bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi‐spectral observations of flares
Authors: Zuccarello F.
Published: November 2016

Observations show that during solar flares radiation can be emitted across the entire electromagnetic spectrum, spanning from gamma rays to radio waves. These emissions, related to the conversion of magnetic energy into other forms of energy (kinetic, thermal, waves) through magnetic reconnection, are due to different physical processes that can occur in different layers of the Sun. This means that flare observations need to be carried out using instruments operating in different wave‐bands in order to achieve a complete scenario of the processes going on. Taking into account that most of the radiative energy is emitted at optical and UV wavelengths, observations carried out from space, need to be complemented by observations carried out from ground‐based telescopes. Nowadays, the possibility to carry on high temporal, spatial and spectral resolution from ground‐based telescopes in coordinated campaigns with space‐borne instruments (like, i.e., IRIS and HINODE) gives the opportunity to investigate the details of the flare emission at different wavelengths and can provide useful hints to understand these phenomena and compare observations with models. However, it is undoubted that sometimes the pointing to the flaring region is not an easy task, due to the necessity to provide the target coordinates to satellites with some hours in advance. Some problems arising from this issue will be discussed. Moreover, new projects related to flare catalogues and archives will be presented. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solar physics at the Einstein Tower
Authors: Denker C. , Heibel C. , Rendtel J. , Arlt K. , Balthasar H. , Diercke A. , González Manrique S.J. , Hofmann A. , Kuckein C. , Önel H. , Senthamizh Pavai V. , Staude J. , Verma M.
Published: November 2016

The solar observatory Einstein Tower (Einsteinturm) at the Telegrafenberg in Potsdam is both a landmark of modern architecture and an important place for solar physics. Originally built for high‐resolution spectroscopy and measuring the gravitational redshift, research shifted over the years to understanding the active Sun and its magnetic field. Nowadays, telescope and spectrographs are used for research and development, i.e., testing instruments and in particular polarization optics for advanced instrumentation deployed at major European and international astronomical and solar telescopes. In addition, the Einstein Tower is used for educating and training of the next generation astro‐physicists as well as for education and public outreach activities directed at the general public. This article comments on the observatory's unique architecture and the challenges of maintaining and conserving the building. It describes in detail the characteristics of telescope, spectrographs, and imagers; it portrays some of the research and development activities. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Helical kink instability in the confined solar eruption on 2002 May 27
Authors: Hassanin A. , Kliem B. , Seehafer N.
Published: November 2016

This paper presents an improved MHD modeling of the confined filament eruption in solar active region NOAA 9957 on 2002 May 27 by extending the parametric studies of the event in Török & Kliem (2005) and Hassanin & Kliem (2016). Here the initial flux rope equilibrium is chosen to possess a small apex height identical to the observed initial filament height, which implies a more realistic inclusion of the photospheric line tying. The model matches the observations as closely as in the preceding studies, with the closest agreement again being obtained for an initial average flux rope twist of about 4π. Thus, the model for strongly writhing confined solar eruptions, which assumes that a kink‐unstable flux rope in the stability domain of the torus instability exists at the onset of the eruption's main acceleration phase, is further substantiated. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Flow and magnetic field properties in the trailing sunspots of active region NOAA 12396
Authors: Verma M. , Denker C. , Böhm F. , Balthasar H. , Fischer C. E. , Kuckein C. , Bello González N. , Berkefeld T. , Collados M. , Diercke A. , Feller A. , González Manrique S. J. , Hofmann A. , Lagg A. , Nicklas H. , Orozco Suárez D. , Pator Yabar A. , Rezaei R. , Schlichenmaier R. , Schmidt D. , Schmidt W. , Sigwarth M. , Sobotka M. , Solanki S. K. , Soltau D. , Staude J. , Strassmeier K. G. , Volkmer R. , von der Lühe O. , Waldmann T.
Published: November 2016

Improved measurements of the photospheric and chromospheric three‐dimensional magnetic and flow fields are crucial for a precise determination of the origin and evolution of active regions. We present an illustrative sample of multiinstrument data acquired during a two‐week coordinated observing campaign in August 2015 involving, among others, the GREGOR solar telescope (imaging and near‐infrared spectroscopy) and the space missions Solar Dynamics Observatory (SDO) and Interface Region Imaging Spectrograph (IRIS). The observations focused on the trailing part of active region NOAA 12396 with complex polarity inversion lines and strong intrusions of opposite polarity flux. The GREGOR Infrared Spectrograph (GRIS) provided Stokes IQUV spectral profiles in the photospheric Si I λ 1082.7 nm line, the chromospheric He I λ 1083.0 nm triplet, and the photospheric Ca I λ 1083.9 nm line. Carefully calibrated GRIS scans of the active region provided maps of Doppler velocity and magnetic field at different atmospheric heights. We compare quick‐look maps with those obtained with the “Stokes Inversions based on Response functions” (SIR) code, which furnishes deeper insight into the magnetic properties of the region. We find supporting evidence that newly emerging flux and intruding opposite polarity flux are hampering the formation of penumbrae, i.e., a penumbra fully surrounding a sunspot is only expected after cessation of flux emergence in proximity to the sunspots. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling immunity and programmed cell suicide in prokaryotes: Life‐or‐death choices
Authors: Koonin Eugene V. , Zhang Feng
Published: November 2016

