bluuebunny/crossref_metadata_2025_split huggingface dataset:
Excited‐State Dynamics of Thienoguanosine, an Isomorphic Highly Fluorescent Analogue of Guanosine
Authors: Martinez‐Fernandez Lara , Gavvala Krishna , Sharma Rajans , Didier Pascal , Richert Ludovic , Segarra Martì Javier , Mori Mattia , Mely Yves , Improta Roberto 
Published: March 2019

AbstractThienoguanosine (thG) is an isomorphic analogue of guanosine with promising potentialities as fluorescent DNA label. As a free probe in protic solvents, thG exists in two tautomeric forms, identified as the H1, being the only one observed in nonprotic solvents, and H3 keto–amino tautomers. We herein investigate the photophysics of thG in solvents of different polarity, from water to dioxane, by combining time‐resolved fluorescence with PCM/TD‐DFT and CASSCF calculations. Fluorescence lifetimes of 14.5–20.5 and 7–13 ns were observed for the H1 and H3 tautomers, respectively, in the tested solvents. In methanol and ethanol, an additional fluorescent decay lifetime (≈3 ns) at the blue emission side (λ≈430 nm) as well as a 0.5 ns component with negative amplitude at the red edge of the spectrum, typical of an excited‐state reaction, were observed. Our computational analysis explains the solvent effects observed on the tautomeric equilibrium. The main radiative and nonradiative deactivation routes have been mapped by PCM/TD‐DFT calculations in solution and CASSCF in the gas phase. The most easily accessible conical intersection, involving an out‐of plane motion of the sulfur atom in the five‐membered ring of thG, is separated by a sizeable energy barrier (≥0.4 eV) from the minimum of the spectroscopic state, which explains the large experimental fluorescence quantum yield.
Metal‐Assisted Opening of Intact P4 Tetrahedra
Authors: Modl Moritz , Heinl Sebastian , Balázs Gabor , Delgado Calvo Fuencisla , Caporali Maria , Manca Gabriele , Keilwerth Martin , Meyer Karsten , Peruzzini Maurizio , Scheer Manfred 
Published: March 2019

AbstractThe reactivity of ruthenium and manganese complexes bearing intact white phosphorus in the coordination sphere was investigated towards the low‐valent transition‐metal species [Cp′′′Co] (Cp′′′=η5‐C5H2‐1,2,4‐tBu3) and [L0M] (L0=CH[CHN(2,6‐Me2C6H3)]2; M=Fe, Co). Remarkably, and irrespective of the metal species, the reaction proceeds by the selective cleavage of two P–P edges and the formation of a square‐planar cyclo‐P4 ligand. The reaction products [{CpRu(PPh3)2}{CoCp′′′}(μ,η1:4‐P4)][CF3SO3] (5), [{CpBIGMn(CO)2}2{CoCp′′′}(μ,η1:1:4‐P4)] (6) and [{CpBIGMn(CO)2}2{ML0}(μ,η1:1:4‐P4)] (CpBIG=C5(C6H4nBu)5; L0=CH[CHN(2,6‐Me2C6H3)]2; M=Fe (7 a), Co (7 b)), respectively, were fully characterized by single‐crystal X‐ray diffraction and spectroscopic methods. The electronic structure of the cyclo‐P4 ligand in the complexes 5–7 is best described as a π‐delocalized P42− system, which is further stabilized by two and three metal moieties, respectively. DFT calculations envisaged a potential intermediate in the reaction to form 5, in which a quasi‐butterfly‐shaped P4 moiety bridges the two metals and behaves as an η3‐coordinated ligand towards the cobalt center.
Total Synthesis, Stereochemical Revision, and Biological Assessment of Iriomoteolide‐2a
Authors: Sakamoto Keita , Hakamata Akihiro , Iwasaki Arihiro , Suenaga Kiyotake , Tsuda Masashi , Fuwa Haruhiko 
Published: March 2019

