bluuebunny/crossref_metadata_2025 huggingface dataset:
A Concise Synthesis of Potential COX Inhibitor BRL‐37959 and Analogs Involving Bismuth(III) Catalyzed Friedel−Crafts Acylation
Authors: Ahmed Shamsul Arefin , Hinz Damon J. , Jellen Marcus J. , Hossain M. Mahmun
Published: September 2018

We report the development of a concise method of synthesizing possible cyclooxygenase (COX) inhibitor BRL‐37959, which is believed to be a potent nonsteroidal anti‐inflammatory drug (NSAID). The four‐step synthesis greatly increased the efficiency of compound production from commercially available salicylaldehydes. The synthesis involved an optimized, bismuth(III) trifluoromethanesulfonate catalyzed benzoylation of a benzofuran ring.
Contemporary Photoligation Chemistry: The Visible Light Challenge
Authors: Offenloch Janin T. , Gernhardt Marvin , Blinco James P. , Frisch Hendrik , Mutlu Hatice , Barner‐Kowollik Christopher
Published: September 2018

Catalyst‐free and bond‐forming light‐induced reactions have seen an unprecedented renaissance in the realm of soft matter materials science due to their efficiency, spatio‐temporal controllability and, sometimes, photoreversible nature. However, many of these reactions rely on the application of high energy UV light that can cause photo‐degradation and is inapplicable in biological environments. If up‐conversion systems or two‐photon processes are to be avoided, strategies for red‐shifting catalyst‐free ligation technology are critically required. This Concept article introduces the reader to recent methods that lead to efficient, catalyst‐free visible‐light‐induced ligation chemistry based on polyaromatic substituted photoreactive compounds—pyrene and anthracene—and, furthermore, emphasizes the broad and facile applicability of these molecules in polymeric material design. Concomitantly, we highlight that a careful action plot analysis of photochemical reactivity can provide deep insights into reactivity patterns, far beyond those suggested by the absorption spectrum. Indeed, we suggest that an action plot analysis is necessary for the evaluation of any photochemical system and its response to structural chemical changes.
Corannulenes with Electron‐Withdrawing Substituents: Synthetic Approaches and Resulting Structural and Electronic Properties
Authors: Haupt Axel , Lentz Dieter
Published: September 2018

Corannulene is a multifaceted polyaromatic compound. It has many interesting properties; for example, it has a bowl‐shaped molecular structure that, in addition, undergoes a dynamic inversion process. It has attracted much attention within the last decades. This is not only due to its structural properties but also its electronic properties and its various potential applications to materials chemistry. Here, synthetic approaches towards corannulene derivatives with electron‐withdrawing substituents are summarized. This includes both selective and unselective methods. Further, the electrochemical properties, that is, the reduction potentials, are analyzed and compared. As a main conclusion, one can state that the electron affinity depends roughly linearly on the number of substituents. Finally, the structural behavior of the substituted buckybowls in the solid state is highlighted. This also allows a general statement about the influence of the electronic and steric nature of substituents on the molecular structures and the solid‐state packing of the corannulene derivatives.
Structural Effects of Fusicoccin upon Upregulation of 14‐3‐3‐Phospholigand Interaction and Cytotoxic Activity
Authors: Ohkanda Junko , Kusumoto Atsushi , Punzalan Louvy , Masuda Ryoma , Wang Chenyu , Parvatkar Prakash , Akase Dai , Aida Misako , Uesugi Motonari , Higuchi Yusuke , Kato Nobuo
Published: September 2018

Fusicoccins (FCs) exhibit various cellular activities in mammalian cells, but details of the mechanism of action are not fully understood. In this study, we synthesized two pairs of model derivatives of FCs differing only in the presence and absence of a 12‐hydroxyl group and evaluated their binding to a 14‐3‐3 protein together with various mode 1 and mode 3 phosphopeptide ligands. Our results demonstrate that the 12‐hydroxyl group hampers binding to 14‐3‐3 with mode 1 phospholigands, presumably due to steric repulsion with the i+2 residue. Furthermore, cell‐based evaluations showed that only non‐substituted FCs exhibit significant cytotoxicity and all 12‐hydroxyl derivatives were inactive, demonstrating a clear correlation with their ability to form ternary complexes with 14‐3‐3 and a mode 1 ligand. These results suggest that binding to 14‐3‐3 and a partner protein(s) possessing a mode 1 sequence plays a role in the mechanism of action of 12‐non‐substituted FCs.
Inspecting the Electronic Architecture and Semiconducting Properties of a Rosette‐Like Supramolecular Columnar Liquid Crystal
Authors: Feringán Beatriz , Folcia César L. , Termine Roberto , Golemme Attilio , Granadino‐Roldán José M. , Navarro Amparo , Serrano José Luis , Giménez Raquel , Sierra Teresa
Published: September 2018

Computational and experimental studies unravel the structural and electronic properties of a novel supramolecular liquid crystal built through a hierarchical assembly process resulting in an H‐bonded melamine rosette decorated with peripheral triphenylenes. The six‐fold symmetry of the mesogen facilitates the formation of a highly organized hexagonal columnar mesophase stable at room temperature. X‐ray diffraction and electron density maps confirm additional intra‐ and intercolumn segregation of functional subunits, and this paves the way for 1D charge transport. Indeed, hole mobility has been measured and found to be higher than for related mesogens. DFT calculations of HOMO and LUMO levels and parameters such as reorganization energy and transfer integral of the rosette structure have been achieved, and not only validate the columnar organization but also establish the way it translates into a favorable electronic architecture and molecular orbital interactions to promote charge carrier mobility.
The use of tranexamic acid for on‐demand and prophylactic treatment of hereditary angioedema—A systematic review
Authors: Horiuchi Takahiko , Hide Michihiro , Yamashita Kouhei , Ohsawa Isao
Published: September 2018

