bluuebunny/crossref_metadata_2025 huggingface dataset:
Epoxide Hydrolase Conformational Heterogeneity for the Resolution of Bulky Pharmacologically Relevant Epoxide Substrates
Authors: Serrano‐Hervás Eila , Casadevall Guillem , Garcia‐Borràs Marc , Feixas Ferran , Osuna Sílvia
Published: April 2018

The conformational landscape of Bacillus megaterium epoxide hydrolase (BmEH) and how it is altered by mutations that confer the enzyme the ability to accept bulky epoxide substrates has been investigated. Extensive molecular dynamics (MD) simulations coupled to active site volume calculations have unveiled relevant features of the enzyme conformational dynamics and function. Our long‐timescale MD simulations identify key conformational states not previously observed by means of X‐ray crystallography and short MD simulations that present the loop containing one of the catalytic residues, Asp239, in a wide‐open conformation, which is likely involved in the binding of the epoxide substrate. Introduction of mutations M145S and F128A dramatically alters the conformational landscape of the enzyme. These singly mutated variants can accept bulky epoxide substrates due to the disorder induced by mutation in the α‐helix containing the catalytic Tyr144 and some parts of the lid domain. These changes impact the enzyme active site, which is substantially wider and more complementary to the bulky pharmacologically relevant epoxide substrates.
Efficiently Photocontrollable or Not? Biological Activity of Photoisomerizable Diarylethenes
Authors: Komarov Igor V. , Afonin Sergii , Babii Oleg , Schober Tim , Ulrich Anne S.
Published: April 2018

Diarylethene derivatives, the biological activity of which can be reversibly changed by irradiation with light of different wavelengths, have shown promise as scientific tools and as candidates for photocontrollable drugs. However, examples demonstrating efficient photocontrol of their biological activity are still relatively rare. This concept article discusses the possible reasons for this situation and presents a critical analysis of existing data and hypotheses in this field, in order to extract the design principles enabling the construction of efficient photocontrollable diarylethene‐based molecules. Papers addressing biologically relevant interactions between diarylethenes and biomolecules are analyzed; however, in most published cases, the efficiency of photocontrol in living systems remains to be demonstrated. We hope that this article will encourage further discussion of design principles, primarily among pharmacologists, synthetic and medicinal chemists.
Die Wahrheit über Michael Jacksons Tod
Authors: Spieler Florian
Published: April 2018

Das ausgezeichnete Seminar „Chemie und Theater“ schlägt eine Brücke zwischen den Schulfächern Chemie und dramatischem Spiel. In selbst geschriebenen Szenen verpacken die 15 Schülerinnen und Schüler die Chemie der Schule neu und innovativ. Ob beim „Tanz der Moleküle“, dem „Nightlife der Elemente“ oder dem „Tod des King of Pop“, jede Szene ist in sich ein Stück kreativer Chemieunterricht.
A multiobjective optimization procedure for the electrode design of cochlear implants
Authors: Ramos‐de‐Miguel Ángel , Escobar José M. , Greiner David , Ramos‐Macías Ángel
Published: April 2018

This paper presents a new procedure to design optimal electrodes for cochlear implants. The main objective of this study is to find a set of electrode designs that maximize the focalization and minimize the power consumption simultaneously. To achieve that, a criterion to measure the ability of focalization of an electrode is proposed. It is presented a procedure to determine (1) the electrical potential induced by an electrode by solving the Laplace equation through the finite element method; (2) the response of a neuron to an applied field using NEURON, a compartmentalized cell model; (3) the optimization to find the best electrode designs according to power consumption and focalization by 2 evolutionary multiobjective methods based on the non‐dominated sorting genetic algorithm II: a straight multiobjective approach and a seeded multiobjective approach. An electrode design formed by 2 conductive rings with a possible difference of potential between them is proposed. It is analyzed that the response of the neuron is determined by the shape and the difference of the potential between the electrode rings. Our procedure successfully achieves a nondominated set of optimum electrode designs improving a standard electrode in both objectives, as designs with better focalization allow to include extra electrodes in the cochlear implant, and designs with lower power consumption extend the length of the battery.
Tuning of the Seebeck Coefficient and the Electrical and Thermal Conductivity of Hybrid Materials Based on Polypyrrole and Bismuth Nanowires
Authors: Hnida Katarzyna E. , Pilarczyk Kacper , Knutelski Marcin , Marzec Mateusz , Gajewska Marta , Kosonowski Artur , Chlebda Damian , Lis Bartłomiej , Przybylski Marek
Published: April 2018

The growing demand for clean energy catalyzes the development of new devices capable of generating electricity from renewable energy resources. One of the possible approaches focuses on the use of thermoelectric materials (TE), which may utilize waste heat, water, and solar thermal energy to generate electrical power. An improvement of the performance of such devices may be achieved through the development of composites made of an organic matrix filled with nanostructured thermoelectric materials working in a synergetic way. The first step towards such designs requires a better understanding of the fundamental interactions between available materials. In this paper, this matter is investigated and the questions regarding the change of electrical and thermal properties of nanocomposites based on low‐conductive polypyrrole enriched with bismuth nanowires of well‐defined geometry and morphology is answered. It is clearly demonstrated that the electrical conductivity and the Seebeck coefficient may be tuned either simultaneously or separately within particular Bi NWs content ranges, and that both parameters may be increased at the same time.
An Effective Heterogeneous Catalyst of [BMIM]3PMo12O40 for Selective Sugar Epimerization
Authors: Bayu Asep , Yoshida Akihiro , Karnjanakom Surachai , Zuo Zhijun , Hao Xiaogang , Abudula Abuliti , Guan Guoqing
Published: April 2018

