bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of Mechanochemical C−H Bond Activation in an Azobenzene Substrate by PdII Catalysts
Authors: Bjelopetrović Alen , Lukin Stipe , Halasz Ivan , Užarević Krunoslav , Đilović Ivica , Barišić Dajana , Budimir Ana , Juribašić Kulcsár Marina , Ćurić Manda
Published: June 2018

Mechanism of C−H bond activation by various PdII catalysts under milling conditions has been studied by in situ Raman spectroscopy. Common PdII precursors, that is PdCl2, [Pd(OAc)2]3, PdCl2(MeCN)2 and [Pd(MeCN)4][BF4]2, have been employed for the activation of one or two C−H bonds in an unsymmetrical azobenzene substrate. The C−H activation was achieved by all used PdII precursors and their reactivity increases in the order [Pd(OAc)2]3<PdCl2(MeCN)2<PdCl2<[Pd(MeCN)4][BF4]2. In situ Raman monitoring in combination with stepwise ex situ NMR, IR and PXRD experiments has provided direct probing of the reaction mechanism and kinetics, and revealed how liquids of different acid‐base properties and proticity as well as selected solids used as additives modify precursors or intermediates and their reactivity. Reaction intermediates that were isolated and structurally characterized agree with the observed species during reaction. In situ Raman spectroscopy has also enabled the derivation of reaction profiles suggesting an electrophilic process which proceeds via a coordination complex (adduct) undergoing deprotonation by a bound or an external base depending on the used PdII precursor. Slow step of the first palladation for two chloride precursors and [Pd(MeCN)4][BF4]2 is the C−H bond cleavage whereas palladation using [Pd(OAc)2]3 depends primarily on breaking of its trimeric structure by the azobenzene substrate and/or liquid additives.
Ruthenium‐Catalyzed Cycloisomerization of 2‐Alkynylstyrenes via 1,2‐Carbon Migration That Leads to Substituted Naphthalenes
Authors: Watanabe Takuma , Abe Haruka , Mutoh Yuichiro , Saito Shinichi
Published: June 2018

A ruthenium‐catalyzed carbocyclization of 2‐alkynylstyrenes that involves a very rare 1,2‐carbon migration of internal alkynes is reported. Various 1,2‐di ‐and 1,4,7‐trisubstituted naphthalenes are synthesized. Mechanistic studies revealed that this reaction proceeds via a disubstituted vinylidene complex as the key intermediate by 1,2‐carbon migration of the 2‐alkynylstyrenes.
Synthesis of α‐Aminophosphines by Copper‐Catalyzed Regioselective Hydroamination of Vinylphosphines
Authors: Takata Tatsuaki , Nishikawa Daiki , Hirano Koji , Miura Masahiro
Published: June 2018

A copper‐catalyzed net hydroamination of vinylphosphine boranes with hydrosilanes and O‐benzoylhydroxylamines has been developed. The reaction proceeds regioselectively to form the corresponding α‐aminophosphine boranes of potent interest in medicinal and pharmaceutical chemistry. This copper catalysis is based on an umpolung, electrophilic amination strategy and provides a new electrophilic amination approach to α‐aminophosphine derivatives. Additionally, although still preliminary, asymmetric synthesis has also been achieved by judicious choice of a chiral bisphosphine‐ligated copper complex.
Theoretical Studies on the Hydroaminoalkylation of Alkenes with Primary and Secondary Amines
Authors: Stelter Luisa , Teusch Thomas , Bielefeld Jens , Doye Sven , Klüner Thorsten
Published: June 2018

The α‐alkylation of amines with alkenes catalyzed by early transition‐metal complexes represents an efficient and atom economic method for the synthesis of functionalized amines from simple and easily available starting materials. While the successful use of secondary amines, such as dimethylamine, strongly underlines the enormous industrial potential of this reaction, the analogous intermolecular α‐alkylation of primary amines, especially methylamine, remains an unsolved synthetic task to this day. Based on calculated thermodynamic data, these experimental findings can now be explained for the first time, whereby several competing reactions, which are explained in detail, are of crucial importance for the different behavior of primary and secondary amines.
Helicenes as Chirality‐Inducing Groups in Transition‐Metal Catalysis: The First Helically Chiral Olefin Metathesis Catalyst
Authors: Karras Manfred , Dąbrowski Michał , Pohl Radek , Rybáček Jiří , Vacek Jaroslav , Bednárová Lucie , Grela Karol , Starý Ivo , Stará Irena G. , Schmidt Bernd
Published: June 2018

Helical chirality is a novel enantioselectivity‐inducing property in transition‐metal‐catalyzed transformations. The principle is illustrated herein for the example of asymmetric olefin metathesis. This work reports the synthesis of the first helically chiral Ru‐NHC alkylidene complex from an aminohelicene‐derived imidazolium salt, which was ligated to the first generation Hoveyda–Grubbs catalyst. Kinetic data were acquired for benchmark test reactions and compared to an achiral catalyst. The helically chiral Ru‐catalyst was evaluated in asymmetric ring‐closing metathesis (RCM) and ring‐opening metathesis–cross‐metathesis (ROM/CM) reactions, which proceeded with promising levels of enantioselectivity. Extensive NMR‐spectroscopic investigations and a DFT geometry optimization were performed. These results led to a topographic steric map and calculation of percent‐buried‐volume values for each quadrant around the metal center.
Mixed X‐Site Formate–Hypophosphite Hybrid Perovskites
Authors: Wu Yue , Halat David M. , Wei Fengxia , Binford Trevor , Seymour Ieuan D. , Gaultois Michael W. , Shaker Sammy , Wang John , Grey Clare P. , Cheetham Anthony K.
Published: June 2018

