bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of seasonality and anthropogenic impoundments on dissolved organic matter dynamics in the Klamath River (Oregon/California, USA)
Authors: Oliver Allison A. , Spencer Robert G. M. , Deas Michael L. , Dahlgren Randy A.
Published: July 2016

Rivers play a major role in the transport and processing of dissolved organic matter (DOM). Disturbances that impact DOM dynamics, such as river impoundments and flow regulation, have consequences for biogeochemical cycling and aquatic ecosystems. In this study we examined how river impoundments and hydrologic regulation impact DOM quantity and quality by tracking spatial and seasonal patterns of DOM in a large, regulated river (Klamath River, USA). Dissolved organic carbon (DOC) concentrations decreased downstream and longitudinal patterns in DOC load varied by season. Export of DOM (as DOC) was largely driven by river flow, while DOM composition was strongly influenced by impoundments. Seasonal algal blooms in upstream lentic reaches provided a steady source of algal DOM that was processed in downstream reaches. DOM at upstream sites had an average spectral slope ratio (SR) > 1, indicating algal‐derived material, but decreased downstream to an average SR < 1, more indicative of terrestrial‐derived material. The increasingly terrestrial nature of DOM exported from reservoirs likely reflects degraded algal material that becomes increasingly more recalcitrant with distance from upstream source and additional processing. As a result, DOM delivered to free‐flowing river reaches below impoundments was less variable in composition. Downstream of impoundments, tributary influences resulted in increasing contributions of terrestrial DOM from the surrounding watershed. Removal of the four lower dams on the Klamath River is scheduled to proceed in the next decade. These results suggest that management should consider the role of impoundments on altering DOM dynamics, particularly in the context of dam removal.
Multistate Resistive Switching Memory for Synaptic Memory Applications
Authors: Hota Mrinal K. , Hedhili Mohamed N. , Wehbe Nimer , McLachlan Martyn A. , Alshareef Husam N.
Published: July 2016

Reproducible low bias bipolar resistive switching memory in HfZnOx based memristors is reported. The modification of the concentration of oxygen vacancies in the ternary oxide film, which is facilitated by adding ZnO into HfO2, results in improved memory operation by the ternary oxide compared to the single binary oxides. A controlled multistate memory operation is achieved by controlling current compliance and RESET stop voltages. A high DC cyclic stability up to 400 cycles in the multistate memory performance is observed. Conventional synaptic operation in terms of potentiation, depression plasticity, and Ebbinghaus forgetting process are also studied. The memory mechanism is shown to originate from the migration of the oxygen vacancies and modulation of the interfacial layers.
Enantioselective Copper‐Catalyzed Propargylic Etherification of Propargylic Esters with Phenols Promoted by Inorganic Base Additives
Authors: Shao Long , Zhang De‐Yang , Wang Ya‐Hui , Hu Xiang‐Ping
Published: July 2016

An enantioselective copper‐catalyzed propargylic etherification of both aromatic and aliphatic propargylic esters with phenols has been developed, in which the employment of inorganic base additives, in particular cesium carbonate (Cs2CO3), was found to significantly promote not only the reactivity but also the enantioselectivity of the reaction. By using a structurally hindered chiral ketimine P,N,N‐ligand, a wide range of optically active propargylic ethers were prepared in high yields and with excellent enantioselectivities (up to 98% ee).

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What Consumers Are Looking for in Strawberries: Implications from Market Segmentation Analysis
Authors: Wang Jingjing , Yue Chengyan , Gallardo Karina , McCracken Vicki , Luby James , McFerson Jim
Published: July 2016

An online choice experiment was conducted to investigate U.S. consumer preferences for attributes of fresh market strawberry fruit. Using a latent class logit model, three different groups of consumers are identified: “Balanced Consumers,” “Experience Attribute Sensitive Consumers,” and “Search Attribute Sensitive Consumers.” This information on consumer segmentation can help the fresh market strawberry industry identify target markets, and provides valuable information to breeders, growers, and retailers to prioritize fruit attributes in their breeding, growing, or product sourcing decisions.
Moving evidence into practice: cost analysis and assessment of macaques’ sustained behavioral engagement with videogames and foraging devices
Authors: Bennett Allyson J. , Perkins Chaney M. , Tenpas Parker D. , Reinebach Alma L. , Pierre Peter J.
Published: July 2016

Environmental enrichment plans for captive nonhuman primates often include provision of foraging devices. The rationale for using foraging devices is to promote species‐typical activity patterns that encourage physical engagement and provide multi‐sensory stimulation. However, these devices have been shown to be ineffective at sustaining manipulation over long periods of time, and often produce minimal cognitive engagement. Here we use an evidence‐based approach to directly compare the amount of object‐directed behavior with a foraging device and a computer‐based videogame system. We recorded 11 adult male rhesus monkeys’ interactions with a foraging device and two tasks within a joystick videogame cognitive test battery. Both techniques successfully produced high levels of engagement during the initial 20 min of observation. After 1 hr the monkeys manipulated the foraging device significantly less than the joystick, F(2,10) = 43.93, P < 0.0001. Subsequent testing showed that the monkeys engaged in videogame play for the majority of a 5 hr period, provided that they received a 94 mg chow pellet upon successful completion of trials. Using a model approach, we developed previously as a basis for standardized cost:benefit analysis to inform facility decisions, we calculated the comprehensive cost of incorporating a videogame system as an enrichment strategy. The videogame system has a higher initial cost compared to widely‐used foraging devices, however, the ongoing labor and supply costs are relatively low. Our findings add to two decades of empirical studies by a number of laboratories that have demonstrated the successful use of videogame‐based systems to promote sustained non‐social cognitive engagement for macaques. The broader significance of the work lies in the application of a systematic approach to compare and contrast enrichment strategies and encourage evidence‐based decision making when choosing an enrichment strategy in a manner that promotes meaningful cognitive enrichment to the animals.
Beyond ‘Getting To Yes’: Using Mediator Insights To Facilitate Long‐Term Business Relationships
Authors: Stipanowich Thomas J.
Published: July 2016

