bluuebunny/crossref_metadata_2025 huggingface dataset:
Hierarchical Porous Carbon Spheres for High‐Performance Na–O2 Batteries
Authors: Sun Bing , Kretschmer Katja , Xie Xiuqiang , Munroe Paul , Peng Zhangquan , Wang Guoxiu
Published: April 2017

As a new family member of room‐temperature aprotic metal–O2 batteries, Na–O2 batteries, are attracting growing attention because of their relatively high theoretical specific energy and particularly their uncompromised round‐trip efficiency. Here, a hierarchical porous carbon sphere (PCS) electrode that has outstanding properties to realize Na–O2 batteries with excellent electrochemical performances is reported. The controlled porosity of the PCS electrode, with macropores formed between PCSs and nanopores inside each PCS, enables effective formation/decomposition of NaO2 by facilitating the electrolyte impregnation and oxygen diffusion to the inner part of the oxygen electrode. In addition, the discharge product of NaO2 is deposited on the surface of individual PCSs with an unusual conformal film‐like morphology, which can be more easily decomposed than the commonly observed microsized NaO2 cubes in Na–O2 batteries. A combination of coulometry, X‐ray diffraction, and in situ differential electrochemical mass spectrometry provides compelling evidence that the operation of the PCS‐based Na–O2 battery is underpinned by the formation and decomposition of NaO2. This work demonstrates that employing nanostructured carbon materials to control the porosity, pore‐size distribution of the oxygen electrodes, and the morphology of the discharged NaO2 is a promising strategy to develop high‐performance Na–O2 batteries.
Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries
Authors: Zhao Qing , Zhu Zhiqiang , Chen Jun
Published: April 2017

Organic carbonyl electrode materials that have the advantages of high capacity, low cost and being environmentally friendly, are regarded as powerful candidates for next‐generation stationary and redox flow rechargeable batteries (RFBs). However, low carbonyl utilization, poor electronic conductivity and undesired dissolution in electrolyte are urgent issues to be solved. Here, we summarize a molecular engineering approach for tuning the capacity, working potential, concentration of active species, kinetics, and stability of stationary and redox flow batteries, which well resolves the problems of organic carbonyl electrode materials. As an example, in stationary batteries, 9,10‐anthraquinone (AQ) with two carbonyls delivers a capacity of 257 mAh g−1 (2.27 V vs Li+/Li), while increasing the number of carbonyls to four with the formation of 5,7,12,14‐pentacenetetrone results in a higher capacity of 317 mAh g−1 (2.60 V vs Li+/Li). In RFBs, AQ, which is less soluble in aqueous electrolyte, reaches 1 M by grafting –SO3H with the formation of 9,10‐anthraquinone‐2,7‐disulphonic acid, resulting in a power density exceeding 0.6 W cm−2 with long cycling life. Therefore, through regulating substituent groups, conjugated structures, Coulomb interactions, and the molecular weight, the electrochemical performance of carbonyl electrode materials can be rationally optimized. This review offers fundamental principles and insight into designing advanced carbonyl materials for the electrodes of next‐generation rechargeable batteries.
A Broadband Fluorographene Photodetector
Authors: Du Sichao , Lu Wei , Ali Ayaz , Zhao Pei , Shehzad Khurram , Guo Hongwei , Ma Lingling , Liu Xuemei , Pi Xiaodong , Wang Peng , Fang Hehai , Xu Zhen , Gao Chao , Dan Yaping , Tan Pingheng , Wang Hongtao , Lin Cheng‐Te , Yang Jianyi , Dong Shurong , Cheng Zhiyuan , Li Erping , Yin Wenyan , Luo Jikui , Yu Bin , Hasan Tawfique , Xu Yang , Hu Weida , Duan Xiangfeng
Published: April 2017

High‐performance photodetectors operating over a broad wavelength range from ultraviolet, visible, to infrared are of scientific and technological importance for a wide range of applications. Here, a photodetector based on van der Waals heterostructures of graphene and its fluorine‐functionalized derivative is presented. It consistently shows broadband photoresponse from the ultraviolet (255 nm) to the mid‐infrared (4.3 µm) wavelengths, with three orders of magnitude enhanced responsivity compared to pristine graphene photodetectors. The broadband photodetection is attributed to the synergistic effects of the spatial nonuniform collective quantum confinement of sp2 domains, and the trapping of photoexcited charge carriers in the localized states in sp3 domains. Tunable photoresponse is achieved by controlling the nature of sp3 sites and the size and fraction of sp3/sp2 domains. In addition, the photoresponse due to the different photoexcited‐charge‐carrier trapping times in sp2 and sp3 nanodomains is determined. The proposed scheme paves the way toward implementing high‐performance broadband graphene‐based photodetectors.
Change in postmenarche anthropometric indicators in indigenous and nonindigenous adolescents from Chile
Authors: Lara Macarena , Bustos Patricia , Amigo Hugo
Published: April 2017

Objective

To analyze the change in anthropometric indicators between menarche and 36 months after menarche among indigenous and non‐indigenous adolescents from the Araucanía Region of Chile.

Method

This was a concurrent cohort study. Of 8,504 girls interviewed, 114 indigenous adolescents and 123 nonindigenous adolescents who had recently experienced menarche were selected. Body mass index (BMI), BMI by age (BMI z‐score), waist circumference (WC) and body fat percentage (BF%) were evaluated at menarche and 6, 12, 18, 24, 30, and 36 months postmenarche. Linear models estimated with generalized estimating equations were used to quantify disparities adjusted for baseline anthropometric values, age at menarche, place of residence, and socioeconomic level.

