bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient Room‐Temperature Methane Activation by the Closed‐Shell, Metal‐Free Cluster [OSiOH]+: A Novel Mechanistic Variant
Authors: Sun Xiaoyan , Zhou Shaodong , Schlangen Maria , Schwarz Helmut
Published: August 2016

The closed‐shell cluster ion [OSiOH]+ is generated in the gas phase and its reactivity towards the thermal activation of CH4 has been examined using Fourier transform‐ion cyclotron resonance (FT‐ICR) mass spectrometry in conjunction with state‐of‐the‐art quantum chemical calculations. Quite unexpectedly at room temperature, [OSiOH]+ efficiently mediates C−H bond activation, giving rise to [SiOH]+ and [SiOCH3]+ with the concomitant formation of methanol and water, respectively. Mechanistic aspects for this unprecedented reactivity pattern are presented, and the properties of the [OSiOH]+/CH4 couple are compared with those of the closed‐shell systems [OCOH]+/CH4 and [MgOH]+/CH4; the last two couples exhibit an entirely different reactivity scenario.
Regio‐ and Stereoselective Aliphatic–Aromatic Cross‐Benzoin Reaction: Enzymatic Divergent Catalysis
Authors: Beigi Maryam , Gauchenova Ekaterina , Walter Lydia , Waltzer Simon , Bonina Fabrizio , Stillger Thomas , Rother Dörte , Pohl Martina , Müller Michael
Published: August 2016

The catalytic asymmetric synthesis of chiral 2‐hydroxy ketones by using different thiamine diphosphate dependent enzymes, namely benzaldehyde lyase from Pseudomonas fluorescens (PfBAL), a variant of benzoylformate decarboxylase from Pseudomonas putida (PpBFD‐L461A), branched‐chain 2‐keto acid decarboxylase from Lactococcus lactis (LlKdcA) and a variant of pyruvate decarboxylase from Acetobacter pasteurianus (ApPDC‐E469G), was studied. Starting with the same set of substrates, substituted benzaldehydes in combination with different aliphatic aldehydes, PfBAL and PpBFD‐L461A selectively deliver the (R)‐ and (S)‐2‐hydroxy‐propiophenone derivatives, respectively. The (R)‐ and (S)‐phenylacetylcarbinol (1‐hydroxy‐1‐phenylacetone) derivatives are accessible in a similar way using LlKdcA and ApPDC‐E469G, respectively. In many cases excellent stereochemical purities (>98 % enantiomeric excess) could be achieved. Hence, the regio‐ and stereochemistry of the product in the asymmetric aliphatic–aromatic cross‐benzoin reaction can be controlled solely by choice of the appropriate enzyme or enzyme variant.
Mechanistic Insight into Heptosyltransferase Inhibition by using Kdo Multivalent Glycoclusters
Authors: Tikad Abdellatif , Fu Huixiao , Sevrain Charlotte M. , Laurent Sophie , Nierengarten Jean‐François , Vincent Stéphane P.
Published: August 2016

The synthesis of unprecedented multimeric Kdo glycoclusters based on fullerene and calix[4]arene central scaffolds is reported. The compounds were used to study the mechanism and scope of multivalent glycosyltransferase inhibition. Multimeric mannosides based on porphyrin and pillar[5]arenes were also generated in a controlled manner. Twelve glycoclusters and their monomeric ligands were thus assayed against heptosyltransferase WaaC, which is an important bacterial glycosyltransferase that is involved in lipopolysaccharide biosynthesis. It was first found that all the multimers interact solely with the acceptor binding site of the enzyme even when the multimeric ligands mimic the heptose donor. Second, the novel Kdo glycofullerenes displayed very potent inhibition (Ki=0.14 μm for the best inhibitor); an inhibition level rarely observed with glycosyltransferases. Although the observed “multivalent effects” (i.e., the enhancement of affinity of a ligand when presented in a multimeric fashion) were in general modest, a dramatic effect of the central scaffold on the inhibition level was evidenced: the fullerene and the porphyrin scaffolds being by far superior to the calix‐ and pillar‐arenes. We could also show, by dynamic light scattering analysis, that the best inhibitor had the propensity to form aggregates with the heptosyltransferase. This aggregative property may contribute to the global multivalent enzyme inhibition, but probably do not constitute the main origin of inhibition.
Ion‐Pair Complexation with Dibenzo[21]Crown‐7 and Dibenzo[24]Crown‐8 bis‐Urea Receptors
Authors: Mäkelä Toni , Kiesilä Anniina , Kalenius Elina , Rissanen Kari
Published: August 2016

Synthesis and ion‐pair complexation properties of novel ditopic bis‐urea receptors based on dibenzo[21]crown‐7 (R1) and dibenzo[24]crown‐8 (R2) scaffolds have been studied in the solid state, solution, and gas phase. In a 4:1 CDCl3/[D6]DMSO solution, both receptors clearly show positive heterotropic cooperativity toward halide anions when complexed with Rb+ or Cs+, with the halide affinity increasing in order I−<Br−<Cl−. In solution, the rubidium complexes of both receptors have higher halide affinities compared to the caesium complexes. However, Rb+ and Cs+ complexes of R2 show stronger affinities toward all the studied anions compared to the corresponding cationic complexes of R1. Similar selectivity of the receptors toward the studied ion pairs was also observed also in the gas phase by competition experiments with mass spectrometry. A total of eight crystal structures with different rubidium and caesium halides and oxyanions were obtained in addition to the crystal structure of R2⋅BaCl2. The selectivity observed in solution and in the gas phase is explainable by the conformational differences observed in the crystal structures of ion‐pair complexes with R1 and R2. In the solid state, R1 has an open conformation due to the asymmetric crown‐ether scaffold, whereas R2 has a compact, folded conformation. Computational studies of the ion‐pair complexes of R2 show that the interaction energies of the complexes increase in the order CsI<CsBr<CsCl<RbCl, supporting the selectivity observed in solution and the gas‐phase.
α‐Diamine Nickel Catalysts with Nonplanar Chelate Rings for Ethylene Polymerization
Authors: Liao Heng , Zhong Liu , Xiao Zefan , Zheng Ting , Gao Haiyang , Wu Qing
Published: August 2016