[Mediation has the] capacity to reorient parties toward each other not by imposing rules on them, but by helping them to achieve a new and shared perception of their relationship, a perception that will redirect their attitudes and dispositions to each other. Lon L Fuller “Mediation: Its Form and Functions” 44 S. Cal. L. Rev. 305, 325 (1971).
Getting the Feel of Feelings
Authors: Creo Robert A.
Published: July 2016

Legal Positivism is based upon the concept that law consists of the enforceable commands of government, and does not depend on the validity of other criteria, such as normative or religious values, or natural law. The concept embraces the idea that natural law does not override government dictates enunciated in statutes, regulations, rules and court precedents.
Fragmentverknüpfung und ‐optimierung von Hemmstoffen der Aspartylprotease Endothiapepsin: Fragmentbasiertes Wirkstoffdesign beschleunigt durch dynamische kombinatorische Chemie
Authors: Mondal Milon , Radeva Nedyalka , Fanlo‐Virgós Hugo , Otto Sijbren , Klebe Gerhard , Hirsch Anna K. H.
Published: July 2016

Fragmentbasiertes Wirkstoffdesign (FBWD) führt zu pharmakologisch aktiven Substanzen für biologische Targets. Obschon es zahlreiche Beispiele für FBWD anhand von Fragmentwachstum und ‐optimierung gibt, wird die Verknüpfung von Fragmenten nur selten verwendet. Dynamische kombinatorische Chemie (DKC) ist zu einer erfolgreichen Strategie für die Identifizierung von Hits für biologische Targets herangewachsen. Wir berichten hier über die synergistische Kombination von Fragmentverknüpfung und DKC, um Inhibitoren der Aspartylprotease Endothiapepsin zu identifizieren. Aufbauend auf Röntgenkristallstrukturen von Endothiapepsin im Komplex mit Fragmenten haben wir eine Bibliothek von Bisacylhydrazonen entworfen und DKC benutzt, um potente Hemmstoffe des Enzyms zu identifizieren: Der stärkste Hemmstoff besitzt einen IC50‐Wert von 54 nm, was eine 240‐fache Steigerung der Affinität im Vergleich zu den Ausgangstreffern darstellt. Anschließend hat die Röntgenkristallographie den vorhergesagten Bindungsmodus bestätigt und somit die Effizienz der Kombination aus Fragmentverknüpfung und DKC als Strategie für die Identifizierung von Hits unterstrichen. Die Methode kann für eine Reihe biologischer Targets Anwendung finden und sollte das Potenzial haben, die Optimierung eines Hits zu einer Leitstruktur zu vereinfachen.
Detection of LacZ‐Positive Cells in Living Tissue with Single‐Cell Resolution
Authors: Doura Tomohiro , Kamiya Mako , Obata Fumiaki , Yamaguchi Yoshifumi , Hiyama Takeshi Y. , Matsuda Takashi , Fukamizu Akiyoshi , Noda Masaharu , Miura Masayuki , Urano Yasuteru
Published: July 2016

The LacZ gene, which encodes Escherichia coli β‐galactosidase, is widely used as a marker for cells with targeted gene expression or disruption. However, it has been difficult to detect lacZ‐positive cells in living organisms or tissues at single‐cell resolution, limiting the utility of existing lacZ reporters. Herein we present a newly developed fluorogenic β‐galactosidase substrate suitable for labeling live cells in culture, as well as in living tissues. This precisely functionalized fluorescent probe exhibited dramatic activation of fluorescence upon reaction with the enzyme, remained inside cells by anchoring itself to intracellular proteins, and provided single‐cell resolution. Neurons labeled with this probe preserved spontaneous firing, which was enhanced by application of ligands of receptors expressed in the cells, suggesting that this probe would be applicable to investigate functions of targeted cells in living tissues and organisms.
Precise Modulation of the Breathing Behavior and Pore Surface in Zr‐MOFs by Reversible Post‐Synthetic Variable‐Spacer Installation to Fine‐Tune the Expansion Magnitude and Sorption Properties
Authors: Chen Cheng‐Xia , Wei Zhangwen , Jiang Ji‐Jun , Fan Yan‐Zhong , Zheng Shao‐Ping , Cao Chen‐Chen , Li Yu‐Hao , Fenske Dieter , Su Cheng‐Yong
Published: July 2016

To combine flexibility and modifiability towards a more controllable complexity of MOFs, a post‐synthetic variable‐spacer installation (PVSI) strategy is used to implement kinetic installation/ uninstallation of secondary ligands into/from a robust yet flexible proto‐Zr‐MOF. This PVSI process features precise positioning of spacers with different length, size, number, and functionality, enabling accurate fixation of successive breathing stages and fine‐tuning of pore surface. It shows unprecedented synthetic tailorability to create complicated MOFs in a predictable way for property modification, for example, CO2 and R22 adsorption/separation, thermal/chemical stability, and extended breathing behavior.
Fragment Linking and Optimization of Inhibitors of the Aspartic Protease Endothiapepsin: Fragment‐Based Drug Design Facilitated by Dynamic Combinatorial Chemistry
Authors: Mondal Milon , Radeva Nedyalka , Fanlo‐Virgós Hugo , Otto Sijbren , Klebe Gerhard , Hirsch Anna K. H.
Published: July 2016