Hereditary angioedema (HAE), caused by inherited deficiency of C1 esterase inhibitor (C1‐INH), is characterized by recurring subcutaneous and/or submucosal edema. Although its efficacy remains controversial, tranexamic acid (TXA) is used to treat HAE in some countries. We analyzed TXA as an on‐demand and prophylactic treatment in patients with HAE. Published data were systematically sourced from PubMed and Embase. All retained articles underwent grading/bias assessment using the “SIGN” grading system, and the quality of retained studies was determined following assessment of design and methodology. Of 353 studies identified, 31 were included. On‐demand treatment and prophylactic treatment were assessed in five (N = 103) and 28 studies (N = 231), respectively. The majority of studies (80%) demonstrated that on‐demand TXA was ineffective for skin, abdominal, or laryngeal swellings. In a single randomized controlled trial, the median time to relief of symptoms was 2 and 12 hours for icatibant and TXA, respectively (P < 0.001). For prophylaxis, while ~50% of case series, case reports, and observational studies reported beneficial effects of TXA, newer therapies, for example, icatibant and pdC1‐INH, were more effective. One study found that breakthrough attacks during TXA prophylaxis lasted significantly longer compared with C1‐INH (median time to resolution; 7 vs 3 hours, P = 0.016). Many studies failed to report safety data (16/31, 52%); however, pruritus, vomiting, and diarrhea were noted in some patients. There is no evidence for on‐demand use of TXA in HAE and limited evidence for prophylaxis. While TXA may be more beneficial than no treatment, newer, more effective therapies should be used when available.
Electrochemical Sensor Based on AgNPs‐NNH Nanocomposites for Hydrogen Peroxide Detection by Zero Current Potentiometry
Authors: Fu Yanyi , Hao Huan , Liu Xiaoli , Zheng Jianbin
Published: September 2018

The layered nickel nitrate hydroxide (NNH) nickel base material was prepared by using hydrothermal method, and the AgNPs were synthesized on the surface of NNH. The layered AgNPs‐NNH nanocomposites were used to construct electrochemical sensor for hydrogen peroxide detection. The morphology, composition and structure of the sensing interface materials were characterized and the relationship between zero current potential signals towards hydrogen peroxide and the response performance was explored. The results of field emission electron microscope (FESEM) and transmission electron microscope (TEM) showed that the NNH was layered material with a uniform thickness of 60 nm, and AgNPs evenly dispersed on the surface of NNH layer, with the size of 15 nm and 23 nm, respectively. Based on zero current potentiometry, the electrochemical results indicated that the linear range was from 1.0 nmol/L to 1.0 mmol/L, with a detection limit of 0.3 nmol/L and a sensitivity of 33.7 μV·mM–1·cm–2. Compared to the chronoamperometry, the detection limit was reduced four orders of magnitude.
Effects of sauna bath on heart failure: A systematic review and meta‐analysis
Authors: Källström Miikka , Soveri Inga , Oldgren Jonas , Laukkanen Jari , Ichiki Tomoko , Tei Chuwa , Timmerman Mark , Berglund Lars , Hägglund Hans
Published: September 2018

Background

Sauna bath has potential as a lifestyle treatment modality for heart failure (HF). It is important to analyze the current evidence to help suggest paths of future study and potential for clinical application.

Hypothesis

Sauna bath has a positive effect on HF patients.

Methods

PubMed, Cochrane Library, and CINAHL databases were searched to identify randomized and nonrandomized controlled studies to compare effects of sauna bath with no sauna bath. Studies were searched for both infrared sauna bath and Finnish sauna bath. The strength of evidence was rated using a modified GRADE approach. Out of 1444 studies, nine met the inclusion criteria and were included in this review. Seven of these nine studies were included in the meta‐analysis. Only studies with infrared sauna bath met the inclusion criteria.

Results

In the meta‐analysis, exposure to an infrared sauna bath in 60°C for 15 minutes, followed by a 30‐minute rest in warm environment, five times a week for 2 to 4 weeks, was associated with a significant reduction in B‐type natriuretic peptide, cardiothoracic ratio, and an improvement in left‐ventricular ejection fraction. There was no significant effect on left‐ventricular end‐diastolic diameter, left atrial diameter, systolic blood pressure, or diastolic blood pressure. The strength of evidence varied from moderate to insufficient.

Conclusion

Infrared sauna bath was associated with short‐term improvement in cardiac function. More evidence is needed about long‐term effects of sauna bath and the effects of a Finnish sauna on cardiovascular health among patients with HF or other cardiovascular diseases.
An On‐Chip Method for Long‐Term Growth and Real‐Time Imaging of Brain Organoids
Authors: Karzbrun Eyal , Tshuva Rami Yair , Reiner Orly
Published: September 2018

Brain organoids are an emerging technique for studying human neurodevelopment in vitro, with biomedical implications. However, three‐dimensional tissue culture poses several challenges, including lack of nutrient exchange at the organoid core and limited imaging accessibility of whole organoids. Here we present a method for culturing organoids in a micro‐fabricated device that enables in situ real‐time imaging over weeks with efficient nutrient exchange by diffusion. Our on‐chip approach offers a means for studying the dynamics of organoid development, cell differentiation, cell cycle, and motion. © 2018 by John Wiley & Sons, Inc.
Recipes for Commonly Encountered Reagents
Authors: Gallagher Sean R.
Published: September 2018

