bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Switching in Confined Spaces: Effects of Encapsulating the DHA/VHF Photo‐Switch in Cucurbiturils
Authors: Petersen Michael Å. , Rasmussen Brian , Andersen Nicolaj N. , Sauer Stephan P. A. , Nielsen Mogens Brøndsted , Beeren Sophie R. , Pittelkow Michael 
Published: September 2017

AbstractConfinement of reactive chemical species uniquely affects chemical reactivity by restricting the physical space available and by restricting access to interactions with the solvent. In Nature, for example, confined protein binding pockets govern processes following photoisomerization reactions and the isomerizations themselves. Here we describe the first example of a dihydroazulene/vinylheptafulvene (DHA/VHF) photo‐switch functioning in water, and we show how its switching behavior is strongly influenced by supramolecular interactions with a series of cucurbit[n]uril (CB) host molecules. In CB7 inclusion complexes, the kinetics of the thermal VHF‐to‐DHA back‐reaction is accelerated, while in CB8 inclusion complexes, the kinetics is slowed down as compared to the free photo‐switch. The effect of the CB encapsulation of the photo‐switch can be effectively canceled by introducing a guest that binds the CB more strongly. According to DFT calculations, a stabilization of the reactive s‐cis VHF conformer relative to the s‐trans VHF appears to be a contributing factor responsible for the accelerated back‐reaction when encapsulated in CB7.
Modulating the Structural Properties of α,γ‐Hybrid Peptides by α‐Amino Acid Residues: Uniform 12‐Helix Versus “Mixed” 12/10‐Helix
Authors: Misra Rajkumar , Raja K. Muruga Poopathi , Hofmann Hans‐Jörg , Gopi Hosahudya N. 
Published: September 2017

AbstractThe most important natural α‐ and 310‐helices are stabilized by unidirectional intramolecular hydrogen bonds along the helical cylinder. In contrast, we report here on 12/10‐helical conformations with alternately changing hydrogen‐bond directionality in sequences of α,γ‐hybrid peptides P1–P5 [P1: Boc‐Ala‐Aic‐Ala‐Aic‐COOH; P2: Boc‐Leu‐Aic‐Leu‐Aic‐OEt; P3: Boc‐Leu‐Aic‐Leu‐Aic‐Leu‐Aic‐Aib‐OMe; P4: Boc‐Ala‐Aic‐Ala‐Aic‐Ala‐Aic‐Ala‐OMe; P5: Boc‐Leu‐Aic‐Leu‐Aic‐Leu‐Aic‐Leu‐Aic‐Aib‐OMe; Aic=4‐aminoisocaproic acid, Aib=2‐aminoisobutyric acid] composed of natural α‐amino acids and the achiral γ4,4‐dimethyl substituted γ‐amino acid Aic in solution and in single crystals. The helical conformations are stabilized by alternating i→i+3 and i→i−1 intramolecular hydrogen bonds. The experimental data are supported by ab initio MO calculations. Surprisingly, replacing the natural α‐amino acids of the sequence by the achiral dialkyl amino acid Ac6c [P6: Boc‐Ac6c‐Aic‐Ac6c‐Aic‐Ac6c‐Aic‐Ac6c‐Aic‐Ac6c‐CONHMe; Ac6c = 1‐aminocyclohexane‐1‐carboxylic acid] led to a 12‐helix with unidirectional hydrogen bonds showing an entirely different backbone conformation. The results presented here emphasize the influence of the structure of the α‐amino acid residues in dictating the helix types in α,γ‐hybrid peptide foldamers and demonstrate the consequences for folding of small structural variations in the monomers.
Generation of Stable Ruthenium(IV) Ketimido Complexes by Oxidative Addition of Oxime Esters to Ruthenium(II): Reactivity Studies Based on Electronic Properties of the Ru−N Bond
Authors: Shimbayashi Takuya , Okamoto Kazuhiro , Ohe Kouichi 
Published: September 2017

