bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Photoswitchable Dualsteric Ligand Controlling Receptor Efficacy
Authors: Agnetta Luca , Kauk Michael , Canizal Maria Consuelo Alonso , Messerer Regina , Holzgrabe Ulrike , Hoffmann Carsten , Decker Michael 
Published: May 2017

AbstractThe investigation of the mode and time course of the activation of G‐protein‐coupled receptors (GPCRs), in particular muscarinic acetylcholine (mACh or M) receptors, is still in its infancy despite the tremendous therapeutic relevance of M receptors and GPCRs in general. We herein made use of a dualsteric ligand that can concomitantly interact with the orthosteric, that is, the neurotransmitter, binding site and an allosteric one. We synthetically incorporated a photoswitchable (photochromic) azobenzene moiety. We characterized the photophysical properties of this ligand called BQCAAI and investigated its applicability as a pharmacological tool compound with a set of FRET techniques at the M1 receptor. BQCAAI proved to be an unprecedented molecular tool; it is the first photoswitchable dualsteric ligand, and its activity can be regulated by light. We also applied BQCCAI to investigate the time course of several receptor activation processes.
AibA/AibB Induces an Intramolecular Decarboxylation in Isovalerate Biosynthesis by Myxococcus xanthus
Authors: Bock Tobias , Luxenburger Eva , Hoffmann Judith , Schütza Vlad , Feiler Christian , Müller Rolf , Blankenfeldt Wulf 
Published: May 2017

AbstractIsovaleryl coenzyme A (IV‐CoA) is an important precursor for iso‐fatty acids and lipids. It acts in the development of myxobacteria, which can produce this compound from acetyl‐CoA through alternative IV‐CoA biosynthesis (aib). A central reaction of aib is catalyzed by AibA/AibB, which acts as a cofactor‐free decarboxylase despite belonging to the family of CoA‐transferases. We developed an efficient expression system for AibA/AibB that allowed the determination of high‐resolution crystal structures in complex with different ligands. Through mutational studies, we show that an active‐site cysteine previously proposed to be involved in decarboxylation is not required for activity. Instead, AibA/AibB seems to induce an intramolecular decarboxylation by binding its substrate in a hydrophobic cavity and forcing it into a bent conformation. Our study opens opportunities for synthetic biology studies, since AibA/AibB may be suitable for the production of isobutene, a precursor of biofuels and chemicals.
Synthesis and Trapping of Iminoboranes by M=B/C=N Bond Metathesis
Authors: Nutz Marco , Borthakur Bitupon , Dewhurst Rian D. , Deißenberger Andrea , Dellermann Theresa , Schäfer Marius , Krummenacher Ivo , Phukan Ashwini K. , Braunschweig Holger 
Published: May 2017

AbstractAlthough the metathesis of metal–boron double bonds with elemental chalcogenides is an established process, no similar reactivity has been observed with element–nitrogen bonds. Such a reaction would provide a new route to iminoborane compounds (RB≡NR′), which have recently experienced renewed synthetic interest. Herein, we present the first observation of M=B/C=N metathesis reactions, which led to the isolation of a stable iminoborane in addition to further iminoborane cycloaddition products.
Tricyanomethane and Its Ketenimine Tautomer: Generation from Different Precursors and Analysis in Solution, Argon Matrix, and as a Single Crystal
Authors: Banert Klaus , Chityala Madhu , Hagedorn Manfred , Beckers Helmut , Stüker Tony , Riedel Sebastian , Rüffer Tobias , Lang Heinrich 
Published: May 2017

AbstractSolutions of azidomethylidenemalononitrile were photolyzed at low temperatures to produce the corresponding 2H‐azirine and tricyanomethane, which were analyzed by low‐temperature NMR spectroscopy. The latter product was also observed after short thermolysis of the azide precursor in solution whereas irradiation of the azide isolated in an argon matrix did not lead to tricyanomethane, but to unequivocal detection of the tautomeric ketenimine by IR spectroscopy for the first time. When the long‐known “aquoethereal” greenish phase generated from potassium tricyanomethanide, dilute sulfuric acid, and diethyl ether was rapidly evaporated and sublimed, a mixture of hydronium tricyanomethanide and tricyanomethane was formed instead of the previously claimed ketenimine tautomer. Under special conditions of sublimation, single crystals of tricyanomethane could be isolated, which enabled the analysis of the molecular structure by X‐ray diffraction.
Synthesis of Co(II), Cu(II), Hg(II), UO2(II) and Pb(II) binuclear nanometric complexes from multi‐donor ligand: Spectral, modeling, quantitative structure–activity relationship, docking and antitumor studies
Authors: Al‐Fahemi Jabir H. , Saad Fawaz A. , El‐Metwaly Nashwa M. , Farghaly Thoraya A. , Elghalban Marwa G. , Saleh Kamel A. , Al‐Hazmi Gamil A. 
Published: May 2017