This unit lists recipes for many of the buffers and other reagents typically found in a molecular biology laboratory. For reagents specific to a given technique, refer to the unit describing the method. © 2018 by John Wiley & Sons, Inc.
Heterogeneous Nucleation onto Monoatomic Ions: Support for the Kelvin‐Thomson Theory
Authors: Tauber Christian , Chen Xiaoshuang , Wagner Paul E. , Winkler Paul M. , Hogan Christopher J. , Maißer Anne
Published: September 2018

In this study, the process of heterogeneous nucleation is investigated by coupling a high‐resolution differential mobility analyser (DMA) to an expansion‐type condensation particle counter, the size‐analyzing nuclei counter (SANC). More specifically, we measured the activation probabilities of monoatomic ions of both polarities by using n‐butanol as condensing liquid. All seed ions were activated to grow into macroscopic sizes at saturation ratios well below the onset of homogeneous nucleation, showing for the first time that the SANC is capable of detecting sub‐nanometer sized, atomic seed ions. The measured onset saturation ratios for each ion were compared to the Kelvin‐Thomson (KT) theory. Despite the fact that certain dependencies of activation behaviour on seed ion properties cannot be predicted by the KT theory, it was found that with a simple adjustment of the n‐butanol molecular volume (9–15 % lower compared to bulk properties) good agreement with experimental results is achievable. The corresponding density increase may result from the dipole‐charge interaction. This study thus offers support for the application of the KT model for heterogeneous, ion‐induced nucleation studies at the sub‐nanometer level.
Photoinduced Intramolecular Charge Transfer and Hyperpolarizability Coefficient in Push‐Pull Pyridinium Salts with Increasing Strength of the Acceptor Group
Authors: Cesaretti Alessio , Bonaccorso Carmela , Elisei Fausto , Fortuna Cosimo G. , Mencaroni Letizia , Spalletti Anna
Published: September 2018

The synthesis of three push‐pull cationic dyes is reported here together with a photophysical study carried out by stationary and ultrafast spectroscopies. The hyperpolarizability (β) values of the three molecules have been estimated through a simple solvatochromic method based on conventional, low‐cost equipment, which had been tested previously with success in our laboratory. The investigated pyridinium salts showing strong negative solvatochromism bear the same piperidine ring as a strong electron‐donor group and the same thiophenes as electron‐rich π‐linkers, but differ in terms of the N‐substituent on the electron‐acceptor pyridinium unit, namely N‐methyl in compound A, N‐pyrimidin‐2yl in B and N‐2,4‐dinitrophenyl in C. The derived β values were found to increase (in the order A<B<C) along with the increasing electron‐acceptor strength of the pyridinium substituent, with the highest polarizability being estimated for the derivative bearing the strongest electron‐withdrawing substituent dinitrobenzene. State‐of‐the‐art femtosecond transient absorption measurements evidenced fast kinetics and dynamics in the singlet excited state in agreement with charge transfer (CT) processes promoted by excitation, with a proper ICT state observed in the case of C. This finding confirms the efficiency of photoinduced intramolecular CT as a significant factor that affects the NLO response.
Whole Genome Next‐Generation Sequencing Mutation Identification in Pseudomonas aeruginosa
Authors: Cetinbas Murat , Yu Shen , Sadreyev Ruslan I.
Published: September 2018

Identification of spontaneous or chemically induced bacterial mutations is a powerful tool for investigation of molecular mechanisms, including the mechanism of action of novel antibiotics. However, a major bottleneck to this approach has been the identification of the causative mutation underlying a phenotype of interest. Until recently, this has required time‐consuming genetic analysis. However, the advent of relatively inexpensive and rapid next‐generation sequencing (NGS) technologies has revolutionized the correlation of bacterial phenotypes and genotypes. In this article we describe a simple bioinformatics pipeline to identify differences between sequenced bacterial genomes. We also describe the procedures involved in growing, extracting, and purifying DNA, and preparation of sequencing libraries for one bacterial species, Pseudomonas aeruginosa. Similar protocols will be applicable to other bacterial species. © 2018 by John Wiley & Sons, Inc.
Dual loop cascode‐Miller compensation with damping factor control unit for three‐stage amplifiers driving ultralarge load capacitors
Authors: Aminzadeh Hamed , Dashti Mohammad Ali
Published: September 2018

An area‐efficient amplifier topology is presented for three‐stage amplifiers driving ultralarge load capacitor with reduced power consumption. It contains two high‐speed ac feedback loops made from embedded current buffers and small‐size compensation capacitors, which pushes the nondominant complex poles to very high frequencies. To further improve the stability, a local impedance damping block is embedded. At the higher frequencies, it suppresses the high resistive property at the second‐stage output, thereby increasing the damping factor of the complex poles and improving the overall gain margin. For identical bandwidth, the overall silicon area of the on‐chip compensation capacitor is therefore decreased, leading to enhanced small‐signal and large‐signal performance metrics. Coined dual loop cascode‐Miller compensation with damping factor control unit, the effectiveness of the proposed approach is investigated through simulation results in 90‐nm complementary metal‐oxide‐semiconductor (CMOS) technology. An implementation based on the proposed technique consumes a quiescent current of 17 μA from a 1.2 V voltage supply. For a load capacitance equal to 560 pF, it achieves a gain‐bandwidth frequency of 4.34 MHz, an average slew‐rate of 1.72 V/μs, and an average settling time of 0.52 μs, when the overall compensation capacitance is set to 1.55 pF. The proposed design can supply the load capacitors up to 35 nF.
A method to detect discontinuities in census data
Authors: Barichievy Chris , Angeler David G. , Eason Tarsha , Garmestani Ahjond S. , Nash Kirsty L. , Stow Craig A. , Sundstrom Shana , Allen Craig R.
Published: September 2018

