bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low‐Coordinated Titanium(III) Alkyl—Molecular and Surface—Complexes: Detailed Structure from Advanced EPR Spectroscopy
Authors: Allouche Florian , Klose Daniel , Gordon Christopher P. , Ashuiev Anton , Wörle Michael , Kalendra Vidmantas , Mougel Victor , Copéret Christophe , Jeschke Gunnar 
Published: June 2018

AbstractThe structure of paramagnetic surface species is notoriously difficult to determine. For TiIII centers related to Ziegler–Natta catalysis, we demonstrate here that detailed structural information can be obtained by advanced EPR spectroscopy and DFT computations, benchmarked on molecular analogs. The hyperfine sublevel correlation (HYSCORE) spectra obtained after reaction with 13C‐labeled ethylene provides information about the coupling with a proton in the first coordination sphere of TiIII as well as significant 13C hyperfine coupling and thereby allows structural assignment of the surface species.
Copper(II) and Sodium(I) Complexes based on 3,7‐Diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide: Synthesis, Characterization, and Catalytic Activity
Authors: Mahmoud Abdallah G. , Guedes da Silva M. Fátima C. , Śliwa Ewelina I. , Smoleński Piotr , Kuznetsov Maxim L. , Pombeiro Armando J. L. 
Published: June 2018

AbstractThe reaction of 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane (DAPTA) with metal salts of CuII or NaI/NiII under mild conditions led to the oxidized phosphane derivative 3,7‐diacetyl‐1,3,7‐triaza‐5‐phosphabicyclo[3.3.1]nonane‐5‐oxide (DAPTA=O) and to the first examples of metal complexes based on the DAPTA=O ligand, that is, [CuII(μ‐CH3COO)2(κO‐DAPTA=O)]2 (1) and [Na(1κOO′;2κO‐DAPTA=O)(MeOH)]2(BPh4)2 (2). The catalytic activity of 1 was tested in the Henry reaction and for the aerobic 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO)‐mediated oxidation of benzyl alcohol. Compound 1 was also evaluated as a model system for the catechol oxidase enzyme by using 3,5‐di‐tert‐butylcatechol as the substrate. The kinetic data fitted the Michaelis–Menten equation and enabled the obtainment of a rate constant for the catalytic reaction; this rate constant is among the highest obtained for this substrate with the use of dinuclear CuII complexes. DFT calculations discarded a bridging mode binding type of the substrate and suggested a mixed‐valence CuII/CuI complex intermediate, in which the spin electron density is mostly concentrated at one of the Cu atoms and at the organic ligand.
Analysis of terizidone in plasma using HPLC‐UV method and its application in a pharmacokinetic study of patients with drug‐resistant tuberculosis
Authors: Mulubwa Mwila , Mugabo Pierre 
Published: June 2018

AbstractA chromatographic method has been developed and validated for the first time for analysis of terizidone in plasma. Terizidone was extracted from plasma by protein precipitation using a mixture of acetonitrile and methanol (1:1, v/v). The chromatographic separation was achieved with a gradient of acetonitrile and water both containing 0.1% formic acid on a Supelco Discovery® HS C18 (150 × 4.6 mm, 5 μm) reversed‐phase column. Propranolol was used as the internal standard. The total run‐time was 18 min. The calibration standard concentrations ranged between 3.125 and 200 μg/mL and calibration curves were linear with coefficient of determination values in the range of 0.9988–0.9999. The inter‐ and intra‐day assay precision (percentage relative standard error) was <15% while mean accuracy was 107%. The mean extraction efficiencies of terizidone and IS were 76 and 89%, respectively. The validation results demonstrated that the method was selective and sensitive, and that terizidone was stable under the studied conditions. The method was successfully applied in a population pharmacokinetic study. The mean plasma concentration of terizidone in patients at all sampling time points was 51.8 ± 28 μg/mL. The method was simple, cheap and hence suitable for therapeutic drug monitoring of terizidone.
Highly Efficient Cell‐Penetrating Probes of Protein Arginine Deiminases for Functional Proteomics
Authors: Kumar Sanjai 
Published: June 2018

AbstractProtein arginine deiminases (PADs) have recently emerged at the forefront of drug‐discovery programs for several human disorders. Despite this, a precise understanding of their functional roles in human biology remains to be fully elucidated. This report highlights a recent development of next‐generation activity‐based PAD probes that are highly efficient, cell active, and metabolically stable. This discovery should rapidly expedite functional assignments of PAD biology in both normal and diseased cells, thereby leading to the development of PAD‐targeted therapeutics in the near future.
Characterization and Reshaping of a Large and Hydrophobic Nucleophile Pocket in Lipases/Acyltransferases
Authors: Jan Deniau Anne‐Hélène , Subileau Maeva , Dubreucq Eric 
Published: June 2018