RESULTS

Indigenous girls presented menarche 4 months later than nonindigenous girls and had significantly higher BMI (1.5 kg/m2), BMI z‐score (0.4), WC (2.9 cm), and BF% (1.7%) at menarche. Adjusted results did not show an association between being indigenous and post‐menarche anthropometric variables: BMI = 0.1 kg/m2 (CI = −0.3; 0.5), BMI z‐score = 0 (CI = −0.1; 0.1), WC = 0.7 cm (CI = −0.6; 2.0), and BF% = 0.5% (CI = −0.2; 1.3). It is important to mention that the mean BMI z‐score of both groups were in the overweight category.

CONCLUSION

At menarche, indigenous girls had higher values than nonindigenous girls for all anthropometric variables, and this trend remained after menarche, with no further change in ethnic disparity over the subsequent three years. This reinforces the need to implement interventions to prevent or control excess weight prior to menarche, with emphasis on indigenous girls.
Unsupported Nanoporous Gold‐Catalyzed Chemoselective Reduction of α,β‐Unsaturated Aldehydes Using Formic Acid as Hydrogen Source
Authors: Butt Madiha , Feng Xiujuan , Yamamoto Yoshinori , Almansour Abdulrahman I. , Arumugam Natarajan , Kumar Raju Suresh , Bao Ming
Published: April 2017

A straightforward, highly chemoselective hydrogenation of α,β‐unsaturated aldehydes was developed using unsupported nanoporous gold (AuNPore) as a heterogeneous catalyst with bio‐renewable formic acid (HCO2H) as hydrogen source. Various α,β‐unsaturated aldehydes were reduced to their corresponding allylic alcohols in good to high chemical yields with excellent selectivity. AuNPore offers several attractive features as a catalyst, such as high activity and selectivity, easy recyclability, and no leaching.
Shear‐wave elastographic ultrasound of metacarpophalangeal synovium in rheumatoid arthritis – A pilot study
Authors: Sammel Anthony Michael , Spies Michael Carl , DeCarle Rohan , Rayment Michael , Joshua Fredrick
Published: April 2017

Introduction

Shear‐wave elastographic ultrasound (SW‐EUS) assesses the stiffness of human tissues. It is used in liver, thyroid and breast imaging but has not been studied in synovium. Soft tissues have a slower shear‐wave velocity (SWV) than stiff tissues. We hypothesised that rheumatoid arthritis (RA) patients would have softer synovium than controls and this could be quantified with a slower SWV. We also assessed whether SWV varied with disease activity.

Methods

Nine patients with RA were consecutively recruited and matched with five controls. Participants underwent clinical assessment, blood sampling, grey scale ultrasound (GSUS), power Doppler ultrasound and SW‐EUS of MCP joints 2–5 on the dominant hand.

Results

Average age was 60. Mean RA disease activity (DAS28‐ESR) was moderate at 3.65. Patients with RA had lower maximum synovial SWV than controls (6.38 m/s vs. 6.99 m/s P = 0.042). Negative Pearson's correlation coefficients (PCC) were observed between maximum SWV and disease activity markers including GSUS graded synovial thickness (PCC = −0.57, P = 0.03) and ESR (PCC = −0.46, P = 0.095). Intra‐ and interobserver reliability was good with intraclass correlation coefficients (ICC) of 0.66 and 0.58, respectively, for quantitative maximum SWV and ICC > 0.80 for colour scale rated SWV.

Conclusion

This is the first pilot study of SW‐EUS in synovium. Maximum synovial SWV was significantly lower in RA than controls. There was a negative correlation between maximum SWV and GSUS synovial thickening. Further study is warranted to confirm the role of SW‐EUS in diagnosing and assessing disease activity in RA.
Donor‐Promiskuität einer thermostabilen Transketolase durch gelenkte Evolution – effektive Komplementierung der 1‐Desoxy‐d‐ xylulose‐5‐phosphat‐Synthase‐Aktivität
Authors: Saravanan Thangavelu , Junker Sebastian , Kickstein Michael , Hein Sascha , Link Marie‐Kristin , Ranglack Jan , Witt Samantha , Lorillière Marion , Hecquet Laurence , Fessner Wolf‐Dieter
Published: April 2017

Enzyme, die asymmetrische C‐C‐Verknüpfungen katalysieren, sind typischerweise hoch spezifisch für ihre nukleophilen Donorsubstrate. Mittels strukturbasierter gerichteter Evolution konnten neue Enzymvarianten der thermostabilen Transketolase aus Geobacillus stearothermophilus erzeugt werden, die anstelle ihrer natürlichen Substrate, wie polyhydroxylierte Ketosephosphate oder Hydroxypyruvat, auch Pyruvat und dessen höhere aliphatische Homologe als Nukleophile für den Acyltransfer verwenden können. Die Einfachvariante H102T war am besten geeignet, 3‐Methyl‐2‐oxobutyrat als Donor zu verwerten, während die Doppelvariante H102L/H474S die höchste katalytische Effizienz für Pyruvat als Donorsubstrat aufwies. Die letztgenannte Variante war in der Lage, den auxotrophen Defekt eines Deletionsstamms von Escherichia coli zu komplementieren, dem das dxs‐Gen für den ersten Schritt in die Terpenoid‐Biosynthese fehlt. Dies eröffnet die Möglichkeit zur weiteren Enzymoptimierung mithilfe eines Wachstumsselektionstests.
Superconductivity Induced by Oxygen Doping in Y2O2Bi
Authors: Cheng Xiyue , Gordon Elijah E. , Whangbo Myung‐Hwan , Deng Shuiquan
Published: April 2017

When doped with oxygen, the layered Y2O2Bi phase becomes a superconductor. This finding raises questions about the sites for doped oxygen, the mechanism of superconductivity, and practical guidelines for discovering new superconductors. We probed these questions in terms of first‐principles calculations for undoped and O‐doped Y2O2Bi. The preferred sites for doped O atoms are the centers of Bi4 squares in the Bi square net. Several Bi 6p x/y bands of Y2O2Bi are raised in energy by oxygen doping because the 2p x/y orbitals of the doped oxygen make antibonding possible with the 6p x/y orbitals of surrounding Bi atoms. Consequently, the condition necessary for the “flat/steep” band model for superconductivity is satisfied in O‐doped Y2O2Bi.
HDPE composites strengthened–toughened synergistically by l‐aspartic acid functionalized graphene/carbon nanotubes hybrid nanomaterials
Authors: Bian J. , Wang G. , Lin H. L. , Zhou X. , Wang Z. J. , Xiao W. Q. , Zhao X. W.
Published: April 2017

