bluuebunny/crossref_metadata_2025_split huggingface dataset:
Azoliniums, Adducts, NHCs and Azomethine Ylides: Divergence in Wanzlick Equilibrium and Olefin Metathesis Catalyst Formation
Authors: Jolly Phillip I. , Marczyk Anna , Małecki Paweł , Ablialimov Osman , Trzybiński Damian , Woźniak Krzysztof , Osella Silvio , Trzaskowski Bartosz , Grela Karol 
Published: February 2018

AbstractThe dimerization of a saturated N‐heterocyclic carbene (NHC) to tricyclic piperazine in preference to the commonly observed Wanzlick dimerization is presented. Mechanistic investigations revealed that the N‐fluorene substituent of the heterocycle is implicated in both ring opening of corresponding carbene dimer and tautomerization of NHC to an azomethine ylide. This has consequences for the fate of the NHC when generated from either an azolinium salt or a pentafluorophenyl adduct. The insights gained permitted the synthesis of a new indenylidene metathesis precatalyst, which exhibits exceptional selectivity and high TONS in self‐metathesis of 1‐octene.
Stable Nitrogen‐Centered Bis(imino)rylene Diradicaloids
Authors: Zeng Wangdong , Hong Yongseok , Medina Rivero Samara , Kim Jinseok , Zafra José L. , Phan Hoa , Gopalakrishna Tullimilli Y. , Herng Tun Seng , Ding Jun , Casado Juan , Kim Dongho , Wu Jishan 
Published: February 2018

AbstractThe synthesis of stable open‐shell singlet diradicaloids is critical for their practical material application. So far, most reported examples are based on carbon‐centered radicals, which are intrinsically reactive, and there are very few examples of stable nitrogen‐centered diradicaloids. In this full paper, a series of soluble and stable bis(imino)rylenes up to octarylene were synthesized on the basis of newly developed dibromorylene intermediates. It was found that from hexarylene onward, these quinoidal rylenes showed open‐shell singlet ground states and could be thermally populated to paramagnetic triplet aminyl diradicals. They are stable due to efficient spin delocalization onto the rylene backbone as well as kinetic blocking of the aminyl sites by the bulky and electron‐deficient 2,4,6‐trichlorophenyl groups. They exhibited very different electronic structures, diradical character, excited‐state dynamics, one‐photon absorption, two‐photon absorption, and electrochemical properties from their respective aromatic rylene counterparts. These bis(imino)rylenes represent a rare class of stable, neutral, nitrogen‐centered aminyl diradicaloids.
Tris(1‐methyl‐imidazol‐2‐yl)phosphane Complexes of Pnictogen, Tetrel, and Triel Cations
Authors: Suter Riccardo , Gray Paul A. , Burford Neil , McDonald Robert 
Published: February 2018

Abstractcationsgalliumindiumnitrogen ligandspnictogenstetrelThe synthesis and characterization of salts with the generic formula [P(Im)3M][OTf]x (Im=1‐methyl‐imidazol‐2‐yl; M=P, As or Sb and x=3; M=Ge or Sn and x=2) are reported. In all cases, the cations adopt a cage structure with two chemically and energetically distinct apical lone pairs. In contrast, complexes of gallium and indium engage two P(Im)3 ligands resulting in a distorted octahedral geometry for the triel center in compounds of the generic formula [{P(Im)3}2M][OTf]3 (M=Ga or In). An assessment of the acidity and basicity of the new compounds is presented.
Differential isotopic characteristics of eco‐hydrologic processes in a subtropical watershed, China
Authors: Hao Zhuo , Gao Yang , Sun Xiaomin , Wen Xuefa 
Published: February 2018

AbstractIn order to better understand isotopic characteristics of eco‐hydrologic processes in subtropical zones, this study selected a typical subtropical watershed in China to investigate and determine the complex differential mechanisms inherent to this water body type. Results showed that stable isotopes in precipitation within a Local Meteoric Water Line in the Xiangxi River basin (where δD = (8.23 ± 0.27)δ18O + (17.97 ± 1.65); R2 = 0.94) weighted δD and δ18O average precipitation values were −22.11‰ and −5.23‰, respectively. Furthermore, enrichment trends in river water δ18O (−4.21‰ to −6.91‰) and δD (−25.11‰ to −38.13‰) and soil solution δ18O (−6.30‰ to −11.21‰) and δD (−11.21‰ to −34.57‰) were greater compared with precipitation δ18O (−0.23‰ to −12.06‰) and δD (0.54‰ to −98.52‰) and throughfall δ18O (−1.11‰ to −4.72‰) and δD (−2.11‰ to −24.95‰). This study found obvious seasonality and higher deuterium excess (d‐excess) values in precipitation during the dry season and lower values during the rainy season. Moreover, the orchard was more enriched and the coniferous and broad‐leaved mixed forest was more depleted in δD and δ18O compared with other land cover types. Precipitation was an important climate variable in subtropical watersheds under the influence of monsoon systems. According to results from the isotopic mixture model, precipitation input fractions were greater than 88% in the soil solution and greater than 21% in river water.
Analysis of ruthenium anticancer agents by MEEKC‐UV and MEEKC–ICP‐MS: Impact of structural motifs on lipophilicity and biological activity
Authors: Giringer Kai , Holtkamp Hannah U. , Movassaghi Sanam , Tremlett William D. J. , Lam Nelson Y. S. , Kubanik Mario , Hartinger Christian G. 
Published: February 2018