AbstractLipases/acyltransferases, such as CpLIP2 from Candida parapsilosis and CduLAc from Candida dubliniensis, catalyze acyl transfer preferentially over hydrolysis if a suitable nucleophile is present, even in a medium with a high thermodynamic activity of water (aW). These enzymes are related to CAL‐A from Moesziomyces antarcticus, which, in comparison, displays a lower acyl transfer ability. The 3D structures of wild types and mutants of CAL‐A, CpLIP2, and CduLAc revealed differences in size and hydrophobicity of a large pocket located under the catalytic triad. The kinetic behavior of site‐directed mutants confirmed the role of this pocket in competition between methanol and water as the nucleophile acceptor for the deacylation step. The mutations provided a better understanding of key structural determinants for variable levels of acyltransferase ability observed and supported the existence of a complex network of nucleophile interactions within the enzymes. The shape and size of the possible nucleophile pocket identified also suggested that multiple binding sites could exist, which supported the hypothesis of non‐overlapping leaving and accepting nucleophile binding sites.
A Split‐Intein‐Based Method for the Efficient Production of Circularized Nanodiscs for Structural Studies of Membrane Proteins
Authors: Miehling Jonas , Goricanec David , Hagn Franz 
Published: June 2018

AbstractPhospholipid nanodiscs are a native‐like membrane mimetic that is suitable for structural studies of membrane proteins. Although nanodiscs of different sizes exist for various structural applications, their thermal and long‐term stability can vary considerably. Covalently circularized nanodiscs are a perfect tool to overcome these limitations. Existing methods for the production of circularized nanodiscs can be time‐consuming and technically demanding. Therefore, an easy in vivo approach, in which circularized membrane scaffold proteins (MSPs) can be directly obtained from Escherichia coli culture, is reported herein. Nostoc punctiforme DnaE split‐intein fusions with MSPs of various lengths are used and consistently provide circularized nanodiscs in high yields. With this approach, a large variety of circularized nanodiscs, ranging from 7 to 26 nm in diameter, that are suitable for NMR spectroscopy and electron microscopy (EM) applications can be prepared. These nanodiscs are superior to those of the corresponding linear versions in terms of stability and size homogeneity, which affects the quality of NMR spectroscopy data and EM experiments. Due to their long‐term stability and homogeneity, the presented small circular nanodiscs are suited for high‐resolution NMR spectroscopy studies, as demonstrated with two membrane proteins of 17 or 32 kDa in size. The presented method will provide easy access to circularized nanodiscs for structural studies of membrane proteins and for applications in which a defined and stable nanodisc size is required.
Dynamic Motion of Organic Ligands in Polar Layered Cobalt Phosphonates
Authors: Cai Zhong‐Sheng , Hoshino Norihisa , Bao Song‐Song , Jia Jiage , Akutagawa Tomoyuki , Zheng Li‐Min 
Published: June 2018

AbstractBy introducing the polar methoxy group into phenyl‐ or benzyl‐phosphonate ligands, four cobalt phosphonates with layered structures are obtained, namely, [Co(4‐mopp)(H2O)] (1), [Co(4‐mobp)(H2O)] (2), [Co(3‐mopp)(H2O)] (3), and [Co(3‐mobp)(H2O)] (4), where 4‐ or 3‐moppH2 is (4‐ or 3‐methoxyphenyl)phosphonic acid and 4‐ or 3‐mobpH2 is (4‐ or 3‐methoxybenzyl)phosphonic acid. Compounds 1, 2, and 4 crystallize in the polar space groups Pmn21 or Pna21, whereas compound 3 crystallizes in the centrosymmetric space group P21/n. The layer topologies in the four structures are similar and can be viewed as perovskite type, where the edge‐sharing [Co4O4] rhombi are capped by the PO3C groups. The phenyl and MeO groups in compounds 1–3 are heavily disordered, whereas that in 4 is ordered. Structural comparison based on the data at 296 and 123 K reveals distinct dynamic motion of the organic groups in compounds 1 and 2. The fluctuation of the polar MeO groups in these two compounds is confirmed by dielectric relaxation measurements. In contrast, the fluctuation of polar groups in compounds 3 and 4 is not evident. Interestingly, the dehydrated samples of 3 and 4 (i.e., 3‐de and 4‐de) exhibit one‐step and two‐step phase transitions associated with the motion of polar organic groups, as proven by DSC and dielectric measurements. The magnetic properties of compounds 1–4 are investigated, and strong antiferromagnetic interactions are found to mediate between the magnetic centers through μ‐O(P) and O‐P‐O bridges.
Charge‐ and Size‐Complementary Multimetal‐Induced Morphology and Phase Control in Zeolite‐Type Metal Chalcogenides
Authors: Chen Xitong , Bu Xianhui , Wang Yuan , Lin Qipu , Feng Pingyun 
Published: June 2018