Host‐pathogen arms race is a universal, central aspect of the evolution of life. Most organisms evolved several distinct yet interacting strategies of anti‐pathogen defense including resistance to parasite invasion, innate and adaptive immunity, and programmed cell death (PCD). The PCD is the means of last resort, a suicidal response to infection that is activated when resistance and immunity fail. An infected cell faces a decision between active defense and altruistic suicide or dormancy induction, depending on whether immunity is “deemed” capable of preventing parasite reproduction and consequent infection of other cells. In bacteria and archaea, immunity genes typically colocalize with PCD modules, such as toxins‐antitoxins, suggestive of immunity‐PCD coupling, likely mediated by shared proteins that sense damage and “predict” the outcome of infections. In type VI CRISPR‐Cas systems, the same enzyme that inactivates the target RNA might execute cell suicide, in a case of ultimate integration of immunity and PCD.
Secondary prophylactic treatment and long‐term prognosis after TIA and different subtypes of stroke. A 25‐year follow‐up hospital‐based observational study
Authors: Eriksson Sven‐Erik
Published: November 2016

Objectives

To assess long‐term prognosis after transient ischemic attack (TIA)/subtypes of stroke relative to secondary prophylactic treatment(s) given.

Materials and Methods

Retro/prospective follow‐up of patients hospitalized in the Stroke Unit or in the Department of Neurology, Linköping, in 1986 and followed up to Feb. 2011.

Results

A total of 288 men were followed up for 2254 years (mean 7.8 years) and 261 women for 1984 years (mean 7.6 years). In men, the distribution to anticoagulants (AC) (warfarin treatment) was 18%, antiplatelet therapy (APT) usually ASA 75 mg/day 54%, untreated 27%, unknown 2%. In women, the distribution to AC was 15%, APT 60%, untreated 23%, unknown 2%, respectively. Mortality rates at 1 year, 10 years, and 25 years for men were 21%, 67%, and 93%, respectively, versus the rates in women of 24%, 71%, and 90%, respectively. Survival curves showed markedly increased risk of death compared to the normal population. AC treatment was more favorable for men regarding the annual risk of stroke, compared with APT (9.4% vs. 9.8%), as well as the risks of MI, (5.6% vs. 6.7%), and death (8.1% vs. 10.3%), compared to women for stroke (11.6% vs. 8.8%) and MI (5.3% vs. 3.7%) but not for death (8.3% vs. 8.4%). The risk of fatal bleeding was 0.86% annually on AC compared to 0.17% on APT. According to Cox regression analysis included patients with TIA/ischemic stroke, first‐line treatment had beneficial effects on survival: AC OR 0.67 (0.5–0.9), APT 0.67 (0.52–0.88) versus untreated.

Conclusions

Patients with a history of TIA/stroke had a higher mortality rate versus controls, providing support for both primary and secondary prophylaxis regarding vascular risk factors for death. This study also provided support for secondary prophylactic treatment with either AC or ASA (75 mg once daily) to reduce the vascular risk of death unless there are contraindications.
Affinity chromatography matrices for depletion and purification of casein glycomacropeptide from bovine whey
Authors: Baieli María F. , Urtasun Nicolás , Martinez María J. , Hirsch Daniela B. , Pilosof Ana M. R. , Miranda María V. , Cascone Osvaldo , Wolman Federico J.
Published: November 2016

Casein glycomacropeptide (CMP) is a 64‐ amino acid peptide found in cheese whey, which is released after κ‐casein specific cleavage by chymosin. CMP lacks aromatic amino acids, a characteristic that makes it usable as a nutritional supplement for people with phenylketonuria. CMP consists of two nonglycosylated isoforms (aCMP A and aCMP B) and its different glycosylated forms (gCMP A and gCMP B). The most predominant carbohydrate of gCMP is N‐acetylneuraminic acid (sialic acid). Here, we developed a CMP purification process based on the affinity of sialic acid for wheat germ agglutinin (WGA). After formation of chitosan beads and adsorption of WGA, the agglutinin was covalently attached with glutaraldehyde. Two matrices with different WGA density were assayed for CMP adsorption. Maximum adsorption capacities were calculated according to the Langmuir model from adsorption isotherms developed at pH 7.0, being 137.0 mg/g for the matrix with the best performance. In CMP reduction from whey, maximum removal percentage was 79% (specifically 33.7% of gCMP A and B, 75.8% of aCMP A, and 93.9% of aCMP B). The CMP was recovered as an aggregate with an overall yield of 64%. Therefore, the matrices developed are promising for CMP purification from cheese whey. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:171–180, 2017
Virus‐like particle of Macrobrachium rosenbergii nodavirus produced in Spodoptera frugiperda (Sf9) cells is distinctive from that produced in Escherichia coli
Authors: Kueh Chare Li , Yong Chean Yeah , Masoomi Dezfooli Seyedehsara , Bhassu Subha , Tan Soon Guan , Tan Wen Siang
Published: November 2016

Macrobrachium rosenbergii nodavirus (MrNV) is a virus native to giant freshwater prawn. Recombinant MrNV capsid protein has been produced in Escherichia coli, which self‐assembled into virus‐like particles (VLPs). However, this recombinant protein is unstable, degrading and forming heterogenous VLPs. In this study, MrNV capsid protein was produced in insect Spodoptera frugiperda (Sf9) cells through a baculovirus system. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that the recombinant protein produced by the insect cells self‐assembled into highly stable, homogenous VLPs each of approximately 40 nm in diameter. Enzyme‐linked immunosorbent assay (ELISA) showed that the VLPs produced in Sf9 cells were highly antigenic and comparable to those produced in E. coli. In addition, the Sf9 produced VLPs were highly stable across a wide pH range (2–12). Interestingly, the Sf9 produced VLPs contained DNA of approximately 48 kilo base pairs and RNA molecules. This study is the first report on the production and characterization of MrNV VLPs produced in a eukaryotic system. The MrNV VLPs produced in Sf9 cells were about 10 nm bigger and had a uniform morphology compared with the VLPs produced in E. coli. The insect cell production system provides a good source of MrNV VLPs for structural and immunological studies as well as for host–pathogen interaction studies. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:549–557, 2017
Can Caring Create Prejudice? An Investigation of Positive and Negative Intergenerational Contact in Care Settings and the Generalisation of Blatant and Subtle Age Prejudice to Other Older People
Authors: Drury Lisbeth , Abrams Dominic , Swift Hannah J. , Lamont Ruth A. , Gerocova Katarina
Published: November 2016