AbstractIriomoteolide‐2a is a marine macrolide metabolite isolated from a cultured broth of the benthic dinoflagellate Amphidinium sp. HYA024 strain. This naturally occurring substance was reported to show remarkable cytotoxic activity against human cancer cell lines HeLa and DG‐75 and in vivo antitumor activity against murine leukemia P388 cell line. Herein, the total synthesis, stereochemical revision, and biological assessment of iriomoteolide‐2a are reported in detail. Total synthesis of the proposed structure 1 of iriomoteolide‐2a featured a late‐stage convergent assembly of three components by a Suzuki–Miyaura coupling, an esterification, and a ring‐closing metathesis. However, the NMR data of synthetic 1 were not identical to those of the natural product. Careful analysis of the NMR data of the authentic material and synthesis/NMR analysis of appropriately designed model compounds led to consideration of four possible stereoisomers 2–5 as candidates for the correct structure. Accordingly, total syntheses of 2–5 were achieved by taking advantage of the convergent strategy, and comparison of the NMR spectra of synthetic 2–5 with those of the natural product led to the conclusion that 5 shows the correct relative configuration of iriomoteolide‐2a. The absolute configuration of this natural product was finally established through chiral HPLC analysis of synthetic 5/ent‐5 with the authentic sample. The antiproliferative activity of the synthetic compounds was assessed against HeLa and A549 cells to show that, in contrast to expectation, synthetic 5 and ent‐5 were only marginally active in these cell lines. This work clearly underscores the vital role of total synthesis in the establishment of the structure and biological activity of natural products.
Ring Expansions of Nonpolar Polyphosphorus Rings
Authors: Piesch Martin , Seidl Michael , Stubenhofer Markus , Scheer Manfred 
Published: March 2019

AbstractThe reaction of the phosphinidene complex [Cp*P{W(CO)5}2] (1 a) (Cp*=C5Me5) with the anionic cyclo‐Pn ligand complex [(η3‐P3)Nb(ODipp)3]− (2, Dipp=2,6‐diisopropylphenyl) resulted in the formation of [{W(CO)5}2{μ3,η3:1:1‐P4Cp*}Nb(ODipp)3]− (3), which represents an unprecedented example of a ring expansion of a polyphosphorus‐ligand complex initiated by a phosphinidene complex. Furthermore, the reaction of the pnictinidene complexes [Cp*E{W(CO)5}2] (E=P: 1 a, As: 1 b) with the neutral complex [Cp′′′Co(η4‐P4)] (Cp′′′=1,2,4‐tBu3C5H2) led to a cyclo‐P4E ring (E=P, As) through the insertion of the pentel atom into the cyclo‐P4 ligand. Starting from 1 a, the two isomers [Cp′′′Co(μ3,η4:1:1‐P5Cp*){W(CO)5}2] (5 a,b), and from 1 b, the three isomers [Cp′′′Co(μ3,η4:1:1‐AsP4Cp*){W(CO)5}2] (6 a–c) with unprecedented cyclo‐P4E ligands (E=P, As) were isolated. The complexes 6 a–c represent unique examples of ring expansions which lead to new mixed five‐membered cyclo‐P4As ligands. The possible reaction pathways for the formation of 5 a,b and 6 a–c were investigated by a combination of temperature‐dependent 31P{1H} NMR studies and DFT calculations.
Production of Viral Constructs for Neuroanatomy, Calcium Imaging, and Optogenetics
Authors: Chen Shih‐Heng , Haam Juhee , Walker Mitzie , Scappini Erica , Naughton John , Martin Negin P. 
Published: March 2019

AbstractAdvances in design and use of light‐sensitive and light‐emitting sensors have facilitated observation, measurement, and control of neuronal activities. Viruses are effective vectors for delivery of these valuable research tools to mammalian brains. Recombinant viruses are optimized to mediate regulatable, long‐term, and cell‐specific gene expression. Here, we describe production methods for three of the most commonly used types of recombinant viruses in neurobiology research: adeno‐associated virus (AAV), retrovirus/lentivirus, and glycoprotein‐deleted rabies virus. These viral constructs are frequently used for calcium imaging or to deliver neural tracers and optogenetic tools. Popular constructs are readily obtained commercially; however, customized virus production through commercial sources is time consuming and costly. This article aims to provide readers with detailed technical information for rapid production and validation of high‐quality viral particles in a laboratory setting while highlighting advantages and limitations of each viral type. © 2019 by John Wiley & Sons, Inc.
Bias through selective inclusion and attrition: Representativeness when comparing provider performance with routine outcome monitoring data
Authors: de Beurs Edwin , Warmerdam Lisanne , Twisk Jos 
Published: March 2019