A series of novel α‐diamine nickel complexes, (ArNH‐C(Me)‐(Me)C‐NHAr)NiBr2, 1: Ar=2,6‐diisopropylphenyl, 2: Ar=2,6‐dimethylphenyl, 3: Ar=phenyl), have been synthesized and characterized. X‐ray crystallographic analysis showed that the coordination geometry of the α‐diamine nickel complexes is markedly different from conventional α‐diimine nickel complexes, and that the chelate ring (N‐C‐C‐N‐Ni) of the α‐diamine nickel complex is significantly distorted. The α‐diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α‐diimine nickel catalyst. Increasing the steric hindrance of the α‐diamine ligand by substitution of the o‐methyl groups with o‐isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1/Et2AlCl at 35 °C or 2/Et2AlCl at 0 °C. The bulky α‐diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure.
Conformationally Constrained Peptidomimetics as Inhibitors of the Protein Arginine Methyl Transferases
Authors: Knuhtsen Astrid , Legrand Baptiste , Van der Poorten Olivier , Amblard Muriel , Martinez Jean , Ballet Steven , Kristensen Jesper L. , Pedersen Daniel Sejer
Published: August 2016

Protein arginine N‐methyl transferases (PRMTs) belong to a family of enzymes that modulate the epigenetic code through modifications of histones. In the present study, peptides emerging from a phage display screening were modified in the search for PRMT inhibitors through substitution with non‐proteinogenic amino acids, N‐alkylation of the peptide backbone, and incorporation of constrained dipeptide mimics. One of the modified peptides (23) showed an increased inhibitory activity towards several PRMTs in the low μm range and the conformational preference of this peptide was investigated and compared with the original hit using circular dichroism and NMR spectroscopy. Introducing two constrained tryptophan residue mimics (l‐Aia) spaced by a single amino acid was found to induce a unique turn structure stabilized by a hydrogen bond and aromatic π‐stacking interaction between the two l‐Aia residues.
Carbon Dioxide Capture and Release by Anions with Solvent‐Dependent Behaviour: A Theoretical Study
Authors: Torrent‐Sucarrat Miquel , Varandas António J. C.
Published: August 2016

Recently, Clyburne and co‐workers [Science, 2014, 344, 75–78] reported the novel synthesis of the elusive cyanoformate anion, NCCO2−. The stability of this anion is dependent on the dielectric constant of the local environment (polarity‐switchable solvent): it is stable in low‐polarity media and unstable in high‐polarity solvents; hence, capturing and then releasing CO2. The possibility of extending such behaviour to other anions is explored herein. Specifically, the CO2 capture process is studied for 26 anions in the gas phase and 3 distinct solvents (water, tetrahydrofuran, and toluene) by using the polarisable continuum model. Calculations are performed with the M06‐2X and B3LYP‐D3 density functionals and the aug‐cc‐pVTZ basis set. The design of new CO2 complexes with the anion, which can be formed or destroyed on demand by changing the solvent, is possible; the results for the alkoxylate and thiolate anions are especially promising. The nature of the substituents connected to the atom that bonds to CO2 in the anion is crucial in modulating the relative stability of the products—a key point for reversibility in the CO2 capture process. A moderate interaction for the anion–CO2 adduct—about 10 kcal mol−1 relative free energy with respect to the isolated reactants in the gas phase—and a relevant effect in the dielectric constant of the local environment are also key ingredients to achieve solvent dependency.
Rational Design of Emissive NIR‐Absorbing Chromophores: RhIII Porphyrin‐Aza‐BODIPY Conjugates with Orthogonal Metal–Carbon Bonds
Authors: Zhou Jinfeng , Gai Lizhi , Zhou Zhikuan , Yang Wu , Mack John , Xu Kejing , Zhao Jianzhang , Zhao Yue , Qiu Hailin , Chan Kin Shing , Shen Zhen
Published: August 2016

The facile synthesis of Group 9 RhIII porphyrin‐aza‐BODIPY conjugates that are linked through an orthogonal Rh−C(aryl) bond is reported. The conjugates combine the advantages of the near‐IR (NIR) absorption and intense fluorescence of aza‐BODIPY dyes with the long‐lived triplet states of transition metal rhodium porphyrins. Only one emission peak centered at about 720 nm is observed, irrespective of the excitation wavelength, demonstrating that the conjugates act as unique molecules rather than as dyads. The generation of a locally excited (LE) state with intramolecular charge‐transfer (ICT) character has been demonstrated by solvatochromic effects in the photophysical properties, singlet oxygen quantum yields in polar solvents, and by the results of density functional theory (DFT) calculations. In nonpolar solvents, the RhIII conjugates exhibit strong aza‐BODIPY‐centered fluorescence at around 720 nm (ΦF=17–34 %), and negligible singlet oxygen generation. In polar solvents, enhancements of the singlet‐oxygen quantum yield (ΦΔ=19–27 %, λex=690 nm) have been observed. Nanosecond pulsed time‐resolved absorption spectroscopy confirms that relatively long‐lived triplet excited states are formed. The synthetic methodology outlined herein provides a useful strategy for the assembly of functional materials that are highly desirable for a wide range of applications in material science and biomedical fields.
Desymmetrizing Electron‐Deficient Diboranes(4): Diverse Products and Their Reactivity
Authors: Arnold Nicole , Braunschweig Holger , Dewhurst Rian D. , Hupp Florian , Radacki Krzysztof , Trumpp Alexandra
Published: August 2016