AbstractNew synthesis of Co(II), Cu(II), Hg(II), UO2(II) and Pb(II) binuclear nanometric complexes derived from multi‐donor ligand is reported. Structural and molecular formulae of all isolated complexes were established. Bi‐negative hexa‐dentate mode of ligand was proposed for the two central atoms in all complexes. Infrared, UV–visible, magnetic moments, electron paramagnetic resonance, thermogravimetric analysis and elemental analysis were used to build all structural formulae. X‐ray diffraction and scanning electron microscopy were used to determine the morphological features of the compounds and to compute particle sizes. Theoretical computations were implemented to support the proposed formulae. Kinetic study was executed over suitable stages to clarify the comparative stabilities. The DFT/B3LYP method, using the Gaussian 09 program, was utilized for optimizing the distribution of atoms over all compounds except the UO22+ complex. This exclusion refers to an inability to find a suitable method. Significant parameters were estimated using frontier energies (highest occupied and lowest unoccupied molecular orbitals) and data log file. A quantitative structure–activity relationship study applying HyperChem was executed for the organic compound tautomer forms to give a significant view about their biological character. AutoDock tools 4.2 were used to investigate the biological trend of organic compounds (keto and enol) against three types of proteins. The types were chosen related to in vitro investigation: breast, prostate and liver carcinoma proteins. IC50 values indicated insignificant inhibition activity towards all carcinoma cell lines under investigation, except for the Hg(II) complex which displayed distinct activity against breast carcinoma compared with reference drug (doxorubicin).
Intensified removal of Malachite green by AgOH‐AC nanoparticles combined with ultrasound: Modeling and optimization
Authors: Solaymani Ehsan , Ghaedi Mehrorang , Karimi Hajir , Ahmadi Azqhandi Mohammad Hossein , Asfaram Arash 
Published: May 2017

In this work Random Forest (RF) and Response surface methodology (RSM) were used to model and predict the efficiency of malachite green removal from aqueous solution by ultrasound‐assisted adsorption onto the silver hydroxide nanoparticles loaded on activated carbon (AgOH‐NPs‐AC). The prepared nanoparticles were characterized by SEM, FTIR, XRD and TEM. The parameters such as pH, initial MG concentration, sonication time and adsorbent dosage involved in the adsorption process were set within the ranges 2.0–10, 4–20 mg L−1, 2–6 min and 0.005–0.025 g, respectively. The performance of the RF and CCD models for the description of experimental data was evaluated in terms of the coefficient of determination (R2), the root mean squared error (RMSE), mean absolute error (MAE) and absolute average deviation (AAD). The obtained results showed that the RF model outperformed in comparison to classical statistical model for modeling the process of dye adsorption. Desirability function approach (DFA) and Genetic algorithm (GA) combined central composite design (CCD) as global optimization technique were used for simultaneous optimization of effective factors. GA and DFA were revealed that 20 mg L−1 MG by 0.025 g AgOH‐NPs‐AC at pH = 8.0 and sonication time for 6 min with adsorption capacity 40.98 and 41.99 mg g−1 can be removed, respectively. The equilibrium adsorption data were analyzed by Langmuir Freundlich, Temkin and Dubinin‐Radushkevich isotherm models. The best fit to the data was obtained from the Langmuir model. Meanwhile, the maximum adsorption capacity for MG by 0.01, 0.02 and 0.025 g of AgOH‐NPs‐AC was estimated 57.143, 42.735 and 40.980 mg g−1, respectively. Analysis of experimental adsorption data to various kinetic models shows the applicability of the second‐order equation model. The variable importance principle also shows that RF give maximum importance to sonication time for removal of MG.
DNA interaction and cleavage studies of ancillary chiral ligand and N,N‐donor ligands coordinated platinum(II) complexes
Authors: Rajesh Jegathalaprathaban , Kesavan Mookkandi Palsamy , Ayyanaar Srinivasan , Karthikeyan Kesavan , Rajagopal Gurusamy , Athappan Periyakaruppan 
Published: May 2017