Ethylenediamine (EDA) covalently functionalized graphene sheets (GS‐EDA) and acidized carbon nanotubes (MWNTs‐COOH) were first prepared, followed by synthesizing l‐aspartic acid functionalized GS‐EDA/MWNTs‐COOH (LGC) hybrid nanomaterials by using l‐aspartic acid as a bridging agent. Then nanocomposites of high density polyethylene‐g‐maleic anhydride (HDPE‐g‐MAH) synergistic strengthening–toughening using LGC hybrids were prepared via melt compounding method. The surface structure of filler was characterized by using infrared (FTIR) and Raman spectrum. The synergistic strengthening–toughening effects of LGC hybrids on the HDPE‐g‐MAH were investigated by scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), tensile, and impact tests. FTIR showed that EDA has been grafted on the graphene sheets, and COOH group has been introduced into MWNTs. The l‐aspartic acid connected GS‐EDA and MWNTs‐COOH through chemical bonds. SEM observations showed that LGC hybrids were homogeneously dispersed in HDPE‐g‐MAH nanocomposites. Tensile and impact tests indicated that the mechanical properties of nanocomposites were improved obviously when LGC hybrid nanomaterials were incorporated simultaneously. DMA analysis indicated that the storage modulus of composites was higher than that of pure HDPE‐g‐MAH matrix. TGA results revealed that the maximum decomposition temperature of HDPE‐g‐MAH composites containing 0.75 wt % of LGC showed 11.5 °C higher than that of HDPE‐g‐MAH matrix. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45055.
Mechanical properties of carbon fiber reinforced bisphenol A dicyanate ester composites modified with multiwalled carbon nanotubes
Authors: Mei Hui , Xia Junchao , Zhang Ding , Li Haiqing , Bai Qianglai , Cheng Laifei
Published: April 2017

A novel electrophoretic deposition (EPD) method was employed for grafting multiwalled carbon nanotubes (MWCNTs) on carbon fibers, which, after impregnation with bisphenol A dicyanate ester (BADCy), synergistically reinforced BADCy matrix composites (CNT‐C/BADCy). The effect of MWCNT presence on the mechanical properties of the composites was investigated. Composite tensile strength increased by 45.2% for an EPD duration of 2 min, while flexural strength exhibited a decreasing trend with EPD duration. Optical microscopy revealed that the existence of MWCNTs enhanced the fiber‐matrix interface while a large number of CNTs were observed to have pulled‐out from the matrix, a finding which explained the observed tensile strength increase in terms of energy dissipation by the specific toughening mechanism. The flexural strength decrease of the composites with CNTs as compared to specimens without nanotubes was found linked to the increased stress concentration in the BADCy matrix due to tube presence which weakens the adhesion between carbon fabrics. In a word, carbon nanotubes will enhance the micro interface and weaken the macro interface of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45100.
Morphometry, Microstructure, and Wear Pattern of Neornithischian Dinosaur Teeth From the Upper Cretaceous Iharkút Locality (Hungary)
Authors: Virág Attila , Ősi Attila
Published: April 2017

Teeth of iguanodontian ornithopods and ceratopsians could be remarkably similar, thus the referral of isolated dental material to particular neornithischian clades can be highly problematic. These groups are represented by the rhabdodontid Mochlodon vorosi and the basal coronosaurian Ajkaceratops kozmai in the Upper Cretaceous Csehbánya Formation at Iharkút (western Hungary). Whereas teeth of Mochlodon are common elements at the locality, no dental material belonging to Ajkaceratops was identified until now. Here we used mathematical statistical approaches, as well as tooth wear and dental microstructure analysis in order to decide whether the teeth previously referred to Mochlodon can be treated as a homogenous sample, or some remains belong rather to Ajkaceratops. According to our results, there was a striking morphological and structural convergence between the teeth of both taxa. However, the wear study revealed the existence of two different patterns within the sample. One is characterized by straight and parallel microstriations that suggest orthal movements during the jaw closure. This pattern was associated with Mochlodon. The other pattern appeared only on a few teeth, and it can be differentiated by its distinctive curved microstriations that indicate circumpalinal chewing. Because curved striations have never been described in ornithopods, but are found in several neoceratopsians, this pattern was associated here with Ajkaceratops. Here we present the first teeth that can provisionally be referred to the latter genus. We believe that the methodology discussed in this article will facilitate distinguishing ceratopsian and ornithopod teeth in other localities as well. Anat Rec, 300:1439–1463, 2017. © 2017 Wiley Periodicals, Inc.
Antibodies to Cyclic Citrullinated Peptides in Patients With Juvenile Idiopathic Arthritis and Patients With Rheumatoid Arthritis: Shared Expression of the Inherently Autoreactive 9G4 Idiotype
Authors: Peckham Hannah , Cambridge Geraldine , Bourke Lauren , Sen Debajit , Radziszewska Anna , Leandro Maria , Ioannou Yiannis
Published: April 2017

Objective

Antibodies to cyclic citrullinated peptides (anti‐CCP) in rheumatoid arthritis (RA) can express the inherently autoreactive gene VH4–34, detected using the rat monoclonal antibody 9G4. Patients with the polyarticular subtype of juvenile idiopathic arthritis (JIA) share some but not all of the features of adult patients with RA. This study was undertaken to compare serologic findings for rheumatoid factor (RF), anti‐CCP, and 9G4‐expressing anti‐CCP in a large JIA cohort with a cohort of adult RA patients.