AbstractWe present here the first comprehensive study on the lipophilicity of ruthenium anticancer agents encompassing compounds with broad structural diversity, ranging from octahedral RuIII(azole) through to RuII(arene) complexes. MEEKC was used to determine the capacity factors of the Ru complexes, and after a complex peak was unambiguously assigned using MEEKC–ICP‐MS, the results were validated through comparison with the log P determined by octanol/water partitioning experiments. Correlation of the two data sets demonstrated a close relationship despite the limited structural overlap of the compounds studied. The capacity factors found by MEEKC allowed for the clustering of complexes based on their structure and this could be used to rationalize the observed cytotoxicity in the human colon carcinoma HCT116 cell line. It was demonstrated that rather than modification of the mono‐ or bidentate coordinated ligands much tighter control over a complexes lipophilic properties could be achieved through modification of the Ru(arene) ligand, with minimal detriment to cytotoxicity. This demonstrates the flexibility and potential of the Ru piano‐stool scaffold. MEEKC proved to be a highly efficient means of screening the anticancer potential of preclinical ruthenium complex candidates for their lipophilic properties and correlate them with their biological activity and structural properties.
Three‐dimensional plotted alginate fibers embedded with diclofenac and bone cells coated with chitosan for bone regeneration during inflammation
Authors: Lin Hsin‐Yi , Chang Tsang‐Wen , Peng Tie‐Kun 
Published: February 2018

AbstractAlginate hydrogel fibers embedded with bone cells and diclofenac were coated with a layer of chitosan hydrogel and made into a porous scaffold by three‐dimensional (3D) printing for drug release and bone regeneration. It was hypothesized that the chitosan coating could improve the scaffold's drug retention and release properties and biocompatibility. Macrophage cells were stimulated and cocultured with the scaffold. Tests were conducted to show how the chitosan coating affected the scaffold's drug release efficacy and how the release efficacy affected the cellular activities of stimulated macrophages and bone cells. The bone cells encapsulated in the coated scaffold demonstrated good viability after the acidic/basic coating process. The coating improved the retention and release efficacy of diclofenac and hence significantly inhibited interleukin‐6 and tumor necrosis factor‐α secretion from macrophages (p < 0.05). The bone cells in the coated sample mineralized more extensively than the control (p < 0.01). They also more actively expressed genes that produce proteins for extracellular matrix remodeling, MMP13, and interacting with the mineral matrix, OPN (both p < 0.01). It is believed that on days 7 and 10, when diclofenac was depleted and the concentrations of inflammatory compounds surged, the coating effectively blocked the harmful compounds and protected the bone cells within the fibers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1511–1521, 2018.
A thermoresponsive, citrate‐based macromolecule for bone regenerative engineering
Authors: Morochnik Simona , Zhu Yunxiao , Duan Chongwen , Cai Michelle , Reid Russell R. , He Tong‐Chuan , Koh Jason , Szleifer Igal , Ameer Guillermo A. 
Published: February 2018

AbstractThere is a need in orthopaedic and craniomaxillofacial surgeries for materials that are easy to handle and apply to a surgical site, can fill and fully conform to the bone defect, and can promote the formation of new bone tissue. Thermoresponsive polymers that undergo liquid to gel transition at physiological temperature can potentially be used to meet these handling and shape‐conforming requirements. However, there are no reports on their capacity to induce in vivo bone formation. The objective of this research was to investigate whether the functionalization of the thermoresponsive, antioxidant macromolecule poly(poly‐ethyleneglycol citrate‐co‐N‐isopropylacrylamide) (PPCN), with strontium, phosphate, and/or the cyclic RGD peptide would render it a hydrogel with osteoinductive properties. We show that all formulations of functionalized PPCN retain thermoresponsive properties and can induce osteodifferentiation of human mesenchymal stem cells without the need for exogenous osteogenic supplements. PPCN‐Sr was the most osteoinductive formulation in vitro and produced robust localized mineralization and osteogenesis in subcutaneous and intramuscular tissue in a mouse model. Strontium was not detected in any of the major organs. Our results support the use of functionalized PPCN as a valuable tool for the recruitment, survival, and differentiation of cells critical to the development of new bone and the induction of bone formation in vivo. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1743–1752, 2018.
Genetic and phenotypic characterizations of drug‐resistant Mycobacterium tuberculosis isolates in Cheonan, Korea
Authors: Jeon Jae‐Sik , Kim Jae Kyung , Choi Qute , Kim Jong Wan 
Published: February 2018