The development of heterogeneous catalysts for the epimerization of sugars has received much less attention than that for the isomerization of sugars. To date, molybdates are the most effective catalysts for the epimerization of sugars, although they lack stability toward hydrolysis of their active sites in water. To solve the issue of the formation of a highly water‐soluble heteropolyblue (PMored) for phosphomolybdates (PMos) in aqueous reaction systems, herein, a 1‐butyl‐3‐methylimidazolium phosphomolybdate ([BMIM]3PMo12O40) was synthesized through an ion‐exchange method. This catalyst was effective and selective for the C2‐epimerization of sugars under mild reaction conditions (<100 °C; 1–2 h) with good water‐tolerant properties. The reaction was confirmed to occur in a heterogeneous manner and no leaching of PMored was detected by means of UV/Vis spectroscopy. Moreover, the catalyst can be simply separated by filtration and reused for at least eight cycles without a drop in catalytic activity. XRD, FTIR, and X‐ray photoelectron spectroscopy measurements indicate that the catalyst is stable under the reaction conditions. In a comparison of the catalytic activity and surface wettability with those of other PMo salts, that is, 1‐ethyl‐3‐methylimidazolium phosphomolybdate ([EMIM]3PMo12O40), 1‐hexyl‐3‐methylimidazolium ([HexMIM]3PMo12O40), [choline]3PMo12O40, and cetyltrimethylammonium phosphomolybdate ([CTA]3PMo12O40), it is found that [BMIM]3PMo12O40 has more appropriate hydrophobic–hydrophilic balance, which should be responsible for better catalytic activity and stability.
The paradoxical nexus between corporate social responsibility and sustainable financial performance: Evidence from the international construction business
Authors: Lu Weisheng , Ye Meng , Chau K.W. , Flanagan Roger
Published: April 2018

The aim of the research is to substantiate the hypothesis of a paradoxical dynamic link between corporate social responsibility (CSR) and its material implications including sustainable corporate financial performance (CFP). By analysing a panel of 67 international construction companies from 2006 to 2015, we found that CSR programs can be detrimental to CFP in the short term but conducive to improving it in the long term. The findings of this research indicate that, in the international construction business, the impact of CSR on CFP is not immediate and unchanging, and it takes time to materialize CSR for sustainable development. A significant practical use of this research is to provide evidence for the assertion that business stakeholders should be relieved from short‐termism in assuming social responsibility. Further research is recommended to test this support in a more general business setting towards developing a general theory on CSR and sustainable development.
Tbx2 is required for the suppression of mesendoderm during earlyXenopusdevelopment
Authors: Teegala Sushma , Chauhan Riddhi , Lei Emily , Weinstein Daniel C.
Published: April 2018

Background: T‐box family proteins are DNA‐binding transcriptional regulators that play crucial roles during germ layer formation in the early vertebrate embryo. Well‐characterized members of this family, including the transcriptional activators Brachyury and VegT, are essential for the proper formation of mesoderm and endoderm, respectively. To date, T‐box proteins have not been shown to play a role in the promotion of the third primary germ layer, ectoderm.Results: Here, we report that the T‐box factor Tbx2 is both sufficient and necessary for ectodermal differentiation in the frogXenopus laevis. Tbx2 is expressed zygotically in the presumptive ectoderm, during blastula and gastrula stages. Ectopic expression of Tbx2 represses mesoderm and endoderm, while loss of Tbx2 leads to inappropriate expression of mesoderm‐ and endoderm‐specific genes in the region fated to give rise to ectoderm. Misexpression of Tbx2 also promotes neural tissue in animal cap explants, suggesting that Tbx2 plays a role in both the establishment of ectodermal fate and its dorsoventral patterning.Conclusions: Our studies demonstrate that Tbx2 functions as a transcriptional repressor during germ layer formation, and suggest that this activity is mediated in part through repression of target genes that are stimulated, in the mesendoderm, by transactivating T‐box proteins. Taken together, our results point to a critical role for Tbx2 in limiting the potency of blastula‐stage progenitor cells during vertebrate germ layer differentiation.Developmental Dynamics 247:903–913, 2018. © 2018 Wiley Periodicals, Inc.
Diel movement of brown trout,Salmo trutta, is reduced in dense populations with high site fidelity
Authors: Slavík Ondřej , Horký Pavel , Maciak Matúš , Horká Petra , Langrová Iva
Published: April 2018