Fragment‐based drug design (FBDD) affords active compounds for biological targets. While there are numerous reports on FBDD by fragment growing/optimization, fragment linking has rarely been reported. Dynamic combinatorial chemistry (DCC) has become a powerful hit‐identification strategy for biological targets. We report the synergistic combination of fragment linking and DCC to identify inhibitors of the aspartic protease endothiapepsin. Based on X‐ray crystal structures of endothiapepsin in complex with fragments, we designed a library of bis‐acylhydrazones and used DCC to identify potent inhibitors. The most potent inhibitor exhibits an IC50 value of 54 nm, which represents a 240‐fold improvement in potency compared to the parent hits. Subsequent X‐ray crystallography validated the predicted binding mode, thus demonstrating the efficiency of the combination of fragment linking and DCC as a hit‐identification strategy. This approach could be applied to a range of biological targets, and holds the potential to facilitate hit‐to‐lead optimization.
Second‐Generation Non‐Covalent NAAA Inhibitors are Protective in a Model of Multiple Sclerosis
Authors: Migliore Marco , Pontis Silvia , Fuentes de Arriba Angel Luis , Realini Natalia , Torrente Esther , Armirotti Andrea , Romeo Elisa , Di Martino Simona , Russo Debora , Pizzirani Daniela , Summa Maria , Lanfranco Massimiliano , Ottonello Giuliana , Busquet Perrine , Jung Kwang‐Mook , Garcia‐Guzman Miguel , Heim Roger , Scarpelli Rita , Piomelli Daniele
Published: July 2016

Palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) are endogenous lipid mediators that suppress inflammation. Their actions are terminated by the intracellular cysteine amidase, N‐acylethanolamine acid amidase (NAAA). Even though NAAA may offer a new target for anti‐inflammatory therapy, the lipid‐like structures and reactive warheads of current NAAA inhibitors limit the use of these agents as oral drugs. A series of novel benzothiazole–piperazine derivatives that inhibit NAAA in a potent and selective manner by a non‐covalent mechanism are described. A prototype member of this class (8) displays high oral bioavailability, access to the central nervous system (CNS), and strong activity in a mouse model of multiple sclerosis (MS). This compound exemplifies a second generation of non‐covalent NAAA inhibitors that may be useful in the treatment of MS and other chronic CNS disorders.
Selective Synthesis of Partially Protected Nonsymmetric Biphenols by Reagent‐ and Metal‐Free Anodic Cross‐Coupling Reaction
Authors: Wiebe Anton , Schollmeyer Dieter , Dyballa Katrin M. , Franke Robert , Waldvogel Siegfried R.
Published: July 2016

The oxidative cross‐coupling of aromatic substrates without the necessity of leaving groups or catalysts is described. The selective formation of partially protected nonsymmetric 2,2′‐biphenols via electroorganic synthesis was accomplished with a high yield of isolated product. Since electric current is employed as the terminal oxidant, the reaction is reagent‐free; no reagent waste is generated as only electrons are involved. The reaction is conducted in an undivided cell, and is suitable for scale‐up and inherently safe. The implementation of O‐silyl‐protected phenols in this transformation results in both significantly enhanced yields and higher selectivity for the desired nonsymmetric 2,2′‐biphenols. The use of a bulky silyl group to block one hydroxyl moiety makes the final product less prone to oxidation. Furthermore, the partially silyl‐protected 2,2′‐biphenols are versatile building blocks that usually require tedious or low‐yielding synthetic pathways. Additionally, this strategy facilitates a large variety of new substrate combinations for oxidative cross‐coupling reactions.
Stereoselective β‐Mannosylation by Neighboring‐Group Participation
Authors: Elferink Hidde , Mensink Rens A. , White Paul B. , Boltje Thomas J.
Published: July 2016

The stereoselective synthesis of glycosidic bonds is the main challenge of oligosaccharide synthesis. Neighboring‐group participation (NGP) of C2 acyl substituents can be used to provide 1,2‐trans‐glycosides. Recently, the application of NGP has been extended to the preparation of 1,2‐cis‐glycosides with the advent of C2 chiral auxiliaries. However, this methodology has been strictly limited to the synthesis of 1,2‐cis‐gluco‐type sugars. Reported herein is the design and synthesis of novel mannosyl donors which provide 1,2‐cis‐mannosides by NGP of thioether auxiliaries. A key element in the design is the use of 1C4 locked mannuronic acid lactones to enable NGP of the C2 auxiliary. In addition to C2 participation a new mode of remote participation of the C4 benzyl group was identified and provides 1,2‐cis‐mannosides.
Highly Efficient Access to Both Geometric Isomers of Silyl Enol Ethers: Sequential 1,2‐Brook/Wittig Reactions
Authors: Matsuya Yuji , Wada Kentaro , Minato Daishiro , Sugimoto Kenji
Published: July 2016

Novel sequential 1,2‐Brook/Wittig reactions were developed for the preparation of silyl enol ethers. This method enables highly selective preparation of both geometric isomers of glyoxylate silyl enol ethers, using aldehydes (E‐selective) and tosylimines (Z‐selective) as a Wittig electrophile. The salt‐free conditions of this reaction system are likely to be advantageous for switching the selectivity. The optimal reaction conditions and generality of the reaction were investigated, and plausible explanations for the observed selectivity were also discussed.
Determination of the minimum sample size for a reliable strength measurement of talc‐filled polypropylene fibers
Authors: Nohut S. , Tascan M.
Published: July 2016