The distribution of pattern across scales has predictive power in the analysis of complex systems. Discontinuity approaches remain a fruitful avenue of research in the quest for quantitative measures of resilience because discontinuity analysis provides an objective means of identifying scales in complex systems and facilitates delineation of hierarchical patterns in processes, structure, and resources. However, current discontinuity methods have been considered too subjective, too complicated and opaque, or have become computationally obsolete; given the ubiquity of discontinuities in ecological and other complex systems, a simple and transparent method for detection is needed. In this study, we present a method to detect discontinuities in census data based on resampling of a neutral model and provide the R code used to run the analyses. This method has the potential for advancing basic and applied ecological research.
Fecal microbiota associated with phytohaemagglutinin‐induced immune response in nestlings of a passerine bird
Authors: Kreisinger Jakub , Schmiedová Lucie , Petrželková Adéla , Tomášek Oldřich , Adámková Marie , Michálková Romana , Martin Jean‐François , Albrecht Tomáš
Published: September 2018

The vertebrate gastrointestinal tract is inhabited by a diverse community of bacteria, the so‐called gut microbiota (GM). Research on captive mammalian models has revealed tight mutual interactions between immune functions and GM. However, our knowledge of GM versus immune system interactions in wild populations and nonmammalian species remains poor. Here, we focus on the association between GM community structure and immune response measured via the phytohaemagglutinin (PHA) skin swelling test in 12‐day‐old nestlings of a passerine bird, the barn swallow (Hirundo rustica). The PHA test, a widely used method in field ecoimmunology, assesses cell‐mediated immunity. GM structure was inferred based on high‐throughput 16S rRNA sequencing of microbial communities in fecal samples. We did not find any association between PHA response and GM diversity; however, our data revealed that the intensity of PHA response was correlated with differences in GM composition at the whole‐community level. Ten bacterial operational taxonomic units corresponding to both putative commensal and pathogens were identified as drivers of the compositional variation. In conclusion, our study suggests existence of GM versus immune system interactions in a free‐living nonmammalian species, which corresponds with previous research on captive vertebrates.
New Mixed‐C^N Ligand Tris‐Cyclometalated IrIII Complexes for Highly‐Efficient Green Organic Light‐Emitting Diodes with Low Efficiency Roll‐Off
Authors: Ma Xiaoyu , Liang Jie , Bai Fuquan , Ye Kaiqi , Xu Jianing , Zhu Dongxia , Bryce Martin R.
Published: September 2018

This article reports new tris‐cyclometalated IrIII complexes containing mixed‐C^N ligands, (C^N1)2Ir(C^N2), which are a rarely explored class of complexes. Two mixed 2‐phenylpyridine (ppy)/4‐methyl‐2,5‐diphenylpyridine (mdp) complexes (ppy)2Ir(mdp) 3 and (ppy)Ir(mdp)2 4 have been synthesized and their optoelectronic properties have been systematically characterized. Photoluminescence quantum yield values are 0.76–0.85; excited state lifetimes are 0.07–0.11 µs. Phosphorescent organic light emitting devices (PhOLEDs) based on these emissive complexes in a very simple device architecture reproducibly showed slightly higher external quantum efficiency (EQE) and power efficiency (PE) values compared with devices using the analogous conventional homoleptic Ir complexes Ir(ppy)3 and Ir(mdp)3, and the heteroleptic complexes (ppy)2Ir(acac) and (mdp)2Ir(acac). The new complexes (ppy)2Ir(mdp) 3 and (ppy)Ir(mdp)2 4 give PhOLEDs with EQEmax and PEmax values of 26.7 and 26.0 %/94.7 and 94.1 lm W–1, respectively, and very high values are retained at the practical luminances of 100 and 1000 cd m–2. The values for (ppy)2Ir(mdp) are 26.3 % and 73.6 lm W–1 (at 100 cd m–2) and 24.6 % and 53.5 lm W–1 (at 1000 cd m–2). These efficiencies are comparable with the highest reported values of PhOLEDs using conventional IrIII emitters in more complicated device structures. Mixed C^N ligand systems are, therefore, a viable strategy for developing new efficient phosphorescent emitters.
Energy Production and Storage Promoted by Organometallic Complexes
Authors: Bellini Marco , Bevilacqua Manuela , Marchionni Andrea , Miller Hamish Andrew , Filippi Jonathan , Grützmacher Hansjörg , Vizza Francesco
Published: September 2018

Organometallic complexes have intrinsically excellent characteristics as a new class of electrocatalyst for clean energy production in fuel cells and electrolyzers. The state‐of‐the‐art materials for these devices are based on precious metal nanoparticles dispersed on conductive carbon‐based supports. Although such materials have reached very high performance levels in terms of activity and stability, they suffer from some intrinsic limitations that contribute to hinder the commercial development of fuel cells and electrolyzers on a large scale. Organometallic‐based electrocatalysts may help to overcome such limitations. For example, they exhibit high selectivity in alcohol and sugar electrooxidation. Additionally, precious metal loadings can be reduced significantly using single site organometallic catalysts where each metal atom is potentially active. In this review, we will discuss various literature examples of organometallic electrocatalysts employed as anodes for fuel cells and electrolyzers and as cathodes for the hydrogen evolution reaction (HER). We will focus our attention on the few examples of electrocatalysts that have been successfully used in complete cells.
An Unsymmetric Ligand with a N5O2 Donor Set and Its Corresponding Dizinc Complex: A Structural and Functional Phosphoesterase Model
Authors: Das Biswanath , Daver Henrik , Pyrkosz‐Bulska Monika , Gumienna‐Kontecka Elzbieta , Himo Fahmi , Nordlander Ebbe
Published: September 2018