AbstractBackgroundObservational research based on routine outcome monitoring is prone to missing data, and outcomes can be biased due to selective inclusion at baseline or selective attrition at posttest. As patients with complete data may not be representative of all patients of a provider, missing data may bias results, especially when missingness is not random but systematic.MethodsThe present study establishes clinical and demographic patient variables relevant for representativeness of the outcome information. It applies strategies to estimate sample selection bias (weighting by inclusion propensity) and selective attrition bias (multiple imputation based on multilevel regression analysis) and estimates the extent of their impact on an index of provider performance. The association between estimated bias and response rate is also investigated.ResultsProvider‐based analyses showed that in current practice, the effect of selective inclusion was minimal, but attrition had a more substantial effect, biasing results in both directions: overstating and understating performance. For 22% of the providers, attrition bias was estimated to be in excess of 0.05 ES. Bias was associated with overall response rate (r = .50). When selective inclusion and attrition bring providers' response below 50%, it is more likely that selection bias increased beyond a critical level, and conclusions on the comparative performance of such providers may be misleading.ConclusionsEstimates of provider performance were biased by selection, especially by missing data at posttest. Results on the extent and direction of bias and minimal requirements for response rates to arrive at unbiased performance indicators are discussed.
A Facile and Versatile “Click” Approach Toward Multifunctional Ionic Metal–organic Frameworks for Efficient Conversion of CO2
Authors: Zhou Li‐Jiao , Sun Wei , Yang Ning‐Ning , Li Peng , Gong Teng , Sun Weng‐Jie , Sui Qi , Gao En‐Qing 
Published: March 2019

AbstractIonic metal–organic frameworks (IMOFs) that integrate synergistic Lewis‐acid sites (intrinsic metal centers of the frameworks) and nucleophilic anions (halides encapsulated within pores) are intriguing platforms for the design of fully heterogeneous catalytic systems for cycloaddition of CO2 to epoxides. A new, facile and versatile synthetic approach has been used to fabricate triazolium‐based IMOFs for the first time. The approach makes use of azide–alkyne click chemistry and subsequent N‐alkylation to post‐synthetically create a cationic triazolium ring and introduce exchangeable counteranions at the same time. The IMOFs are efficient and recyclable heterogeneous catalysts for CO2 conversion under mild and cocatalyst‐free conditions. In particular, the click‐accessible triazolium ring provides a handle to incorporate further functionality. The MIL‐101‐tzmOH‐Br catalyst, which integrates hydrogen‐bonding hydroxy groups besides metal centers and bromide anions, shows superior catalytic performance under mild conditions.
Lignin valorization meets synthetic biology
Authors: Zhang Renkuan , Zhao Chen‐Hui , Chang Han‐Chen , Chai Meng‐Zhe , Li Bing‐Zhi , Yuan Ying‐Jin 
Published: March 2019

AbstractLignin, an abundant renewable resource in nature, is a highly heterogeneous biopolymer consisting of phenylpropanoid units. It is essential for sustainable utilization of biomass to convert lignin to value‐added products. However, there are technical obstacles for lignin valorization due to intrinsic heterogeneity. The emerging of synthetic biology technologies brings new opportunities for lignin breakdown and utilization. In this review, we discussed the applications of synthetic biology on lignin conversion, especially the production of value‐added products, such as aromatic chemicals, ring‐cleaved chemicals from lignin‐derived aromatics and bio‐active substances. Synthetic biology will offer new potential strategies for lignin valorization by optimizing lignin degradation enzymes, building novel artificial converting pathways, and improving the chassis of model microorganisms.
Induction and genetic identification of a callus‐like growth developed in the brown alga Fucus vesiculosus
Authors: Zayed Ahmed , Kovacheva Mariya , Muffler Kai , Breiner Hans‐Werner , Stoeck Thorsten , Ulber Roland 
Published: March 2019

AbstractInduction of an axenic filamentous‐like callus growth from the brown algae Fucus vesiculosus is described. Different treatments were investigated in various combinations to develop axenic cultures based on identification of surface symbionts via 18S ribosomal RNA. Moreover, viability was confirmed after such processes by 2,3,5‐triphenyl tetrazolium chloride assay that demonstrated an average viability of 29%, relative to nonsterilized explants. After six weeks of a phototrophic cultivation on artificial sea water‐12‐nitrilotriacetic acid (0.5% w/v agar), a filamentous‐like callus growth was observed, which was identified genetically through its mitochondrial DNA after subculturing. Achievement of confirmed marine callus cultures might enrich old previously established blue biotechnology techniques and open new chances for cultivation of brown algae for production of good manufacturing practice‐compliant bioproducts.
Optimal placement and sizing of photovoltaics and battery storage in distribution networks
Authors: Chedid Riad , Sawwas Ahmad 
Published: March 2019