Accurate determination of mechanical properties plays an important role to comment on improvement in the mechanical properties of particle‐filled PP fibers. However, the existing standards are not totally suitable for reliable strength determination of particle‐filled PP fibers. In the framework of this study, microsized talc particle‐filled PP fibers were produced with different talc ratio and tensile strength measurements were performed with various gage lengths. Statistical Akaike Information Criterion analysis shows that strength distribution of talc‐filled PP fibers is best characterized by Weibull distribution function. It is reported that, the gage length has almost no influence of Weibull parameters of pure PP fibers while strong effects on Weibull parameters of talc‐filled PP fibers. It is shown that if the tensile strength of talc‐filled PP fibers is to be measured, at least 50 samples, which is more than value suggested by existing standard, should be used for a reliable determination of Weibull parameters. Therefore, the main aim of this study is to question the feasibility of minimum sample size suggested by the existing ASTM D3822 standard for reliable strength measurement of talc filled PP fibers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44083.
Functionalized galactoglucomannan‐based hydrogels for the removal of metal cations from aqueous solutions
Authors: Elgueta Elizabeth , Sánchez Julio , Dax Daniel , Xu Chunlin , Willför Stefan , Rivas Bernabé L , González Marianela
Published: July 2016

New types of hydrogels derived from O‐acetyl galactoglucomannan (AcGGM) hemicellulose have been synthesized and characterized. The objective of this work was to analyze the sorption capacity (S) of three types of hydrogels containing AcGGM derivatives incorporated into the carboxylic groups of the polymer chain in the AA hydrogel, sulfonic groups in the APA hydrogel, and amide groups in the acrylamide (Aam) hydrogel. These hydrogels are capable of interacting and removing ions such as cadmium [Cd(II)], copper [Cu(II)], lead [Pb(II)], nickel [Ni(II)], and zinc [Zn(II)]. The results show that AA and Aam hydrogels had a lower sorption capacity of ions compared to the APA hydrogel, which had a high sorption capacity. The maximal sorption capacity was determined by the successive enrichment method, obtaining Pb(II) amount of 48.3 mg/g of AA hydrogel, 65.8 mg/g of APA hydrogel, and 40.8 mg/g of Aam hydrogel. Hence, Pb(II) ions are greatly retained by the three hydrogels. These results are promising for the development of new materials with potential applications in metal ion removal. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44093.
Improvement of actuation performance of dielectric elastomers by barium titanate and carbon black fillers
Authors: Poikelispää Minna , Shakun Alexandra , Das Amit , Vuorinen Jyrki
Published: July 2016

Dielectric elastomers are promising materials for actuators resembling human muscle. Among elastomers, acrylic rubbers (ACM) have shown good actuation performance but its use is limited by the high operating voltages required. The present work demonstrates that simultaneous incorporation of nanostructured carbon black and dielectric fillers offers an increase in a dielectric permittivity and a suitable modulus of the elastomers matrix, enabling an improved electro‐mechanical actuation performance at low voltages. By the use of reinforcing carbon black and barium titanate in an acrylic elastomer matrix a sixfold increase in the dielectric permittivity was realized. A fine tuning of the actuation stress and, consequently, actuation strain can be done by a judicial selection of the different filler concentrations in the soft rubber matrix. Finally, a synergistic effect of the fillers was observed in the improved actuation performance of the developed materials. This work may pave the way to design dielectric elastomers for actuator fabrication. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44116.
Synthesis and Anti‐Proliferative Activity of Sulfanyltriazolylnaphthalenols and Sulfanyltriazolylnaphthalene‐1,4‐diones
Authors: Chaaban Ibrahim , El Khawass El Sayeda M. , Abd El Razik Heba A. , El Salamouni Nehad S. , Redondo‐Horcajo Mariano , Barasoain Isabel , Díaz José Fernando , Yli‐Kauhaluoma Jari , Moreira Vânia M.
Published: July 2016

A series of new sulfanyltriazolylnaphthalenols (10a–f and 13a–f) and sulfanyltriazolylnaphthalene‐1,4‐diones (14a–f) were synthesized and evaluated against a panel of cancer cell lines. Among the tested compounds, 10b and 10d showed the best anti‐proliferative activity with GI50 values ranging from 2.72 to 10 and 3.13 to 13.1 µM, respectively, in several of the tumor cell lines tested. Compound 10d is highly selective toward leukemia cell lines and can be regarded as a good model for the development of new anti‐leukemic agents.
Why are estimates of the strength and direction of natural selection from wild populations not congruent with observed rates of phenotypic change?
Authors: Brookfield John F.Y.
Published: July 2016

Observing adaptive evolution is difficult. In the fossil record, phenotypic evolution happens much more slowly than in artificial selection experiments or in experimental evolution. Yet measures of selection on phenotypic traits, with high heritabilities, suggest that phenotypic evolution should also be rapid in the wild, and this discrepancy often remains even after accounting for correlations between different traits (i.e. making predictions using the multivariate version of the breeder's equation). Are fitness correlations with quantitative traits adequate measures of selection in the wild? We should instead view fitnesses as average properties of genotypes, while acknowledging that they can be environment‐dependent. Populations will tend to remain at fitness equilibria, once these are attained, and phenotypes will then be stable. Thus, studying the causes of adaptive change at a genotypic rather than phenotypic level may reveal that, typically, it is occurring too slowly to be easily observed.
Enhanced stiffness of silk‐like fibers by loop formation in the corona leads to stronger gels
Authors: Rombouts Wolf H. , Domeradzka Natalia E. , Werten Marc W.T. , Leermakers Frans A.M. , de Vries Renko J. , de Wolf Frits A. , van der Gucht Jasper
Published: July 2016