AbstractThe reaction of an oxime ester with [Ru(PPh3)3X2] proceeded smoothly at room temperature to afford a stable RuIV ketimido complex as oxidative adduct. The structure of the complex was unambiguously determined by X‐ray crystallographic analysis, which showed an almost linear Ru−N−C array. The electronic properties of the nitrogen atom were estimated by DFT calculations, and the results suggested double‐bond character of the Ru−N bond. Kinetic studies and consideration of the substituent effect on the oxime ester led to the proposal of a reaction mechanism involving oxidative addition, which could proceed by N,O‐chelating coordination to the Ru center prior to N−O bond cleavage. The obtained Ru ketimido complex could be transformed into a ruthenacycle by C−H activation by a concerted metalation–deprotonation mechanism in dichloromethane/methanol. Ru ketimido complexes with a tethered alkyne or alkene moiety underwent chloroamination of unsaturated C−C bonds followed by C−H activation, which resulted in the formation of a ruthenacycle. Considering the LUMO of an isolated Ru ketimido complex, the chloroamination should proceed by a synchronous 1,3‐dipolar cycloaddition‐type mechanism. Insight into the character and reactivity of Ru ketimido complexes will be helpful for developments in the catalytic transformation of oxime esters.
Accessing Two‐Coordinate ZnII Organocations by NHC Coordination: Synthesis, Structure, and Use as π‐Lewis Acids in Alkene, Alkyne, and CO2 Hydrosilylation
Authors: Specklin David , Hild Frédéric , Fliedel Christophe , Gourlaouen Christophe , Veiros Luis F. , Dagorne Samuel 
Published: September 2017

AbstractDiscrete two‐coordinate ZnII organocations of the type (NHC)Zn−R+ are reported, thanks to NHC stabilization. In preliminary reactivity studies, such entities, which are direct cationic analogues of long‐known ZnR2 species, act as effective and tunable π‐Lewis acid catalysts in alkene, alkyne, and CO2 hydrosilylation.
A Combined Experimental and Theoretical Approach to Understand the Structure and Properties of N‐Methylpyrrolidone‐Based Protic Ionic Liquids
Authors: Panda Somenath , Kundu Kaushik , Umapathy Siva , Gardas Ramesh L. 
Published: September 2017

AbstractCorrelation of the structure and properties of ionic liquids (ILs) is essential for the development of optimized materials in the fields of gas capture and separation, battery electrolytes, and cellulose dissolution processes. In view of this, a detailed vibrational spectroscopic analysis and quantum‐chemical calculations were performed to explore the interionic interactions in ILs based on the N‐methylpyrrolidone cation and a carboxylate anion. FTIR and Raman spectroscopy were applied to identify the hydrogen‐bonding interactions between ion pairs, in which redshifted vibrational modes were observed as a function of the anion chain length. This observation was verified by the bond lengthening and enhanced hydrogen‐bonding energies, as manifested in the structure and natural bond orbital (NBO) calculations. Furthermore, conductivity was measured at different temperatures to envisage the effect of the alkyl chain on the mobility of ions in the ILs. Finally, rheological measurements were implemented to explain the flow behavior of these ILs, which revealed a decrease in shear viscosity with an increase in temperature, that is, a Newtonian trend over a range of shear rates. The observed trend in transport properties was supported by the ion‐pair binding energy. Stronger interactions between the IL cations and anions led to a decrease in the number of free ions and lowered the conductivity. In these protic ILs, the intermolecular N−H⋅⋅⋅O and C−H⋅⋅⋅O interactions played an important role in governing their physicochemical properties.
Nucleoside‐O‐Methyl‐(H)‐Phosphinates: Novel Monomers for the Synthesis of Methylphosphonate Oligonucleotides Using H‐Phosphonate Chemistry
Authors: Kostov Ondřej , Páv Ondřej , Rosenberg Ivan 
Published: September 2017

AbstractThis unit comprises the straightforward synthesis of protected 2′‐deoxyribonucleoside‐O‐methyl‐(H)‐phosphinates in both 3′‐ and 5′‐series. These compounds represent a new class of monomers compatible with the solid‐phase synthesis of oligonucleotides using H‐phosphonate chemistry and are suitable for the preparation of both 3′‐ and 5′‐O‐methylphosphonate oligonucleotides. The synthesis of 4‐toluenesulfonyloxymethyl‐(H)‐phosphinic acid as a new reagent for the preparation of O‐methyl‐(H)‐phosphinic acid derivatives is described. © 2017 by John Wiley & Sons, Inc.
Link abstraction models for multicarrier systems: A logistic regression approach
Authors: Carreras Mesa Alberto , Aguayo‐Torres Mari Carmen , Martin‐Vega Francisco J. , Gómez Gerardo , Blanquez‐Casado Francisco , Delgado‐Luque Isabel M. , Entrambasaguas Jose 
Published: September 2017