The movement of individuals within preferred areas is reduced by a high availability of food and information about its distribution, while high number of competitors promotes increased movement. Experienced animals use information about social and physical environment to improve resources exploitation, tended to maintain positions within the preferred areas and reuse the environment that is often referred to as site fidelity. In this study, radio‐telemetry was used to observe the movements of 98 adult brown trout,Salmo trutta, in oligotrophic streams with different population densities; to determine subpopulation site fidelity, 5,195 conspecifics from 14 subpopulations were individually tagged during spring and autumn. During a 7‐year‐long field study, we tested the hypothesis that brown trout individuals from subpopulations with high site fidelity would display lower movement. The hypothesis was supported, and reduced movement was further related to high subpopulation density in association with high slope indicating the physical environment‐influenced movement. The probability of contact between individuals increased with subpopulation site fidelity and subpopulation density. No influence of food abundance on brown trout movement was found. Furthermore, increased body size predicted higher movement (and vice versa). The least movement occurred during the day and during the full moons. Our study tended to show that individuals reused preferred areas and needed less movement to exploit available resources.
Timber harvest as the predominant disturbance regime in northeastern U.S. forests: effects of harvest intensification
Authors: Brown Michelle L. , Canham Charles D. , Murphy Lora , Donovan Therese M.
Published: April 2018

Harvesting is the leading cause of adult tree mortality in forests of the northeastern United States. While current rates of timber harvest are generally sustainable, there is considerable pressure to increase the contribution of forest biomass to meet renewable energy goals. We estimated current harvest regimes for different forest types and regions across the U.S. states of New York, Vermont, New Hampshire, and Maine using data from the U.S. Forest Inventory and Analysis Program. We implemented the harvest regimes inSORTIE‐ND, an individual‐based model of forest dynamics, and simulated the effects of current harvest regimes and five additional harvest scenarios that varied by harvest frequency and intensity over 150 yr. The best statistical model for the harvest regime described the annual probability of harvest as a function of forest type/region, total plot basal area, and distance to the nearest improved road. Forests were predicted to increase in adult aboveground biomass in all harvest scenarios in all forest type and region combinations. The magnitude of the increase, however, varied dramatically—increasing from 3% to 120% above current landscape averages as harvest frequency and intensity decreased. The variation can be largely explained by the disproportionately high harvest rates estimated for Maine as compared with the rest of the region. Despite steady biomass accumulation across the landscape, stands that exhibited old‐growth characteristics (defined as ≥300 metric tons of biomass/hectare) were rare (8% or less of stands). Intensified harvest regimes had little effect on species composition due to widespread partial harvesting in all scenarios, resulting in dominance by late‐successional species over time. Our analyses indicate that forest biomass can represent a sustainable, if small, component of renewable energy portfolios in the region, although there are tradeoffs between carbon sequestration in forest biomass and sustainable feedstock supply. Integrating harvest regimes into a disturbance theory framework is critical to understanding the dynamics of forested landscapes, especially given the predominance of logging as a disturbance agent and the increasing pressure to meet renewable energy needs.
Understanding biological effectiveness before scaling up range‐wide restoration investments for Gunnison sage‐grouse
Authors: Doherty Kevin E. , Hennig Jacob D. , Dinkins Jonathan B. , Griffin Kathleen A. , Cook Avery A. , Maestas Jeremy D. , Naugle David E. , Beck Jeffrey L.
Published: April 2018

Imperiled species recovery is a high‐stakes endeavor where uncertainty surrounding effectiveness of conservation actions can be an impediment to implementation at necessary scales, especially where habitat restoration is required. Gunnison sage‐grouse (Centrocercus minimus) represents one such species in need of large‐scale habitat restoration. It is a federally threatened sagebrush (Artemisia spp.) obligate bird with a limited range in Colorado and Utah. Threats to recovery of Gunnison sage‐grouse include conifer expansion into sagebrush along with additional habitat loss and degradation attributed to human development and agricultural conversion. Recovery of Gunnison sage‐grouse and other sensitive species can be aided by spatial tools that forecast plausible outcomes of conservation actions. We illustrate this by using a novel framework for predicting outcomes of proactive tree removal and subsequent sagebrush restoration for the Gunnison sage‐grouse. To assess threats on Gunnison sage‐grouse lek presence, we developed a spatially explicit breeding habitat model to compare active lek and random pseudo‐absence locations from 2015. Models identified land cover, climatic, and abiotic variables at landscape‐level scales (0.56 and 4 km) most important for predicting breeding habitat. Our model correctly differentiated between lek and pseudo‐absence locations 94% of the time. All but one of the active leks (n = 94) were in areas with >0.65 probability of lek occurrence. Using this probability value as a threshold, we predicted 15% of the current grouse range as high‐quality breeding habitat. Simulated removal of trees in areas with ≤30% tree canopy cover (0.56‐km scale) increased extent of high‐quality habitat fourfold (59%). Hypothetical restoration of sagebrush cover in the same areas increased habitat quality an additional 11%. Our breeding habitat model indicated that targeted tree removal and sagebrush restoration have potential to improve Gunnison sage‐grouse breeding habitat. While our habitat treatment scenarios were not meant to be prescriptive, they highlight that considerable uplift in Gunnison sage‐grouse breeding habitat may be possible across much of its range with cooperation from multiple stakeholders and illustrates the utility of this approach for predicting biological return on investment.
Leaf‐level trade‐offs between drought avoidance and desiccation recovery drive elevation stratification in arid oaks
Authors: Fallon Beth , Cavender‐Bares Jeannine
Published: April 2018