A comprehensive study of the reactivity of Lewis bases with dihalodiboranes(4) is presented. Diaryldihalodiboranes provide rearranged monoadducts when treated with cyclic (alkyl)(amino)carbenes, but halide‐bridged adducts when treated with a range of pyridyl bases. Alternatively, the combination of diaminodihalodiboranes with strong carbene donors leads to boraborenium salts. The reduction and halide‐abstraction reactivity of these adducts was also explored, leading to intramolecular C−H activation and the first 1,2‐bis(borenium) dication.
Large Easy‐Plane Magnetic Anisotropy in a Three‐Coordinate Cobalt(II) Complex [Li(THF)4][Co(NPh2)3]
Authors: Deng Yi‐Fei , Wang Zhenxing , Ouyang Zhong‐Wen , Yin Bing , Zheng Zhiping , Zheng Yan‐Zhen
Published: August 2016

Magnetic anisotropy is the key element in the construction of single‐ion magnets, a kind of nanomagnets for high‐density information storage. This works describes an unusual large easy‐plane magnetic anisotropy (with a zero‐field splitting parameter D of +40.2 cm−1), mainly arising from the second‐order spin‐orbit coupling effect in a trigonal‐planar CoII complex [Li(THF)4][Co(NPh2)3], revealed by combined studies of magnetism, high frequency/field electron paramagnetic resonance spectroscopy, and ab initio calculations. Meanwhile, the field‐induced slow magnetic relaxation in this complex was mainly attributed to the Raman process.
Katalytische Methanisierung von Kohlenstoffdioxid
Authors: Ghaib Karim , Nitz Korbinian , Ben‐Fares Fatima‐Zahrae
Published: August 2016

Power‐to‐Methane ist ein technisch realisierbares Verfahren, das große Mengen an elektrischer Energie langfristig speichern kann. Das Produktgas des Verfahrens kann in das Erdgasnetz eingespeist oder als Kraftstoff verwendet werden. Ein wesentlicher Teil der Prozesskette ist die katalytische Methanisierung von Kohlenstoffdioxid. Bei dem Methanisierungsprozess werden Kohlenstoffdioxid und Wasserstoff zu Methan und Wasserdampf umgesetzt. Kohlenstoffdioxid kann aus industriellen Prozessen, Umgebungsluft oder Biogasanlagen gewonnen werden. Wesentliche Grundlagen und Verfahrensentwicklungen der Methanisierung von Kohlenstoffdioxid werden in diesem Beitrag vorgestellt.
A multiparametric model‐based optimization and control approach to anaesthesia
Authors: Naşcu Ioana , Pistikopoulos Efstratios N.
Published: August 2016

In this work we present PAROC, an integrated framework software platform for the development of explicit model predictive controllers, and we apply it to the intravenous anaesthesia process. First, we overview the main features of PAROC, including high‐fidelity modelling, state‐of‐the‐art multiparametric optimization techniques, explicit/multiparametric model predictive control strategies, and a closed loop validation step. We then apply PAROC to the anaesthesia process, in particular for the development of explicit/multiparametric model predictive controllers for the induction and maintenance phases of intravenous anaesthesia validated on a set of 12 patients.
The changing landscape of papillary thyroid cancer: Epidemiology, management, and the implications for patients
Authors: Lubitz Carrie C. , Sosa Julie A.
Published: August 2016

The incidence of thyroid cancer has tripled over the past 3 decades, with the vast majority of the increase noted to be among small, indolent papillary thyroid carcinomas. Substantial overdiagnosis and potential overtreatment have led to a shift in clinical practice toward less aggressive approaches and a focus on improved risk stratification. This shift in practice may be associated with recent evidence suggesting that the increase in the incidence of thyroid cancer is slowing. Because patients are often young when they are diagnosed with thyroid cancer and because there is excellent long‐term, disease‐specific survival, there is an ever‐growing population of survivors of thyroid cancer in the United States who accumulate substantial associated health care costs as they undergo surveillance and/or remedial treatment. Survivors of thyroid cancer can experience significant detriments to their quality of life and endure financial hardship. Future research should focus on the appropriateness of treatment as well as the financial and quality‐of‐life effects of thyroid cancer survivorship. Cancer 2016;122:3754–3759. © 2016 American Cancer Society.
Design methodology for workload‐aware loop scheduling strategies based on genetic algorithm and simulation
Authors: Penna Pedro H. , Castro Márcio , Freitas Henrique C. , Broquedis François , Méhaut Jean‐François
Published: August 2016

In high‐performance computing, the application's workload must be evenly balanced among threads to deliver cutting‐edge performance and scalability. In OpenMP, the load balancing problem arises when scheduling loop iterations to threads. In this context, several scheduling strategies have been proposed, but they do not take into account the input workload of the application and thus turn out to be suboptimal. In this work, we introduce a design methodology to propose, study, and assess the performance of workload‐aware loop scheduling strategies. In this methodology, a genetic algorithm is employed to explore the state space solution of the problem itself and to guide the design of new loop scheduling strategies, and a simulator is used to evaluate their performance. As a proof of concept, we show how the proposed methodology was used to propose and study a new workload‐aware loop scheduling strategy named smart round‐robin (SRR). We implemented this strategy into GNU Compiler Collection's OpenMP runtime. We carry out several experiments to validate the simulator and to evaluate the performance of SRR. Our experimental results show that SRR may deliver up to 37.89% and 14.10% better performance than OpenMP's dynamic loop scheduling strategy in the simulated environment and in a real‐world application kernel, respectively. Copyright © 2016 John Wiley & Sons, Ltd.
Highly Twisted Isomers of Triphenylacrylonitrile Derivatives with High Emission Efficiency and Mechanochromic Behavior
Authors: Li Sijun , Sun Jingwei , Qile Moge , Cao Feng , Zhang Yujian , Song Qingbao
Published: August 2016