SummaryEvaluation of complex wireless systems through simulations is commonly tackled with an abstraction of physical link behavior. This procedure is performed in 2 phases: Firstly, training is performed at the link level, resulting in a mapping function from signal‐to‐interference‐plus‐noise ratio (SINR) to block error rate (BLER); and secondly, physical layer signal processing is replaced by the resulting link‐level mapping function. Several methods have been proposed in the literature for link abstraction. The well‐known exponential effective SINR mapping (EESM) is likely to be the most extensively used procedure for multicarrier transmission. In short, EESM estimates an effective SINR from the whole set of SINRs of useful subcarriers by means of a single parameter mapping function, which must be previously optimized through training. Later on, BLER is assumed as that of the effective SINR over an additive white Gaussian noise channel. In this paper, we propose a novel method for BLER prediction named as logistic regression‐based link method (LRLM). Mean and standard deviation of the SINR set can accurately capture BLER behavior for wideband multicarrier systems through a simpler function, thus reducing the amount of information to be stored compared to EESM. Moreover, LRLM is very flexible and may include extra predictors to reduce the number of different models to be stored. Performance results show that LRLM is able to predict accurately the BLER for all modulation and coding schemes and transport block sizes defined for Long‐Term Evolution technology.
Fine needle aspiration biopsy diagnosis of primary clear cell chondrosarcoma: A case report
Authors: McHugh Kelsey E. , Emory Cynthia L. , Parks Graham E. , Kilpatrick Scott E. 
Published: September 2017

AbstractClear cell chondrosarcoma is a rare chondrosarcoma variant often involving the long bone epiphyses of young to middle aged adults. We report herein a case involving the left femoral head in a 25‐year‐old female with a 3‐month history of worsening left hip pain. Radiographs revealed a complex, multifocal and lytic lesion centered in the left proximal femoral epiphysis with involvement of the femoral neck. Computed tomography‐guided fine needle aspiration biopsy with concomitant core needle biopsy was performed, and a diagnosis of clear cell chondrosarcoma was rendered. Cytologic smears revealed aggregates of matrix material accompanied by a population of mostly uniform spindled to epithelioid and histiocytoid cells, rarely accompanied by osteoclast‐type giant cells. The patient underwent surgical resection with ‐total hip replacement, and subsequent pathologic examination confirmed the initial needle biopsy diagnosis. There has been no evidence of local recurrence or distant metastases with 3‐years follow‐up. To our knowledge, this is the first reported example of a primary clear cell chondrosarcoma initially evaluated by fine needle aspiration biopsy.
Invasive legumes can associate with many mutualists of native legumes, but usually do not
Authors: La Pierre Kimberly J. , Simms Ellen L. , Tariq Mohsin , Zafar Marriam , Porter Stephanie S. 
Published: September 2017

AbstractMutualistic interactions can strongly influence species invasions, as the inability to form successful mutualisms in an exotic range could hamper a host's invasion success. This barrier to invasion may be overcome if an invader either forms novel mutualistic associations or finds and associates with familiar mutualists in the exotic range. Here, we ask (1) does the community of rhizobial mutualists associated with invasive legumes in their exotic range overlap with that of local native legumes and (2) can any differences be explained by fundamental incompatibilities with particular rhizobial genotypes? To address these questions, we first characterized the rhizobial communities naturally associating with three invasive and six native legumes growing in the San Francisco Bay Area. We then conducted a greenhouse experiment to test whether the invasive legume could nodulate with any of a broad array of rhizobia found in their exotic range. There was little overlap between the Bradyrhizobium communities associated with wild‐grown invasive and native legumes, yet the invasive legumes could nodulate with a broad range of rhizobial strains under greenhouse conditions. These observations suggest that under field conditions in their exotic range, these invasive legumes are not currently associating with the mutualists of local native legumes, despite their potential to form such associations. However, the promiscuity with which these invading legumes can form mutualistic associations could be an important factor early in the invasion process if mutualist scarcity limits range expansion. Overall, the observation that invasive legumes have a community of rhizobia distinct from that of native legumes, despite their ability to associate with many rhizobial strains, challenges existing assumptions about how invading species obtain their mutualists. These results can therefore inform current and future efforts to prevent and remove invasive species.
Proglacial erosion rates and processes in a glacierized catchment in the Swiss Alps
Authors: Delaney Ian , Bauder Andreas , Huss Matthias , Weidmann Yvo 
Published: September 2017