AbstractZeolite‐type chalcogenides are desirable due to their integration between porosity and semiconductivity. CPM‐120, with super‐sodalite topology (Zeolite Structure Code: RWY), is among the few zeolite‐type chalcogenides with permanent porosity, and is the only chalcogenide with a zeolite code. Importantly, the RWY‐type has evolved into a platform for studying properties of porous chalcogenides. Yet so far, few studies have been made to probe the effects of synthetic parameters and framework compositions on this platform. Here, we probe the effects of the third metal type (Ga3+, In3+, Cd2+, and Sn4+) on the Zn2+/Ge4+/S2− platform. We find that charge‐complementary and size‐compatible Ga3+ leads to the synthesis of CPM‐120‐ZnGaGeS which is the first trimetallic zeolite‐type chalcogenide, with improved crystal morphology and reproducibility. We also find that charge‐compatible and size‐complementary cations (Cd2+ or Sn4+) can induce an abrupt phase transition from super‐sodalite to super‐diamond, also with unprecedented trimetallic T2 clusters. For In3+, which is dual‐complementary (charge and size), a gradual phase transition is observed with increasing In3+ amount. Furthermore, by controlling the cluster composition, tunable band gaps can be realized. These materials show promising properties such as high CO2 uptake (4.32 mmol cm−3, 298 K, 1 bar) and high photocatalytic activity.
Ultrafine FeCu Alloy Nanoparticles Magnetically Immobilized in Amine‐Rich Silica Spheres for Dehalogenation‐Proof Hydrogenation of Nitroarenes
Authors: Bao Hongjie , Li Yunong , Liu Lei , Ai Yongjian , Zhou Junjie , Qi Li , Jiang Ruihang , Hu Zenan , Wang Jingting , Sun Hongbin , Liang Qionglin 
Published: June 2018

AbstractA novel core–shell structured nanocatalyst (Fe3O4@SiO2‐NH2‐FeCu nanoparticles) with ultrafine FeCu alloy NPs magnetically immobilized in porous silica has been fabricated. The obtained catalyst revealed excellent activity and chemoselectivity for catalyzing the hydrogenation of nitroarenes to corresponding anilines using hydrazine hydrate as the hydrogen source, and the reaction could be carried out smoothly in water, which is an environmentally friendly solvent. The FeCu alloy effectively prevented the dehalogenation of halonitroarenes, and X‐ray photoelectron spectroscopy (XPS) study showed that it resulted from the electron‐enrichment of Fe from Cu. A kinetics study indicated that the reaction order was about 1.5 towards 4‐CNB and the apparent active energy (Ea) was 48.1 kJ mol−1, which is a relatively low value. Furthermore, the FeCu NPs are magnetically immobilized in the silica spheres (Fe3O4@SiO2), therefore the catalyst can be easily recovered by use of an external magnet and also possesses a long life time.
Absorption Spectroscopy and Photophysics of a ReI‐dppz Probe for DNA‐Mediated Charge Transport
Authors: Fumanal Maria , Vela Sergi , Gattuso Hugo , Monari Antonio , Daniel Chantal 
Published: June 2018

AbstractOptical properties of [Re(CO)3(dppz)(py)]+ (dppz=dipyrido[3,2‐a:2′,3′‐c]phenazine; py=pyridine) in acetonitrile, water and DNA have been investigated based on DFT, time‐dependent‐DFT (TD‐DFT)/ conductor‐like screening model, with and without explicit solvent molecules, and molecular dynamics. Whereas implicit solvent model is not appropriate to model optical properties of dppz‐substituted metal complexes, adding explicit solvent molecules in interaction with dppz stabilizes the metal‐to‐ligand‐charge‐transfer (MLCT) transitions. Classical molecular dynamics simulations point to an important conformational flexibility, as evidenced by the coexistence of two conformers A and B. When considering the conformational sampling, the lowest band of the absorption spectrum is red‐shifted and broadened up to 500 nm in agreement with the experimental spectra supporting important dynamical effects. The absorption spectra of [Re(CO)3(dppz)(py‐R)]+/GC‐DNA and [Re(CO)3(dppz)(py‐R)]+/AT‐DNA (R=CH2‐CH2‐COO−) intercalated in both major or minor grooves exhibit a lowest energy charge separated (CS) band at about 600 nm and 500 nm, respectively, corresponding mainly to excitations from guanine and adenine to dppz. These states may play a central role into DNA‐mediated charge transport processes. The over stabilization of the lowest 3ILdppz state of [Re(CO)3(dppz)(py)]+ in water as compared to acetonitrile could be responsible for the quenching of emission in water.
Advances in Native Chemical Ligation–Desulfurization: A Powerful Strategy for Peptide and Protein Synthesis
Authors: Jin Kang , Li Xuechen 
Published: June 2018