Methods

Serum from 88 patients with polyarticular JIA, 29 patients with enthesitis‐related arthritis, 38 patients with extended oligoarthritis, 31 adolescent controls, 35 patients with RA, and 30 adult controls were tested for RF, for IgG, IgA, and IgM anti‐CCP, and for 9G4‐expressing anti‐CCP by enzyme‐linked immunosorbent assay. Total serum 9G4‐positive IgM was also measured.

Results

Of 65 patients with RF‐negative polyarticular JIA, 4 (6.2%) were IgG anti‐CCP positive. Sera from 20 of 23 patients with RF‐positive polyarticular JIA (87.0%), 24 of 35 patients with RA (68.6%), and 1 patient with extended oligoarthritis contained IgG anti‐CCP. IgA and IgM anti‐CCP levels were lower in the adolescent group (P < 0.01). Levels of 9G4‐expressing anti‐CCP were higher in patients with RF‐positive polyarticular JIA than in those with RF‐negative polyarticular JIA (P < 0.0001). Median levels of 9G4‐expressing anti‐CCP in patients with RF‐positive polyarticular JIA and those with RA did not differ. Expression of 9G4 on serum total IgM was greater in patients with RF‐positive polyarticular JIA than other adolescent groups (P < 0.01), but similar to adult RF‐positive RA.

Conclusion

In healthy individuals, 9G4‐positive B cells comprise 5–10% of the peripheral blood pool but serum immunoglobulins utilizing VH4–34 are disproportionately low. The idiotope recognized by 9G4 was detected on anti‐CCP antibodies in >80% of patients with RF‐positive polyarticular JIA. VH4–34 usage by anti‐CCP in both JIA and RA patients suggest elicitation of these autoantibodies through shared pathogenic B cell selection processes.
Model moist bias in the middle and upper troposphere during DEEPWAVE
Authors: Yang Yang , Moore Stuart , Uddstrom Michael , Turner Richard , Carey‐Smith Trevor
Published: April 2017

Data from 279 dropsonde profiles collected during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) over New Zealand between 4 June and 20 July 2014 were used to verify the relative humidity (RH) fields simulated by regional configurations of the UK Met Office Unified Model (MetUM) in the troposphere. Significant RH biases (predictions up to 28% too high) were found in the middle and upper troposphere during this period. This RH bias was found to be mainly caused by the errors in the simulated‐specific humidity. It is demonstrated here that evaporation from the lower boundary (mainly sea surface) is not a factor leading to the moist bias. A similar magnitude of moist bias was also found in the Global UM (the global configuration of the MetUM) and from a preliminary inspection is also very likely to occur in ERA‐interim and NCEP‐GFS reanalyses. This study suggests that the moist bias is very likely not a regional or a model specific issue.
Long‐term variations in sunspot magnetic field–area relation
Authors: Nagovitsyn Y. A. , Pevtsov A. A. , Osipova A. A.
Published: April 2017

Background

Several recent studies indicated possible long‐term variations of physical properties of sunspots.

Materials and Methods

Using observations of sunspot magnetic field strengths (H) from the Crimean Astrophysical Observatory and area (S) of sunspots from the Kislovodsk Mountain Astronomical Station of Pulkovo Observatory, we investigate the changes in the relation between H and S over the period of about two solar cycles (1994– 2013). The data were fitted by H = A + B log S, where A = (778 ± 46) and B = (778 ± 25).

Results

We show that the correlation between H and S varies with the phase of solar cycle, and A coefficient decreases significantly after year 2001, while B coefficient does not change significantly. Furthermore, our data confirm the presence of two distinct populations in the distribution of sunspots (small sunspots with weaker field strength and large sunspots with stronger field). We show that the relative contribution of each component to the distribution of sunspots by their area changes with the phase of solar cycle and on longer‐than‐cycle periods.

Conclusion

We interpret these changes as a signature of a long‐term (centennial) variations in the properties of sunspots.
Autarkie – Tendenzen der solarthermischen Selbstversorgung
Authors: Goeke Johannes , Krükel Felix
Published: April 2017

Unter Autarkie in Gebäuden versteht man im Allgemeinen die Selbstversorgung mit elektrischer Energie und Wärme. Der Beitrag konzentriert sich allein auf die Wärmeversorgung und stellt eine Untersuchung vor, der frei verfügbare Daten über teilweise selbstversorgende Gebäude zugrunde liegen. Im Wesentlichen wird hier die Teilautarkie bzw. der Autarkiegrad der Selbstversorgung von Gebäuden mit Wärme betrachtet, da komplett selbstversorgende Gebäude bisher kaum realisiert wurden. Der Autarkiegrad bezieht sich dabei sowohl auf die Erzeugung von Wärmeenergie als auch auf deren Verbrauch in den Bilanzgrenzen des Gebäudes. Die Auswertung betrachtet die entscheidenden Größen wie den Wärmebedarf, die solare Wärmeproduktion in Form der Kollektorfläche der Solarpanels und den maximalen Energieinhalt von Warmwasserspeichern. Damit ein Vergleich unabhängig von der Gebäudegröße gemacht werden kann, werden aus diesen Daten Relationen (Autarky Performance Indicators) gebildet und zum Autarkiegrad in Beziehung gesetzt. Dabei werden Tendenzen bezüglich der Kollektorflächen und den Speicherinhalten im Verlauf der Trendlinien des Autarkiegrades sichtbar.
Robust MOFs of “tsg” Topology Based on Trigonal Prismatic Organic and Metal Cluster SBUs: Single Crystal to Single Crystal Postsynthetic Metal Exchange and Selective CO2 Capture
Authors: Chandrasekhar Pujari , Savitha Govardhan , Moorthy Jarugu Narasimha
Published: April 2017