Understanding the extent to which climate limitations drive elevation stratification among species is integral to predicting the impacts of climate change. Zonation patterns of species within mountains have been well documented, and shifts in these patterns have been correlated with recent warming. However, the physiological mechanisms that explain these zonation patterns are not well understood. We used a system of broadly sympatric oak species within semi‐arid mountains to (1) investigate the extent to which species elevation ranges correlate with climate, (2) test for associations of cold and drought resistances with upper and lower elevation limits, and for trade‐offs between resistance mechanisms with elevation, and (3) examine the extent to which species‐wide climatic ranges predict traits that drive local community assembly along an elevation gradient. We found that aridity gradients but not winter minimum temperatures predict oak stratification. Species differed in drought resistance, demonstrating a trade‐off between drought avoidance and drought recovery. At lower elevations, species avoided drought stress during the dry season through leaf abscission; at upper elevations, they maintained transpiration but recovered from daily desiccation via higher leaf water storage capacity, rather than tolerating desiccation via lower turgor loss points. Freezing resistance, measured as stem electrolyte leakage, was not correlated with elevation differences. Taken together, these results indicate that elevation stratification is linked to drought resistance rather than freezing resistance. We also found evidence of niche partitioning among closely related oaks linked to contrasting leaf phenology. The functional, phenological, and physiological traits important for elevation stratification were correlated with species’ range‐wide mean annual precipitation and precipitation seasonality, but not aridity. Our findings indicate that drought resistance along a leaf avoidance–recovery trade‐off is integral to species stratification within this semi‐arid montane system. Additionally, the mechanism of stratification acts upon traits and strategies conserved at the species level. Species within this system are likely vulnerable to range retraction under increased drought as a consequence of this phenological avoidance–physiological tolerance trade‐off.
Dissolved oxygen concentration affects δ15N values in oyster tissues: implications for stable isotope ecology
Authors: Patterson Heather K. , Carmichael Ruth H.
Published: April 2018

To investigate the potential effects of physiological stress on stable isotope (SI) ratios in oysters, we transplanted hatchery‐reared oysters to reefs that experienced different concentrations of dissolved oxygen (DO) in Mobile Bay, Alabama, USA, a freshwater dominated estuary that experiences periodic hypoxia. We monitored physical, biological, and chemical parameters of the environment and biological responses in oysters, including growth, survival, and carbon and nitrogen SI ratios in tissues. Oysters at the low DO site (3.66 ± 0.05 mg/L) had ~1 ‰ higher δ15N values in tissue than oysters at the higher DO site (6.00 ± 0.06 mg/L). Oysters grown at the low DO site also had lower survival (25%) and no growth compared to oysters at the higher DO site, which had 96% survival and growth rates up to 38 mm/d. Multivariate and regression statistics related DO concentration to changes in δ15N values in three different oyster tissues (adductor muscle, gut gland, and gill), regardless of similarity in suspended particulate matter and chlorophyll a concentrations (food quantity), C:N (food quality), and SI composition in available foods between sites. The increased δ15N values in oyster tissues under low DO conditions during this study were consistent with known starvation responses in which oysters stop feeding and catabolize tissues. These data indicate that environmental conditions related to physiological stress can affect SI ratios in oysters in a similar manner to changes in diet composition. Small changes in SI ratios, therefore, may be physiologically significant indicators of environmental stress. When analyzing SI ratios for food web dynamics and source tracing, potential for confounding effects of environmental stressors should be considered.
Unsuccessful invaders structure a natural freshwater phytoplankton community
Authors: Buchberger Felicitas , Stockenreiter Maria
Published: April 2018

Species invasion dynamics are a core topic in ecology and the effects of species invasions on ecosystems are well described. However, the knowledge about the mechanisms during the invasion process itself is limited. Many interactions between invaders and resident species occur during the invasion process. These interactions influence individual species abundance and subsequently community composition. Even though invaders are often unsuccessful, the very short interactions with the resident species can influence species abundances and therefore community composition. The prominent effects of unsuccessful invaders on community composition were already predicted in a theoretical model. To empirically test the effect of such unsuccessful invaders on a resident phytoplankton community, we conducted a mesocosm experiment in a mesotrophic freshwater pond. Six freshwater algae belonging to three taxonomic groups (chlorophyta, cyanobacteria, and bacillariophyta) were added as potential invader species to the natural phytoplankton community of the pond (as single species or as combination of two species of the same taxonomic group). After nine days, the invasion success and the impact on the natural phytoplankton community were estimated. Results show that although all invaders were unsuccessful, they had lasting effects on the resident community. In all communities exposed to invasion, biodiversity (H′) was maintained. In contrast, in control communities, the diversity at the end of the experiment was lower compared to the initial community. Furthermore, communities exposed to invasion were less similar to control communities without invasion than to the other invaded communities. Differences were found in taxonomic group composition as well as in species composition. Additionally, we found evidence for synergistic effects between the combined added species. Our results give clear evidence of strong transient effects of unsuccessful invaders on freshwater phytoplankton community composition.
Mechanisms of surviving burial: Dune grass interspecific differences drive resource allocation after sand deposition
Authors: Brown Joseph K. , Zinnert Julie C.
Published: April 2018