AbstractCysteine‐based native chemical ligation (NCL) has been a very powerful approach for convergent synthesis of peptides and proteins. However, owing to the low abundance of cysteine (Cys) in proteins, applications of NCL in protein chemical synthesis are limited. To expand the peptide ligation toolbox, NCL followed by desulfurization has been developed to enable peptide ligation at Xaa‐Ala conjunctions, that is, formal “alanine ligation”. In this regard, effective peptide desulfurization methods are critical. This Concept article summarizes the development of different desulfurization strategies for peptide and protein chemical synthesis.
Azaacenes Bearing Five‐Membered Rings
Authors: Ganschow Michael , Koser Silke , Hodecker Manuel , Rominger Frank , Freudenberg Jan , Dreuw Andreas , Bunz Uwe H. F. 
Published: June 2018

AbstractWe report the synthesis of processible (dihydro)pyracyclene‐ and acenaphthylene‐substituted azaacenes using condensation reactions in solution. The targets are characterized via cyclic voltammetry, X‐ray crystallography, UV/Vis, fluorescence spectroscopy and DFT/NICS calculations. Formal hydrogenation of the annulated five‐membered ring surprisingly alters emission in the solid‐state as a consequence of modulation of aromaticity and HOMO–LUMO overlap. Five highly fluorescent, crystalline azaacenes were investigated as emitters in organic light‐emitting diodes, and their performance with respect to luminance and efficiency was compared to that of structurally related azaacenes.
Comparative Bioavailability of Sildenafil 50‐mg Film‐Coated Tablets and 50‐mg Orally Disintegrating Films in Healthy Mexican Subjects: Results From a Randomized, Open‐Label, Crossover Study
Authors: Aguirre Luis García , Olmedo Isabel Ruiz , Nolasco Araceli Medina , Romo Yamanqui Ibáñez , Reyes Liz Medina , Hernández Dolores Adriana Aguilera , Vargas Ana Laura Rojas 
Published: June 2018

AbstractAn orally disintegrating film formulation of sildenafil 50 mg (CL Pharm Co, Ltd) was used in this study and compared to the market‐available product film coated tablets (Viagra®, Pfizer, Mexico). The objective was to compare the pharmacokinetic properties of these products after a single‐dose administration to 47 healthy male volunteers (aged 19‐48 years) in a randomized, open‐label, 2‐way crossover study. Each subject received a single oral dose of 50 mg of sildenafil test or reference product administered under fasting conditions at each of the 2 study periods according to a crossover design. There was a 3‐day washout period between drug administrations. Blood samples for pharmacokinetic analysis were collected predose and at different times postdosing. The maximum plasma concentration and area under the curve from administration to last observed concentration time of test and reference products were compared. Pharmacokinetic parameters shown to be within the confidence interval 80% to 125% for log‐transformed data and Shuirmann and Anderson Hauck tests showed a high probability that area under the curve values for the test product were within 80% to 125% (P < .05). Adverse events occurred at similar rates for the 2 formulations (8 for each product), headache being the most prevalent. The results suggest that the 2 sildenafil formulations, orally disintegrating films and film‐coated tablets, are similar in terms of bioavailability, making the test product a good alternative to treat erectile dysfunction and improving dosing convenience.
Experiences of a transdiagnostic group, the Take Control Course, for clients with common mental health problems: A qualitative study
Authors: Morris Lydia , Mansell Warren , Amos Rebekah , Edge Dawn 
Published: June 2018