The self‐assembly of a rigid and trigonal prismatic triptycene‐hexaacid H6THA with Co(NO3)2 or Mn(NO3)2 leads to isostructural metal‐organic frameworks (MOFs) that are sustained by 6‐connecting metal cluster [M3(μ3‐O)(COO)6] secondary building units (SBUs). The Co‐ and Mn‐MOFs, constructed from organic and metal‐cluster building blocks that are both trigonal prismatic, correspond to the heretofore unknown “tsg” topology. Due to the rigidity and concave attributes of H6THA, the networks in the Co‐ and Mn‐MOFs are highly porous and undergo 3‐fold interpenetration. The interpenetration imparts permanent microporosity and high thermal stability to the MOFs to permit postsynthetic metal exchange (PSME) and gas sorption. The PSME occurs in a single crystal to single crystal fashion when the crystals of Co‐ or Mn‐MOFs are immersed in a solution of Cu(NO3)2 in MeOH/H2O. Further, the isostructural robust MOFs exhibit significant gas sorption and remarkable selectivity for CO2 over N2 (ca. 100 fold) at ambient conditions. In fact, the postsynthetically‐engineered Cu‐THA exhibits better CO2 sorption than Co‐THA and Mn‐THA. A composite of effects that include pore dimensions (ca. 0.7 nm), unsaturated metal centers, and basic environments conferred by the quinoxaline nitrogen atoms appears to be responsible for the observed high CO2 capture and selectivity. The high symmetry and structural attributes of the organic linker seemingly dictate adoption of the trigonal‐prismatic metal cluster SBU by the metal ions in the MOFs.
Reversible Folding of a β‐Hairpin Peptide by a Metal‐Chelating Amino Acid
Authors: Reutzel Jan , Diogo Timm M. , Geyer Armin
Published: April 2017

5‐(1‐Hydroxy‐pyridin‐2(1H)‐onyl)‐l‐alanine (Hop) is a N‐hydroxy‐1,2‐pyridone functionalized α‐amino acid with the desired metal‐chelating properties of DOPA (3,4‐dihydroxy phenylalanine) but without its unwanted redox activity. The Fmoc‐protected amino acid Fmoc‐l‐Hop(tBu)‐OH (11) was synthesized from glycine phosphonate followed by enzymatic hydrolysis of the methyl ester yielding the Hop l‐isomer in 96 % ee. The amino acid 11 is used in automated peptide synthesis for the assembly of a 14mer β‐hairpin peptide with the sequence [dsb1, 14]H‐CHXETGKHGHKLVC‐OH (X=W, l‐Hop). While the 10 π electron containing indole side chain of l‐Trp in peptide 14 completes the formation of a hydrophobic cluster and results in 90 % folding, the folded fraction is significantly decreased to approximately 30 % for the 6 π electron l‐Hop side chain in peptide 16. Metal chelation of Ga3+ reconstitutes the folding of 16 to above 60 % due to the formation of the Ga(16)3 trimer. The chelation process of 16 is monitored by NMR spectroscopy and the subsequent release of Ga3+ by a competitive metal chelator exemplifies the reversible oligomerization of peptide epitopes by metal chelation, bearing the opportunity to synthesize protein‐sized aggregates on the basis of reversible chemistry in water.
Advances in Phosphasilene Chemistry
Authors: Nesterov Vitaly , Breit Nora C. , Inoue Shigeyoshi
Published: April 2017

Heavier alkene analogues possess unique electronic properties and reactivity, encouraging multidisciplinary research groups to utilize them in the rational design of novel classes of compounds and materials. Phosphasilenes are heavier imine analogues, containing highly reactive Si=P double bonds. Recent achievements in this field are closely related to the progress in the chemistry of stable low‐coordinate silicon compounds. In this Review, we have attempted to summarize in a comprehensive way the available data on the structures, syntheses, electronic and chemical properties of these compounds, with an emphasis on recent achievements.
Self‐Exfoliated Metal‐Organic Nanosheets through Hydrolytic Unfolding of Metal‐Organic Polyhedra
Authors: Garai Bikash , Mallick Arijit , Das Anuja , Mukherjee Rabibrata , Banerjee Rahul
Published: April 2017

Few‐layers thick metal‐organic nanosheets have been synthesized using water‐assisted solid‐state transformation through a combined top‐down and bottom‐up approach. The metal‐organic polyhedra (MOPs) convert into metal‐organic frameworks (MOFs) which subsequently self‐exfoliate into few‐layered metal‐organic nanosheets. These MOP crystals experience a hydrophobicity gradient with the inner surface during contact with water because of the existence of hydrophobic spikes on their outer surface. When the amount of water available for interaction is higher, the resultant layers are not stacked to form bulk materials; instead few‐layered nanosheets with high uniformity were obtained in high yield. The phenomenon has resulted high yield production of uniformly distributed layered metal‐organic nanosheets from three different MOPs, showing its general adaptability.
Modular Synthesis of Diverse Natural Product‐Like Macrocycles: Discovery of Hits with Antimycobacterial Activity
Authors: Dow Mark , Marchetti Francesco , Abrahams Katherine A. , Vaz Luis , Besra Gurdyal S. , Warriner Stuart , Nelson Adam
Published: April 2017

A modular synthetic approach was developed in which variation of the triplets of building blocks used enabled systematic variation of the macrocyclic scaffolds prepared. The approach was demonstrated in the synthesis of 17 diverse natural product‐like macrocyclic scaffolds of varied (12–20‐membered) ring size. The biological relevance of the chemical space explored was demonstrated through the discovery of a series of macrocycles with significant antimycobacterial activity.
Effects of N‐Oxidation on Heteroaromatic Macrocycles: Synthesis, Electronic Structures, Spectral Properties, and Reactivities of Tetraazaporphyrin meso‐N‐Oxides
Authors: Toriumi Naoyuki , Yanagi Shunsuke , Muranaka Atsuya , Hashizume Daisuke , Uchiyama Masanobu
Published: April 2017