Sand dunes are important geomorphic formations of coastal ecosystems that are critical in protecting human populations that live in coastal areas. Dune formation is driven by ecomorphodynamic interactions between vegetation and sediment deposition. While there has been extensive research on responses of dune grasses to sand burial, there is a knowledge gap in understanding mechanisms of acclimation between similar, coexistent, dune‐building grasses such as Ammophila breviligulata (C3), Spartina patens (C4), and Uniola paniculata (C4). Our goal was to determine how physiological mechanisms of acclimation to sand burial vary between species. We hypothesize that (1) in the presence of burial, resource allocation will be predicated on photosynthetic pathway and that we will be able to characterize the C3 species as a root allocator and the C4 species as leaf allocators. We also hypothesize that (2) despite similarities between these species in habitat, growth form, and life history, leaf, root, and whole plant traits will vary between species when burial is not present. Furthermore, when burial is present, the existing variability in physiological strategy will drive species‐specific mechanisms of survival. In a greenhouse experiment, we exposed three dune grass species to different burial treatments: 0 cm (control) and a one‐time 25‐cm burial to mimic sediment deposition during a storm. At the conclusion of our study, we collected a suite of physiological and morphological functional traits. Results showed that Ammophila decreased allocation to aboveground biomass to maintain root biomass, preserving photosynthesis by allocating nitrogen (N) into light‐exposed leaves. Conversely, Uniola and Spartina decreased allocation to belowground production to increase elongation and maintain aboveground biomass. Interestingly, we found that species were functionally distinct when burial was absent; however, all species became more similar when treated with burial. In the presence of burial, species utilized functional traits of rapid growth strategy, although mechanisms of change were interspecifically variable.
Do novel ecosystems provide habitat value for wildlife? Revisiting the physiognomy vs. floristics debate
Authors: Kennedy Patricia L. , Fontaine Joseph B. , Hobbs Richard J. , Johnson Tracey N. , Boyle Rafeena , Lueders Andrea S.
Published: April 2018

Although novel ecosystems are increasing globally, their utility for biodiversity conservation is poorly understood. Native fauna are predicted to use novel ecosystems when those ecosystems provide structure and resources similar to the native habitat. We modified existing terminology on wildlife functional groups to develop a conceptual model that illustrates fundamental differences in how native wildlife respond to novel ecosystems: novel ecosystem avoiders, novel ecosystem utilizers, and novel ecosystem flourishers. We postulate that species membership in these functional groups is related to the relative importance habitat physiognomy and floristics play in habitat selection cues. An excellent opportunity to test this conceptual model exists with birds in historic and novel ecosystems. A long‐standing, equivocal literature investigating relative contribution of physiognomy vs. floristics to avian abundance and community diversity in native ecosystems exists. Using data from grassland and woodland biomes in western North America (Oregon, USA) and Western Australia, respectively, we evaluated use of habitats by indigenous bird species in relation to physiognomy and floristics. Our two case studies represent two extremes on the novelty spectrum: (1) urban gardens in the metropolitan region of Perth, Western Australia, which are designed ecosystems that vary in the percentage of native plantings; and (2) the Zumwalt Prairie in northeastern Oregon where native grassland plants still dominate the ecosystem but non‐native plants are present and available for use as breeding sites. Using an information‐theoretic perspective, we asked whether habitat use based on occurrence (Perth gardens) or breeding success (Oregon grassland) was best explained by physiognomy, floristics, or both. Using these two case studies, our evidence shows that species or guilds within a community will not respond equally to novelty as predicted. We found strong evidence for only one taxon showing sensitivity to floristics and two to physiognomy. All taxa considered were either grouped as novel ecosystem avoiders or utilizers; no flourishers were identified. These results suggest novel ecosystems providing appropriate physiognomy can provision suitable habitat for some taxa.
Synthesis of Potassium Oligosilanides in Benzene
Authors: Zitz Rainer , Baumgartner Judith , Marschner Christoph
Published: April 2018

Despite the initial assumption that the reaction of methylated oligosilanes, like (Me3Si)4Si, with tBuOK to afford potassium oligosilanides requires ethereal solvents or crown ether, we found that the reaction also proceeds in benzene. However, forced reaction conditions and long reaction times are required to obtain complete conversion. The related reaction of the phenyl‐substituted oligosilane (PhMe2Si)3SiMe proceeds much faster and suggests interaction of the substrate's phenyl groups with the potassium ions, facilitating the reaction. Attempts to accelerate the reaction of methylated oligosilanes by using large excess amounts of tBuOK are successful. However, the silanides formed in this reaction co‐crystallize with tBuOK.
Optical and Electrochemical Study of Acridine‐Based Polyaza Ligands for Anion Sensing
Authors: Bettazzi Francesca , Voccia Diego , Bencini Andrea , Giorgi Claudia , Palchetti Ilaria , Valtancoli Barbara , Conti Luca
Published: April 2018