Four new platinum(II) complexes [Pt(dpen)(bpy)](ClO4)2 (1), [Pt(dpen)(phen)](ClO4)2 (2), [Pt(dpen)(dpq)](ClO4)2 (3) and [Pt(dpen)(dppz)](ClO4)2 (4) comprising of different N,N‐donor ligands, viz., 2,2′‐bipyridine (bpy), 1,l0‐phenanthroline (phen), dipyridoquinoxaline (dpq), dipyrido‐[3,2‐d:2¢,3¢‐f–phenazine] (dppz), and chiral ancillary ligand 1R,2R‐1,2‐diphenylethylenediamine (dpen) have been synthesized and characterized. The interaction of these complexes 1–4 with calf‐thymus DNA (CT‐DNA) has been explored using absorption, circular dichroism spectral and cyclic voltammetric studies. The absorption spectrum of complex 4 with dppz ligand exhibits a major red shift with an overall hypochromic as well as a hyperchromic effect in the presence of DNA, other complexes (1–3) show only hypochromism. From these absorption spectral studies, the intercalative ability of the complexes follows the order as, 4 > 3 > 2 > 1, which is further confirmed by CD and cyclic voltammetry measurements. CD spectral studies show that DNA becomes more A‐like upon interaction with the complexes 1 & 2 but the complexes 3 & 4 bring about B‐form to Z‐ form DNA conformational transition. The DNA cleavage study of these Pt(II) complexes 1–4 carried out by gel electrophoresis revealed that complexes 1–4 can cleave super coiled (SC) pUC18 DNA efficiently into open circular form (form II) under hydrolytic and oxidative conditions.
An investigation of thermal and tribological behaviors of PTFE‐based silicon composites filled with AlN and flake graphite particles
Authors: Xi Xiang , Xia Yan‐Qiu 
Published: May 2017

ABSTRACTThe thermal and tribological properties of silicon composites were improved by choosing polytetrafluoroethylene (PTFE) as a thickener and alumina nitride (AlN) and flake graphite (FG) as thermal conductive additives, producing AlN‐modified, FG‐modified, and AlN/FG‐modified PTFE‐based thermal silicon composites (AlN–PTSC, FG–PTSC, and AlN/FG–PTSC, respectively). Three‐dimensional network‐configuration representative volume element models were built to investigate the thermal properties of these composites by applying a Monte Carlo, controllable, spatial distribution algorithm. The composites’ thermal conductivity and volume resistance were also measured. Tribological tests were conducted using a ball‐on‐disk reciprocating friction and wear tester. Scanning electron microscopy and energy dispersive spectroscopy were used to analyze the morphologies and elements of worn surfaces. The results showed that AlN/FG–PTSC possessed the best thermal properties, which were ascribed to a compact thermal conductive network; thermal conductivity was 88.8% and 44.8% greater than the highest value of AlN–PTSC and FG–PTSC, respectively. The numerical values of thermal conductivity were in a good agreement with experimental results. The optimal electrical tribological properties of AlN/FG–PTSC were ascribed to the functions of thermal and electrical properties combined, which could be helpful in abating the arc erosion on friction contacts. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 45263.
Encapsulation of salicylic acid in acylated low molecular weight chitosan for sustained release topical application
Authors: Tiew Shu Xian , Misran Misni 
Published: May 2017

ABSTRACTAcylated low molecular weight chitosan was used to encapsulate salicylic acid (SA) for sustained release in topical delivery. Chitosan nanoparticles were prepared from the depolymerization of commercial chitosan and further acylated with short alkyl chains. The successful acylation of butyryl chitosan [low molecular weight chitosan (LMWC)‐B] were proved by Fourier transform infrared (FTIR) and 1H‐NMR. Successful encapsulation of SA was observed by the shift of amide I band from 1648 cm−1 in LMWC‐B to 1641–1633 cm−1 in SA‐loaded LMWC‐B in FTIR analysis, which further confirmed with the size increment from dynamic light scattering and transmission electron microscopy analyses by comparing its unencapsulated LMWC‐B. SA release from LMWC‐B studied by Franz diffusion experiment followed Korsmeyer–Peppas model where the release component n value (0.502) indicated diffusion and polymer swelling were involved in release mechanism. The slow release study of SA showed the acylated chitosan exhibited sustained release property toward SA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45273.
On‐demand Antimicrobial Treatment with Antibiotic‐Loaded Porous Silicon Capped with a pH‐Responsive Dual Plasma Polymer Barrier
Authors: Vasani Roshan B. , Szili Endre J. , Rajeev Gayathri , Voelcker Nicolas H. 
Published: May 2017