Heteroaromatic N‐oxides such as pyridine and quinoline N‐oxides are well studied in organic chemistry, and N‐oxide formation has long been utilized for tuning the reactivities of heteroaromatics. However, the scope of aromatic N‐oxidation is still restricted to relatively small azine or azole skeletons, and there has been little investigation of the photophysical/chemical effects of N‐oxidation on larger heteroaromatic systems. Here, the synthesis and unique properties of new macrocyclic heteroaromatic N‐oxides, tetraazaporphyrin (TAP) meso‐N‐oxides, are reported. N‐Oxidation of TAP reduced the 18π‐aromaticity of the TAP ring compared with that of the parent TAP owing to the cross‐conjugated resonance structure. The optical properties of TAPs were significantly changed by N‐oxidation: the N‐oxides did not exhibit azaporphyrin‐like but instead porphyrin‐like optical properties, that is, weak Q absorption bands, strong Soret absorption bands, and weak fluorescence. These features can be explained by the near‐degenerate frontier molecular orbitals resulting from N‐oxide formation. Singlet oxygen quantum yields were greatly increased to almost quantitative levels by N‐oxidation. The N‐oxides showed near‐IR‐responsive photoredox properties and were suitable as both oxidants and sensitizers for oxidation reactions. Protonation of the N‐oxides restored TAP‐like intense Q bands and red fluorescence, offering a potential design strategy for fluorescence switches.
Facile Synthesis of Cellulose Acetate Ultrafiltration Membrane with Stimuli‐Responsiveness to pH and Temperature Using the Additive of F127‐b‐PDMAEMA
Authors: Li Naixu , Yin Jun , Wei Lingfei , Shen Quanhao , Tian Wei , Li Jing , Chen Yong , Jin Jing , Teng Hongcheng , Zhou Jiancheng
Published: April 2017

We fabricate a novel cellulose acetate (CA) ultrafiltration membrane modified by block copolymer F127‐b‐ PDMAEMA, which is synthesized using F127 and DMAEMA via the ARGET ATRP method. Compared to conventional ultrafiltration membranes, the incorporation of both F127 and PDMAEMA can not only readily increase the hydrophilicity of the membrane, but also exhibit stimuli‐responsiveness to temperature and pH. Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC) are employed to analyze the structure of the F127‐b‐PDMAEMA. The membrane properties are evaluated via scanning electron microscope (SEM) imaging, porosity test, automatic target recognition Fourier transform infrared spectroscopy (ATR‐FTIR), water contact angle test and permeation test. The results indicate that the F127‐b‐PDMAEMA is an excellent pore agent, which contributes to an enhancement of the membrane in sensitivity to temperature and pH. The modified membrane also exhibits lower water contact angle (64.5°), which is attributed to the good anti‐fouling performance and high water permeation.
Direct Visualization of Model Membrane Remodeling by α‐Synuclein Fibrillization
Authors: Chaudhary Himanshu , Subramaniam Vinod , Claessens Mireille M. A. E.
Published: April 2017

The interaction of α‐synuclein (αS) with membranes is thought to be critical in the etiology of Parkinson's disease. Besides oligomeric αS aggregates that possibly form membrane pores, the aggregation of αS into amyloid fibrils has been reported to disrupt membranes. The mechanism by which aggregation affects the integrity of membranes is, however, unknown. Here, we show that whereas mature αS fibrils only weakly adhere to POPC/POPG giant unilamellar vesicles (GUVs), fibrillization of αS on the membrane results in large‐scale membrane remodeling. Fibrils that grow on the vesicle surface stiffen the membrane and make the initially spherical membrane become polyhedral. Additionally, membrane‐attached fibrils extract lipids. The lipid extraction and membrane remodeling of growing fibrils can consume the complete bilayer surface and results in loss of vesicle content. These observations suggest that there are several mechanisms by which growing fibrils can disrupt membrane function.
One‐Pot Hybrid SnO2/Poly(methyl methacrylate) Nanocomposite Formation through Pulsed Laser Irradiation
Authors: Caputo Gianvito , Scarpellini Alice , Palazon Francisco , Athanassiou Athanassia , Fragouli Despina
Published: April 2017

The localized in situ formation of tin dioxide (SnO2) nanoparticles embedded in poly(methyl methacrylate) (PMMA) films is presented. This is achieved by the photoinduced conversion of the tin acetate precursor included in polymeric films, through controlled UV or visible pulsed laser irradiation at λ=355 and 532 nm, respectively. The evolution of the formation of nanoparticles is followed by UV/Vis spectroscopy and shows that their growth is affected in different ways by the laser pulses at the two applied wavelengths. This, in combination with electron microscopy analysis, reveals that, depending on the irradiation wavelength, the size of the nanoparticles in the final nanocomposites differs. This difference is attributed to distinct mechanistic pathways that lead to the synthesis of small nanoparticles (from 1.5 to 4.5 nm) at λ=355 nm, whereas bigger ones (from 5 to 16 nm) are formed at λ=532 nm. At the same time, structural studies with both X‐ray and electron diffraction measurements demonstrate the crystallinity of SnO2 nanoparticles in both cases, whereas XPS analysis confirms the light‐induced oxidation of tin acetate into SnO2. Taken all together, it is demonstrated that the pulsed laser irradiation at λ=355 and 532 nm leads to the formation of SnO2 nanoparticles with defined features highly dispersed in PMMA solid matrices.
Analysis of Membrane Protein Interactions with a Bacterial Adenylate Cyclase–Based Two‐Hybrid (BACTH) Technique
Authors: Ouellette Scot P. , Karimova Gouzel , Davi Marilyne , Ladant Daniel
Published: April 2017