Following the recent discovery of a new family of hybrid ABX3 perovskites where X=(H2POO)− (hypophosphite), this work reports a facile synthesis for mixed X‐site formate perovskites of composition [GUA]Mn(HCOO)3−x(H2POO)x, with two crystallographically distinct, partially ordered intermediate phases with x=0.84 and 1.53, corresponding to ca. 30 and 50 mol % hypophosphite, respectively. These phases are characterised by single‐crystal XRD and solid‐state NMR spectroscopy, and their magnetic properties are reported.
Aggregate structures formed by hyperbranched functionalized polyethylene (HBfPE) treatment of oil sands tailings
Authors: Costine Allan D. , Vajihinejad Vahid , Botha Linda , Fawell Phillip D. , Soares João B. P.
Published: June 2018

The unique chemical and physical properties of oil sands tailings require the development of new classes of polymer flocculants to achieve efficient flocculation and dewatering. Fast and direct performance measurements of flocculation and dewatering efficiency are essential for the development of new polymer flocculants. The microscopic characterization of settling velocity and size for free settling aggregates then allows the derivation of the aggregate density as a function of size. Aggregate density is an indication of the internal aggregate structure that directly influences sedimentation, resistance to shear, and dewatering. Aggregate structures formed during oil sands tailings flocculation with a commercially‐available anionic polyacrylamide (A‐PAM) were compared with that of novel hyperbranched functionalized polyethylene (HBfPE) flocculants, showing that aggregates made with some HBfPE formulations were denser and settled faster than those formed with A‐PAM. This paper demonstrates that this approach can usefully quantify the structure of aggregates formed during the treatment of oil sands tailings with polymer flocculants.
Replacement and desmoplastic histopathological growth patterns: A pilot study of prediction of outcome in patients with uveal melanoma liver metastases
Authors: Barnhill Raymond , Vermeulen Peter , Daelemans Sofie , van Dam Pieter‐Jan , Roman‐Roman Sergio , Servois Vincent , Hurbain Ilse , Gardrat Sophie , Raposa Graça , Nicolas André , Dendale Rémi , Pierron Gaëlle , Desjardins Laurence , Cassoux Nathalie , Piperno‐Neumann Sophie , Mariani Pascale , Lugassy Claire
Published: June 2018

Up to 50% of uveal melanomas (UM) metastasise to the liver within 10 years of diagnosis, and these almost always prove rapidly fatal. As histopathological growth patterns (HGPs) of liver metastases of the replacement and desmoplastic type, particularly from colon and breast carcinoma, may import valuable biological and prognostic information, we have studied HGP in a series of 41 UM liver metastases originating from 41 patients from the period 2006–2017. Twenty patients underwent enucleation while 21 had radiation therapy. Analysis of UM by array comparative genomic hybridisation revealed: 25 (64%) patients with high risk (monosomy3/8q gain); 13 (33%) intermediate risk (M3/8normal or disomy3/8q gain); and 1 low risk (disomy3/8normal). The principal HGP was replacement in 30 (73%) cases and desmoplastic in 11 (27%) cases. Cases with replacement demonstrated striking vascular co‐option/angiotropism. With the development of liver metastasis, only the replacement pattern, largest primary tumour diameter, and R2 (incomplete resection) status predicted diminished overall survival (OS; p < 0.041, p < 0.017, p < 0.047, respectively). On multivariate analysis, only HGP (hazard ratio; HR = 6.51, p = 0.008) and resection status remained significant. The genomic high‐risk variable had no prognostic value at this stage of liver metastasis. Chi‐square test showed no association of HGP with monosomy 3 or 8q gain. Eighteen of 41 (44%) patients are alive with disease and 23 (56%) patients died with follow‐up ranging from 12 to 318 months (mean: 70 months, median: 47 months). In conclusion, we report for the first time the frequency of the replacement and desmoplastic HGPs in liver UM metastases resected from living patients, and their potential important prognostic value for UM patients, as in other solid cancers. These results may potentially be utilised to develop radiological correlates and therapeutic targets for following and treating patients with UM metastases.
Design and Synthesis of Pyrophosphate‐Targeting Vancomycin Derivatives for Combating Vancomycin‐Resistant Enterococci
Authors: Guan Dongliang , Chen Feifei , Faridoon  , Liu Junjie , Li Jian , Lan Lefu , Huang Wei
Published: June 2018

As the last resort for intractable Gram‐positive bacterial infections, vancomycin is losing efficacy with the emergence of vancomycin‐resistant bacteria, especially vancomycin‐resistant Enterococci (VRE). To combat this threat, we rationally designed and synthesized 39 novel vancomycin derivatives by respective or combined modifications using metal‐chelating, lipophilic, and galactose‐attachment strategies for extensive structure–activity relationship (SAR) analysis. In a proposed mechanism, the conjugation of dipicolylamine on the seventh amino acid resorcinol position or C‐terminus endowed the vancomycin backbone with binding capacity for the pyrophosphate moiety in lipid II while maintaining the intrinsic binding affinity for the dipeptide terminus of the bacterial cell wall peptidoglycan precursor. The in vitro antibacterial activities were evaluated, and the optimal compounds indicated 16‐ to 1024‐fold higher activity against VRE than that of vancomycin. Compound 11 b (3′,5′‐bis(dipicolylaminomethyl)tyrosine [1,2,3]triazolylmethoxylethyoxyl ethylaminomethyl‐N‐decylvancomycin) was found to have particularly potent activity against VRE through synergistic effects brought about by combining two peripheral modifications.
Effects of Intrinsic Factors on the Clinical Pharmacokinetics of Vortioxetine
Authors: Chen Grace , Nomikos George G. , Affinito John , Jacobson William , Zhao Zhen , Wang Shining , Xie Jinhui
Published: June 2018