Two novel triphenylacrylonitrile derivatives (TPAN‐C2 and TPAN‐C3) with highly twisted conformations have been successfully prepared by Suzuki coupling reaction. Both of them show mechanochromic (MC) fluorescent behaviour and exhibit remarkable fluorescence redshifts from sky‐blue to light green upon fully grinding them. Interestingly, the ground powders recover their original states upon heating at 100 °C for 1 min or fuming with solvents vapour. Such intriguing MC properties of TPAN‐C2 and TPAN‐C3 are attributed to their phase transitions between crystalline and amorphous states, which are confirmed by powder X‐ray diffraction (XRD) data. Moreover, the behaviour of both TPAN‐C2 and TPAN‐C3 indicates that the aggregation‐induced emission (AIE) gives rise to rather high fluorescence quantum efficiencies (Φf) of 0.78 and 0.97, respectively. The influences of stacking mode and molecular conformation on MC properties and the high Φf of TPAN‐C2 and TPAN‐C3 are discussed.
A Vanadium(V) Oxide Nanorod Promoted Platinum/Reduced Graphene Oxide Electrocatalyst for Alcohol Oxidation under Acidic Conditions
Authors: Umeshbabu Ediga , Ranga Rao G.
Published: August 2016

A Pt‐V2O5/rGO ternary hybrid electrocatalyst was designed by using active vanadium(V) oxide (V2O5) nanorods and reduced graphene oxide (rGO) components. The V2O5 nanorods were synthesized by a simple polyol‐assisted solvothermal method and were incorporated uniformly onto rGO sheets by intermittent microwave heating. Subsequently, Pt nanoparticles (2–3 nm in size) were deposited over the V2O5/rGO composite by the conventional polyol reflux method. The electrocatalytic performance of the Pt‐V2O5/rGO ternary hybrid and bare Pt/rGO catalysts towards the oxidation of simple alcohols was evaluated in acidic media. The ternary hybrid catalyst exhibited higher electrocatalytic activity than bare Pt/rGO and also showed good stability. The higher electrocatalytic activity of the Pt‐V2O5/rGO ternary hybrid was attributed to a synergistic effect among the Pt, V2O5, and rGO components. In addition, oxygen‐containing species, such as OH groups, were generated on V2O5 at lower potentials. These groups were able to scavenge intermediate species such as COads on the Pt surfaces and helped to regenerate the active sites on the Pt surface more effectively for the routine alcohol oxidation reaction.
Direct PCR of Intact Bacteria (Colony PCR)
Authors: Woodman Michael E. , Savage Christina R. , Arnold William K. , Stevenson Brian
Published: August 2016

This protocol describes an efficient method for screening intact bacteria for the presence of desired DNA sequences using the polymerase chain reaction (PCR). This method is commonly referred to as colony PCR. © 2016 by John Wiley & Sons, Inc.
Burkholderia thailandensis: Growth and Laboratory Maintenance
Authors: Garcia Erin C. , Cotter Peggy A.
Published: August 2016

Burkholderia thailandensis is a nonpathogenic Gram‐negative bacterium found in tropical soils. Closely related to several human pathogens, its ease of genetic manipulation, rapid growth in the laboratory, and low virulence make B. thailandensis a commonly used model organism. This unit describes the fundamental protocols for in vitro growth and maintenance of B. thailandensis in the laboratory. © 2016 by John Wiley & Sons, Inc.
Impact of Precursor Compositions on the Structural and Photovoltaic Properties of Spray‐Deposited Cu2ZnSnS4 Thin Films
Authors: Nguyen Thi Hiep , Fujikawa Shotaro , Harada Takashi , Chantana Jakapan , Minemoto Takashi , Nakanishi Shuji , Ikeda Shigeru
Published: August 2016

Pure sulfide Cu2ZnSnS4 thin films were fabricated on Mo‐coated glass substrates by facile spray deposition of aqueous precursor solutions containing Cu(NO3)2, Zn(NO3)2, Sn(CH3SO3)2, and thiourea followed by annealing at 600 °C. When a precursor solution containing a stoichiometric composition of Cu, Zn, and Sn was used, the resulting Cu2ZnSnS4 thin film contained a Cu2−xS impurity phase owing to the evaporation of Sn components during the annealing process. The Cu2−xS impurity in the Cu2ZnSnS4 thin film was removed by reducing the concentration of Cu in the precursor solution. This resulted in an improvement of the structural features (i.e., grain sizes and compactness) as well as the electric properties such as acceptor densities, the nature of the acceptor defects, and carrier lifetimes. A solar cell based on the Cu2ZnSnS4 film with an empirically optimal composition showed conversion efficiency of 8.1 %. The value achieved was one of the best efficiencies of Cu2ZnSnS4‐based cells derived from a non‐vacuum process.
Electrochemically Driven Deactivation and Recovery in PrBaCo2O5+δ Oxygen Electrodes for Reversible Solid Oxide Fuel Cells
Authors: Zhu Lin , Wei Bo , Wang Zhihong , Chen Kongfa , Zhang Haiwu , Zhang Yaohui , Huang Xiqiang , Lü Zhe
Published: August 2016

The understanding of surface chemistry changes on oxygen electrodes is critical for the development of reversible solid oxide fuel cell (RSOFC). Here, we report for the first time that the electrochemical potentials can drastically affect the surface composition and hence the electrochemical activity and stability of PrBaCo2O5+δ (PBCO) electrodes. Anodic polarization degrades the activity of the PBCO electrode, whereas the cathodic bias could recover its performance. Alternating anodic/cathodic polarization for 180 h confirms this behavior. Microstructure and chemical analysis clearly show that anodic bias leads to the accumulation and segregation of insulating nanosized BaO on the electrode surface, whereas cathodic polarization depletes the surface species. Therefore, a mechanism based on the segregation and incorporation of BaO species under electrochemical potentials is considered to be responsible for the observed deactivation and recovery process, respectively.
A flow cytometry‐based method for a high‐throughput analysis of drug‐stabilized topoisomerase II cleavage complexes in human cells
Authors: de Campos‐Nebel Marcelo , Palmitelli Micaela , González‐Cid Marcela
Published: August 2016