Caring is a positive social act, but can it result in negative attitudes towards those cared for, and towards others from their wider social group? Based on intergroup contact theory, we tested whether care workers' (CWs) positive and negative contact with old‐age care home residents (CHRs) predicts prejudiced attitudes towards that group, and whether this generalises to other older people. Fifty‐six CWs were surveyed about their positive and negative contact with CHRs and their blatant and subtle attitudes (humanness attributions) towards CHRs and older adults. We tested indirect paths from contact with CHRs to attitudes towards older adults via attitudes towards CHRs. Results showed that neither positive nor negative contact generalised blatant ageism. However, the effect of negative, but not positive, contact on the denial of humanness to CHRs generalised to subtle ageism towards older adults. This evidence has practical implications for management of CWs' work experiences and theoretical implications, suggesting that negative contact with a subgroup generalises the attribution of humanness to superordinate groups. Because it is difficult to identify and challenge subtle prejudices such as dehumanisation, it may be especially important to reduce negative contact. © 2016 The Authors. Journal of Community & Applied Social Psychology Published by John Wiley & Sons Ltd.
Structural Rearrangement from Oligomer to Fibril Detected with FRET in a Designed Amphiphilic Peptide
Authors: Chi Heng , Keiderling Timothy A.
Published: November 2016

β‐Sheet conformation is promoted in peptides with amphiphilic design, and stable β‐turn formation is favored with the unnatural amino acid d‐Pro followed by a flexible residue such as Gly. A 19‐residue peptide (B3) was synthesized with alternating hydrophobic and hydrophilic residues connected by symmetrical d‐Pro‐Gly and Gly‐d‐Pro turns. B3 forms an oligomeric aggregate, rich in β‐sheet conformation, that reversibly transforms into an unordered structure on heating, as evidenced by its temperature‐dependent IR spectra. When a dansyl moiety was added to the N terminus of B3, the resulting peptide (B3D) can convert into a fibrillar structure after higher temperature incubation, as detected spectroscopically as well as by TEM. The fibrillization process involves an initial unfolding step monitored by the quenching of dansyl emission; in contrast, subsequent enhanced thioflavin T emission is seen on its binding to the fibril. A possible mechanism is proposed: B3D forms a low‐temperature oligomer, which is at least partially unfolded by heat and subsequently reassembles more slowly as a fibril.
Iterative Nonproteinogenic Residue Incorporation Yields α/β‐Peptides with a Helix–Loop–Helix Tertiary Structure and High Affinity for VEGF
Authors: Checco James W. , Gellman Samuel H.
Published: November 2016

Inhibition of specific protein–protein interactions is attractive for a range of therapeutic applications, but the large and irregularly shaped contact surfaces involved in many such interactions make it challenging to design synthetic antagonists. Here, we describe the development of backbone‐modified peptides containing both α‐ and β‐amino acid residues (α/β‐peptides) that target the receptor‐binding surface of vascular endothelial growth factor (VEGF). Our approach is based on the Z‐domain, which adopts a three‐helix bundle tertiary structure. We show how a two‐helix “mini‐Z‐domain” can be modified to contain β and other nonproteinogenic residues while retaining the target‐binding epitope by using iterative unnatural residue incorporation. The resulting α/β‐peptides are less susceptible to proteolysis than is their parent α‐peptide, and some of these α/β‐peptides match the full‐length Z‐domain in terms of affinity for receptor‐recognition surfaces on the VEGF homodimer.
Active Site Crowding of Cytochrome P450 3A4 as a Strategy To Alter Its Selectivity
Authors: Schiavini Paolo , Cheong Kin J. , Moitessier Nicolas , Auclair Karine
Published: November 2016

Substrate‐promiscuous enzymes are a promising starting point for the development of versatile biocatalysts. In this study, human cytochrome P450 3A4, known for its ability to metabolise hundreds of drugs, was engineered to alter its regio‐ and stereoselectivity. Rational mutagenesis was used to introduce steric hindrance in a specific manner in the large active site of P450 3A4 and to favour oxidation at a more sterically accessible position on the substrate. Hydroxylation of a synthetic precursor of (R)‐lisofylline, a compound under investigation for its anti‐inflammatory properties, was chosen as a first proof‐of‐principle application of our protein engineering strategy. In a second example, increasing active site crowding led to an incremental shift in the selectivity of oxidation from an internal double bond to a terminal phenyl group in a derivative of theobromine. The same correlation between crowding and selectivity was found in a final case focused on the hydroxylation of the steroid sex hormone progesterone.
Contrast‐induced encephalopathy following cardiac catheterization
Authors: Spina Roberto , Simon Neil , Markus Romesh , Muller David WM , Kathir Krishna
Published: November 2016

Objectives

To describe the epidemiology, pathophysiology, clinical presentation, and management of contrast‐induced encephalopathy (CIE) following cardiac catheterization.

Background

CIE is an acute, reversible neurological disturbance directly attributable to the intra‐arterial administration of iodinated contrast medium.