A variety of transition metal organometallic and coordination receptor systems that can recognize and sense anionic guest species in organic and aqueous media by electrochemical and optical methods have already been reported in literature. In many cases, a redox‐active/photo‐active transition metal reporter group is used. Here, we describe two novel molecules consisting of a polyaza receptor unit for anion coordination and an acridine moiety as signal generating unit for anion sensing. The optical and electrochemical behavior of the two compounds was investigated in order to define novel detection schemes. In this regard, selenium anionic species selenite (SeO32–) and selenate (SeO42–) were chosen as model system.
Visible‐Light‐Promoted Copper‐Catalyzed Regioselective Benzylation of Pyridine N‐Oxides versus Thermal Acylation Reaction with Toluene Derivatives
Authors: Kianmehr Ebrahim , Gholamhosseyni Maral
Published: April 2018

Copper‐catalyzed visible light mediated direct C–H bond benzylation of pyridine N‐oxides with toluene derivatives was accomplished by recent developments in photochemical carbon–carbon bond formation through a photo‐induced bond‐dissociation strategy. This visible light driven protocol has been successfully applied to a broad scope of pyridine N‐oxides and toluene derivatives. Furthermore, preliminary research indicates that the acylation reaction can be carried out under thermal reaction conditions. This protocol provides easy access to 2‐benzyl and 2‐acyl pyridine N‐oxide derivatives in the presence of a copper catalyst.
Synthesis of Bi(hetero)aryls via Sequential Oxidation and Decarboxylation of Benzylamines in a Batch/Fully Automated Continuous Flow Process
Authors: Mahajan Bhushan , Aand Dnyaneshwar , Singh Ajay K.
Published: April 2018

Catalytic dehydrogenative cross‐coupling of two C–H bonds represents a green strategy in view of the atom‐ and step‐economy. However, the challenge is to discover a new innovative bond strategy, especially for the direct coupling between Csp2–H and benzylamines (BzAs). A series of biaryls and bi(hetero)aryls were prepared from commercially available substituted BzAs, AgNO3, cheap K2S2O8 as an oxidant, and benzene/pyridines as the coupling source in batch and flow processes. The batch reaction is somewhat problematic in terms of safety (peroxides, high temperature, high pressure, toxic pyridines), we have chosen an automated flow setup to perform the reaction in a controlled and safe manner in one pot for the synthesis of biaryls. The mechanistic studies revealed that the current protocol involves radical initiation, multi‐step BzA oxidation, and subsequent decarboxylative coupling for the generation of biaryls.
Synthesis of 7‐Membered Ring Carbocycles via a Palladium‐Catalyzed Intramolecular Allylic Alkylation–Isomerization–Cope Rearrangement Cascade
Authors: Tsuruda Kazuki , Tokumoto Takahisa , Inoue Naoya , Nakajima Masaya , Nemoto Tetsuhiro
Published: April 2018

We developed a novel method for synthesizing seven‐membered ring carbocycles via a palladium‐catalyzed intramolecular allylic alkylation–isomerization–Cope rearrangement cascade. Using easily available lactone derivatives as substrates, the target cascade reaction proceeded in the presence of 5 mol‐% of Pd(dba)2 and 6 mol‐% of 1,3‐diphenylphosphinopropane (dppp) in THF, affording a series of seven‐membered ring carbocycles in 59–88 % yield (11 examples). DFT calculations suggested that, in addition to the reaction cascade including the cis‐divinylcyclopropane Cope rearrangement, there is another possible pathway based on the palladium‐catalyzed intramolecular allylic substitution to construct the seven‐membered ring through a retro‐cyclopropanation‐mediated oxidative addition.
Breakthrough cancer pain: The importance of the right treatment at the right time
Authors: O'Hagan P. , Mercadante S.
Published: April 2018

Background

Confusion remains over the definition of breakthrough cancer pain (BTcP) potentially leading to delayed diagnosis and treatment.

Methods

An on‐line survey was conducted in four EU countries among relevant healthcare professionals and cancer patients diagnosed with BTcP. The roles of healthcare professionals (HCPs) were examined and their knowledge and use of available medications recorded. Patients were questioned on how BTcP affected their lives and on the medications they had received/were receiving.

Results

There was a ‘time lag’ of 58 and 13 weeks in Germany and Spain respectively between the initial diagnosis of BTcP and its treatment. Four in ten oncologists across the four countries considered themselves not fully confident in their choice of the appropriate therapy. A quarter of patients in Germany, Italy and Spain and four in ten in France were treated only with increased dosages of the therapy already prescribed for their background pain – often morphine. Almost another quarter received morphine in addition to their treatment for background pain. Oncologists indicated a need for faster‐acting treatments revealing a potential lack of awareness of rapid onset oral opioids and patients expressed a desire for more effective pain relief and better psychological support.

Conclusions

There is a need for a universal definition of BTcP to facilitate earlier and more accurate diagnosis. It is essential that BTcP is treated immediately on diagnosis with therapies that more closely mirror its temporal characteristics to ensure that patients’ desire for more effective pain relief is fulfilled.