Vortioxetine is an antidepressant agent with multimodal activity that is approved for the treatment of major depressive disorder at doses of 5 to 20 mg once daily. Vortioxetine is a medium‐clearance drug that undergoes extensive metabolism via several cytochrome P450 isozymes. A series of single‐ and multiple‐dose pharmacokinetic studies were performed to evaluate the impact of intrinsic (ie, subject‐related) factors, such as age, sex, race, and renal and hepatic function, on the pharmacokinetics of vortioxetine. The point estimates on the ratios and their 90% confidence intervals (CIs) for the central values of AUC (area under the concentration‐time curve) and Cmax (maximum plasma concentration) were obtained by taking the antilog of the differences and 90%CIs in the log‐transformed least‐squares means. The results demonstrate that there were no clinically meaningful differences (defined as exposure difference between 50% and 2‐fold change) in the exposure to vortioxetine (as assessed by AUC and Cmax) between elderly and younger subjects, men and women, and blacks and whites and among subjects with varying degrees of renal or hepatic impairment. These results suggest that no dosing adjustments of vortioxetine are required for the intrinsic factors investigated in these studies.
Ternary Polymeric Composites Exhibiting Bulk and Surface Quadruple‐Shape Memory Properties
Authors: Buffington Shelby L. , Posnick Benjamin M. , Paul Justine , Mather Patrick T.
Published: June 2018

We report the design and characterization of a multiphase quadruple shape memory composite capable of switching between 4 programmed shapes, three temporary and one permanent. Our approach combined two previously reported fabrication methods by embedding an electrospun mat of PCL in a miscible blend of epoxy monomers and PMMA as a composite matrix. As epoxy polymerization occurred the matrix underwent phase separation between the epoxy and PMMA materials. This created a multiphase composite with PCL fibers and a two‐phase matrix composed of phase‐separated epoxy and PMMA. The resulting composite demonstrated three separate thermal transitions and amenability to mechanical programming of three separate temporary shapes in addition to one final, equilibrium shape. In addition, quadruple surface shape memory abilities are successfully demonstrated. The versatility of this approach offers a large degree of design flexibility for multi‐shape memory materials.
Protein−Protein Interfaces Probed by Methyl Labeling and Proton‐Detected Solid‐State NMR Spectroscopy
Authors: Zinke Maximilian , Fricke Pascal , Lange Sascha , Zinn‐Justin Sophie , Lange Adam
Published: June 2018

Proton detection and fast magic‐angle spinning have advanced biological solid‐state NMR, allowing for the backbone assignment of complex protein assemblies with high sensitivity and resolution. However, so far no method has been proposed to detect intermolecular interfaces in these assemblies by proton detection. Herein, we introduce a concept based on methyl labeling that allows for the assignment of these moieties and for the study of protein−protein interfaces at atomic resolution.
Design of Active Sites on Nickel in the Anode of Intermediate‐Temperature Solid Oxide Fuel Cells using Trace Amount of Platinum Oxides
Authors: Rednyk Andrii , Mori Toshiyuki , Yamamoto Shunya , Suzuki Akira , Yamamoto Yuta , Tanji Takayoshi , Isaka Noriko , Kúš Peter , Ito Shigeharu , Ye Fei
Published: June 2018

Invited for this month's cover is the group of Prof. Dr. Toshiyuki Mori at National Institute for Materials Science (NIMS), Japan. The front cover picture shows the formation of new active sites on Ni in the anode of a solid oxide fuel cell (SOFC), which displays high performance at intermediate temperature. The combination of processing route design, microanalysis, and surface atomistic simulation provides us with a new design paradigm for fabrication of high‐performance SOFCs. Read the full text of the article at 10.1002/cplu.201800170.
CAPTURE: In Situ Analysis of Chromatin Composition of Endogenous Genomic Loci by Biotinylated dCas9
Authors: Liu Xin , Zhang Yuannyu , Chen Yong , Li Mushan , Shao Zhen , Zhang Michael Q. , Xu Jian
Published: June 2018

Cis‐regulatory elements (CREs) play a pivotal role in spatiotemporal control of tissue‐specific gene expression, yet the molecular composition of the vast majority of CREs in native chromatin remains unknown. In this article, we describe the clustered regularly interspaced short palindromic repeats (CRISPR) affinity purification in situ of regulatory elements (CAPTURE) approach to simultaneously identify locus‐specific chromatin‐regulating protein complexes and long‐range DNA interactions. Using an in vivo biotinylated nuclease‐deficient Cas9 (dCas9) protein and programmable single guide RNAs (sgRNAs), this approach allows for high‐resolution and locus‐specific isolation of protein complexes and long‐range chromatin looping associated with single copy CREs in mammalian cells. Unbiased analysis of the compositional structure of developmentally regulated or disease‐associated CREs identifies new features of transcriptional regulation. Hence, CAPTURE provides a versatile platform to study genomic locus‐regulating chromatin composition in a mammalian genome. © 2018 by John Wiley & Sons, Inc.
A generalized family of memristor‐based voltage controlled relaxation oscillator
Authors: Hezayyin Haneen G. , Ahmed Gehad M. , Fouda Mohammed E. , Said Lobna A. , Madian Ahmed H. , Radwan Ahmed G.
Published: June 2018