AbstractA two‐step optimization approach is proposed to study the effects of adding a battery energy storage system (BESS) to a distribution network incorporating renewable energy sources. In this article, the first step finds the optimal size and placement of the photovoltaic (PV) arrays that lead to the lowest possible losses, cost and voltage deviation from the reference bus, while the second step starts by performing another optimization in order to find the optimal size and placement of the BESS that lead to a further reduction in the same objectives. The optimized Grid‐PV and Grid‐PV‐BESS configurations are subjected to a time domain power flow so that the annual energy losses and voltage profile of each bus can be observed. The article provides a novel formulation that treats the problem as a multi‐objective optimization and uses the Genetic Algorithm technique to reach optimal configuration in both steps. An Institute of Electrical and Electronic Engineers 13‐Bus test feeder is used to demonstrate the usefulness of the proposed technique.
Better thermal management options with heat storage systems for various applications: An Evaluation
Authors: Acar Canan , Dincer Ibrahim 
Published: March 2019

AbstractWith increasing worldwide population and rising standards of living, the global energy consumption is increasing at significant rates. Together with climate change concerns and negative impacts of fossil fuel use, the need for clean and smart energy systems is becoming more obvious. Clean and smart systems provide energy to all types of end‐use applications in an environmentally friendly, affordable, reliable, and efficient manner. Heat losses are recognized as some of the most significant causes of efficiency degradation in energy systems. Therefore, this study overviews and investigates current and future thermal management options for different end‐use purposes for a more sustainable future. In this study, a smart approach is taken when evaluating existing and emerging thermal management systems and smart targets are introduced for better thermal management systems. In addition, some novel thermal management systems for various applications such as electric/hybrid vehicles, power systems, and industrial processes are introduced as case studies and the energy and exergy efficiencies of these case studies are compared. In addition, some key future directions are provided in terms of better thermal management options for a sustainable future. The case study results of this study show that with better thermal management strategies, it is possible to reach energy and exergy efficiencies up to 60% and 50%, respectively in hybrid vehicles, industrial processes, and robotic applications.
Automated Essay Scoring at Scale: A Case Study in Switzerland and Germany
Authors: Rupp André A. , Casabianca Jodi M. , Krüger Maleika , Keller Stefan , Köller Olaf 
Published: March 2019

AbstractIn this research report, we describe the design and empirical findings for a large‐scale study of essay writing ability with approximately 2,500 high school students in Germany and Switzerland on the basis of 2 tasks with 2 associated prompts, each from a standardized writing assessment whose scoring involved both human and automated components. For the human scoring aspect, we describe the methodology for training and monitoring human raters as well as for collecting their ratings within a customized platform. For the automated scoring aspect, we describe the methodology for training, evaluating, and selecting appropriate automated scoring models as well as correlational patterns of resulting task scores with scores from secondary measures. Analyses show that the human ratings were highly reliable and that effective prompt‐specific automated scoring models could be built with state‐of‐the‐art features and machine learning methods, which resulted in correlational patterns with secondary measures that were in line with general expectations. In closing, we discuss the methodological implications for conducting this kind of work at scale in the future.
Using hydrogeochemical data to trace groundwater flow paths in a cold alpine catchment
Authors: Hu Yalu , Ma Rui , Wang Yanxin , Chang Qixin , Wang Shuo , Ge Mengyan , Bu Jianwei , Sun Ziyong 
Published: March 2019

AbstractSignificant uncertainty remains in understanding the groundwater flow pathways in the northeastern Qinghai–Tibet Plateau. Hydrogeochemical and isotopic data as well as hydrogeological data were combined to explore the groundwater flow path in a representative cold alpine catchment in the headwater region of the Heihe River. The results indicate that the suprapermafrost groundwater chemical components were mainly affected by calcite dissolution and evaporation, whereas the geochemistry of subpermafrost groundwater was controlled by dolomite and gypsum dissolution, calcite precipitation, and albite and halite dissolution. Distinct hydrogeochemical characteristics and controlling processes suggest a poor hydraulic connectivity between the suprapermafrost and subpermafrost groundwater. The hydraulic connectivity between permafrost groundwater and groundwater in the seasonally frozen area was confirmed by their similar hydrogeochemical features. In the seasonally frozen area, a silty clay layer with low permeability separates the aquifer into the deep (depth >20 m) and shallow (depth <20 m) flow paths. The deep groundwater was characterized by the enhanced dedolomitization and enhanced cation exchange processes compared with the shallow groundwater. Groundwater in the seasonally frozen area finally discharges as base flow into the stream. These results provide useful information about the groundwater flow systems in the unique alpine gorge catchments in Qinghai–Tibet Plateau. The above findings suggest that the permafrost distribution and the aquifer structures within the seasonally frozen area have significant impact on groundwater flow paths. Cross‐validation by drilling work and hydrograph data confirms that the hydrogeochemical and isotopic tracers combined with field investigations can be relatively low‐cost tools in interpreting the groundwater flow paths in similar alpine catchments.
Photochemically crosslinked cell‐laden methacrylated collagen hydrogels with high cell viability and functionality
Authors: Nguyen Thuy‐Uyen , Watkins Kori E. , Kishore Vipuil 
Published: March 2019