AbstractIn the Swiss Alps, climatic changes have not only caused glacier retreat, but also likely increased sedimentation downstream of glaciers. This material either originates from below the glacier or from periglacial environments, which are exposed as glaciers retreat, and often consist of easily erodible sediment. Griesgletscher's catchment in the Swiss Alps was examined to quantify erosion in the proglacial area, possible hydrological drivers and contributions of the sub‐ and periglacial sources. Digital elevation models, created from annual aerial photographs, were subtracted to determine annual volume changes in the proglacial area from 1986 to 2014. These data show a strong increase in proglacial erosion in the decade prior to 2012, coincident with increasing proglacial area size. However, examination of the gradient between discharge and sediment evacuation, and modeled sediment transport, could suggest that the proglacial area began to stabilize and sediment supply is limited. The large influx of sediment into the proglacial reservoir, which is roughly 2.5 times greater than the amount of sediment eroded from the proglacial area, demonstrates the importance of subglacial erosion to the catchment's sediment budget. Although far more sediment originates subglacially, erosion rates in the proglacial area are over 50 times greater than the rest of the catchment. In turn, both sub‐ and periglacial processes, in addition to constraining sediment supply, must be considered for assessing future sediment dynamics as glacier area shrinks and proglacial areas grow. ©  2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.
On a planar thermal analysis of intumescent coatings
Authors: Ogrin Anita , Saje Miran , Hozjan Tomaž 
Published: September 2017

SummaryThe paper discusses a complex model for a nonstationary planar thermal analysis of expandable intumescent coatings. Following the existing one‐dimensional models, we develop novel and improved equations for the two‐dimensional thermal analysis of intumescent coatings. A progressive expansion due to chemical reactions, phase changes, and the time and temperature‐dependent thermal properties of the coating are considered. In the heating process, the coating may locally experience virgin, intumesced, or charred phases, and their transition with time. The rate of the density loss due to the pyrolysis reaction is described with the Arrhenius equation. The thickness of the coating is assumed to increase enormously during the pyrolysis. Consequently, the energy and mass equilibrium equations are formulated with respect to both the deformed and undeformed configuration. Since most of material properties of commercial products are not given by manufacturers, an innovative procedure is proposed to determine the time‐dependent thermal conductivities and remaining fundamental properties of the coating from the set of measured temperatures. This, together with the two‐dimensional formulation of the thermal equations with respect to the undeformed configuration, makes the present model unique and appropriate for the thermal analyses of an arbitrary steel cross section protected with intumescent coatings.
Loss of Gas6 and Axl signaling results in extensive axonal damage, motor deficits, prolonged neuroinflammation, and less remyelination following cuprizone exposure
Authors: Ray Alex K. , DuBois Juwen C. , Gruber Ross C. , Guzik Hillary M. , Gulinello Maria E. , Perumal Geoffrey , Raine Cedric , Kozakiewicz Lauren , Williamson Julie , Shafit‐Zagardo Bridget 
Published: September 2017

AbstractThe TAM (Tyro3, Axl, and MerTK) family of receptor tyrosine kinases (RTKs) and their ligands, Gas6 and ProS1, are important for innate immune responses and central nervous system (CNS) homeostasis. While only Gas6 directly activates Axl, ProS1 activation of Tyro3/MerTK can indirectly activate Axl through receptor heterodimerization. Therefore, we generated Gas6–/–Axl–/– double knockout (DKO) mice to specifically examine the contribution of this signaling axis while retaining ProS1 signaling through Tyro3 and MerTK. We found that naïve young adult DKO and WT mice have comparable myelination and equal numbers of axons and oligodendrocytes in the corpus callosum. Using the cuprizone model of demyelination/remyelination, transmission electron microscopy revealed extensive axonal swellings containing autophagolysosomes and multivesicular bodies, and fewer myelinated axons in brains of DKO mice at 3‐weeks recovery from a 6‐week cuprizone diet. Analysis of immunofluorescent staining demonstrated more SMI32+ and APP+ axons and less myelin in the DKO mice. There were no significant differences in the number of GFAP+ astrocytes or Iba1+ microglia/macrophages between the groups of mice. However, at 6‐weeks cuprizone and recovery, DKO mice had increased proinflammatory cytokine and altered suppressor of cytokine signaling (SOCS) mRNA expression supporting a role for Gas6‐Axl signaling in proinflammatory cytokine suppression. Significant motor deficits in DKO mice relative to WT mice on cuprizone were also observed. These data suggest that Gas6‐Axl signaling plays an important role in maintaining axonal integrity and regulating and reducing CNS inflammation that cannot be compensated for by ProS1/Tyro3/MerTK signaling.
Stem cells and differentiated cells differ in their sensitivity to urine in vitro
Authors: Pokrywczyńska Marta , Kloskowski Tomasz , Balcerczyk Daria , Buhl Monika , Jundziłł Arkadiusz , Nowacki Maciej , Męcińska‐Jundziłł Kaja , Drewa Tomasz 
Published: September 2017