Methods

The PubMed database was searched and all cases in the literature were retrieved and reviewed.

Results

52 reports of CIE following cardiac catheterization were found. Encephalopathy, motor and sensory disturbances, vision disturbance, opthalmoplegia, aphasia, and seizures have been reported. Transient cortical blindness is the most commonly reported neurological syndrome, occurring in approximately 50% of cases. The putative mechanism involves disruption of the blood brain barrier and direct neuronal injury. Contrast‐induced transient vasoconstriction has also been implicated. Symptoms typically appear within minutes to hours of contrast administration and resolve entirely within 24–48 hr. Risk factors may include hypertension, diabetes mellitus, renal impairment, the administration of large volumes of iodinated contrast, percutaneous coronary intervention or selective angiography of internal mammary grafts, and previous adverse reaction to iodinated contrast. Characteristic findings on cerebral imaging include cortical and sub‐cortical contrast enhancement on computed tomography (CT). Imaging findings in CIE may mimic subarachnoid hemorrhage or cerebral ischemia; the Hounsfield scale on CT and the apparent diffusion coefficient on magnetic resonance imaging (MRI) are useful imaging tools in distinguishing these entities. In some cases, brain imaging is normal. Prognosis is excellent with supportive management alone. CIE tends to recur, although re‐challenge with iodinated contrast without adverse effects has been documented.

Conclusions

CIE is an important clinical entity to consider in the differential diagnosis of stroke following cardiac catheterization. Given that prognosis is excellent with supportive management only, physicians should be aware of it, and consider it prior to initiating thrombolysis. © 2016 Wiley Periodicals, Inc.
Novel delivery technique for atrial septal defect closure in young children utilizing the GORE® CARDIOFORM® septal occluder
Authors: Anderson Jason H. , Fraint Hannah , Moore Phillip , Cabalka Allison K. , Taggart Nathaniel W.
Published: November 2016

Objectives

To develop a novel delivery technique to overcome vascular size limitations for device closure of a secundum ASD in the young patient.

Background

The efficacy, clinical utility, and safety of transcatheter closure in comparison to surgical closure are well established; however, access vessel size remains a potential limitation to device selection in the young patient.

Methods

A retrospective medical record review of all cases of secundum ASD closure between April 2015 and April 2016 utilizing a novel delivery method described herein at two separate academic institutions. The device is disassembled allowing the delivery sheath to serve as the introducer. It is advanced to the RA with re‐introduction of the device allowing for deployment in the standard fashion.

Results

Overall, 10 patients underwent secundum ASD closure via this novel delivery technique. There were six females (60%) and the average age at time of the procedure was 4.2 years ± 1.6 years (range 2–6 years). The majority of patients had an isolated secundum ASD (70%) with the primary indication for closure being right ventricular volume overload (90%). All patients had successful placement of a GORE® CARDIOFORM® Septal Occluder (GCSO) with no or trivial residual shunt. No patients had vascular complications related to the procedure.

Conclusions

We describe a novel technique for ASD closure using the GCSO delivery sheath as the access sheath, which reduces the vascular access size requirement by 25%, thus addressing one common limitation for percutaneous device closure of a secundum ASD in young patients. © 2016 Wiley Periodicals, Inc.
Balloon Valvuloplasty to Predict X‐ray Projection Angles that are Perpendicular to Cardiovascular Structures
Authors: Fetterly Kenneth , Greason Kevin , Mathew Verghese
Published: November 2016

Objectives

The purpose of this work is to describe methods to measure the 3D angular orientation of cardiovascular structures based on a planar image of a valvuloplasty balloon. These methods facilitate X‐ray beam alignment with respect to the anatomy of interest.

Background

X‐ray beam projections which are perpendicular to the long axis of cardiovascular structures are required to support interventional procedures, including transcatheter aortic valve implant (TAVI).

Methods

During the TAVI procedure, the 3D angular orientation of the LVOT of 10 patients was measured from a single planar image of an aortic valvuloplasty balloon and the continuous range of X‐ray projection angles which are aligned with the aortic valve plane were calculated (research method). Misalignment of the X‐ray beam and TAVI valve frame was measured from images of the deployed valve. The accuracy of the research method was compared to clinical standard method to determine appropriate X‐ray projection angles, which utilized CT and aortography.

Results

Using the clinical standard method, the median misalignment of the X‐ray beam and TAVI valve frame was 8.6° (range 2.6° to 21°). Misalignment was reduced to 2.5° (range 0° to 10°) using the research method.

Conclusions

The 3D angular orientation of cardiovascular structures can be measured accurately from a single X‐ray projection image of a known cardiovascular device contained within the anatomy of interest. For TAVI procedures, improved X‐ray beam alignment may help facilitate procedural success. © 2016 Wiley Periodicals, Inc.
Low‐Temperature Preparation of a Mesoporous Silica Superbase by Employing the Multifunctionality of a La2O3 Interlayer
Authors: Liu Ning , Wu Zhimin , Li Meng , Li Shanshan , Luo Zhantao , Li Yongfei , Pan Langsheng , Liu Yuejin
Published: November 2016