AbstractIrgacure 2959 (I2959) is widely used as a photoinitiator for photochemical crosslinking of hydrogels. However, the free radicals generated from I2959 have been reported to be highly cytotoxic. In this study, methacrylated collagen (CMA) hydrogels were photochemically crosslinked using two different photoinitiators (i.e., I2959 and VA086) and the effect of photoinitiator type, photoinitiator concentration (i.e., 0.02 and 0.1%) and crosslinking time (1 and 10 min) on gel morphology, compressive modulus, and stability were investigated. In addition, Saos‐2 cells were encapsulated within the hydrogels and the effect of photochemical crosslinking conditions on cell viability, metabolic activity, and osteoblast functionality was assessed. Scanning electron microscopy imaging showed that photochemical crosslinking decreased the porosity of the hydrogels resulting in decrease in water retention ability compared to uncrosslinked hydrogels. On the other hand, photochemical crosslinking improved the stability of CMA hydrogels (p < 0.05). Uniaxial compression tests showed that increasing the photoinitiator concentration significantly improved the compressive modulus of CMA hydrogels (p < 0.05). Results from the live–dead assay showed that VA086 crosslinked hydrogels exhibited higher cell viability compared to I2959 (p < 0.05) crosslinked hydrogels indicating that VA086 is more cytocompatible compared to I2959. Furthermore, Alizarin Red S staining revealed a significantly more pronounced cell‐mediated mineralization on VA086 crosslinked hydrogels (p < 0.05) indicating that Saos‐2 cells retain their normal functionality in the presence of VA086. In summary, these results indicate that VA086 is a more biocompatible photoinitiator compared to I2959 for the generation of photochemically crosslinked CMA hydrogels for tissue engineering applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.
Effects of cerium oxide nanoparticles on hemostasis: Coagulation, platelets, and vascular endothelial cells
Authors: Del Turco Serena , Ciofani Gianni , Cappello Valentina , Parlanti Paola , Gemmi Mauro , Caselli Chiara , Ragusa Rosetta , Papa Angela , Battaglia Debora , Sabatino Laura , Basta Giuseppina , Mattoli Virgilio 
Published: March 2019

AbstractCerium oxide nanoparticles (nanoceria [NC]) have attracted much attention in biomedicine due to their surface composition that confers interesting redox activities and regenerative properties. Studies have demonstrated that the application of NPs in biomedicine can influence components of hemostatic system, inducing blood clotting, alterations of blood cells, and endothelial cell functions. NC were testedin vitroto assess their hemocompatibility and anticoagulant, anti‐inflammatory, and anti‐senescence activity in human endothelial cells. Hemocompatibility has been evaluatedin vitrolooking at the impact of NC on coagulation times, fibrinogen, and platelet aggregation. The effect of NC on vascular endothelial cells were assayed by testing cell viability, antioxidant activity, anticoagulant (tissue factor [TF]‐mRNA expression) and anti‐inflammatory properties (VCAM‐1 exposure, cytokine release), and senescence (telomere shortening). NC did not show significant effects on coagulation process, hemolysis, or platelet aggregation. In endothelial cells, NC did not affect cell viability, reduced oxidative stress, inhibited mRNA‐TF expression, VCAM‐1 expression, and cytokine release. Moreover, NC reduce telomere shortening, possibly counteracting premature senescence. The hemocompatibility combined with anticoagulant and anti‐inflammatory phenotype and the ability of counteract the premature senescence in vascular cells make NC a promising therapeutic tool in oxidative stress‐related conditions. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.