AbstractObjectivesDespite the promising effectiveness findings for transdiagnostic groups, studies have not explored clients' experiences. There is a risk that clients could perceive that the content of transdiagnostic groups is not sufficiently tailored to their specific problems. Our aims were to examine whether a brief transdiagnostic group, the Take Control Course (TCC), was acceptable to participants and to explore participants' perceptions of psychological change.MethodsQualitative data were collected via 12 semistructured, in‐depth interviews. Data collection and thematic analysis were concurrent and iterative.ResultsThree superordinate themes were identified: “Style and format,” “Control and flexibility,” and “Change.” The flexible group format was appreciated, as participants felt able to engage at their own pace and adapt relevant aspects. Greater clarity regarding what was within participants' control reduced distress and enabled effective pursuit of valued goals. Participants described significant (predominantly gradual) changes, including substantial improvements within relationships.ConclusionsThe transdiagnostic format did not prevent participants experiencing the TCC as individually relevant. The flexibility and consistent theoretical framework seemed to contribute to this. The results indicated that greater consideration of control and mindfulness allowed greater cognitive flexibility, an ability to reprioritize and let go of unhelpful habits, which better enabled participants to meet their goals. Implications for group therapy include (a) clearly explaining the format of such groups to clients and (b) providing flexibility in the way the group is delivered where possible. Additional qualitative studies of transdiagnostic groups are required to establish if themes generalize to other transdiagnostic groups.
Salmon‐supported bears, seed dispersal, and extensive resource subsidies to granivores
Authors: Shakeri Yasaman N. , White Kevin S. , Levi Taal 
Published: June 2018

AbstractIn salmon‐rich environments, which once spanned much of the Northern Hemisphere, bears occur at exceptionally high densities. Salmon, by growing bear populations, have the potential to exert wide‐ranging effects on ecosystem processes. Salmon‐supported bears provide seed dispersal services to plants, and bear scats containing thousands of seeds may then be efficient nutritional resources for granivorous small mammals that also function as secondary seed dispersers while hoarding seeds for winter. We taxonomically identified and enumerated seeds in individual bear scats to characterize patterns of bear frugivory. We then combined estimates of seed abundance and digestible energy content to quantify the energy available to granivorous small mammals, and we quantified the proportion of the mouse population that could be supported by locally abundant bear populations in lowland salmon systems. We additionally monitored seed‐filled bear scats with remote cameras to quantify small mammal visitation rates, and live‐trapped small mammals seasonally to determine whether rodents visited bear scats proportional to their densities or whether some species preferentially selected for bear scats, and to assess whether seasonal variation in scat visitation was driven by density or selection. Bears were an important initial dispersal agent for 12 species of fruit, particularly devil's club (Oplopanax horridus) and blueberry (Vaccinium spp.), which occurred in 80% (5839 seeds/scat) and 50% (10,719 seeds/scat) of scats, respectively. Seeds in bear scats were intensively utilized and dispersed by small mammals, primarily scatter‐hoarding northwestern deer mice (Peromyscus keeni; 8.5 visits per day/4295 total visits) and larder‐hoarding northern red‐backed voles (Myodes rutilus; 2.2 visits per day/1099 total visits), with visitation rates proportional to the seasonal density of each species. Small mammals likely incurred significant nutritional benefits from seeds deposited in bear scats (kcal/scat, mean = 114, n = 71). In coastal Alaska riparian areas, bears are potentially capable of indirectly subsidizing the energy needs of 45–65% of local deer mouse populations. Thus, this work helps elucidate the role that salmon, by supporting abundant bears, plays in ecological communities via influencing seed dispersal and resource subsidies to the small mammals that compose the base of the food web.
Recent spring warming limits near‐treeline deciduous and evergreen alpine dwarf shrub growth
Authors: Weijers Stef , Beckers Niklas , Löffler Jörg 
Published: June 2018

AbstractWarming may lead to a cover increase of tundra shrubs and a north‐ and upward shift of treelines. The latter may be inhibited by a densification of shrub stands. However, the climatic drivers of near‐treeline shrub growth are relatively unexplored, especially that of shrub species from different functional groups growing intertwined, in competition for light and resources. We measured ring widths from two dominant dwarf shrubs species, the deciduous Betula nana and the evergreen Empetrum nigrum ssp. hermaphroditum from a near‐treeline alpine ridge in the Central Norwegian Scandes, and tested the influence of on‐site and regional climate, and changes therein, over the past 55 yr. Radial growth of B. nana was found to be negatively influenced by early summer (June–July) precipitation, possibly related to low amounts of photosynthetically active radiation and nitrogen leaching, and positively by July temperatures. That of E. hermaphroditum was positively correlated with late summer (July–August) temperatures. In recent decades, the influence of summer climate on both species’ growth has declined and been replaced by a negative influence of May temperatures. Rising spring temperatures in recent decades have likely advanced key phenology events in B. nana and E. hermaphroditum, such as budburst and flowering. This may have left the shrubs’ soft tissues vulnerable to late frost events, which in recent decades occur more frequently after the advanced start of the growing season, resulting in suppressed growth.