Invited for the cover of this issue is Ebbe Nordlander from Lund University, Sweden. The cover image shows a dizinc complex that catalyzes phosphoester hydrolysis and the computed catalytic transition state with the depicted substrate.
A DFT Perspective on Diels–Alder Organocatalysts Based on Substituted Phosphoramides
Authors: Wåhlander Jakob , Amedjkouh Mohamed , Balcells David
Published: September 2018

Phosphoramides are an interesting alternative to the thiourea motif that has long been used in organocatalysis. In the R1N(H)‐P(O)(R3)‐N(H)R2 formulation, phosphoramides give the advantage of having a third variable substituent, R3, compared to the two available in thioureas, and the possibility of introducing chirality with an asymmetric phosphorus center. In this work, we present a systematic computational study on the catalytic properties of these underexplored compounds. These studies show the catalytic potential of a series of substituted phosphoramides in Diels–Alder reactions, including the asymmetric [4+2] cycloaddition of pro‐chiral substrates. The nature of the phosphorus‐bound R3 substituent has a significant impact both on catalytic activity and enantioselectivity. Remarkably, several of the phosphoramides studied are predicted to be more active than the Schreiner's thiourea organocatalyst.
Decarboxylative Arylation of α,β‐Unsaturated Carboxylic Acids Using Aryl Triazenes by Copper/Ionic Liquid Combination in PEG‐400
Authors: Kumar Saurabh , Kumar Pandey Anand , Singh Rahul , Nand Singh Krishna
Published: September 2018

A practical method for the construction of stilbene derivatives has been developed via catalytic cross‐coupling of cinnamic acids with aryl triazenes. The methodology offers high stereoselectivity and is endowed with broad substrate scope, high yield, and significant functional group tolerance.
Total Synthesis of an Anticancer Natural Product (±)‐Peharmaline A and Its Analogues
Authors: Kulkarni Akshay S. , Shingare Rahul D. , Dandela Rambabu , Reddy D. Srinivasa
Published: September 2018

First total synthesis of a rare β‐carboline–vasicinone hybrid alkaloid (±)‐peharmaline A has been accomplished in just 3 steps starting from known compounds. Stereoselective Pictet–Spengler reaction to nitrogenated tertiary carbon center and one‐pot construction of the tricyclic skeleton of vasicinone are the highlights of present synthesis. We have also synthesized structurally close analogues of the natural product by following the developed route.
Conformationally Restricted Triarylmethanes: Synthesis, Photophysical Studies, and Applications
Authors: Mondal Sankalan , Verma Abhineet , Saha Satyen
Published: September 2018

Triarylmethanes, compounds in which the central carbon atom is attached to three aryl rings, have a wide variety of photophysical properties which are utilized in the dye industry and also in the development of novel fluorescent tags and biomarkers. The aryl rings attached to the central carbon atom of the parent molecule triphenylmethane can freely rotate. Bridging the aryl rings of triarylmethanes with heteroatoms or through bonds decreases the conformational flexibility enjoyed by the parent molecules. Conformationally restricted triarylmethane (CRT) molecules like 9‐arylxanthenes (oxygen bridging), 9‐arythioxanthenes (sulfur bridging), 9,10‐dihydro,9‐arylacridines (nitrogen bridging), and 9‐arylfluorenes (bridging through C–C bond) have decreased conformational flexibility and display amphihydric behavior which results in benzenoid structure and quinoid structure of these molecules. The quinoid form of these molecules displays very rich photophysical properties which are the subject of this review. These molecules also have widespread utility, and over the last decade, a number of studies have been focused on the synthesis, photophysical properties, and applications of molecules derived from this core structure. Through this review, we intend to give the readers an outlook on the different strategies employed to synthesize these molecules and also provide a broader perspective on the various intriguing properties of these molecules. The applications of these classes of molecules in diverse fields like photocatalysis, chemical biology, pharmaceutical chemistry, and bio‐imaging are discussed. Also, the areas that need to be further developed are highlighted, which may provide a further impetus in the development of this class of molecules.
Diazepane Carboxylates as Organocatalysts in the Diels–Alder Reaction of α‐Substituted Enals
Authors: Häggman Nicklas O. , Zank Benjamin , Jun HyunJune , Kaldre Dainis , Gleason James L.
Published: September 2018

Ethyl diazepane carboxylate efficiently catalyzes the Diels–Alder cycloaddition of α‐substituted‐α,β‐unsaturated aldehydes via iminium ion organocatalysis. The reaction is applicable to a range of dienes and dienophiles and generally proceeds at room temperature in the presence of 5 mol‐% catalyst and 2.5 mol‐% triflic acid co‐catalyst. The incorporation of a stereogenic center on the diazepane backbone in combination with a menthyl carbamate produces a catalyst which affords enantioselectivities of 70–95 % ee for the cycloaddition of cyclopentadiene with a range of dienophiles. The enantioselectivity is rationalized via a transition state in which electrostatic stabilization by the carboxylate directs the diene to the more hindered face of the dienophile.
Analysis of Stability and (Anti)aromaticity of BN‐Dibenzo[a,e]pentalenes
Authors: Stojanović Milovan , Baranac‐Stojanović Marija
Published: September 2018