AbstractUrinary tract regeneration using tissue engineering is one of the most challenging issues in the field of reconstructive urology. Cells seeded on scaffold are exposed to urine immediately after the implantation. The outcome of urinary bladder regeneration is depended on the ability of these cells to survive, proliferate, and regenerate. The aim of this study was to compare a sensitivity of three different cell lines to urine in vitro. Three different cell lines were isolated from porcine bladder (urothelial cells, UCs and smooth muscle cells, SMCs) and adipose tissue (adipose‐derived stem cells, ADSCs). Cell viability (MTT assay), proliferation (real‐time cell analysis using xCELLigence system) and apoptosis/necrosis (flow cytometry) were analyzed after exposition to urine. ADSCs were the most sensitive to urine compared to two other tested cell lines. Among the bladder cell lines the UCs were more resistant to urine than SMCs. Twenty four hour incubation of UCs, SMCs, and ADSCs with urine lead to ∼40%, ∼70%, and ∼90% reduction of their viability, respectively. The mechanism of urine mediated cytotoxicity differed depending on the tested cell type. Urothelial and SMCs seems to be more suitable for urinary bladder regeneration compared to mesenchymal stem cells, however, these cells have limited application especially in the case of urinary bladder cancer.
Combined use of Clauss and prothrombin time‐derived methods for determining fibrinogen concentrations: Screening for congenital dysfibrinogenemia
Authors: Xiang Liqun , Luo Meiling , Yan Jie , Liao Lin , Zhou Weijie , Deng Xuelian , Deng Donghong , Cheng Peng , Lin Faquan 
Published: September 2017

BackgroundIn this study, the significance of fibrinogen concentration assessed by a combination of Clauss and prothrombin time (PT)‐derived methods for screening for congenital dysfibrinogenemia were investigated, and the screening efficiency of fibrinogen PT‐derived/Clauss ratio on congenital dysfibrinogenemia was analyzed.MethodsWe compared fibrinogen concentrations determined by the Clauss, PT‐derived, and enzyme‐linked immunosorbent assay (ELISA) methods in 73 patients with congenital dysfibrinogenemia and 81 normal controls. Receiver operating characteristic (ROC) curves were utilized to evaluate the efficacy of fibrinogen PT‐derived/Clauss ratio in screening for congenital dysfibrinogenemia.ResultsFibrinogen concentrations determined by the Clauss method were dramatically lower than by the PT‐derived method and ELISA, and correlated poorly with the latter two methods in patients with congenital dysfibrinogenemia. Fibrinogen concentrations in normal controls were slightly lower according to the Clauss method than to the PT‐derived method and ELISA; however, each method yielded results within the normal range and the correlation was good. The area under the ROC curve of fibrinogen PT‐derived/Clauss ratio for diagnosis of congenital dysfibrinogenemia was 1 with a standard error of 0, 95% confidence interval of 0.976‐1.00, and optimal critical diagnosis point of 1.43. When fibrinogen PT‐derived/Clauss ratio was >1.43, the sensitivity and specificity for diagnosis of congenital dysfibrinogenemia were both 100%.ConclusionsThe combined use of Clauss and PT‐derived methods for determining fibrinogen concentrations improves the efficiency of screening for congenital dysfibrinogenemia, as the fibrinogen PT‐derived/Clauss ratio has high sensitivity and specificity in diagnosis of congenital dysfibrinogenemia. This ratio could serve an important screening tool for this disease.