Recently, memristive oscillators are a significant topic in the nonlinear circuit theory where there is a possibility to build relaxation oscillators without existence of reactive elements. In this paper, a family of voltage‐controlled memristor‐based relaxation oscillator including two memristors is presented. The operation of two memristors‐based voltage relaxation oscillator circuits is demonstrated theoretically with the mathematical analysis and with numerical simulations. The generalized expressions for the oscillation frequency and conditions are derived for different cases, where a closed form is introduced for each case. The effect of changing the circuit parameters on the oscillation frequency and conditions is investigated numerically. In addition, the derived equations are verified using several transient PSPICE simulations. The power consumption of each oscillator is obtained numerically and compared with its PSPICE counterpart. Furthermore, controlling the memristive oscillator with a voltage grants the design an extra degree of freedom which increases the design flexibility. The nonlinear exponential model of memristor is employed to prove the oscillation concept. As an application, two examples of voltage‐controlled memristor‐based relaxation oscillator are provided to elaborate the effect of the reference voltage on the output voltage. This voltage‐controlled memristor‐based relaxation oscillator has nano size with storage property that makes it more efficient compared with the conventional one. It would be helpful in many communication applications.
Parasite rearing and infection temperatures jointly influence disease transmission and shape seasonality of epidemics
Authors: Shocket Marta S. , Vergara Daniela , Sickbert Andrew J. , Walsman Jason M. , Strauss Alexander T. , Hite Jessica L. , Duffy Meghan A. , Cáceres Carla E. , Hall Spencer R.
Published: June 2018

Seasonal epidemics erupt commonly in nature and are driven by numerous mechanisms. Here, we suggest a new mechanism that could determine the size and timing of seasonal epidemics: rearing environment changes the performance of parasites. This mechanism arises when the environmental conditions in which a parasite is produced impact its performance—independently from the current environment. To illustrate the potential for “rearing effects”, we show how temperature influences infection risk (transmission rate) in a Daphnia‐fungus disease system through both parasite rearing temperature and infection temperature. During autumnal epidemics, zooplankton hosts contact (eat) fungal parasites (spores) reared in a gradually cooling environment. To delineate the effect of rearing temperature from temperature at exposure and infection, we used lab experiments to parameterize a mechanistic model of transmission rate. We also evaluated the rearing effect using spores collected from epidemics in cooling lakes. We found that fungal spores were more infectious when reared at warmer temperatures (in the lab and in two of three lakes). Additionally, the exposure (foraging) rate of hosts increased with warmer infection temperatures. Thus, both mechanisms cause transmission rate to drop as temperature decreases over the autumnal epidemic season (from summer to winter). Simulations show how these temperature‐driven changes in transmission rate can induce waning of epidemics as lakes cool. Furthermore, via thermally dependent transmission, variation in environmental cooling patterns can alter the size and shape of epidemics. Thus, the thermal environment drives seasonal epidemics through effects on hosts (exposure rate) and the infectivity of parasites (a rearing effect). Presently, the generality of parasite rearing effects remains unknown. Our results suggest that they may provide an important but underappreciated mechanism linking temperature to the seasonality of epidemics.
Competitive and agonistic interactions between the invasive Asian shore crab and juvenile American lobster
Authors: Baillie Christopher J. , Grabowski Jonathan H.
Published: June 2018

Invasive species can have profound ecological and evolutionary impacts on native fauna, particularly those from overlapping guilds. Intraguild predation and competition often occur simultaneously, and ontogenetic shifts in competitive strength can dictate the magnitude and direction of species interactions. The recent introduction of the Asian shore crab Hemigrapsus sanguineus to the Atlantic coast of North America has resulted in the potential for considerable intraguild interactions with juvenile American lobsters Homarus americanus, with which it now co‐occupies rocky intertidal and shallow subtidal habitats. We present data from 5 yr of monthly (May–October) field sampling revealing a significant decline in lobster density as H. sanguineus density increased in the low intertidal. To investigate potential mechanisms behind this pattern, we conducted three mesocosm experiments designed to examine whether competitive interactions between H. americanus and H. sanguineus are size‐ or density‐dependent. Larger early benthic phase lobsters (16–34 mm CL) outcompeted H. sanguineus for both food and shelter resources. These lobsters fed faster and more in the presence of H. sanguineus, effectively defended shelter, were responsible for the majority of agonistic interactions, and, in multiple instances, killed and consumed H. sanguineus. Effects on sheltering and agonstic interactions by these lobsters were independent of H. sanguineus density; however, prior shelter residency increased lobster agonistic behavior towards crabs. In contrast, H. sanguineus outcompeted smaller, early benthic phase lobsters (7.2–11.2 mm CL) for shelter, and these interactions were density dependent. Displacement of lobsters from shelter by crabs and cumulative agonistic interactions instigated by crabs towards lobsters scaled positively with H. sanguineus density. Given the similarity of the invasion documented here and others occurring globally, these experiments demonstrate the importance of considering how factors such as ontogeny, density‐dependence, and primacy influence the outcomes of interactions between intraguild predators. Disentangling how these factors structure intraguild interactions between invasive and endemic species will both advance our fundamental understanding of community ecology and enhance efforts to conserve and manage natural resources.
Study on correlation between geometrical correction and aerodynamic performance of microscale supersonic wind tunnel
Authors: Murai Naoki , Yamamoto Ryouto , Rikuno Kouhei , Toriyama Toshiyuki
Published: June 2018

In this paper, flow visualization of the oblique shock waves of a single‐crystal silicon microscale supersonic wind tunnel is described. The microscale supersonic wind tunnel has a convergent–divergent section and a throat area of 1000 μm × 300 μm, and designed for realizing supersonic flow of Mach 2 in microscale domain. The schlieren system with integrated optical microscope was used for visualization of the oblique shock waves generated in the microscale domain. To investigate the effect of nonisentropic flow state on the inclination angle to the shock, a numerical integration of the modified Shapiro's differential equation was applied.
Synthesis, Transformation, Catalysis, and Gas Sorption Investigations on the Bismuth Metal–Organic Framework CAU‐17
Authors: Köppen Milan , Dhakshinamoorthy Amarajothi , Inge A. Ken , Cheung Ocean , Ångström Jonas , Mayer Peter , Stock Norbert
Published: June 2018