Relatively scarce literature data on BN/CC isosterism in 4nπ‐electronic systems have prompted us to investigate theoretically the influence of BN pair position within the central butadiene fragment of dibenzo[a,e]pentalene on two fundamental molecular properties: stability and (anti)aromaticity. It was found that stability and aromaticity follow the same trend only for BN‐orientational isomers. The source of different stability of other isomers was examined first by an analysis of bond types and their dissociation energies and then by isomerization energy decomposition analysis and was explained in terms of classical electrostatic interactions, quantum‐mechanical orbital interactions, structural changes and electronic changes (transition from charge‐separated π‐system to the neutral one). (Anti)aromaticity was investigated by using three kinds of indices, HOMA, FLUπ, and NICS(1)zz, which indicated that delocalization at the central pentalene motif is almost unaffected by various BN arrangements, molecular perimeter is slightly affected, while the most affected subunits are five‐membered rings and benzene‐fused five‐membered rings containing only one heteroatom.
Conformational Distortion Using a Molecular Lever: Synthesis and Conformational Studies of Galactoside Derivatives
Authors: Häner Markus , Herrstedt Hammelev Christian , Pedersen Christian Marcus
Published: September 2018

Novel bicyclic d‐galactose derivatives containing a molecular lever were synthesized and their conformations studied by 1H‐NMR and crystallography. Increasing the bulkiness in the alkylidene ring in combination with introducing bulky O‐protective groups on the pyranoside ring, causes a ring flip from a 4C1 into the axial rich 1C4 conformation. With less bulky protective groups, the pyranoside ring resides in the 4C1 conformation despite distortion of the external alkylidene ring.
Impact of the α‐Ferrocenyl Group on the Solvolytic Reactivity – Electrofugality – of Ferrocenylphenylmethyl Cations
Authors: Marijan Marijan , Jurić Sandra , Mihalić Zlatko , Kronja Olga
Published: September 2018

The electron‐donating effect of the ferrocenyl group in α‐position to the reaction center on SN1 solvolytic reactivity has been quantified by determining the electrofugalities (Ef) of a series of ferrocenyl‐X‐phenylmethyl cations according to the LFER equation: log k = sf(Ef + Nf). Due to highly stabilized transition state, the Ef values are about eight units higher than those of the corresponding benzhydryl cations. Impact of the phenyl group in ferrocenylphenylmethyl derivatives on stabilization of the positive charge is somewhat leveled by the ferrocenyl group, so the rate effect of the substituents on the phenyl ring is suppressed, causing narrow range of Ef parameters and small absolute values of the ρ+ constant. Calculations at B2PLYP‐D3/may‐cc‐pVTZ level of theory showed that the positive charge in ferrocenylphenylmethyl cation is largely shifted from the phenyl to ferrocenyl moiety, and that the substituents on the phenyl ring have small impact on its stability.
Diastereoselective Radical Couplings Enable the Asymmetric Synthesis of anti‐β‐Amino‐α‐hydroxy Carboxylic Acid Derivatives
Authors: Hidasová Denisa , Janák Martin , Jahn Emanuela , Císařová Ivana , Jones Peter G. , Jahn Ullrich
Published: September 2018

anti‐β‐Amino‐α‐(aminoxy) esters or amides are synthesized by merging polar asymmetric aza‐Michael additions of lithium 1‐phenylethylamides to α,β‐unsaturated carboxylic acid derivatives and diastereoselective radical couplings with the persistent free radical TEMPO mediated or catalyzed by ferrocenium hexafluorophosphate. Aliphatic α,β‐unsaturated carboxylic derivatives gave good to excellent anti‐diastereoselectivity for the radical coupling step, whereas the selectivity remained lower for cinnamic acid derivatives. The method allows the convenient introduction of a protected oxygen functionality, which is stable to acidic, basic, hydride and hydrogenolytic reductive conditions, but can be deprotected with zinc and acetic acid in the presence of TBDMS and Boc groups without noticeable epimerization. The tandem aza‐Michael/oxygenation strategy was applied in total syntheses of the TH2 cytokine secretion modulator cytoxazone, and dipeptide fragments of the anti‐β‐amino‐α‐hydroxy acid containing macrocyclic peptides perthamide C and largamide H.
An Efficient Metal‐Free Mono N‐Alkylation of Anilines via Reductive Amination Using Hydrosilanes
Authors: Thakur Maheshwar S. , Nayal Onkar S. , Sharma Arti , Rana Rohit , Kumar Neeraj , Maurya Sushil K.
Published: September 2018

2‐Aminoquinazolin‐4‐one based efficient organocatalytic eco‐friendly reductive amination approach was developed for the mono N‐alkylation of anilines using hydrosilane as a reducing agent. This practically easy and sustainable approach works under neat reaction conditions and utilizes non‐toxic environmentally benign acetic acid as a dehydrating agent. The developed protocol have several advantages, such as broad substrate scope, wide functional group tolerance, short reaction time, and absence of metal catalyst in the reaction.
One Step Electrode Fabrication for Direct Electron Transfer Cholesterol Biosensor Based on Composite of Polypyrrole, Green Reduced Graphene Oxide and Cholesterol Oxidase
Authors: Pramanik Krishnendu , Sarkar Priyabrata , Bhattacharyay Dipankar , Majumdar Pavel
Published: September 2018