Significance

Many cancer patients suffered episodes of BTcP needlessly over many months due to missed diagnosis. Even after diagnosis, many physicians were not fully confident in their choice of ‘rescue’ therapy which perhaps is not surprising given the very low level of awareness of treatment guidelines, both national and international.
Do the potential benefits outweigh the risks? An update on the use of ziconotide in clinical practice
Authors: Bäckryd E.
Published: April 2018

Ziconotide is a selective and potent blocker of N‐type voltage‐gated calcium channels. It was approved by the Food and Drug Administration in 2004 and by the European Medicines Agency in 2005 for the treatment of severe chronic pain in patients needing intrathecal analgesia (ITA). The aim of this paper is to provide a practitioner‐oriented, educational, narrative, up‐to‐date review on the use of ziconotide in clinical pain medicine. Of special concern regarding safety is the partial incongruity between dosing statements in the Summary of Product Characteristics and novel low‐dosage, slow uptitration recommendations. Even though ziconotide has obvious advantages compared to opioids, pain practitioners pondering the use of ziconotide nonetheless have to balance its proved potential analgesic effect against its neurological side effects, with special consideration being given to dosing and neuropsychiatric dangers. Using a seesaw analogy, the paper discusses what factors pain physicians should weigh in when considering ziconotide asITAdrug, the non‐opioid advantages of ziconotide being counterbalanced by its potential psychiatric side effects. Ziconotide is an important part of the armamentarium of modern interventional pain medicine. IfITAis deemed necessary, ziconotide is a rational alternative, at least in chronic (neuropathic) non‐cancer pain. However, in many European countries, ziconotide treatment is only available in a few (if any) centres. The safety profile of ziconotide is not fundamentally more worrying than that of opioids or cannabinoids; it is just different. This paper provides a concise, up‐to‐date and clinically‐oriented summary of the use of ziconotide in clinical practice, not least concerning safety and dosage issues.
Short‐term swimming exercise attenuates the sensitization of dorsal horn neurons in rats with NGF‐induced low back pain
Authors: de Azambuja G. , Hortscht U. , Hoheisel U. , Oliveira Fusaro M.C. , Mense S. , Treede R.‐D.
Published: April 2018

Background

Physical exercise has been shown to be an effective therapy for non‐specific low back pain. The study investigated if swimming exercise is a means to reduce the spinal sensitization in an animal model of non‐specific low back pain.

Methods

In deeply anesthetized rats, dorsal horn neurons were recorded in spinal segment L2. To induce sensitization of dorsal horn neurons, two injections of nerve growth factor were made into the lumbar multifidus muscle at an interval of 5 days. Swimming exercise for 30 min was performed on the 5 days between both NGF injections. A control group received the NGF injections without exercise treatment.

Results

Swimming exercise caused a significant decrease in the NGF‐induced hyperexcitability of dorsal horn neurons. Compared to control, the proportion of neurons with input from deep somatic tissues and of convergent neurons with input from at least two types of different tissues decreased significantly (50% vs. 25% and 37% vs. 15%; both p < 0.05). Swimming exercise also reduced the NGF‐induced increase in neuronal resting activity. Both the proportion of active neurons and the mean discharge frequency of all neurons decreased significantly (60%, 76.3 ± 23.1 imp/min; vs. 25%, 51.7 ± 35.1 imp/min; both p < 0.01).

Conclusions

In our animal model of low back pain, short‐term swimming exercise effectively reduced the latent sensitization of spinal dorsal horn neurons. Swimming exercise decreased the hyperexcitability of the neurons to low back input and lowered the resting activity of sensitized neurons.

Significance

Physical exercise is a common treatment for low back pain. The possible mechanisms underlying the effects of exercise are probably multifold. This work shows that swimming exercise prevents sensitization of dorsal horn neurons, which may be one mechanism for the positive effects of exercise.
Socioeconomic status is not judged equally: Target race shifts standards in interpersonal judgments of SES
Authors: Weeks Matthew
Published: April 2018

Across three studies, respondents made SES judgments of targets varying in Race (White or Black) and SES (Low or High), including global subjective SES, financial success, and educational attainment. As Whites and Blacks are stereotypically associated with upper and lower SES, respectively, the Shifting Standards Model (SSM) of stereotype judgments predicted the pattern of interpersonal objective and subjective judgments. In Study 1, in a between‐subjects design, respondents rated Black targets significantly higher on subjective measures than White targets, even as the targets were rated as comparable on objective measures. Study 2 replicated these effects with a broader range of stimulus materials. In Study 3, the shifting standards effect was replicated using a within‐subjects design, further supporting the effect. The findings support the application of the SSM to race‐based shifts in interpersonal judgments of SES and are discussed regarding their implications for intergroup relations and workplace evaluations.
Multivariate Determination of Total Sugar Content and Ethanol in Bioethanol Production Using Carbon Electrodes Modified with MWCNT/MeOOH and Chemometric Data Treatment
Authors: Cardoso de Sá Acelino , Cipri Andrea , González‐Calabuig Andreu , Stradiotto Nelson Ramos , del Valle Manel
Published: April 2018