We study the self‐assembly of protein polymers consisting of a silk‐like block flanked by two hydrophilic blocks, with a cysteine residue attached to the C‐terminal end. The silk blocks self‐assemble to form fibers while the hydrophilic blocks form a stabilizing corona. Entanglement of the fibers leads to the formation of hydrogels. Under oxidizing conditions the cysteine residues form disulfide bridges, effectively connecting two corona chains at their ends to form a loop. We find that this leads to a significant increase in the elastic modulus of the gels. Using atomic force microscopy, we show that this stiffening is due to an increase of the persistence length of the fibers. Self‐consistent‐field calculations indicate a slight decrease of the lateral pressure in the corona upon loop formation. We argue that this small decrease in the repulsive interactions affects the stacking of the silk‐like blocks in the core, resulting in a more rigid fiber.
Intramolecular backbone···backbone hydrogen bonds in polypeptide conformations. The other way around: ɛ‐turn
Authors: Toniolo Claudio , Crisma Marco , Formaggio Fernando , Alemán Carlos , Ramakrishnan Chandrasekharan , Kalmankar Neha , Balaram Padmanabhan
Published: July 2016

In this study, we performed a detailed literature survey of the ɛ‐turn in peptides and proteins. This three‐dimensional structural feature is characterized by an eleven‐membered pseudo‐cycle closed by an intramolecular backbone…backbone H‐bond. Interestingly, in this motif the direction of the N‐H…O = C H‐bond runs opposite to that of the much more popular and extensively investigated α‐, β‐, and γ‐turns. We did not authenticate unequivocally the ɛ‐turn main‐chain reversal topology in any linear short peptide. However, it is frequently observed in small cyclic peptides formed by four, five, and six amino acid residues with stringent geometric requirements. Rather surprisingly, ɛ‐turns do occur in proteins, although to a relatively moderate extent, as an isolated feature or in the turn segment of hairpin motifs based on two antiparallel, pleated β‐strands. Moreover, the ɛ‐turn may also host not only the seven‐membered, intramolecularly H‐bonded, pseudo‐cycle termed γ‐turn, either of the classic or inverse type, but also one (or even two) cis peptide bond(s) or a β‐bulge conformation. Based on their ϕ, ψ backbone torsion angles, we were able to classify the protein ɛ‐turns in six different families. Conformational energy computations using the DFT methodology were also performed on the ɛ‐turns adopted by the amino acid triplet ‐Gly‐Gly‐Gly‐ (Gly is the most commonly found residue at each of the three positions in our analysis of proteins). Again, in this computational study, six families of turns were identified, but only some of them resemble rather closely those extracted from our investigation on proteins.
Crystal structures of peptidic catalysts of the H‐dPro‐Pro‐Xaa type
Authors: Grünenfelder Claudio E. , Kisunzu Jessica K. , Trapp Nils , Kastl Robert , Wennemers Helma
Published: July 2016

Crystal structures of catalytically active tripeptides of the general type H‐dPro‐Pro‐Xaa and related N‐acetylated analogs were compared. The influence of acylation at the N‐terminus, the nature of the C‐terminal residue, coordinating groups, and intramolecular hydrogen bonds on the conformation of the tripeptides was examined. Regardless of the presence or absence of stabilizing intramolecular H‐bonds or n → π* interactions, all of the analyzed peptides share a β‐turn‐like conformation, which highlights the structural rigidity of the dPro‐Pro motif and its value for conformational preorganization. The C‐terminal residues and coordinating moieties were found to affect the turn‐conformation, which suggests that H‐dPro‐Pro‐Xaa type peptides are sufficiently flexible to adopt distinctly different but related conformations.
Feasibility of hybrid off pump artery bypass grafting and transaortic transcatheter aortic valve implantation: A case series
Authors: Manoly Imthiaz , Hasan Ragheb , Brazier Andrew , Farooq Vasim , Thompson Thomas , Karunaratne Devinda , Naylor Heather , Fraser Douglas
Published: July 2016

Introduction

Patients with complex coronary artery disease and severe aortic stenosis unsuitable for conventional cardiac surgery pose a significant treatment challenge. This is especially difficult for patients where percutaneous revascularization is technically very challenging and/or would not offer as complete revascularisation compared to surgical revascularisation. In addition, patients who are unsuitable for transfemoral transcatheter aortic valve implantation (TAVI) pose an additional technical challenge, particularly with dual antiplatelet therapy (DAPT) following percutaneous coronary intervention (PCI). As a potential solution we describe the first case series of hybrid off‐pump coronary artery bypass grafting (CABG) combined with transaortic TAVI.

Methods and results

Over a ten‐month‐period, four patients underwent hybrid off‐pump CABG combined with transaortic TAVI. A full sternotomy allowed off‐pump arterial and vein graft anastomosis to significantly stenosed coronaries. The first three patients had severe aorto‐iliac disease precluding femoral access; the fourth patient was deemed unsuitable for PCI. Transaortic TAVI using Edwards Sapien 3 valves were performed without complication in all four patients.

Conclusion

The hybrid off‐pump CABG and transaortic TAVI procedure allows for more complete coronary revascularization, negates the need for DAPT, and minimizes treatment delay of a TAVI procedure, particularly in patients unsuitable for transfemoral access. We propose this as an important treatment option for the heart team to consider. © 2016 Wiley Periodicals, Inc.
Saphenous vein bypass graft intervention and embolic protection devices: Time for reassessment (and revision of percutaneous coronary intervention guidelines)
Authors: Safian Robert D.
Published: July 2016

Key Points

Professional societies recommend embolic protection devices (EPDs) during percutaneous intervention of saphenous vein bypass grafts (SVGs; class I, level of evidence B).

Practice patterns indicate that 21% of SVG interventions are performed with EPDs. Despite a single randomized trial that demonstrated efficacy for EPDs, other studies suggest that the benefits of EPDs are controversial.