Very few microporous bismuth metal‐organic frameworks have been discovered to date. Of these, no detailed experimental characterization of the synthesis and properties have been reported until now for the only one which can be prepared from inexpensive starting materials: CAU‐17 [Bi(BTC)(H2O)], with H3BTC = trimesic acid. In‐situ powder X‐ray diffraction during solvothermal synthesis of CAU‐17 revealed that it crystallizes rapidly within 2 minutes, and if the reaction is not stopped, the MOF transforms into a nonporous dense purely inorganic material within one hour, revealing that CAU‐17 is a crystalline intermediate phase. Synthesis scale‐up employing more concentrated reaction mixtures resulted in another Bi trimesate of composition [Bi(HBTC)(NO3)(MeOH)]·MeOH, which structurally decomposes upon storage under ambient conditions. Sorption experiments showed that CAU‐17 is microporous with a BET surface area of 530 m2/g. As a potential greenhouse gas sorbent, CAU‐17 showed high SF6/N2 and CO2/N2 selectivity > 31 and 29, respectively. Furthermore, the catalytic activity of CAU‐17 was studied in the regioselective ring‐opening of styrene oxide by methanol to obtain 2‐methoxy‐2‐phenylethanol, thus demonstrating the existence of coordinatively unsaturated sites in the crystal structure of CAU‐17.
A Trifunctional Luminescent 3D Microporous MOF with Potential for CO2 Separation, Selective Sensing of a Metal Ion, and Recognition of a Small Organic Molecule
Authors: Chand Santanu , Pal Arun , Pal Shyam Chand , Das Madhab C.
Published: June 2018

A 3D microporous luminescent metal–organic framework {[Zn(oba)(L)0.5]·dma}n (IITKGP‐9, IITKGP represents the Indian Institute of Technology Kharagpur; L = 3,3′‐azodipyridine, H2oba = 4,4′‐oxydibenzoic acid) with 1D rhombus‐shaped channels has been synthesized by employing a bent organic linker with an unexploited azo‐functionalized N,N′ spacer. The metal–organic framework (MOF) exhibits potential for highly selective sorption of CO2 with excellent selectivity of CO2 from CO2/N2 (291 at 273 K and 118 at 295 K) and CO2/CH4 (17.5 at 273 K and 4.8 at 295 K) at a pressure of 1 bar, as demonstrated by ideal adsorbed solution theory (IAST) calculations. Such high separation ability, especially at 273 K for CO2/N2, can be attributed to the microporous (5.8 × 6.6 Å2) nature of this MOF and the enhanced interactions of the adsorbed CO2 molecules with the functional azo groups decorating the pore channels. This MOF is highly emissive at 374 nm upon excitation at 310 nm. The free azo groups exposed in the channels serve as functional sites for the sensing of metal ions and the recognition of small organic molecules through the quenching of fluorescence. Fluorescence measurements revealed that this MOF can selectively sense Fe3+ and also detect toxic nitromethane with high sensitivity. Elemental mapping by energy‐dispersive X‐ray spectroscopy and powder XRD analysis of the Fe3+‐loaded MOF material, recyclability tests, and a plausible quenching mechanism are presented. Thus, this MOF demonstrates potential as a trifunctional MOF material for three different applications, namely selective gas separation, selective ion sensing, and selective recognition of organic molecules.
A Trinuclear Zr‐Substituted Decanuclear Hetero‐Metal Sandwich Tungstoantimonate: Synthesis, Structure and Properties
Authors: Li Hai‐Lou , Zhang Zhong , Wang Yue‐Lin , Yang Guo‐Yu
Published: June 2018

A new trinuclear Zr4+ cluster substituted decanuclear hetero‐metal sandwich tungstoantimonate aggregate [H2N(CH3)2]7Na3H5{[Zr3(OAc)W7(H2O)O25][B‐α‐SbW9O33]2}·22H2O (1) has been synthesized under hydrothermal condition by reacting [B‐α‐SbW9O33]9– precursor, ZrOCl2·8H2O, Na2WO4·2H2O and dimethylamine hydrochloride in sodium acetate buffer (pH = 4.8) and structurally characterized by elemental analyses, IR spectrum, thermogravimetric analysis (TGA), powder X‐ray diffraction (PXRD) and single‐crystal X‐ray diffraction. The structure unit of 1 consists of a new sandwich tungstoantimonate (TA) unit {[Zr3(OAc)W7(H2O)O25][B‐α‐SbW9O33]2}15– constituted by two trivacant Keggin [B‐α‐SbW9O33]9– fragments linked through an unseen hetero‐metal cluster [Zr3(OAc)W7(H2O)O25]3+. In addition, the polyoxoanion can also be described as two trivacant Keggin [B‐α‐SbW9O33]9– fragments and one divacant Lindqvist [W4O16]8– linked by a hexanuclear hetero‐metal cluster [Zr3(OAc)W3(H2O)O9]11+ link. Moreover, the solid‐state electrochemistry and electrocatalytic performances of 1 have been measured in 0.5 mol L–1 Na2SO4 + H2SO4 aqueous solution, and the results show that 1 illustrates comparatively apparent catalytic activities toward the BrO3– and H2O2 reduction.
Thiacalix[4]‐bis‐crown with Hard Cavities and Soft Bridges Exhibiting Endocyclic Potassium(I) Complexes and Exocyclic Silver(I) Coordination Polymers
Authors: Ju Huiyeong , Kim Chungsik , Choi Kyu‐Seong , Lee Eunji , Kim Seulgi , Jung Jong Hwa , Habata Yoichi , Lindoy Leonard F. , Lee Shim Sung
Published: June 2018