AbstractChronic wounds are a major socio‐economic problem. Bacterial infections in such wounds are a major contributor to lack of wound healing. An early indicator of wound infection is an increase in pH of the wound fluid. Herein, we describe the development of a pH‐responsive drug delivery device that can potentially be used for wound decontamination in situ and on‐demand in response to an increase in the pH of the wound environment. The device is based on a porous silicon film that provides a reservoir for encapsulation of an antibiotic within the pores. Loaded porous silicon is capped with dual plasma polymer layers of poly(1,7‐octadiene) and poly(acrylic acid), which provide a pH‐responsive barrier for on‐demand release of the antibiotic. We demonstrate that release of the antibiotic is inhibited in aqueous buffer at pH 5, whereas the drug is released in a sustainable manner at pH 8. Importantly, the released drug was bacteriostatic against the Pseudomonas aeruginosa wound pathogen. In the future, incorporation of the delivery device into wound dressings could potentially be utilized for non‐invasive decontamination of wounds.
Remembering Friends as Not So Friendly in Competitive and Bargaining Social Interactions
Authors: Danziger Shai , Disatnik David , Shani Yaniv 
Published: May 2017

AbstractFrom children's schoolyard play to executives' boardroom negotiations, competitive and bargaining interactions are common to everyday life. Sometimes, the interacting parties are socially close and sometimes not. In this research, we examine how friendship influences memory for actions in such interactions. Dyads consisting of either friends or strangers played a competitive card game (Study 1) or the ultimatum game (Studies 2 and 4) and then recalled the interaction. We find that participants remembered friends' play as more competitive (Study 1) and less generous (Studies 2 and 4) than strangers' play, even when friends' actual play was more generous than that of strangers (Studies 2 and 4). Friendship did not affect recall for one's own play. In a workplace setting, Study 3 reveals people expect more of work colleagues who are friends than of work colleagues who are acquaintances. Study 4 tests our complete model and shows that people expect more of friends than of strangers and that this difference in expectations explains the less favorable memory for friend's actions. Our findings are consistent with a negative disconfirmation account whereby people expect their friends to be less competitive and more generous, and when these expectations are violated, people remember friends' actions more negatively than they actually were. Much research shows positive effects of friendship norms on actual behavior. We demonstrate a negative effect on people's memory of friends' behavior in competitive and bargaining social interactions. Copyright © 2017 John Wiley & Sons, Ltd.
Convergent mechanisms favor fast amyloid formation in two lambda 6a Ig light chain mutants
Authors: Valdés‐García Gilberto , Millán-Pacheco César , Pastor Nina 
Published: May 2017

AbstractExtracellular deposition as amyloids of immunoglobulin light chains causes light chain amyloidosis. Among the light chain families, lambda 6a is one of the most frequent in light chain amyloidosis patients. Its germline protein, 6aJL2, and point mutants, R24G and P7S, are good models to study fibrillogenesis, because their stability and fibril formation characteristics have been described. Both mutations make the germline protein unstable and speed up its ability to aggregate. To date, there is no molecular mechanism that explains how these differences in amyloidogenesis can arise from a single mutation. To look into the structural and dynamical differences in the native state of these proteins, we carried out molecular dynamics simulations at room temperature. Despite the structural similarity of the germline protein and the mutants, we found differences in their dynamical signatures that explain the mutants’ increased tendency to form amyloids. The contact network alterations caused by the mutations, though different, converge in affecting two anti‐aggregation motifs present in light chain variable domains, suggesting a different starting point for aggregation in lambda chains compared to kappa chains.
Stories that move them: Changing children's behaviour toward diverse peers
Authors: McKeown Shelley , Williams Amanda , Pauker Kristin 
Published: May 2017

AbstractGlobally, our social worlds are becoming increasingly racially and ethnically diverse. Despite this, little attention has been given to how children negotiate this diversity. In this study, we examine whether a value‐in‐diversity storybook intervention encourages young children to engage in intergroup contact with racially diverse peers. The lunchroom seating behaviour of 4‐ to 6‐year olds attending 3 racially diverse primary schools was recorded at 3 different points during a 1‐week period. Seating behaviour was coded based on the race of the children, and levels of segregation were calculated. Before hearing the story, we observed racial self‐segregation; the children were more likely to sit with same‐race peers. However, immediately following the story, the children were no longer significantly racially segregated. This effect was not maintained; up to 48 hr later, the children again showed evidence of racial self‐segregation. Our findings suggest that exposure to racially diverse peers alone is not sufficient for promoting intergroup contact. We argue that it is vital to develop sustainable teacher‐led interventions if we are to harness the potential of diverse school settings for bolstering intergroup relations.
From tolerance to understanding: Exploring the development of intercultural competence in multiethnic contexts from early to late adolescence
Authors: Schwarzenthal Miriam , Juang Linda P. , Schachner Maja K. , van de Vijver Fons J.R. , Handrick Anna 
Published: May 2017