Consideration should be given toward performing a contemporary EPD trial to incorporate new technologies and pharmacotherapies; in the meantime, guideline recommendations for use of EPDs should be downgraded.
Is there a Specific Ecological Niche for Electroactive Microorganisms?
Authors: Koch Christin , Harnisch Falk
Published: July 2016

The core of primary microbial electrochemical technologies (METs) is the ability of the electroactive microorganisms to interact with electrodes via extracellular electron transfer (EET), allowing wiring of current flow and microbial metabolism. Geobacter sulfurreducens and Shewanella oneidensis are the model organisms for understanding and engineering EET. Many other microorganisms are reported being electroactive but are often sparsely characterized. Based on a literature survey 94 species are ascribed as electroactive. Their apparent diversity raises questions on the natural importance and distribution of the EET capacity, that is, of the ecological niche of microbial electroactivity. To identify this potential niche the environmental preferences and natural habitat characteristics of all electroactive species were combined with their metabolic, growth and EET characteristics and an extensive meta‐analysis performed. The results indicate that there is not a single ecological niche for electroactive microorganisms. Significantly more electroactive species presumably exist in nature as well as already existing strain collections but due to current cultivation techniques their EET potential is not leveraged. Thus, in the light of specific traits required for industrial application, microbial resource mining based on ecological knowledge bears a great potential for broadening the foundation of microbial electrochemistry as well as for future developments of primary METs.
Competitive Excimer Formation and Energy Transfer in Zr‐Based Heterolinker Metal–Organic Frameworks
Authors: Gutiérrez Mario , Sánchez Félix , Douhal Abderrazzak
Published: July 2016

The spectroscopy and dynamics of a series of Zr‐based MOFs in dichloromethane suspension are reported. These Zr‐NADC MOFs were constructed by using different mixtures of 2,6‐naphthalenedicarboxylate (NDC) and 4‐amino‐2,6‐naphthalenedicarboxylate (NADC) as organic linkers. The fraction of NADC relative to NDC in these heterolinker MOFs ranges from 2 to 35 %. The results indicate two competitive photoprocesses: NDC excimer formation and an energy transfer (ET) from excited NDC linkers to NADC linkers. Increasing the fraction of NADC linkers in the Zr‐NADC nanostructure decreases the mean time constant of NDC excimer formation, while the NADC emission intensity experiences a drop at the highest fraction of this linker in the MOF. The first observation is explained by an increase in the energy‐transfer probability between the two linkers, and the second by emission quenching in the NADC linkers due to ultrafast charge transfer assisted by the amino group. Femtosecond time‐resolved emission studies showed that the ET process (recorded as decaying and rising components) from excited NDC to NADC takes place in 1.2 ps. Direct excitation of the NADC linkers (at 410 nm) shows a decaying, but not rising, component of 250–480 fs, which could reflect the formation of a nonemissive charge‐separation state. The results show that by using MOFs having heterolinkers it is possible to trigger and tune excimer formation and ET processes.
Light‐ and Solvent‐Controlled Self‐Assembly Behavior of Spiropyran–Polyoxometalate–Alkyl Hybrid Molecules
Authors: Chu Yang , Saad Ali , Yin Panchao , Wu Jiayingzi , Oms Olivier , Dolbecq Anne , Mialane Pierre , Liu Tianbo
Published: July 2016

A molecular photochromic spiropyran–polyoxometalate–alkyl organic–inorganic hybrid has been synthesized and fully characterized. The reversible switching of the hydrophobic spiropyran fragment to the hydrophilic merocyanine one can be easily achieved under light irradiation at different wavelengths. This switch changes the amphiphilic feature of the hybrid, leading to a light‐controlled self‐assembly behavior in solution. It has been shown that the hybrid can reversibly self‐assemble into vesicles in polar solvents and irreversibly into reverse vesicles in non‐polar solvents. The sizes of the vesicles and the reverse vesicles are both tunable by the polarity of the solvent, with the hydrophobic interactions being the main driving force.
Design of Assembled Systems Based on Conjugated Polyphenylene Derivatives and Carbon Nanohorns
Authors: Iglesias Daniel , Guerra Javier , Gómez M. Victoria , Rodríguez Antonio M. , Prieto Pilar , Vázquez Ester , Herrero M. Antonia
Published: July 2016

Promising materials have been designed and fully characterised by an effective interaction between versatile platforms such as carbon nanohorns (CNHs) and conjugated molecules based on thiophene derivatives. Easy and non‐aggressive methods have been described for the synthesis and purification of the final systems. Oligothiophenephenylvinylene (OTP) systems with different geometries and electron density are coupled to the CNHs. A wide range of characterization techniques have been used to confirm the effective interaction between the donor (OTP) and the acceptor (CNH) systems. These hybrid materials show potential for integration into solar cell devices. Importantly, surface‐enhanced Raman spectroscopy (SERS) effects are observed without the presence of any metal surface in the system. Theoretical calculations have been performed to study the optimised geometries of the noncovalent interaction between the surface and the organic molecule. The calculations allow information on the monoelectronic energies of HOMO–LUMO orbitals and band gap of different donor systems to be extracted.
Azulenylcarbenes: Rearrangements on the C11H8 Potential Energy Surface
Authors: Henkel Stefan , Pollok Corina H. , Schleif Tim , Sander Wolfram
Published: July 2016

Four isomeric azulenylcarbenes were synthesized in argon matrices by photolysis of the corresponding diazo precursors, and the photochemistry of these carbenes was studied. The carbenes and their rearranged products were characterized by IR, UV/Vis, and EPR spectroscopy, and the experimental data were compared to results from DFT calculations. While 2‐, 5‐ and 6‐azulenylcarbene show triplet ground states, 1‐azulenylcarbene exhibits a singlet ground state, in accord with theoretical predictions. The rearrangements of the azulenylcarbenes give access to a number of unusual C11H8 isomers, such as other carbenes and strained allenes.
Ionic Liquids Can Permanently Modify Porous Silicon Surface Chemistry
Authors: Trivedi Shruti , Coombs Sidney G. , Wagle Durgesh V. , Bhawawet Nakara , Baker Gary A. , Bright Frank V.
Published: July 2016