Thiacalix[4]‐bis‐crown‐5 (L) was employed as a model host molecule, which shows both HSAB concept and endo/exo‐coordination modes. In the K+ complexations, a dinuclear complex [K2(L)](ClO4)2·CH3CN (1) as well as a mononuclear complex [K(L)][Pt(tht)Cl5] (2) (tht = tetrahydrothiophene) were isolated: the latter as first example in such symmetrical hosts. Each K+ in both species is stabilized not only by K+–O bondings (hard acid – hard base) in the crown cavities (endo‐coordination) but also by K+‐π interactions. The Ag+ complexations afforded infinite products (3 and 4) in which the Ag+ binds to the sulphur bridges (soft acid – soft base) from outside the cavity (exo‐coordination). When silver(I) perchlorate was used, a 1‐D coordination polymer {[Ag2(L)(ClO4)2]·CH2Cl2}n (3) was obtained, while silver(I) nitrate afforded a 2‐D coordination polymer {[Ag2(L)(µ‐NO3)2]·CH3OH}n (4). The dimensional difference between 3 and 4 is responsible for the coordination mode of anions where the perchlorate ion and the nitrate ion act as a terminal ligand and a bridging ligand, respectively. The solution studies by NMR titrations indicate the endo‐coordination with K+ and the exo‐coordination with Ag+, similar to those observed in the solid state.
Decorating Pt/C Nanoparticles with Ru by Wall‐Jet Configuration: The Role of Coverage Degree on the Catalyst Activity for Glycerol Electrooxidation
Authors: Alencar Leticia M. , Martins Cauê A.
Published: June 2018

Here, we built Ru‐decorated Pt/C nanoparticles with different coverage degrees (θRu) by wall‐jet configuration for the first time, and we investigated their catalytic properties towards glycerol electrooxidation in acidic medium. Moreover, we used the most active catalysts as the anode in electrolysis to produce carbonyl compounds. The use of an electrochemical cell in wall‐jet configuration allows for the controlling of electrodeposition through easily handling parameters; namely, the θRu is controlled by changing the concentration of the metallic precursor, speed, and volume of injection onto a Pt/C‐modified glassy carbon electrode under applied potential. Excess of Ru on a Pt surface inhibits glycerol dissociative adsorption, which limits further electrooxidation; whereas low θRu do not provide surface oxygen species to the anodic reaction. Hence, intermediates θRu reveal active catalysts – namely, θRu=0.42 shifts the onset potential 170 mV towards lower values and increases 1.65‐fold the current density at 0.5 V. The stability of this catalyst is also enhanced by maintaining a more constant current density during successive potential cycles in the presence of glycerol and by avoiding Ru leaching from the surface. The electrolysis on Ru‐decorated Pt/C is shown to lead the reaction towards formic acid (‘high oxidation state’), decreasing the amounts of glyceradehyde, glycolic acid, and dihydroxyacetone, as a result of the improved catalytic properties.
Living landscapes: Muddy and vegetated floodplain effects on fluvial pattern in an incised river
Authors: Kleinhans Maarten G. , de Vries Bente , Braat Lisanne , van Oorschot Mijke
Published: June 2018

Cohesive floodplain sediment and vegetation are both thought to cause meandering river patterns. Our aims are to compare the isolated and combined effects of mud and vegetation on river planform and morphodynamics in the setting of intermediate‐sized valley rivers. We use a numerical model for century‐scale simulation of flow, sediment transport and morphology coupled with riparian vegetation settlement, growth and mortality as functions of species traits on which flow resistance depends. Mud fluxes were predicted by excess shear stress relations in combination with the active layer formulation. We found that valley‐flooding water levels increase with vegetation density, causing a higher braiding intensity rather than meandering tendency. The shear stress during floods carves channels through the muddy floodplain surface. Higher mud concentration, on the other hand, increases floodplain aggradation, reduces the overbank flow frequency and ultimately causes formation of a single‐thread channel. Vegetation causes mud to deposit closer to the river channel as a levee, showing that mud sedimentation and vegetation settling mutually enhance floodplain formation. However, mud and vegetation counteract in two ways. First, vegetation enhances floodplain accretion, which ultimately increases plant desiccation for high mud concentrations. Second, vegetation increases the tendency of periodic chute cutoffs in valleys. The chute cutoffs locally reset the landscape and create new windows of opportunity for the vegetation. Surprisingly, in systems with a high mud concentration this causes hysteretic loops of vegetation cover and delayed mud deposition. Ramifications for the interpretation of Palaeozoic fluvial facies are that even rootless vegetation, capturing cohesive mud closer to the river channel to form thicker floodplain on the point bar, can enhance the tendency to meander and, under high mud supply, form stable channels. However, meandering is more unlikely in narrower valley rivers with higher vegetation density. © 2018 John Wiley & Sons, Ltd.
Analysis and rate optimization of GFDM‐based cognitive radios
Authors: Mohammadian Amirhossein , Baghani Mina , Tellambura Chintha
Published: June 2018

Generalized frequency division multiplexing (GFDM) is suitable for cognitive radio networks due to its low out‐of‐band emission and high spectral efficiency. In this paper, we thus consider the use of GFDM to allow an unlicensed secondary user (SU) to access a spectrum hole. However, in extremely congested spectrum scenarios, both active incumbent primary users on the left and right channels of the spectrum hole will experience out‐of‐band interference. While constraining this interference, we thus investigate the problem of power allocation to the SU transmitter to maximize the overall data rate where the SU receiver is employing a matched filter or zero‐forcing receiver. The power allocation problem is thus solved as a classic convex optimization problem. Finally, total transmission rate of GFDM is compared with that of orthogonal frequency division multiplexing. For instance, when right and left interference should be below 10 dBm, the capacity gain of GFDM over OFDM is 400%.
An overview of outdoor visible light communications
Authors: Ndjiongue A.R. , Ferreira H.C.
Published: June 2018