A simple and effective approach for the preparation of the solid superbasic La2O3–SBA‐15‐supported KF (KF/La2O3–SBA‐15) was developed by a low‐temperature strategy. The KF/La2O3–SBA‐15 with ordered mesostructure and a high base strength (H−=27.0) was realized at 350 °C in still air, which breaks the traditional method of thermally induced decomposition of basic metal nitrate derived species KNO3 under higher temperatures (>600 °C). The resultant mesoporous basic materials were adopted for the production of 1‐methoxy‐2‐propanol from propylene oxide and methanol. It showed excellent catalytic performance exhibiting 93 % conversion of propylene oxide and 93 % selectivity to 1‐methoxy‐2‐propanol. This performance is better than that over the catalysts without mesoporous silica despite having a higher KF content.
Pinacol Rearrangement and Direct Nucleophilic Substitution of Allylic Alcohols Promoted by Graphene Oxide and Graphene Oxide CO2H
Authors: Gómez‐Martínez Melania , Baeza Alejandro , Alonso Diego A.
Published: November 2016

Graphene oxide (GO) and carboxylic acid functionalized GO (GO–CO2H) have been found to efficiently promote the heterogeneous and environmentally friendly pinacol rearrangement of 1,2‐diols and the direct nucleophilic substitution of allylic alcohols. In general, high yields and regioselectivities are obtained in both reactions using 20 wt % of catalyst loading and mild reaction conditions.
Formal Enantioselective Hydroamination of Non‐Activated Alkenes: Transformation of Styrenes into Enantiomerically Pure 1‐Phenylethylamines in Chemoenzymatic One‐Pot Synthesis
Authors: Uthoff Florian , Sato Hirofumi , Gröger Harald
Published: November 2016

As a complementary approach to current asymmetric synthetic methods, a direct transformation of styrenes into 1‐phenylethylamines was developed. The one‐pot process represents a formal hydroamination of a non‐activated alkene with ammonia and is based on the combination of a Pd/Cu‐catalyzed Wacker‐oxidation with an enzymatic transamination. A key feature of this process is the compartmentation of the catalytic systems, which turned out to be essential to avoid deactivation of the transaminase by the Cu‐component. This one‐pot synthesis can be applied to a broad substrate range, which leads to the chiral amines with high conversions and excellent enantioselectivities of >99 % ee.
Dinuclear α‐Diimine NiII and PdII Complexes that Catalyze Ethylene Polymerization and Copolymerization
Authors: Na Yinna , Wang Xingbao , Lian Kunbo , Zhu Yun , Li Weimin , Luo Yi , Chen Changle
Published: November 2016

A series of dinucleating α‐diimine ligands and the corresponding nickel and palladium complexes were synthesized and characterized. The dinucleating α‐diimine ligands are designed to incorporate naphthalene‐, biphenylene‐, and xanthene‐bridged structures, which may lead to different metal–metal distances. The properties of these dinuclear complexes in ethylene polymerization and copolymerization with methyl acrylate are investigated. Higher catalytic activity, higher polyethylene molecular weight, and much lower polyethylene branching density were observed for the dinuclear Ni complexes compared with the mononuclear analogue in ethylene polymerization. For the dinuclear palladium complexes, much more dramatic differences in activity and polyethylene molecular weight were observed. Most interestingly, similar catalytic activities were observed for the dinuclear and mononuclear palladium complexes in ethylene–methyl acrylate copolymerization, whereas only the mononuclear complex was able to incorporate an appreciable amount of the methyl acrylate monomer.
Influence of Nanoeffects on the Oxidation of Cr–C/Ag Thin Films Containing Silver Nanoparticles
Authors: Nygren Kristian , Folkenant Matilda , Jansson Ulf , Nyholm Leif
Published: November 2016

Well‐controlled functionalization of carbide‐based nanocomposite films with noble‐metal surface nanoparticles of different sizes may lead to new materials with novel multifunctional properties. In this work, magnetron sputtering was used to deposit nanocomposite films comprising amorphous chromium carbide (a‐CrCx), amorphous carbon (a‐C), and a minority of silver in the form of embedded nanoclusters. Up to 5⋅1010 surface nanoparticles per cm2 with different size distributions were also found to be formed, owing to the diffusion of silver from the bulk of the film. The influences of these conductive nanoparticles on the electrochemical behavior of the films were investigated in dilute sulfuric acid. Although silver is a noble metal, the oxidation potential of the nanoparticles was about 0.4 V more negative than the Ag+/Ag standard potential, meaning that the nanoparticles were oxidized in the Cr passive potential region. While this effect can mainly be explained by a low concentration of Ag+ in the electrolyte, the sizes of the nanoparticles and interactions with the matrix were also found to be important. Scanning electron microscopy and X‐ray photoelectron spectroscopy were used to analyze the surface chemistries. As Ag can be replaced by other noble metals, the concept is of general interest for further studies.
Acid‐Mediated Synthesis of Ordered Mesoporous Aluminosilicates: The Challenge and the Promise
Authors: Krishna Nunna V. , Selvam Parasuraman
Published: November 2016

A new intrinsic hydrolysis method was employed, for the first‐time, to synthesize well‐ordered H‐AlSBA‐15 with trivalent aluminium exclusively in the tetrahedral framework structure of SBA‐15. Unlike other methods, which involve incorporation of aluminium ions in both the framework (Brønsted) and non‐framework (Lewis) sites of the silicate matrix, the intrinsic hydrolysis method isomorphously substitutes aluminium ions in the tetrahedral network even at high aluminium content. This unique approach relies mainly on the hydrolysis rates of the inorganic (silicon and aluminium) precursors used for the preparation in such a way that the condensation occurs simultaneously so as to overcome the usually encountered difficulties in stabilizing aluminium ions in the silicate matrix. In this way, we could successfully synthesize high quality Brønsted acidic H‐AlSBA‐15, hitherto not reported. The synthesized materials were systematically characterized by various analytical, spectroscopic, and imaging techniques, including XRD, Brunauer–Emmett–Teller (BET) surface area measurements, TEM, SEM, 29Si and 27Al magic angle spinning NMR spectroscopy, X‐ray fluorescence (XRF), and NH3 temperature‐programmed desorption (TPD). The characterization results reveal the presence of a highly porous structure (with narrow pores) and tetrahedrally coordinated trivalent aluminium in the silicate matrix with more medium to strong Brønsted acid sites. The resulting high quality catalysts exhibit excellent activity for tert‐butylation of phenol with high selectivity towards para‐tert‐butyl phenol and 2,4‐di‐tert‐butyl phenol.
Enzymatic Activity and Thermodynamic Stability of Biliverdin IXβ Reductase Are Maintained by an Active Site Serine
Authors: Chu Wen‐Ting , Nesbitt Natasha M. , Gnatenko Dmitri V. , Li Zongdong , Zhang Beibei , Seeliger Markus A. , Browne Seamus , Mantle Timothy J. , Bahou Wadie F. , Wang Jin
Published: November 2016