This work reports the characterization and application of a voltammetric electronic tongue using an array of glassy carbon electrodes modified with multi‐walled carbon nanotubes containing metal (Pd, Au, Cu) and oxy‐hydroxide nanoparticles (MetalsOOH of Ni, Co) towards the determination of total sugar content in products related with sugarcane‐bioethanol production. The prediction model based on Artificial Neural Networks (ANN) has given satisfactory results for the carbohydrate sum and the obtained response had shown an adequate accuracy. Voltammetric data was first adapted for the computation using the Fast Fourier transform, and results from the electronic tongue approach were compared with use of different electrodes alone. Final performance was better using uniquely the Ni oxy‐hydroxide modified electrode, especially in the quantification of ethanol, a side‐effect of counter‐balancing its interference.
Mechanistic Pathways and Identification of the Electrochemically Generated Oxidation Products of Flavonoid Eriodictyol in the Presence of Glutathione
Authors: Newair Emad F. , Nafady Ayman , Abdel‐Hamid Refat , Al‐Enizi Abdullah M. , Garcia François
Published: April 2018

The metabolic oxidation pathways of dietary flavonoid eriodictyol (Er) are not very well‐probed. In the present work, the electrochemical oxidation behavior of Er was studied in aqueous Britton‐Robinson (B‐R) buffer solution using cyclic voltammetry (CV), chronoamperometry (CA), and bulk‐electrolysis (BE). The oxidation products and reaction pathways of Er in the absence and the presence of glutathione (GSH) were proposed and identified in view of the results obtained by ultra‐high‐performance liquid chromatography coupled with mass spectrometry (UPLC‐MS). In the absence of GSH, eriodictyol shows one quasi‐reversible oxidation process at E1/2=0.305 V, followed by a totally irreversible anodic peak at a more positive potential (Epa=1.05 V vs. Ag/AgCl, 3 M KCl). Putatively, the first process corresponds to the oxidation of the catechol moiety on the B ring of Er while the second one is attributed to the oxidation of the resorcinol moiety on the A ring. In the presence of GSH, however, the anodic oxidation of Er was proposed to be an ECEC‐type mechanism. The Er molecule first underwent a two‐electron oxidation coupled with loss of two‐proton to generate the corresponding quinone, which was either reduced to the original Er molecule by GSH, or further interacted with GSH to produce mono‐ and bi‐ glutathione conjugates of Er. The proposed mechanism was confirmed by digital simulation of the cyclic voltammograms.
Characterization of White Wines by Electrochemical Indexes Obtained Using Carbon Nanotube‐modified Electrodes
Authors: Sánchez Arribas Alberto , Moreno Mónica , Moreno Gabriel A. , Bermejo Esperanza , Zapardiel Antonio , Chicharro Manuel
Published: April 2018

In this study, the development of a fast electroanalytical method for the characterization of wines through the evaluation of their phenolic content has been reported. A critical analysis of the influence of some experimental conditions on the efficient dispersion of carbon nanotubes (CNT) in water was carried out. The selected procedure consisted of: 1) 2.0 mg CNT were dispersed in 4.0 mL of 0.25 % (w/v) PEI solution by ultrasonic treatment of 2000‐J energy; 2) dispersions were centrifuged at 2500 rpm for 20 min and sedimented CNT were subsequently washed with pure water; and 3) recovered CNT were re‐dispersed in 4.0 mL of water by ultrasonic treatment of 2000‐J energy. Glassy carbon electrodes modified with CNT films produced from these dispersions showed excellent electrochemical performance for the detection of different polyphenols usually found in wine using flow injection analysis, with good sensitivity, wide linear range and excellent stability. This behaviour allowed the estimation of total polyphenol content in white wines with a remarkable long‐term stability in the measurements. In addition, different polyphenols fractions, expressed as “electrochemical indexes” (EI), can be obtained just by tuning the detection potential. These EI might be employed as characteristic markers of wines related to grape varietal, with potential application for classification purposes as suggested after the analysis of white wines produced using “verdejo” and “airén” grapes.
A Novel Electrochemical Aptasensor for Carcinoembryonic Antigen Detection Based on Target‐induced Bridge Assembly
Authors: Taghdisi Seyed Mohammad , Danesh Noor Mohammad , Ramezani Mohammad , Emrani Ahmad Sarreshtehdar , Abnous Khalil
Published: April 2018

The present study describes a novel electrochemical aptasensor for detection of carcinoembryonic antigen (CEA), a key cancer biomarker. The sensing strategy relied on the CEA‐induced bridge assembly, as a physical barrier, on the surface of gold electrode, resulting in a significant increase of the sensor sensitivity. Under optimal conditions, the aptasensing platform showed a wide linear range (3 pg/mL to 40 ng/mL) and a low detection limit (0.9 pg/mL). Some possible interfering materials were also assessed and the results indicated that the designed aptasensor had good specificity toward CEA. The quantitation of CEA in the spiked human serum samples confirmed the reliability and applicability of the electrochemical aptasensor. So, the developed sensing method has a potential application in the clinical diagnosis.