Topoisomerase II (Top2) is an important target for anticancer therapy. A variety of drugs that poison Top2, including several epipodophyllotoxins, anthracyclines, and anthracenediones, are widely used in the clinic for both hematologic and solid tumors. The poisoning of Top2 involves the formation of a reaction intermediate Top2‐DNA, termed Top2 cleavage complex (Top2cc), which is persistent in the presence of the drug and involves a 5′ end of DNA covalently bound to a tyrosine from the enzyme through a phosphodiester group. Drug‐induced Top2cc leads to Top2 linked‐DNA breaks which are the major responsible for their cytotoxicity. While biochemical detection is very laborious, quantification of drug‐induced Top2cc by immunofluorescence‐based microscopy techniques is time consuming and requires extensive image segmentation for the analysis of a small population of cells. Here, we developed a flow cytometry‐based method for the analysis of drug‐induced Top2cc. This method allows a rapid analysis of a high number of cells in their cell cycle phase context. Moreover, it can be applied to almost any human cell type, including clinical samples. The methodology is useful for a high‐throughput analysis of drugs that poison Top2, allowing not just the discrimination of the Top2 isoform that is targeted but also to track its removal. © 2016 International Society for Advancement of Cytometry
Analysis of red blood cells’ dynamic status in a simulated blood circulation system using an ultrahigh‐speed simultaneous framing optical electronic camera
Authors: Zhang Qiang , Li Zeren , Zhao Shuming , Wen Weifeng , Chang Lihua , Yu Helian , Jiang Tianlun
Published: August 2016

Alterations in the morphologic and mechanical properties of red blood cells (RBCs) are considered direct indicators of blood quality. Current measures of characterizing these properties in vivo are limited by the complicated hemodynamic environment. To better evaluate the quality of fresh and stored blood, a new research platform was constructed to evaluate the hemodynamic characteristics of RBCs. The research platform consists mostly of a microfluidic chip, microscope, and ultrahigh‐speed simultaneous framing optical electronic camera (USFOEC). The microfluidic chip was designed to simplify the complicated hemodynamic environment. The RBCs were diluted in erythrocyte preservative fluid and infused into the microfluidic channels. After approximately 600× magnification of using the microscope and camera, the RBCs’ dynamic images were captured by the USFOEC. Eight sequential and blur‐free images were simultaneously captured by the USFOEC system. Results showed that RBC deformation changed with flow velocity and stored RBCs were less sensitive to deformation (Kfresh < Kstored). The frozen‐stored RBCs were better able to sustain hydrodynamic stress (DI49day = 0.128 vs. DIfrozen = 0.118) than cold‐stored RBCs but more sensitive to variations in flow speed (K49day = 1626.2 vs. Kfrozen = 1318.2). Results showed that the stored RBCs had worse deformability than fresh RBCs, but frozen‐stored RBCs may incur less damage during storage than those stored at merely cold temperatures. This USFOEC imaging system can serve as a platform for direct observation of cell morphological and mechanical properties in a medium similar to a physiologic environment. © 2016 International Society for Advancement of Cytometry
Development of a Cluster Burst Pulse Generator Based on a SOS Diode for Medical Applications
Authors: MINAMITANI YASUSHI , TOYOOKA TAKASHI
Published: August 2016

This work focuses on the design of a compact high‐power pulsed electromagnetic wave generator using a nanosecond pulsed power generator for the cancer treatment. In the previous study, since the output voltage waveform of the pulsed power generator was damping oscillation, the duration of the burst pulse was under 100 ns. So the generator uses a magnetic switch instead of the gap switch and uses a SOS diode with current cutoff time of nanoseconds. The cluster pulse has six burst pulses that are repeated at 2 Mpps. The frequency of the burst pulse is 50 MHz. The peak output voltage is 7.5 kV.
Low‐Temperature Formation of NiSi2 Phase in Ni/Si System
Authors: NOYA ATSUSHI , TAKEYAMA MAYUMI B.
Published: August 2016

The silicide phase formation is examined in the Ni/Si system. The multiphase of NiSi and NiSi2 is confirmed in a specimen, in which a 30‐mm‐thick Ni film is sputter‐deposited on Si(100) at 350 °C and subsequently annealed at 400 °C for 1 h. This is interpreted that the NiSi and NiSi2 phases nucleate from the amorphous alloys, as a super‐cooled melt, at a composition corresponding to those of eutectic points in different composition, which appear in the intermixed Ni–Si alloy layer with a Ni concentration gradient owing to intermixing between Ni and Si at the interface. To confirm this idea, we performed Ni deposition on a 350 °C‐heated Si substrate with a thin SiO2 layer. The results show the direct formation of NiSi2 in a nonuniform fashion. This is because the thin SiO2 layer suppresses Ni diffusion into Si, resulting in the formation of a Ni–Si alloy with a Si‐rich composition, from which NiSi2 nucleates at a low temperature. We can demonstrate that the high‐temperature phase of NiSi2 nucleates under kinetic constraints from an amorphous alloy with a suitable composition.
Twin‐Probe Atomic Force Microscopy with Optical Beam Deflection Using Vertically Incident Lasers by Two Beam Splitter
Authors: SATOH NOBUO , TSUNEMI EIKA , KOBAYASHI KEI , KOMATSUBARA TAKASHI , HIGUCHI SEIJI , MATSUSHIGE KAZUMI , YAMADA HIROFUMI
Published: August 2016

We developed a twin‐probe atomic force microscopy (AFM) system using Si cantilever‐probes. The system utilizes the optical beam deflection method in order to detect the deflection of each cantilever‐probe mounted on each tube‐type actuator. The cantilever‐probes mounted on each actuator are able to realize independent control of the probe positions, which are attached to manual sliders. A sensitivity 90 fm/or less is achieved for the displacement sensor activity for the two cantilever‐probes. We succeeded in the simultaneous observation of a topographic image in the state in which they approached each other to within 40 μm.
Two‐Step Synthetic Route toward Asymmetric and Symmetric Boron Dipyrromethenes: Synthesis, Optical Properties, and Electrochemistry
Authors: Swavey Shawn , Coladipietro Michael , Burbayea Aliah , Krause Jeanette A.
Published: August 2016