Biliverdin reductase IXβ (BLVRB) is a crucial enzyme in heme metabolism. Recent studies in humans have identified a loss‐of‐function mutation (Ser111Leu) that unmasks a fundamentally important role in hematopoiesis. We have undertaken experimental and thermodynamic modeling studies to provide further insight into the role of the cofactor in substrate accessibility and protein folding properties regulating BLVRB catalytic mechanisms. Site‐directed mutagenesis with molecular dynamic (MD) simulations establish the critical role of NAD(P)H‐dependent conformational changes on substrate accessibility by forming the “hydrophobic pocket”, along with identification of a single key residue (Arg35) modulating NADPH/NADH selectivity. Loop80 and Loop120 block the hydrophobic substrate binding pocket in apo BLVRB (open), whereas movement of these structures after cofactor binding results in the “closed” (catalytically active) conformation. Both enzymatic activity and thermodynamic stability are affected by mutation(s) involving Ser111, which is located in the core of the BLVRB active site. This work 1) elucidates the crucial role of Ser111 in enzymatic catalysis and thermodynamic stability by active site hydrogen bond network; 2) defines a dynamic model for apo BLVRB extending beyond the crystal structure of the binary BLVRB/NADP+ complex; 3) provides a structural basis for the “encounter” and “equilibrium” states of the binary complex, which are regulated by NAD(P)H.
Single‐Molecule Conductance Studies of Organometallic Complexes Bearing 3‐Thienyl Contacting Groups
Authors: Bock Sören , Al‐Owaedi Oday A. , Eaves Samantha G. , Milan David C. , Lemmer Mario , Skelton Brian W. , Osorio Henrry M. , Nichols Richard J. , Higgins Simon J. , Cea Pilar , Long Nicholas J. , Albrecht Tim , Martín Santiago , Lambert Colin J. , Low Paul J.
Published: November 2016

The compounds and complexes 1,4‐C6H4(C≡C‐cyclo‐3‐C4H3S)2 (2), trans‐[Pt(C≡C‐cyclo‐3‐C4H3S)2(PEt3)2] (3), trans‐[Ru(C≡C‐cyclo‐3‐C4H3S)2(dppe)2] (4; dppe=1,2‐bis(diphenylphosphino)ethane) and trans‐[Ru(C≡C‐cyclo‐3‐C4H3S)2{P(OEt)3}4] (5) featuring the 3‐thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3–5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break‐junction (STM‐BJ) and STM‐I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM‐I(s) methods, and a higher feature by the STM‐BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi‐parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non‐resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2–5.
CuOTf‐Catalyzed Selective Generation of 2‐Aminopyrimidines from Carbodiimides and Diaryliodonium Salts by a Triple C(sp3)−H Functionalization
Authors: Chi Yue , Yan Haihan , Zhang Wen‐Xiong , Xi Zhenfeng
Published: November 2016

The selective C(sp3)−H bond functionalization is an ideal and atom‐economical method in organic synthesis. In this work, 2‐aminopyrimidines are generated from a Cu‐catalyzed reaction between carbodiimides and diaryliodonium salts, by cleavage of four C(sp3)−H, one C−N, and one C=N bonds in the carbodiimides. It is the first triple C(sp3)−H bond functionalization neighboring a C=N bond. The selective synthesis of 2‐aminopyrimidines is controlled by the amount of the diaryliodonium salts. The novel mechanism involving a C−N formation/1,5‐H shift/1,7‐H shift/6 π‐electrocyclic ring‐closing/aromatization is well elucidated by the detection of important intermediates and DFT calculations.
Adaptive Self‐Assembly Behavior Restrained by Supramolecular Crystallization and Molecular Recognition
Authors: Roy Bappaditya , Noguchi Takao , Yoshihara Daisuke , Sakamoto Junji , Yamamoto Tatsuhiro , Shinkai Seiji
Published: November 2016

The control over supramolecular interactions and obtaining information beyond the molecular scale is an extended challenge. The intriguing self‐assembly of a perylene‐3,4,9,10‐tetracarboxylic acid diimide (PDI)‐based novel bolaamphiphilic probe is experienced within an artificial environment that is restrained by using supramolecular crystallization and molecular recognition. The bolaamphiphile with a hydrophilic [18]‐azacrown ether ring produced nanoaggregates due to differing solubilities in organic and aqueous media. A structural evolution was observed in the presence of alkali metal ions as guests. The metal complexes form a pseudo‐cationic structure, which is further involved in an ionic self‐assembly with biomolecules, thus resulting new spectroscopic information on the dye self‐assembly. The overarching aim of this study is to emphasize the importance of the concept of supramolecular adaptability, which has been used to establish an environment‐friendly behavior based on noncovalent forces, thus leading to the evolution of new assembly structures and photophysical properties.
Soluble Graphene Nanoribbons from Planarization of Oligophenylenes
Authors: Sen Choong Ping , Valiyaveettil Suresh
Published: November 2016