To develop ionic liquid/porous silicon (IL/pSi) microarrays we have contact pin‐printed 20 hydrophobic and hydrophilic ionic liquids onto as‐prepared, hydrogen‐passivated porous silicon (ap‐pSi) and then determined the individual IL spot size, shape and associated pSi surface chemistry. The results reveal that the hydrophobic ionic liquids oxidize the ap‐pSi slightly. In contrast, the hydrophilic ionic liquids lead to heavily oxidized pSi (i.e., ox‐pSi). The strong oxidation arises from residual water within the hydrophilic ILs that is delivered from these ILs into the ap‐pSi matrix causing oxidation. This phenomenon is less of an issue in the hydrophobic ILs because their water solubility is substantially lower.
Electrons Mediate the Gas‐Phase Oxidation of Formic Acid with Ozone
Authors: van der Linde Christian , Tang Wai‐Kit , Siu Chi‐Kit , Beyer Martin K.
Published: July 2016

Gas‐phase reactions of CO3.− with formic acid are studied using Fourier transform ion cyclotron resonance (FT‐ICR) mass spectrometry. Signal loss indicates the release of a free electron, with the formation of neutral reaction products. This is corroborated by adding traces of SF6 to the reaction gas, which scavenges 38 % of the electrons. Quantum chemical calculations of the reaction potential energy surface provide a reaction path for the formation of neutral carbon dioxide and water as the thermochemically favored products. From the literature, it is known that free electrons in the troposphere attach to O2, which in turn transfer the electron to O3. O3.− reacts with CO2 to form CO3.−. The reaction reported here formally closes the catalytic cycle for the oxidation of formic acid with ozone, catalyzed by free electrons.
Direct Synthesis of α‐Allenols from TMS‐Protected Alkynes and Aldehydes Mediated by Tetrabutylammonium Fluoride
Authors: Huang Xiaojun , Bugarin Alejandro
Published: July 2016

A unique chemoselective synthesis of α‐allenic alcohols is presented. Tetrabutylammonium fluoride (TBAF) mediated this transformation under mild reaction conditions. A range of functional groups is well‐tolerated in this reaction, while affording adducts in moderate to excellent yields (48–96 %, average 76 %). Mechanistic studies, including the use of tetrabutylammonium hydroxide (TBAH), revealed that the hydroxide ion can be the responsible for the observed rearrangement.
A Novel Ratiometric Oxygen Sensor Based On a Sextuple Hydrogen‐Bonding Self‐Assembly Molecular Heterodimer
Authors: Zeng Hui , Zhang Cheng , Huang Yan , Lu Zhiyun
Published: July 2016

A novel sextuple hydrogen‐bonding (HB) self‐assembly molecular heterodimer bearing an iridium complex as the indicator dye and two carbazoles as the reference dye, namely 6HB‐Irbt‐Cz, was synthesized, and its molecular structure was confirmed by 1H NMR, 13CNMR, TOF‐MS and 2D NMR. Because of the inefficient energy transfer process between the carbazole and iridium complex units, 6HB‐Irbt‐Cz exhibits distinct ?uorescence/phosphorescence dual emission in neat film state. More importantly, the neat film sample of 6HB‐Irbt‐Cz could display linear ratiometric optical response toward oxygen in the full oxygen concentration range from 0 to 100 vol%, together with good stability, reversibility and rapid response‐recovery times. Note that this represents the first discovery of neat‐film‐based oxygen sensor capable of showing strictly linear ratiometric Stern‐Volmer behavior in the oxygen concentration of 0–100 vol%.
Efficient Synthesis of Isoquinolines by AgNO3‐Catalyzed Sequential Imination‐Annulation of 2‐Alkynyl Aldehydes with Ammonium Bicarbonate
Authors: Zhao Yunhui , Luo Mingjian , Li Yubo , Liu Xiong , Tang Zilong , Deng Keqin , Zhao Gang
Published: July 2016

An operationally simple approach for the tandem synthesis of isoquinolines by the reaction of o‐alkynylaldehydes with ammonium bicarbonate via Ag‐catalyzed 6‐endo‐dig ring closure is described. The reaction conditions and the scope of the reaction are examined, and a variety of substituted isoquinolines are prepared in moderate to excellent yields.
Characterization of Dissolved Organic Matter in Lake Baiyangdian Using Spectroscopic Techniques and Multivariate Statistical Analysis
Authors: Cui Jun , Yuan Dong‐hai , Guo Xu‐jing , He Lian‐sheng , He Jiang‐wei , Li Hai‐yan , Li Jun‐qi
Published: July 2016