A two‐step synthetic route toward BODIPY dyes is accomplished by reaction of the readily available naphtho[1,2‐c]pyrrole with various aldehydes followed by coordination of BF2. Synthesis of the dipyrromethene is achieved by simply heating the pyrrole and aldehyde at moderate temperatures for less than 30 min. In addition to the absence of solvent this reaction does not require an acid catalyst or an oxidizing agent to achieve the dipyrromethene. Investigation of various aldehydes by this method suggests that the choice of aldehyde plays a role in the formation of either symmetric or asymmetric BODIPYs. The dyes have exceptionally high molar absorptivities (> 100000 m–1 cm–1) in the far visible region of the electromagnetic spectrum with intense emission and high quantum efficiency.
Beneficial Effects of Electrochemistry in Cross‐Coupling Reactions: Electroreductive Synthesis of 4‐Aryl‐ or 4‐Heteroaryl‐6‐pyrrolylpyrimidines
Authors: Sengmany Stéphane , Vasseur Stéphane , Lajnef Abdelmoumen , Le Gall Erwan , Léonel Eric
Published: August 2016

The rarely described 4‐(hetero)aryl‐6‐pyrrolylpyrimidines are prepared by electroreductive nickel‐catalysed cross‐coupling reactions between aryl halides and chloropyrimidines. Inherent predictable issues of such metal‐catalysed reactions that involve or produce highly nitrogenated compounds – like catalyst poisoning – are tackled by the process described in this paper. The relevance of the strategy is validated by a thorough comparison of the results obtained under electrochemical conditions with those obtained under classical Suzuki–Miyaura conditions.
Library Screening in Aqueous Media To Develop a Highly Active Peptide Catalyst for Enantioselective Michael Addition of a Malonate
Authors: Akagawa Kengo , Iwasaki Yumika , Kudo Kazuaki
Published: August 2016

Screenings of peptide libraries with N‐terminal l‐ or d‐proline were performed under aqueous conditions to obtain capable catalysts for the asymmetric Michael addition of a malonate. From a d‐prolyl peptide library, a consensus sequence, d‐Pro‐d‐Pro‐X‐Trp‐X3, was found, and the peptide possessing lysine in this framework showed good reactivity and enantioselectivity. The presence of the tryptophan residue at the fourth position was essential and replacing it with a pyrenylalanine residue further improved the catalytic ability. With an optimum peptide, the reaction could be promoted efficiently in aqueous media at a low catalyst loading.
Flavonolignan Conjugates as DNA‐binding Ligands and Topoisomerase I Inhibitors: Electrochemical and Electrophoretic Approaches
Authors: Zatloukalová Martina , Vavříková Eva , Pontinha Ana Dora Rodrigues , Coufal Jan , Křen Vladimír , Fojta Miroslav , Ulrichová Jitka , Oliveira‐Brett Ana Maria , Vacek Jan
Published: August 2016

In this work, the electrochemical behavior of flavonolignan silybin (SB) and 2,3‐dehydrosilybin (DHSB) and their respective conjugates SB‐SB and DHSB‐DHSB were studied using voltammetric techniques at a glassy carbon electrode. The redox mechanism of SB and its conjugate occurs in two oxidation steps where the hydroxy groups of the guaiacyl and resorcinol moiety are involved. DHSB and its conjugate are oxidized in three subsequent steps. The enol group in DHSB and DHSB‐DHSB is involved in the additional oxidation step, due to the enhanced electron‐donor capacity and reactivity of the 2,3‐dehydroderivatives compared to the parent flavonolignan molecule. The developed voltammetric methods were subsequently used for the analysis of flavonolignan‐DNA interactions. Comparative experiments revealed a remarkable binding affinity between the flavonolignan homoconjugates and double‐helical calf thymus DNA, compared to the corresponding monomeric compounds. In addition, biochemical and electrophoretic experiments revealed the flavonolignan‐dsDNA binding not to involve intercalation as the major interaction mode. The same experiments have also shown that both flavonolignan conjugates inhibit the activity of type I topoisomerase, which is a DNA topology (superhelicity) modulating enzyme. We suppose that our results could be used in further studies focused on DNA flavonolignan binding and DNA processing protein inhibition by flavonolignan 2,3‐dehydroderivatives.
Selective Detection of Dopamine in the Presence of Ascorbic and Uric Acids through its Covalent Immobilization on Gold Mercaptopropionic Acid Self‐assembled Monolayer
Authors: Karimi Shervedani Reza , Bahrani Sonia , Samiei Foroushani Marzieh , Momenbeik Fariborz
Published: August 2016

A simple, stable and recoverable sensor is developed based on selective and covalent immobilization of dopamine (DA) on the gold (Au) electrode modified by mercaptopropionic acid (MPA) self‐assembled monolayers and then, activated with 1‐ethyl‐3(3‐(dimethylamino)propyl)‐carbodiimide hydrochloride (EDC)/n‐hydroxysuccinimide (NHS) activators. Fabrication steps and analytical application of this modified electrode toward quantitative determination of DA in the presence of ascorbic and uric acids are verified by cyclic and differential pulse voltammetry (CV and DPV) methods in the absence of any redox probe. The oxidation peak current of adsorbed DA changed linearly with the concentration of DA in the range of 0.5 to 600.0 μM with a detection limit of 0.064 μM, and the RSDs varied from 1.4 to 3.5 % for n=3 at each point. Finally, the fabricated sensor is used successfully for electroanalytical determination of DA in human blood plasma and pharmaceutical injection real samples.
Ionic Liquid and Nitrogen Doped Carbon Nanotubes Composite Material for Sensitive and Selective Detection of Dopamine
Authors: Joshi Anju , Chavan Santosh N. , Mandal Debaprasad , Nagaiah Tharamani C.
Published: August 2016