A solution‐based chemical synthesis of two graphene nanoribbons with armchair edges is reported. The precursor oligophenylene molecules are synthesized and subjected to oxidative cyclodehydrogenation to afford the target molecules, G‐1 and G‐2. These molecules have good solubility in organic solvents, and show a large redshift in their absorption edge (up to 185 nm) and emission maximum (up to 125 nm) after planarization. Fibrous structures are formed upon self‐assembly of molecules through columnar π–π stacking. Such molecular assemblies may be useful for various applications.
Fe‐Catalyzed Amination of (Hetero)Arenes with a Redox‐Active Aminating Reagent under Mild Conditions
Authors: Liu Jianzhong , Wu Kai , Shen Tao , Liang Yujie , Zou Miancheng , Zhu Yuchao , Li Xinwei , Li Xinyao , Jiao Ning
Published: November 2016

A novel and efficient Fe‐catalyzed direct C−H amination (NH2) of arenes is reported using a new redox‐active aminating reagent. The reaction is simple, and can be performed under air, mild, and redox‐neutral conditions. This protocol has a broad substrate scope and could be used in the late‐stage modification of bioactive compounds. Mechanistic studies demonstrate that a radical pathway could be involved in this transformation.
Genuine brands or high quality counterfeits: An investigation of luxury consumption in China
Authors: Jiang Ling , Shan Juan
Published: November 2016

This study examines the effects of different marketing and manufacturing factors on the perceived quality gap and willingness to pay (WTP) for genuine luxury brands. Using the survey data of 786 Chinese consumers, the results show that three marketing factors (product innovation, price promotion, and sales environment) and two manufacturing factors (production in country of brand origin and difficulty in producing the products) all indirectly influence WTP through a perceived quality gap between originals and counterfeits. These effects differ significantly among consumers with different counterfeit and genuine brand purchasing experiences. For consumers with counterfeit purchasing experience, it is important to emphasize the manufacturing factors in the marketing strategies; however, for consumers who only buy genuine brands, marketing factors play a more important role. Copyright © 2016 ASAC. Published by John Wiley & Sons, Ltd.
Structure‐Based Drug Design of Mineralocorticoid Receptor Antagonists to Explore Oxosteroid Receptor Selectivity
Authors: Nordqvist Anneli , O'Mahony Gavin , Fridén‐Saxin Maria , Fredenwall Marlene , Hogner Anders , Granberg Kenneth L. , Aagaard Anna , Bäckström Stefan , Gunnarsson Anders , Kaminski Tim , Xue Yafeng , Dellsén Anita , Hansson Eva , Hansson Pia , Ivarsson Ida , Karlsson Ulla , Bamberg Krister , Hermansson Majlis , Georgsson Jennie , Lindmark Bo , Edman Karl
Published: November 2016

The mineralocorticoid receptor (MR) is a nuclear hormone receptor involved in the regulation of body fluid and electrolyte homeostasis. In this study we explore selectivity triggers for a series of nonsteroidal MR antagonists to improve selectivity over other members of the oxosteroid receptor family. A biaryl sulfonamide compound was identified in a high‐throughput screening (HTS) campaign. The compound bound to MR with pKi=6.6, but displayed poor selectivity over the glucocorticoid receptor (GR) and the progesterone receptor (PR). Following X‐ray crystallography of MR in complex with the HTS hit, a compound library was designed that explored an induced‐fit hypothesis that required movement of the Met852 side chain. An improvement in MR selectivity of 11‐ to 79‐fold over PR and 23‐ to 234‐fold over GR was obtained. Given the U‐shaped binding conformation, macrocyclizations were explored, yielding a macrocycle that bound to MR with pKi=7.3. Two protein–ligand X‐ray structures were determined, confirming the hypothesized binding mode for the designed compounds.
UV‐Induced Synthesis and Stabilization of Surfactant‐Free Colloidal Pt Nanoparticles with Controlled Particle Size in Ethylene Glycol
Authors: Kacenauskaite Laura , Quinson Jonathan , Schultz Hannibal , Kirkensgaard Jacob Judas Kain , Kunz Sebastian , Vosch Tom , Arenz Matthias
Published: November 2016

The conventional temperature‐induced polyol synthesis of platinum nanoparticles is a powerful and well‐established method for the preparation of stable, surfactant‐free platinum nanoparticles (Pt NPs) with controlled shape, size and size distribution. Recently, we reported that exposure to daylight leads to the formation of Pt NPs from precursor solutions, suggesting that a parallel approach of UV‐induced polyol synthesis could be a cheaper and more widely applicable alternative. Here we report a controlled size and size distribution for Pt NPs prepared using UV irradiation instead of thermal treatment. Results demonstrate that, depending on the concentration of NaOH in the reaction mixture, the size of produced nanoparticles can vary between 1 and 5.8 nm. We also show, for the first time, how NaOH affects the formation of organic side products, which alters Pt NPs stability, and demonstrate a method for the preparation of stable nanoparticle suspensions with an average particle size of 5.8 nm.
Sequential Recognition of Zinc and Pyrophosphate Ions in a Terpyridine‐Functionalized Single Nanochannel
Authors: Zhang Yuqi , Zhou Ru , Zhao Zhiju , Kong Xiang‐Yu , Xie Ganhua , Liu Qian , Li Pei , Zhang Zhen , Xiao Kai , Liu Zhengping , Wen Liping , Jiang Lei
Published: November 2016