AbstractWe investigated intercultural competence among immigrant and non‐immigrant background adolescents in multiethnic schools in relation to intercultural contact, age, and ethnic identity exploration. The sample included 631 adolescents in Germany (49.4% of immigrant background, 48.2% female), aged 11 to 18 years (Mage = 13.69 years, SDage = 1.83). Intercultural competence was measured using a self‐report questionnaire and situational judgment tests capturing the adolescents' interpretation of and reaction to intercultural conflicts. Intercultural contacts and ethnic identity exploration were measured using self‐report questionnaires. Results showed that among immigrant and non‐immigrant background adolescents, intercultural contact and ethnic identity exploration were positively related to different aspects of intercultural competence. As predicted, self‐reported intercultural competence was unrelated to age in both groups, whereas this competence, as measured by the situational judgment tests, increased with age. Thus, learning about others (e.g., by engaging in intercultural contact) and learning about yourself (e.g., by exploring your own ethnic background) are both important for developing pivotal intercultural skills.
Passive Membrane Penetration of the Serotonin Precursor 5‐Hydroxytryptophan is Controlled by Its Zwitterion
Authors: Mazák Károly , Noszál Béla 
Published: May 2017

Species‐specific partition coefficients in the octanol/water system were determined for the neurotransmitter serotonin (5‐HT) and its precursor 5‐hydroxytryptophan (5‐HTP). The pH‐independent partition coefficients (p) of the individual microspecies were determined by combination of experimentally measured distribution constants and a custom‐tailored evaluation method, using highly similar auxiliary compounds. Experimental microscopic partition coefficients for triprotic molecules have only been reported before for thyroxine and its derivatives. The parabolic pH‐distribution profile of 5‐HT shows the dominance of the lipophilic non‐charged microspecies, with a log p of 0.66. However, the most lipophilic non‐charged form of 5‐HTP, with a log p of 0.31, has no significant contribution to the distribution coefficient at any pH value. Instead, the less lipophilic zwitterionic protonation isomer dominates the distribution in the pH range 2.10 – 11.11. Although the non‐charged microspecies of 5‐HTP is 151 times more lipophilic than its zwitterionic protonation isomer, the overwhelming dominance of the zwitterionic form ensures that its contribution to the overall lipophilicity exceeds 1320 times that of the non‐charged one. This fact is another counter‐example of the widespread belief that passive diffusion into lipophilic media is predominated by the non‐charged species. The lipophilicity profile of 5‐HT and 5‐HTP is depicted in terms of species‐specific lipophilicities.
Quantitative Assessment of Sialo‐Glycoproteins and N‐Glycans during Cardiomyogenic Differentiation of Human Induced Pluripotent Stem Cells
Authors: Konze Sarah A. , Cajic Samanta , Oberbeck Astrid , Hennig René , Pich Andreas , Rapp Erdmann , Buettner Falk F. R. 
Published: May 2017

AbstractHuman induced pluripotent stem‐cell‐derived cardiomyocytes (hiPSC CMs) may be used in regenerative medicine for individualized tissue transplants in the future. For application in patients, the generated CMs have to be highly pure and well characterized. In order to overcome the prevalent scarcity of CM‐specific markers, we quantitatively assessed cell‐surface‐exposed sialo‐glycoproteins and N‐glycans of hiPSCs, CM progenitors, and CMs. Applying a combination of metabolic labeling and specific sialo‐glycoprotein capture, we could highly enrich and quantify membrane proteins during cardiomyogenic differentiation. Among them we identified a number of novel, putative biomarkers for hiPSC CMs. Analysis of the N‐glycome by capillary gel electrophoresis revealed three novel structures comprising β1,3‐linked galactose, α2,6‐linked sialic acid and complex fucosylation; these were highly specific for hiPSCs. Bisecting GlcNAc structures strongly increased during differentiation, and we propose that they are characteristic of early, immature CMs.