In visible light communication (VLC) technology, the outdoor applications are less explored when compared to those indoors. This is due to the fact that: (1) the dual use of light‐emitting diodes is not always practicable in the outdoor VLC environment; (2) the level of interference and noise is considerably higher in outdoor VLC; (3) many other communication technologies are available to be used which, due to their specific characteristics, adapt better to the outdoor environment when compared to VLC technology. Nevertheless, several outdoor VLC applications have been identified. They include and are not limited to building‐to‐building, vehicle‐to‐vehicle, and road‐to‐vehicle communications. Deploying light fidelity (Li‐Fi) using street and park lights is also feasible. Finally, some applications exploit the ability of solar panels to simultaneously harvest the electrical energy and serve as a VLC receiving antenna. The implementation of these communication systems faces lots of challenges. Most of them are related to environmental factors such as fog, rain, sunlight, haze, snow, dust, and atmospheric disturbances. Some challenges are based on parameters such as the geometrical aspect of the light diffusion, which is Lambertian in most cases. These challenges contribute to lower interest in outdoor VLC to date. However, the environment presents several opportunities. In this article, we explore the outdoor VLC environment, review, and present some promising applications selected from the literature. Furthermore, we underline likely research opportunities based on the actual state‐of‐the‐art and our outdoor VLC characterization experiments.
Hybrid Cellulose–Silica Materials from Renewable Secondary Raw Resources: An Eco‐friendly Method
Authors: Vasquez‐Zacarias Leticia , Ponce‐Peña Patricia , Pérez‐López Tezozomoc , Franco‐Urquiza Edgar A. , Ramirez‐Galicia Guillermo , Poisot Martha
Published: June 2018

Hybrid organic–inorganic materials based on cellulose matrix and silica particles are obtained from wastes of the local paper recycling mill and sugarcane mill as renewable secondary raw materials. The performance comparison of these hybrid materials made from secondary raw materials against the materials made from pure, raw sources is discussed. The Fourier transform infrared spectra show that cellulose features prevail even at 43 wt% silica nanoparticles in the hybrid materials. Such a high content of silica originated from sugarcane bagasse ash and hollow glass microspheres contributes to the high thermal stability of the final composites, as seen by thermogravimetric analysis with very low water absorption. This one‐step approach of biobased hybrid materials represents an excellent way to produce high‐performance materials with high content of inorganic nanoparticles for a wide variety of applications like energy efficient building material completely cement‐free.
A Typology of Scientific Advisory Committees
Authors: Groux Gaëlle M. N. , Hoffman Steven J. , Ottersen Trygve
Published: June 2018

The era of evidence‐informed decision‐making has seen increased use of the scientific advisory committee (SAC) to provide decision‐makers with scientific advice, despite limited evidence of the effectiveness or best strategies for designing these committees. In this study, an in‐depth review of academic and gray literature is undertaken to outline the global landscape of SACs. The development of a typology is also undertaken that categorizes SACs along six dimensions: 1) sector, 2) level of operation, 3) permanence, 4) target audience, 5) autonomy, and 6) nature of advice. It is found that SACs differ profoundly in each of these dimensions and provide examples demonstrating this variation. The landscape and typology can help decision‐makers understand the key elements of SAC design and reform, and the results will also inform future research on the design and effectiveness of SACs. With SACs expected to promote evidence‐informed decision‐making, it is imperative that the design of these committees themselves is guided by evidence.
Douropteris alvareziigen. nov., sp. nov., a new medullosalean pteridosperm from the Late Pennsylvanian of Portugal
Authors: Correia Pedro , Šimůnek Zbynĕk , Cleal Christopher J. , Sá Artur A.
Published: June 2018

A new plant fossil‐genus,Douropteris alvareziigen. nov., sp. nov., is described from the Douro Basin (lower Stephanian C [lower Gzhelian], Upper Pennsylvanian) in north‐western Portugal.Douropteris alvareziihas a remarkable morphology characterized by an unusual combination of features seen in several different fossil‐genera belonging to ferns and pteridosperms. Its unique and distinguishing features place it nearest to the medullosalean pteridospermsMargaritopterisandCallipteridium, suggesting close affinities with the fossil‐family Cyclopteridaceae. Morphologically,Margaritopterisis the closest relative with basis on the strong resemblance to the veining pattern ofDouropterisgen. nov. Here,Douropterisrepresents a potential “Lazarus taxon” or evolutionary descendant from theMargaritopterislineage.
Geochemistry and tectonic implications of Early Permian granitic rocks in the Xingxingxia area of Chinese Central Tianshan Arc Terrane
Authors: Wen Ding‐Jun , He Zhen‐Yu , Zhang Ze‐Ming
Published: June 2018