A highly selective recognition system for zinc(II) and pyrophosphate ions is constructed using a single conical nanochannel covalently functionalized with N′‐{4‐[(2,2′:6′,2′′‐terpyridine)‐4‐yl]benzyl}ethane‐1,2‐diamine (TPYD). The immobilized TPYD acts as a specific coordination site for Zn2+ to form TPYD–Zn2+ complexes in preference over other metal ions, and subsequently, the resulting Zn2+‐coordinated nanochannel can be used as a selective recognition element for the pyrophosphate ion based on the coordination reaction between hydroxyl oxygen atoms of pyrophosphate and Zn2+. Ion recognition is monitored by measuring the current–voltage curves of the solutions. The ionic current of the TPYD‐functionalized system at −2.0 V undergoes a clear decrease after exposure to Zn2+ ions and is followed with an obvious increase after subsequent treatment with a pyrophosphate solution. The change of ionic current can be primarily attributed to the variation of charge density of the nanochannel. This functionalized single nanochannel might provide a simple and universal means to recognize other targets by modifying different functional molecules onto the inner surfaces of nanochannels.
Site‐Specific Reactivity of Ethylene at Distorted Dangling‐Bond Configurations on Si(001)
Authors: Pecher Lisa , Mette Gerson , Dürr Michael , Tonner Ralf
Published: November 2016

Differences in adsorption and reaction energetics for ethylene on Si(001) are reported with respect to distorted dangling‐bond configurations induced by hydrogen precoverage, as obtained by DFT calculations. This can help to understand the influence of surface defects and precoverage on the reactivity of organic molecules on semiconductor surfaces in general. The results show that the reactivity of surface dimers fully enclosed by hydrogen‐covered atoms is essentially unchanged compared to the clean surface. This is confirmed by scanning tunneling microscopy measurements. On the contrary, adsorption sites with partially covered surface dimers show a drastic increase in reactivity. This is due to a lowering of the reaction barrier by more than 50 % relative to the clean surface, which is in line with previous experiments. Adsorption on dimers enclosed by molecule (ethylene)‐covered surface atoms is reported to have a strongly decreased reactivity, as a result of destabilization of the intermediate state due to steric repulsion; this is quantified through periodic energy decomposition analysis. Furthermore, an approach for the calculation of Gibbs energies of adsorption based on statistical thermodynamics considerations is applied to the system. The results show that the loss in molecular entropy leads to a significant destabilization of adsorption states.
Intrinsic Kinetics of Dimethyl Ether Synthesis from Plasma Activation of CO2 Hydrogenation over Cu–Fe–Ce/HZSM‐5
Authors: Su Tongming , Zhou Xinhui , Qin Zuzeng , Ji Hongbing
Published: November 2016

CO2 is activated in a plasma reactor followed by hydrogenation over a Cu–Fe–Ce/HZSM‐5 catalyst, and the intrinsic kinetics of the plasma catalytic process are studied. Compared with CO2 hydrogenation using Cu–Fe–Ce/HZSM‐5 alone, the CO2 conversion and the dimethyl ether selectivity for the plasma catalytic process are increased by 16.3 %, and 10.1 %, respectively, indicating that the CO2 was activated by the plasma to promote hydrogenation. A study of the intrinsic kinetics shows that the activation energies of methanol formation, the reverse water–gas shift reaction, and methanol dehydration to dimethyl ether are 149.34, 75.47, and 73.18 kJ mol−1, respectively, which are lower than if Cu–Fe–Ce/HZSM‐5 is used without plasma, indicating that the activation of CO2 in the plasma reduces the activation energy of the hydrogenation reaction and improves the yield of dimethyl ether.
Choice of Capping Group in Tripeptide Hydrogels Influences Viability in the Three‐Dimensional Cell Culture of Tumor Spheroids
Authors: Wojciechowski Jonathan P. , Martin Adam D. , Mason Alexander F. , Fife Christopher M. , Sagnella Sharon M. , Kavallaris Maria , Thordarson Pall
Published: November 2016

Two peptide‐derived low‐molecular‐weight gelators bearing different capping groups, 9‐fluorenylmethyloxycarbonyl (Fmoc) and phenothiazine, were synthesized and their gel networks were characterized. The variation of the N‐terminal capping group affects the viability of these hydrogels as a three‐dimensional cell culture for multicellular tumor spheroids. These results indicate that the phenothiazine capping group is a more biocompatible alternative to the widely used Fmoc moiety.
Applications of Liquid/Liquid Biphasic Oxidations by Hydrogen Peroxide with Ionic Liquids or Deep Eutectic Solvents
Authors: Guajardo Nadia , Carlesi Carlos , Schrebler Rodrigo , Morales Jaime
Published: November 2016

This Minireview focuses on recent applications of ionic liquids (ILs) and deep eutectic solvents (DESs) in biphasic oxidations in which the oxidizing agent corresponds to hydrogen peroxide. Biphasic reactions are accomplished when the substrate presents low or moderate solubility in aqueous (polar) systems and/or when separation of products and byproduct is an issue. The properties of the IL and DES allows the reaction activity to be intensified. On the other hand, the high chemical stability of the ionic solvents allows the use of hydrogen peroxide to minimize solvent degradation and unwanted byproducts. The experimental evidence presented herein shows that ILs and DESs can be used as cocatalysts, catalysts, and solvents to achieve enhanced yields and conversions. The process advantages, in terms of a reduction of volatile solvents, improve the safety and use of the oxidizing agent, which implies the possibility of developing new process improvements in the future.