global climate change is predicted to stimulate primary production and consequently increases litter inputs. Changing precipitation regimes together with enhanced litter inputs may affect plant community composition and structure, with consequent influence on diversity and ecosystem functioning. Responses of plant community to increased precipitation and belowground litter addition were examined lasting 5 years in a semiarid temperate grassland of northeastern China. Increased precipitation enhanced community species richness and abundance of annuals by 16.8% and 44%, but litter addition suppressed them by 25% and 54.5% after 5 years, respectively. During the study period, perennial rhizome grasses and forbs had consistent negative relationship under ambient plots, whereas positive relationship between the two functional groups was found under litter addition plots after 5 years. In addition, increased precipitation and litter addition showed significant interaction on community composition, because litter addition significantly increased biomass and abundance of rhizome grasses under increased precipitation plots but had no effect under ambient precipitation levels. Our findings emphasize the importance of water availability in modulating the responses of plants community to potentially enhanced litter inputs in the semiarid temperate grassland.
Do artificial velocity refuges mitigate the physiological and behavioural consequences of hydropeaking on a freshwater Iberian cyprinid?
Authors: Costa M.J. , Boavida I. , Almeida V. , Cooke S.J. , Pinheiro A.N.
Published: April 2018

The rapid flow fluctuations experienced downstream of hydropeaking facilities can alter the river hydromorphology. Given the dependence of riverine fish on physical habitat, those alterations have the potential to change the physiology and behaviour of fish. We assessed whether artificial velocity refuges mitigated the physiological and behavioural consequences of hydropeaking for the Iberian barbel (Luciobarbus bocagei). Hydropeaking trials were conducted in an indoor flume equipped with deflectors that created low flow velocity areas to serve as refuges. The FLOW‐3D was used to obtain detailed characterizations of the different velocity fields, which facilitated the interpretation of fish responses. Changes in flow magnitude and duration triggered stress responses, demonstrated by the increased blood glucose levels in the single up‐ramping event for 60 L s−1and in the step up‐ramping event. Fish tended to seek out velocity refuges to avoid higher flow velocities and harsh hydraulic conditions at peak flows, and during the longer events. The movement behaviour frequency increased when fish were subjected to the highest peak flow (60 L s−1), particularly the individual sprints and the drifts. For the base flow (7 L s−1) and the lowest peak flow (20 L s−1) conditions, fish swam freely in the flume, whereas in the harshest hydraulic conditions they showed more difficulty in finding velocity refuges. This research presents a novel approach by combining physiology and behavioural observations with hydraulic modelling to assess the extent to which artificial flow refuges mitigate the consequences of hydropeaking. Our work serves as a model approach for future mitigation studies for fish in hydropeaking rivers.