The composites of IL (BmimBF4) and various nitrogen doped carbon nanotubes (NCNTs) synthesized by post treatment under NH3 at different temperatures have been explored as a novel composite material for the sensitive and selective detection of dopamine (DA). The electrocatalytic activity of these various NCNTs‐IL composites for the detection of DA was examined by voltammetric and rotating disc electrode (RDE) measurements. These novel NCNTs‐IL composites exhibit a superior sensitivity and selectivity towards the oxidation of DA in presence of higher concentration of AA (500 µM). A linear response between the peak current and the concentration of DA was found to be in the concentration range of 0.001 µM–40 µM and 0.001 µM–10 µM for individual and even in presence of 500 µM of AA respectively.
Potential‐modulated Electrocapacitive Properties of Soft Microstructured Polypyrrole
Authors: Vagin Mikhail Yu. , Wannapob Rodtichoti , Liu Yu , Mak Wing Cheung
Published: August 2016

Microstructured materials are becoming important for high performance electrochemical device especially for energy storage due to their advantageous diffusion and flux properties. Utilizing a rationally designed hollow structured polypyrrole microparticles (PPyMPs) with controllable wall thicknesses of ∼110 to 340 nm, we observed a significant morphological effect on electrocapacitive kinetics of the PPyMPs modulated by the voltammetric potential window and scan rate. The thin‐hollow architecture of PPyMPs revealed significant enhancement of charge storage performance (up to 447 %), high retention at high scan rate and faster charge/discharge kinetics compared to the thick‐hollow PPyMPs due to the larger accessible surface area and decrease of diffusion length. These findings demonstrated the electrocapacitive kinetics performance of microstructured soft materials related to morphological effect modulated by operational conditions. Our study provides new insight on electrochemistry of soft electrode materials with controlled nanostructured morphology for understanding the mechanism of charge insertion and mass diffusion for the future development of high performance porous electrode material.
A Simple Flow Amperometric Electrochemical Biosensor Based on Chitosan Scaffolds and Gold Nanowires Modified on a Glassy Carbon Electrode for Detection of Glutamate in Food Products
Authors: Kitikul Jiraporn , Satienperakul Sakchai , Preechaworapun Anchana , Pookmanee Pusit , Tangkuaram Tanin
Published: August 2016

A glutamate biosensor based on cross‐linked glutamate oxidase with chitosan (CHIT) on a carbon nanotube (CNT)‐modified gold nanowire (AuNW) was constructed and applied in a flow injection analysis (FIA) system. The AuNW was produced using an alumina template membrane and characterized using scanning electron microscopy (SEM) with a 120‐nm diameter. The CHIT cross‐linked CNT slurry was mixed with AuNW and cast on the surface of a glassy carbon electrode (GCE), followed by immobilization with the glutamate oxidase. Optimization of the experimental parameters, including the applied potential, enzyme loading, flow rate, type of buffer and pH, resulted in values of 0.7 V, 30 μL, 1.0 mL min−1, phosphate buffer, and pH 7.4, respectively. The analytical working curve was linear in the ranges from 10 to 100 (R2=0.9981) and 100 to 20,000 μM glutamate (R2=0.9821) with a low detection limit of 1.2 μM (S/N=3). A glutamate biosensor with an FIA system was used to determine glutamate in samples of Thai commercial food products.
Oxygen Electroreduction versus Bioelectroreduction: Direct Electron Transfer Approach
Authors: Shleev Sergey , Andoralov Viktor , Pankratov Dmitry , Falk Magnus , Aleksejeva Olga , Blum Zoltan
Published: August 2016

Being inspired by a very recent review entitled: “Electrocatalysis and bioelectrocatalysis – Distinction without a difference” and following the general approach employed by Prof. Dr. Schuhmann, in the current work we point to the similarities and differences between oxygen electroreduction and bioelectroreduction processes. To additionally distinct our paper from the recent review we touch on different bioelements, such as redox proteins and living cells, but we still keep a special emphasis on oxidoreductases, biocatalysts par excellence. Moreover, we also exclusively focus on oxygen electroreduction based on direct electron transfer reactions. On the one hand, we corroborate the previously made conclusion regarding intrinsically high activity of the active sites of biological catalysts, especially redox enzymes, which results in mass transfer and heterogeneous electron transfer limited currents from oxygen reducing bioelectrodes. On the other hand, we disagree with the statements regarding the exceptionality of precious metal catalysts, and the notion of a huge trade‐off between high activity and stability of non‐precious metal catalysts and bioelements. We show that the activity and stability of noble metal based cathodes is very far from perfect, especially when these electrodes operate in complex electrolytes, such as physiological fluids, e.g. human blood.
Electrochemical Reduction and Intramolecular Electron Communication of Nitro Substituted Thiacalix[4]arenes
Authors: Liška Alan , Lhoták Pavel , Ludvík Jiří
Published: August 2016

This contribution is focused on the question, what is the influence of the sulphur bridging units in thiacalix[4]arenes on their electrochemical response. For this reason, two series of oligonitro thiacalix[4]arenes were investigated, where the “classic” methylene groups are replaced by the sulphur bridge. The reduction pattern of p‐tetranitro‐1,3‐alt‐thiacalix[4]arenes (2+2+12 electrons) resembles that of the p‐tetranitro‐cone‐calix[4]arenes and refers to the presence of two different couples of non‐interacting nitro groups in the molecule. In contrast, m‐oligonitro‐1,3‐alt‐thiacalix[4]arenes exhibit a mutual intramolecular communication between multiple redox centers (nitro groups) due to the combination of two circumstances: nitro groups in the m‐positions towards the lower rim are in fact in para‐ and/or ortho position towards the thia‐bridges enabling thus 1,2‐ and 1,4‐quinoid resonance structure, and larger sulphur bridging atom forms two adjacent C‐S bonds, which are able to exhibit a hyperconjugative effect. In any case, the intramolecular electron communication takes place via the skeleton, not through space. Consequently, the substituent (inductive, mesomeric) and charge effects are observable, additive and partly quantifiable. Classic polarography proved to be the optimal technique for such investigations.
A Facile Synthesis of Cd(OH)2‐rGO Nanocomposites for the Practical Electrochemical Detection of Acetaminophen
Authors: Sakthivel Mani , Sivakumar Mani , Chen Shen‐Ming , Hou Yu‐Shen , Veeramani Vediyappan , Madhu Rajesh , Miyamoto Nobuyoshi
Published: August 2016