The bacterial two‐hybrid (BACTH, for “Bacterial Adenylate Cyclase‐based Two‐Hybrid”) technique is a simple and fast genetic approach to analyze protein‐protein interactions in vivo. In this system, the proteins of interest are genetically fused to two complementary fragments from the catalytic domain of Bordetella pertussis adenylate cyclase and co‐expressed in strains of Escherichia coli deficient in adenylate cyclase. Association of the hybrid proteins restores synthesis of cyclic AMP (cAMP), which then triggers the expression of catabolic operons such as the lactose operon or the maltose regulon. As BACTH uses a cAMP second messenger, the association between the chimeric proteins can take place at a distance from the transcription machinery. This technique is therefore particularly appropriate for studying interactions involving integral‐membrane or membrane‐associated proteins that may not be soluble in the cytoplasm, and/or that may only associate in the plane of the membrane. This unit describes the basic procedures to characterize protein‐protein interactions with the BACTH genetic system and to search for potential partners of known proteins. © 2017 by John Wiley & Sons, Inc.
Selective Proteomic Proximity Labeling Assay Using Tyramide (SPPLAT): A Quantitative Method for the Proteomic Analysis of Localized Membrane‐Bound Protein Clusters
Authors: Rees Johanna Susan , Li Xue‐Wen , Perrett Sarah , Lilley Kathryn Susan , Jackson Antony Philip
Published: April 2017

This manuscript describes a new and general method to identify proteins localized into spatially restricted membrane microenvironments. Horseradish peroxidase (HRP) is brought into contact with a target protein by being covalently linked to a primary or secondary antibody, an antigen or substrate, a drug, or a toxin. A biotinylated tyramide‐based reagent is then added. In the presence of HRP and hydrogen peroxide, the reagent is converted into a free radical that only diffuses a short distance before covalently labeling proteins within a few tens to hundreds of nanometers from the target. The biotinylated proteins can then be isolated by standard affinity chromatography and identified by liquid chromatography (LC) and mass spectrometry (MS). The assay can be made quantitative by using stable isotope labeling with amino acids in cell culture (SILAC) or isobaric tagging at the peptide level. © 2017 by John Wiley & Sons, Inc.
In Silico Modeling of the Antiplatelet Pharmacodynamics of Low‐dose Aspirin in Health and Disease
Authors: Giaretta A , Rocca B , Di Camillo B , Toffolo GM , Patrono C
Published: April 2017

The influence of platelet turnover on cyclooxygenase (COX‐1) inhibition by low‐dose aspirin remains largely uncharacterized due to limited feasibility of studying aspirin pharmacodynamics in bone marrow precursors. We developed an in silico compartmental model describing the aspirin effects on COX‐1 activity in a population of megakaryocytes (MK) and in peripheral platelets. Model parameters were inferred from the literature and calibrated using measurements of serum thromboxane B2 (sTXB2), as proxy of COX‐1 activity in peripheral platelets, in 17 healthy subjects and 24 patients with essential thrombocythemia (ET). The model reproduced well the average time‐course of sTXB2 inhibition in healthy (accuracy = 10.4%), the reduced inhibition of sTXB2 observed in ET, and the effect of different dosing regimens. In conclusion, the in silico model accurately describes COX‐1 inactivation by low‐dose aspirin in MK and platelets in different clinical settings, and might help personalize aspirin regimens in conditions of altered megakaryopoiesis.
Atomically Altered Hematite for Highly Efficient Perovskite Tandem Water‐Splitting Devices
Authors: Gurudayal  , John Rohit Abraham , Boix Pablo P. , Yi Chenyi , Shi Chen , Scott M. C. , Veldhuis Sjoerd A. , Minor Andrew M. , Zakeeruddin Shaik M. , Wong Lydia Helena , Grätzel Michael , Mathews Nripan
Published: April 2017

Photoelectrochemical (PEC) cells are attractive for storing solar energy in chemical bonds through cleaving of water into oxygen and hydrogen. Although hematite (α‐Fe2O3) is a promising photoanode material owing to its chemical stability, suitable band gap, low cost, and environmental friendliness, its performance is limited by short carrier lifetimes, poor conductivity, and sluggish kinetics leading to low (solar‐to‐hydrogen) STH efficiency. Herein, we combine solution‐based hydrothermal growth and a post‐growth surface exposure through atomic layer deposition (ALD) to show a dramatic enhancement of the efficiency for water photolysis. These modified photoanodes show a high photocurrent of 3.12 mA cm−2 at 1.23 V versus RHE, (>5 times higher than Fe2O3) and a plateau photocurrent of 4.5 mA cm−2 at 1.5 V versus RHE. We demonstrate that these photoanodes in tandem with a CH3NH3PbI3 perovskite solar cell achieves overall unassisted water splitting with an STH conversion efficiency of 3.4 %, constituting a new benchmark for hematite‐based tandem systems.
Free energy of the uniform electron gas: Testing analytical models against first‐principles results
Authors: Groth Simon , Dornheim Tobias , Bonitz Michael
Published: April 2017

The uniform electron gas is a key model system in the description of matter, including dense plasmas and solid‐state systems. However, the simultaneous occurrence of quantum, correlation, and thermal effects makes the theoretical description challenging. For these reasons, over the last half century, many analytical approaches have been developed, the accuracy of which has remained unclear. We have recently obtained the first ab initio data for the exchange correlation free energy of the uniform electron gas, which now provides the opportunity to assess the quality of the mentioned approaches and parameterizations. Particular emphasis is placed on the warm, dense matter regime, where we find significant discrepancies between the different approaches.
Modeled hydrologic metrics show links between hydrology and the functional composition of stream assemblages
Authors: Patrick Christopher J. , Yuan Lester L.
Published: April 2017