Dissolved organic matter (DOM) collected from the surface and overlying waters in different functional regions in Lake Baiyangdian were analyzed by spectroscopic techniques combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA), to interpret water quality, and sources of pollutants. The results showed that the deterioration of water quality has intensified at river estuary and aquaculture area. Meanwhile, these regions dominated by plants had relatively low dissolved oxygen concentrations. UV‐vis spectra showed lower humification degree and simpler molecular structure in the DOM collected from the pollutant‐receiving region. The analysis of PCA combined with synchronous fluorescence spectra yielded two principal components (PCs) that account for 99.44% of the variance. PC1 showed a dominant protein‐like fluorophore at 279 nm and PC2 was characterized by dominated fulvic‐like fluorophores (325 and 331 nm). The results of PCA indicated that DOM collected from the river estuary, the aquaculture region, and the eutrophication area exhibited a higher protein‐like fluorophore, and higher PC1 and lower PC2 loadings (PC1 > 0.7, PC2 < 0.4). Meanwhile, a higher fulvic‐like fluorophore existed in the DOM samples collected from a clean region (PC1 < 0.4, PC2 > 0.7). HCA identified four clusters that accorded with the PCA results. This study suggested that water quality and the sources, and spectral characteristics of DOM were influenced mainly by human activities (agriculture, industrial, and domestic wastewater from upstream, food and excrement from aquaculture) and natural processes (aquatic‐plant and microorganism activities).
Validation study of HPV DNA detection from stained FNA smears by polymerase chain reaction: Improving the diagnostic workup of patients with a tumor on the neck
Authors: Channir Hani Ibrahim , Grønhøj Larsen Christian , Ahlborn Lise Barlebo , van Overeem Hansen Thomas , Gerds Thomas Alexander , Charabi Birgitte Wittenborg , Vainer Ben , von Buchwald Christian , Lajer Christel Bræmer , Kiss Katalin
Published: July 2016

BACKGROUND

Human papillomavirus (HPV)–related oropharyngeal squamous cell carcinoma (OPSCC) often presents with cystic cervical metastasis and a small primary tumor localized in the palatine tonsils or base of the tongue, which is diagnostically challenging. Testing for HPV DNA in fine‐needle aspiration (FNA) smears from metastases may facilitate a targeted diagnostic workup for identifying the primary tumor. This study was designed to assess the ability to detect HPV DNA in FNA smears with polymerase chain reaction (PCR).

METHODS

May‐Grünvald‐Giemsa (MGG)–stained FNA smears from metastases and corresponding surgical specimens were collected from 71 patients with known HPV‐positive OPSCC, 12 patients with oral squamous cell carcinoma (OSCC), 20 patients with branchial cleft cysts, and 20 patients with Warthin tumors. Thirty‐eight patients with OPSCC and 7 patients with OSCC had FNA smears available from metastases and also surgical specimens from the primary tumor and the metastases. The scraped cell material from FNA smears and corresponding surgical specimens were analyzed for HPV DNA by PCR. p16 immunohistochemistry was performed on surgical specimens from the carcinomas.

RESULTS

HPV DNA was detected in 68 of the 71 FNA smears from OPSCC metastases. All corresponding surgical specimens from primary tumors (n = 71) and metastases (n = 38) were p16‐ and HPV DNA–positive. All the surgical specimens and corresponding FNA smears from OSCCs, Warthin tumors, and branchial cleft cysts were HPV DNA–negative. The sensitivity and specificity were 94.7% and 100%, respectively.

CONCLUSIONS

The detection of HPV DNA in MGG‐stained FNA smears by PCR is a valid method that could be implemented in routine clinical practice. Cancer Cytopathol 2016;124:820‐7. © 2016 American Cancer Society.
Antisolvent crystallization of aqueous ammonium dihydrogen phosphate solutions by addition of acetone at different rates
Authors: Sangwal Keshra , Mielniczek‐Brzóska Ewa
Published: July 2016

Results of an investigation of in situ measurements of laser‐beam intensity Is and Im transmitted through aqueous ammonium dihydrogen phosphate (ADP) solutions saturated at 30 °C and water, respectively, and temperature Ts of solution and Tm of water during feeding of antisolvent acetone at different rates RA, using an indigenously designed experimental setup, are presented and discussed. It was found that: (1) for the measurement of MSZW, defined as the maximum volume fraction of acetone content Δxmax in the solution, obtained from temperature measurements are more reliable than transmitted laser‐beam intensity measurements for solutions, (2) two minima ΔTmin1 and ΔTmin2 associated with endothermic reactions, separated by a maximum ΔTmax due to exothermic reactions appear in the plots of temperature difference ΔT = Ts−Tm against acetone feeding time t, and (3) in the ΔT(t) plots there are time intervals Δt of constant rates RT of increase in ΔT of aqueous ADP solutions, and these values of RT increase linearly with acetone feeding time rate RA. The experimental data on the observed dependence of MSZW on antisolvent feeding rate RA, the appearance of minima ΔTmin1 and ΔTmin2 and maximum ΔTmax and their dependence on RA, and the relationship between RT and RA are discussed from consideration of processes of nucleation and growth of crystallites.
Red Mud and Li‐Ion Batteries: A Magnetic Connection
Authors: Suryawanshi Anil , Aravindan Vanchiappan , Madhavi Srinivasan , Ogale Satishchandra
Published: July 2016

Exceptional Li‐ion battery performance is presented with the oxide component of the anode was extracted from red mud by simple magnetic separation and applied directly without any further processing. The extracted material has γ‐Fe2O3 as the major phase with inter‐dispersed phases of Ti, Al, and Si oxides. In a half‐cell assembly, the phase displayed a reversible capacity (∼697 mA h g−1) with excellent stability upon cycling. Interestingly, the stability is rendered by the multiphase constitution of the material with the presence of other electrochemically inactive metal oxides, such as Al2O3, SiO2, and Fe2TiO4, which could accommodate the strain and facilitate release during the charge–discharge processes in the electrochemically active maghemite component. We fabricated the full‐cell assembly with eco‐friendly cathode LiMn2O4 by adjusting the mass loading. Prior to full‐cell assembly, an electrochemical pre‐lithiation was enforced to overcome the irreversible capacity loss obtained from the anode. The full‐cell delivered a capacity of ∼100 mA h g−1 (based on cathode loading) with capacity retention of ∼61 % after 2000 cycles under ambient conditions.