Herein, we report the preparation of nanorods‐like Cd(OH)2‐rGO nanocomposites via using a simple co‐precipitation method. The as‐prepared Cd(OH)2‐rGO materials were characterized by a variety of analytical and spectroscopy techniques such as scanning electron microscope (SEM), elemental analysis (EDX), X‐ray diffraction (XRD), and Raman spectroscopy. Interestingly, Cd(OH)2‐rGO modified glassy carbon electrode (GCE) employed for the electrochemical detection of acetaminophen (AP) sensor for first time by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The AP sensor exhibited an ultra‐high sensitivity of 24.452 µA µM−1 cm−2 and a low detection limit 0.08 µM with wider linear ranges from 0.1 to 102 µM. Notably, the obtained analytical parameters of the AP sensor using nanorods‐like Cd(OH)2‐rGO modified GCE is superior than several rGO based nanocomposites suggesting more suitable for several practical pharmaceutical applications.
A mobility shift assay for DNA detection using nanochannel gradient electrophoresis
Authors: Startsev Michael A. , Ostrowski Martin , Goldys Ewa M. , Inglis David W.
Published: August 2016

Conventional detection of pathogenic or other biological contamination relies on amplification of DNA using sequence‐specific primers. Recent work in nanofluidics has shown very high concentration enhancement of biomolecules with some degree of simultaneous separation. This work demonstrates the combination of these two approaches by selectively concentrating a mobility‐shifted hybridization product, potentially enabling rapid detection of rare DNA fragments such as highly specific 16S ribosomal DNA. We have performed conductivity gradient electrofocusing within nanofluidic channels and have shown concentration of hybridized peptide nucleic acids and DNA oligomers. We also show selectivity to single base‐pair mismatch on 18‐mer oligos. This approach may enable sensitive optical detection of small amounts of DNA.
Assessment of the Production of Value‐Added Chemical Compounds from Sewage Sludge Pyrolysis Liquids
Authors: Fonts Isabel , Navarro‐Puyuelo Andrea , Ruiz‐Gómez Nadia , Atienza‐Martínez María , Wisniewski Alberto , Gea Gloria
Published: August 2016

A procedure to analyze sewage sludge (SS) pyrolysis liquids based on solvent fractionation has been developed. Pyrolysis liquids are separated into three different fractions: heptane soluble (Hep‐sol), dichloromethane soluble (DCM‐sol), and hydrochloric acid soluble (HCl‐sol). Diverse techniques (GC‐MS, UPLC‐TOF‐MS) were employed to qualitatively and quantitatively analyze liquid fractions to assess the potential production of value‐added chemicals. Aliphatic hydrocarbons, aliphatic nitriles, and steroids were mostly separated in the Hep‐sol fraction, phenols and fatty acids in the DCM‐sol fraction, and carboxylic acids and amides in the HCl‐sol fraction. The largest production was obtained for ammonia (10–14 kg per tonne of SS) and α‐olefins (8–9 kg per tonne of SS). The potential production of some of these value‐added chemicals from SS pyrolysis liquid was compared with their current European production. In the case of α‐olefins, 16 % of their European production could be achieved by SS pyrolysis.
Ecotoxicological assessment of glyphosate-based herbicides: Effects on different organisms
Authors: de Brito Rodrigues Laís , de Oliveira Rhaul , Abe Flávia Renata , Brito Lara Barroso , Moura Diego Sousa , Valadares Marize Campos , Grisolia Cesar Koppe , de Oliveira Danielle Palma , de Oliveira Gisele Augusto Rodrigues
Published: August 2016

Glyphosate-based herbicides are the most commonly used worldwide because they are effective and relatively nontoxic to nontarget species. Unlimited and uncontrolled use of such pesticides can have serious consequences for human health and ecological balance. The present study evaluated the acute toxicity and genotoxicity of 2 glyphosate-based formulations, Roundup Original (Roundup) and Glyphosate AKB 480 (AKB), on different organisms: cucumber (Cucumis sativus), lettuce (Lactuca sativa), and tomato (Lycopersicon esculentum) seeds, and microcrustacean Artemia salina and zebrafish (Danio rerio) early life stages. For the germination endpoint, only L. esculentum presented significant sensitivity to AKB and L. sativa to Roundup, whereas both formulations significantly inhibited the root growth of all species tested. Both AKB and Roundup induced significant toxicity to A. salina; both are classified as category 3, which indicates a hazard for the aquatic environment, according to criteria of the Globally Harmonized Classification System. However, Roundup was more toxic than AKB, with 48-h median lethal concentration (LC50) values of 14.19 mg/L and 37.53 mg/L, respectively. For the embryo–larval toxicity test, Roundup proved more toxic than AKB for the mortality endpoint (96-h LC50 values of 10.17 mg/L and 27.13 mg/L, respectively), whereas for the hatching parameter, AKB was more toxic than Roundup. No significant genotoxicity to zebrafish larvae was found. We concluded that AKB and Roundup glyphosate-based formulations are phytotoxic and induce toxic effects in nontarget organisms such as A. salina and zebrafish early life stages. Environ Toxicol Chem 2017;36:1755–1763. © 2016 SETAC