A simple single‐step fabrication of a novel biocomposite electrode was used for cholesterol sensing through direct electron transfer. The bio‐composite was prepared by polypyrrole, green reduced graphene oxide (gRGO) and cholesterol oxidase (ChOx). The graphene oxide (GO) was “green” reduced, with the Paederia foetide (PFL) plant extract at 60 °C to improve its biocompatibility. The adherence of gRGO to the electrode surface was improved through its co‐deposition during electro‐polymerization of pyrrole. Interestingly, the enzyme ChOx also could be immobilized during this co‐deposition process, resulting in one step biosensor fabrication. The optimization of electrochemical deposition parameters on glassy carbon electrode for this enzymatic bioelectrode (ChOx‐gRGO‐PPy/GCE) has resulted in excellent sensitivity (1095.3 μA mM−1 cm−2), wide linear range (0.01–6 mM), and low detection limit (3.78 μM) of cholesterol. Also, the Dubinin‐Radushkevitch (D−R) adsorption study revealed the occurrence of physisorption (ϵ=3.35) process in this bioelectrode, confirming diffusion‐controlled reaction. Reproducibility of electrodeposition procedure, impeccable selectivity in the presence of interferrants, repeatability for multiple use and long‐term stability for practical use were also ensured. This could be used to construct the cost‐effective device for cholesterol diagnosis.
Simple Synthesis of Multilayer‐shaped CeO2 Nanomaterial and its Electrochemical Detection of Clenbuterol
Authors: Xiao Xin , Wang YiHui , Tan Wei , Liu HongJie , Duan YangYang , Zhang XiaoBo , Zhang DongEn , Jiang YouXiang , Wang Jie , Gong JunYan , Ma JuanJuan , Yang Tao , Tong ZhiWei
Published: September 2018

A novel multilayer‐shaped CeO2 with obvious electrocatalytic activity was synthesized using a simple heat treatment method. The structure and morphology of the multilayer‐shaped CeO2 were characterized by X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Clenbuterol, a kind of β‐agonist drugs, has recently become a serious issue to human body due to the illegal addition in the food additive for livestocks. The drug residue in the human body may cause muscular pain, cardiac palpitation, glaucoma, prostatitis, dizziness and and even death in old people. Therefore, the detection of clenbuterol (CLB) has a important significance. The as‐prepared CeO2 was found to have unique electrocatalytic oxidation activities towards clenbuterol (CLB). The electrochemical sensor was constructed by fixing stable nafion‐modified multilayer‐shaped CeO2 film on a glassy carbon electrode. Compared with the CeO2‐modified electrode and the nafion‐modified electrode, the nafion‐modified multilayer‐shaped CeO2 electrode showed better electrocatalytic performance for clenbuterol in HClO4 solution. There was a good linear relationship between the oxidation peak current and the concentration of CLB between 0.39∼2.79 μmol/L, and the detection limit was 0.08 μmol/L (R=0.99). The nafion‐modified multilayer‐shaped CeO2 electrode exhibited high stability and reproducibility.
Local Electrodeposition of Metals by Tip Electrode Dissolution Using Scanning Electrochemical Microscopy
Authors: Jo Ara , Lee Youngmi , Lee Chongmok
Published: September 2018

We have electrodeposited palladium and gold micropatternings using scanning electrochemical microscopy (SECM) with the metal precursor ions generated via anodic dissolution of the ultramicroelectrode (UME) tip itself. Concurrently, in‐situ reduction of the metal ions occurred at the substrate electrode, where the deposition parameters were optimized. In particular, this is the first direct Pd patterning using Pd dissolution without any mediators. The catalytic activities of oxygen reduction on the Pd or Au were studied with tip generation‐substrate collection mode of SECM. The possibility of simultaneous co‐deposition of Pd and Au was also demonstrated using a dual Pd and Au UME.
Development of a Novel Electrochemical Sensor Based on a Carbon Paste Electrode Decorated with Nd2O3 for the Simultaneous Detection of Tartrazine and Sunset Yellow
Authors: Marquez‐Mariño Karen , Penagos‐Llanos Johisner , García‐Beltrán Olimpo , Nagles Edgar , Hurtado John J.
Published: September 2018

The simultaneous detection of tartrazine (TZ) and sunset yellow (SY) using a carbon paste‐decorated neodymium (III) oxide electrode (NdOx/CPE) is reported for the first time in this work. The surface properties of the NdOx/CPE were studied by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The anodic peak currents for TZ and SY increased by more than 60 %, and the anodic peak potentials for TZ and SY were observed at potential values less positive than those of the carbon paste without NdOX. Under the optimal parameters (pH 3.0; accumulation time tACC 30 s; and accumulation potential EACC 0.10 V), the detection limits for TZ and SY observation were 0.02 μmol L−1 (10.6 μg L−1) and 0.09 μmol L−1 (40.6 μg L−1), respectively. The new sensor was sensitive, stable, easily manufactured, and very convenient for the detection of TZ and SY in food samples and pharmaceutical materials and provided consistent results.
Nanostructured DNA Microarrays for Dual SERS and Electrochemical Read‐out
Authors: Kayran Yasin U. , Jambrec Daliborka , Schuhmann Wolfgang
Published: September 2018

We present a strategy to fabricate nanostructured microarrays ready to perform a dual read‐out, namely electrochemical (EC) as well as surface‐enhanced Raman spectroscopy (SERS) based detection of DNA hydridization. A polystyrene nanobeads monolayer assembly, obtained by means of a Langmuir Blodgett type technique, followed by electrochemical Au deposition, was employed to construct homogeneous nanostructures in the form of inverse‐opal nanovoids on a 32‐electrode Au microarray chip. Characterization of the obtained nanostructured electrodes of the array by means of cyclic voltammetry demonstrated high reproducibility of the surface modification process. The performance of the obtained array platform was investigated by modifying the microarray electrodes with three different oligonucleotide capture probes using a previously developed potential‐assisted surface modification protocol. Two ferrocene‐labeled target DNA sequences and one target RNA sequence with a Texas red label were detected electrochemically and via SERS, respectively.
Forecasting electricity spot price for Nord Pool market with a hybridk‐factor GARMA–LLWNN model
Authors: Ben Amor Souhir , Boubaker Heni , Belkacem Lotfi
Published: September 2018