The Chinese Central Tianshan Arc Terrane (CTA) in the southern Central Asian Orogenic Belt is characterized by voluminous Palaeozoic to Mesozoic (500–240 Ma) granites, with a magmatic “flare‐up” at Early Permian time (ca. 280 Ma). However, the tectonic setting of the Early Permian granites in the CTA is highly debated. In this study, Early Permian (ca. 280 Ma) granitic intrusions, including quartz diorite and dioritic enclave, amphibole granite, biotite granite, dioritic porphyry dyke, and a weakly mylonitic granitic dyke, were revealed from the Xingxingxia area of the CTA by LA‐ICP‐MS zircon UPb dating. These granitic rocks show magnesian and calc‐alkaline affinities and are characterized by Nb, Ta, P, Ti, and MREE depletion [(Dy/Yb)N = 1.02–1.51] with no significant Eu anomalies, suggesting geochemical characteristics of typical active continental margin magmatic rocks. Zircon trace element geochemistry of these Early Permian granitic rocks also indicates a continental arc setting with high U/Yb and Gd/Yb ratios. Among these granitic intrusions, the dioritic porphyry dyke has negative zirconεHf(t) values (−8.0 to −5.7), suggesting that the magma was produced by partial melting of the ancient crustal basements of the CTA. The rest intrusions show positive but largely varied zirconεHf(t) values of +4.1 to +10.9 (5 samples), suggesting that the magmas were probably derived from the mantle wedge with variable contributions from ancient crustal component during the magma evolution. These granitic intrusions were coeval with high‐temperature metamorphic rocks, mafic‐ultramafic rocks, and Cu‐Ni sulphide deposits in the CTA. Therefore, we propose a geodynamic model of oceanic ridge subduction of the South Tianshan Ocean during Early Permian involving upwelling of asthenospheric mantle through slab window and partial melting of the mantle wedge. The multiple‐derived magmas, including those from mantle wedge and/or ancient crustal basement, and their blendings formed the studied Early Permian granitic associations in the CTA.
Hours worked by general practitioners and waiting times for primary care
Authors: Swami Megha , Gravelle Hugh , Scott Anthony , Williams Jenny
Published: June 2018

The decline in the working hours of general practitioners (GPs) is a key factor influencing access to health care in many countries. We investigate the effect of changes in hours worked by GPs on waiting times in primary care using the Medicine in Australia: Balancing Employment and Life longitudinal survey of Australian doctors. We estimate GP fixed effects models for waiting time and use family circumstances to instrument for GP's hours worked. We find that a 10% reduction in hours worked increases average patient waiting time by 12%. Our findings highlight the importance of GPs' labor supply at the intensive margin in determining the length of time patients must wait to see their doctor.
The impact of the 2008/2009 financial crisis on specialist physician activity in Canada
Authors: Lavergne M. Ruth , Hedden Lindsay , Law Michael R. , McGrail Kim , Ahuja Megan , Barer Morris
Published: June 2018

Fee‐for‐service physicians are responsible for planning for their retirements, and there is no mandated retirement age. Changes in financial markets may influence how long they remain in practice and how much they choose to work. The 2008 crisis provides a natural experiment to analyze elasticity in physician service supply in response to dramatic financial market changes. We examined quarterly fee‐for‐service data for specialist physicians over the period from 1999/2000 to 2013/2014 in Canada. We used segmented regression to estimate changes in the number of physicians receiving payments, per‐physician service counts, and per‐physician payments following the 2008 financial crisis and explored whether patterns differed by physician age. The number of specialist physicians increased more rapidly in the period since 2008 than in earlier years, but increases were largest within the youngest age group, and we observed no evidence of delayed retirement among older physicians. Where changes in service volume and payments were observed, they occurred across all ages and not immediately following the 2008 financial crisis. We conclude that any response to the financial crisis was small compared with demographic shifts in the physician population and changes in payments per service over the same time period.
Lung clearance index is elevated in young children with symptom‐controlled asthma
Authors: Racette Christine , Lu Zihang , Kowalik Krzysztof , Cheng Olivia , Bendiak Glenda , Amin Reshma , Dubeau Aimee , Jensen Renée , Balkovec Susan , Gustafsson Per , Ratjen Felix , Subbarao Padmaja
Published: June 2018

Background

Pulmonary function testing has been recommended as an adjunct to symptom monitoring for assessment of asthma control. Lung clearance index (LCI) measures ventilation inhomogeneity and is thought to represent changes in the small airways. It has been proposed as a useful early marker of airway disease in asthmatic subjects, and determining it is feasible in preschool children. This study aims to assess whether LCI remains elevated in symptomatically controlled asthmatic children with a history of severe asthma, compared with healthy controls. A secondary aim was to determine whether the results were consistent across the preschool and school‐aged populations.

Methods

Using a case‐control design, we compared 33 children with currently well‐controlled symptoms who had a history of severe asthma, to 45 healthy controls (age 3‐15 years) matched by age, height, and sex. We performed multiple breath washout tests using sulfur hexafluoride as a tracer gas, to determine their LCI and Scond values.

Results

In the overall study, LCI z‐score values were on average 0.86 units (95% confidence interval: 0.24‐1.47, P = 0.01, t‐test) higher in children with a history of severe asthma with current well‐controlled symptoms compared with healthy controls. In addition, within the subgroup of preschool children (age ≤ 6), the asthmatic had significantly higher LCI z‐score values than their healthy controls peers (mean (SD), 0.57 (2.18) vs −1.10 (1.00), P = 0.03, t‐test). Twenty‐seven percent (27%; 9/33) of subjects had an LCI value greater than the upper limit of our healthy controls despite being symptom controlled. Amongst preschool children, 5 (42%; 5/12) of the asthmatic children had abnormal LCI at the individual level.

Conclusions

LCI is elevated in children with asthma, which may be driven by differences in the preschool population. LCI may be useful in defining preschool asthma endotypes with persistent ventilation inhomogeneity despite symptomatic control.
The mental health burden of Mayan women in rural Guatemala
Authors: Hernandez Sasha , Han Esther , Ajanel Juan M.C. , Jones Leah , Edwardson Jill
Published: June 2018

Indigenous women in Guatemala with mental health disorders are likely to be from urban areas, have multiple comorbidities, and to not work outside the home.

This article includes a Spanish translation, available in the Supporting Information section.