Flow alteration is widespread in streams, but current understanding of the effects of differences in flow characteristics on stream biological communities is incomplete. We tested hypotheses about the effect of variation in hydrology on stream communities by using generalized additive models to relate watershed information to the values of different flow metrics at gauged sites. Flow models accounted for 54–80% of the spatial variation in flow metric values among gauged sites. We then used these models to predict flow metrics in 842 ungauged stream sites in the mid‐Atlantic United States that were sampled for fish, macroinvertebrates, and environmental covariates. Fish and macroinvertebrate assemblages were characterized in terms of a suite of metrics that quantified aspects of community composition, diversity, and functional traits that were expected to be associated with differences in flow characteristics. We related modeled flow metrics to biological metrics in a series of stressor–response models. Our analyses identified both drying and base flow instability as explaining 30–50% of the observed variability in fish and invertebrate community composition. Variations in community composition were related to variations in the prevalence of dispersal traits in invertebrates and trophic guilds in fish. The results demonstrate that we can use statistical models to predict hydrologic conditions at bioassessment sites, which, in turn, we can use to estimate relationships between flow conditions and biological characteristics. This analysis provides an approach to quantify the effects of spatial variation in flow metrics using readily available biomonitoring data.
Validation of the German fear of pain questionnaire in a sample of children with mixed chronic pain conditions
Authors: Flack F. , Gerlach A.L. , Simons L.E. , Zernikow B. , Hechler T.
Published: April 2017

Background

To date, no German instrument exists to measure pain‐related fear in paediatric pain populations. The objective of the current study was to determine the construct validity of the translated German fear of pain questionnaire for children (GFOPQ‐C) in a sample of children with mixed chronic pain disorders by testing the underlying factor structure, and its psychometric properties.

Method

N = 241 children with mixed chronic pain disorders (aged 8–19 years) presenting to a specialized pain clinic completed the GFOPQ‐C and several other pain, fear and disability measures.

Results

The two‐factor structure of the FOPQ‐C (fear, avoidance) was replicated. Internal consistency for the shortened German version was good for both subscales (Fear subscale: α = 0.89; avoidance subscale: α = 0.76). As expected, the fear subscale correlated highly with anxiety sensitivity (r = 0.63), pain catastrophizing (r = 0.62) and general anxiety (r = 0.54), while the avoidance subscale was more closely related to disability (r = 0.24) and school functioning (r = 0.28). Pain‐related fear differed in children with chronic pain depending on their pain location with higher fear ratings in children with abdominal pain and musculoskeletal pain.

Conclusion

The GFOPQ‐C is a valid instrument that assesses two distinct dimensions of pain‐related fear in children: fear and avoidance. Future research is needed to evaluate the impact of increased pain‐related fear on outcomes over time as well as to examine pain‐related fear among healthy children. This will enhance our knowledge of who might be particularly vulnerable to potentially dysfunctional trajectories, such as ongoing pain or anxiety symptoms.

Significance

The current study validates the first tool to assess pain‐related fear in German‐speaking children with chronic pain. Findings support two distinct domains: fear and activity avoidance.
A genome‐wide linkage and association analysis of imputed insertions and deletions with cardiometabolic phenotypes in Mexican Americans: The Insulin Resistance Atherosclerosis Family Study
Authors: Gao Chuan , Hsu Fang‐Chi , Dimitrov Latchezar M. , Okut Hayrettin , Chen Yii‐Der I. , Taylor Kent D. , Rotter Jerome I. , Langefeld Carl D. , Bowden Donald W. , Palmer Nicholette D.
Published: April 2017

Insertions and deletions (INDELs) represent a significant fraction of interindividual variation in the human genome yet their contribution to phenotypes is poorly understood. To confirm the quality of imputed INDELs and investigate their roles in mediating cardiometabolic phenotypes, genome‐wide association and linkage analyses were performed for 15 phenotypes with 1,273,952 imputed INDELs in 1,024 Mexican‐origin Americans. Imputation quality was validated using whole exome sequencing with an average kappa of 0.93 in common INDELs (minor allele frequencies [MAFs] ≥ 5%). Association analysis revealed one genome‐wide significant association signal for the cholesterylester transfer protein gene (CETP) with high‐density lipoprotein levels (rs36229491, P = 3.06 × 10−12); linkage analysis identified two peaks with logarithm of the odds (LOD) > 5 (rs60560566, LOD = 5.36 with insulin sensitivity (SI) and rs5825825, LOD = 5.11 with adiponectin levels). Suggestive overlapping signals between linkage and association were observed: rs59849892 in the WSC domain containing 2 gene (WSCD2) was associated and nominally linked with SI (P = 1.17 × 10−7, LOD = 1.99). This gene has been implicated in glucose metabolism in human islet cell expression studies. In addition, rs201606363 was linked and nominally associated with low‐density lipoprotein (P = 4.73 × 10−4, LOD = 3.67), apolipoprotein B (P = 1.39 × 10−3, LOD = 4.64), and total cholesterol (P = 1.35 × 10−2, LOD = 3.80) levels. rs201606363 is an intronic variant of the UBE2F‐SCLY (where UBE2F is ubiquitin‐conjugating enzyme E2F and SCLY is selenocysteine lyase) fusion gene that may regulate cholesterol through selenium metabolism. In conclusion, these results confirm the feasibility of imputing INDELs from array‐based single nucleotide polymorphism (SNP) genotypes. Analysis of these variants using association and linkage replicated previously identified SNP signals and identified multiple novel INDEL signals. These results support the inclusion of INDELs into genetic studies to more fully interrogate the spectrum of genetic variation.
20 years of CCS
Authors: Cozier Muriel
Published: April 2017

It is very easy to get so caught up and focused on the task ahead that one forgets just how much has been achieved. This is very much the case in carbon capture and storage (CCS). However, a report from the International Energy Agency (IEA), published in November 2016, provides a timely reminder of the progress that has been made in the area of CCS capacity and technologies over the last two decades, while giving a perspective on the steps that need to be taken to increase the rate of CCS deployment. In this Feature, Muriel Cozier looks at some of the main findings from the report. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.