This paper proposes a new hybrid approach, based on the combination of parametric and nonparametric models by adopting wavelet estimation approach, to model and predict the price electricity for Nord Pool market. Our hybrid methodology consists into two steps. The first step aims at modeling the conditional mean of the time series, using a generalized fractional model withk‐factor of Gegenbauer termed thek‐factor GARMA model; the parameters of this model are estimated using the wavelet approach based on the discrete wavelet packet transform (DWPT). The second step aims at estimating the conditional variance, so we adopt the local linear wavelet neural network (LLWNN) model. The proposed hybrid model is tested using the hourly log‐returns of electricity spot price from the Nord Pool market. The empirical results were compared with the predictions of the ARFIMA–LLWNN, thek‐factor GARMA–FIGARCH and the individual LLWNN models. It is shown that the proposed hybridk‐factor GARMA–LLWNN model outperforms all other competing methods. Hence it is a robust tool in forecasting time series.
Spectral properties of conservative, dispersive, and absorptive photonic crystals
Authors: Engström Christian , Torshage Axel
Published: September 2018

This article reviews both recent progress on the mathematics of dispersive and absorptive photonic crystals and well‐established results on conservative photonic crystals. The focus is on properties of the photonic band structures and we also provide results that are of importance for the understanding of lossy metal‐dielectric photonic crystals.
Adjustment for covariates using summary statistics of genome‐wide association studies
Authors: Wang Tao , Xue Xiaonan , Xie Xianhong , Ye Kenny , Zhu Xiaofeng , Elston Robert C.
Published: September 2018

Linear regression is a standard approach to identify genetic variants associated with continuous traits in genome‐wide association studies (GWAS). In a standard epidemiology study, linear regression is often performed with adjustment for covariates to estimate the independent effect of a predictor variable or to improve statistical power by reducing residual variability. However, it is problematic to adjust for heritable covariates in genetic association analysis. Here, we propose a new method that utilizes summary statistics of the covariate from additional samples for reducing the residual variability and hence improves statistical power. Our simulation study showed that the proposed methodology can maintain a good control of Type I error and can achieve much higher power than a simple linear regression. The method is illustrated by an application to the GWAS results from the Genetic Investigation of Anthropometric Traits consortium.
Einfluss des Hohlraumquerschnitts auf die Verheilung im Steinsalz
Authors: Hente Jonas Frederik , Gährken Andreas , Stahlmann Joachim
Published: September 2018

Im Zuge der Tiefenlagerung radioaktiver Reststoffe im Steinsalz entsteht an Hohlräumen aufgrund des viskosen Verformungsverhaltens des Wirtsgesteins ein geschädigter Bereich, die Auflockerungszone (ALZ). Durch die Konvergenz des Wirtsgesteins treten in der ALZ dilatante Schädigungen auf, die zu Veränderungen der Permeabilität des Wirtsgesteins führen. Nach erfolgter Einlagerung der radioaktiven Reststoffe werden die entsprechenden Strecken mit einem Abdichtungsbauwerk verschlossen. Dieses stellt mit dem umgebenden Steinsalz eine Barriere zwischen den radioaktiven Reststoffen und dem übrigen Grubengebäude dar. Die Barriere hat die Aufgabe, einen Fluid‐ sowie Gasaustausch und damit die Ausbreitung radioaktiver Strahlung zu unterbinden. In der ALZ ist die Permeabilität des Wirtsgesteins gegenüber dem intakten Wirtsgestein deutlich erhöht, weshalb die Möglichkeit eines Gas‐ oder Fluidtransports entlang des Abdichtungsbauwerks erhöht ist. Kriecht das Steinsalz nach Verschluss der Einlagerungskammer auf das Abdichtungsbauwerk auf, verheilen die dilatanten Schädigungen im Wirtsgestein, sodass die Permeabilität der ALZ reduziert wird. Die Verheilung der ALZ stellt daher einen wichtigen Prozess zur sicheren Endlagerung radioaktiver Reststoffe im Steinsalz dar. Die nachfolgenden numerischen Untersuchungen im FDM‐Programm FLAC3D ergaben, dass sowohl der Schädigungs‐ als auch der Verheilungsprozess durch den gewählten Streckenquerschnitt des Hohlraums maßgeblich beeinflusst werden.
Sulfur and phosphorus heteroatom‐containing compounds as corrosion inhibitors: An overview
Authors: Verma Chandrabhan , Verma Dakeshwar K. , Ebenso Eno E. , Quraishi Mumtaz A.
Published: September 2018

Use of organic compounds containing nitrogen (N), oxygen (O), sulfur (S), and phosphorus (P) heteroatoms in their molecular structures is one of the most effective, economic, and practical corrosion inhibitors. The effectiveness of the heteroatoms toward metallic corrosion inhibition follows the order: P > S > N > O. The metal‐inhibitor interactions involve the charge sharing between the heteroatoms and empty d‐orbitals of the surface metallic atoms; therefore, a heteroatom with lower electronegativity value is more potent to form strong bonding (charge sharing) with metallic surface as compared to more electronegative heteroatom. Literature study reveals that almost all corrosion inhibitors have either one or more heteroatoms in their molecular structures particularly in the form of polar functional groups, which enhance their adsorption tendency on metallic surface. Present review paper features the collection of some major works that have been published on metallic corrosion inhibition containing these P, S, O, and N heteroatoms. Since now, several review articles have been published describing the application of N and O atoms; however, the reviews on use of P and S heteroatoms are scare. Therefore, aim of the present article was to mainly describe the collection of corrosion inhibitors containing S and P heteroatoms.