BackgroundMycobacterium tuberculosis (MTB) causes tuberculosis (TB), which is a fatal disease. Cases of drug‐resistant MTB have increased in recent years. In this study, we analyzed 7 sites of MTB DNA sequences, including the rpoB and inhA gene, to investigate the relationship between gene mutations and drug resistance in MTB.MethodsMycobacterium tuberculosis liquid culture samples (197 specimens from 74 cases) were collected between June 2015 and May 2016 and sequenced. The results were compared with those obtained from antibiotic susceptibility tests.ResultsIn 65 (87.8%) cases, the antibiotic‐resistant phenotype was consistent with genotyping results, whereas in 9 (12.2%) cases, there was no match. Eight mutations were detected in the rpoB gene, which showed the highest mutation rate. Sequencing results indicated that these mutations were present in 12 cases.ConclusionPreviously published data on antibiotic resistance genes are insufficient for effective prevention of multidrug‐ or extensive drug‐resistant TB. Additional studies are needed to characterize the complement of antibiotic resistance genes in MTB.
A plausible atmospheric trigger for the 2017 coastal El Niño
Authors: Garreaud René D. 
Published: February 2018

ABSTRACTThe far eastern tropical Pacific experienced a rapid, marked warming in early 2017, causing torrential rains along the west coast of South America with a significant societal toll in Peru and Ecuador. This strong coastal El Niño was largely unpredicted, even a few weeks before its onset, and it developed differently from either central or eastern events. Here we provide an overview of the event, its impacts and concomitant atmospheric circulation. It is proposed that a remotely forced, sustained weakening of the free tropospheric westerly flow impinging the subtropical Andes leads to a relaxation of the southeasterly (SE) trades off the coast, which in turn may have warmed the eastern Pacific throughout the weakening of upwelling in a near‐coastal band and the lessening of the evaporative cooling farther offshore.
Thermoplastic Polyurethane Elastomers with Aliphatic Hard Segments Based on Plant‐Oil‐Derived Long‐Chain Diisocyanates
Authors: Schemmer Brigitta , Kronenbitter Cathrin , Mecking Stefan 
Published: February 2018

AbstractNovel plant‐oil‐derived long‐chain (C19 and C23) α,ω‐diisocyanates, optionally in combination with the corresponding long‐chain diols, provide entirely aliphatic hard segments in segmented thermoplastic polyurethane elastomers (TPUs), with carbohydrate‐based poly(trimethylene glycol) soft segments. Compared to materials based on a mid‐chain monomer analog, phase separation is higher due to an increased flexibility of the aliphatic segments. Although melting points are slightly lower than for HDPE, the long‐chain TPU's solid‐state structure is still dominated by hydrogen‐bonding.
Medium Resolution 1H‐NMR at 62 MHz as a New Chemically Sensitive Online Detector for Size‐Exclusion Chromatography (SEC–NMR)
Authors: Höpfner Johannes , Ratzsch Karl‐Friedrich , Botha Carlo , Wilhelm Manfred 
Published: February 2018

AbstractA state‐of‐the‐art, medium‐resolution 1H‐NMR spectrometer (62 MHz) is used as a chemically sensitive online detector for size‐exclusion chromatography of polymers such as polymethylmethacrylate (PMMA) and polystyrene (PS). The method uses protonated eluents and works at typical chromatographic conditions with trace amounts of analytes (<0.5 g L−1 after separation). Strong solvent suppression, e.g., by a factor of 500, is achieved by means of T1‐filtering and mathematical subtraction methods. Substantial improvements are made with respect to previous work in terms of the sensitivity (signal‐to‐noise ratio up to 130:1, PMMA OCH3) and selectivity (peak width, full width half maximum (FWHM) 4 Hz on‐flow). Typical homopolymers and a blend are investigated to deformulate their composition along the dimensions of molecular weight and NMR chemical shift. These results validate this new hyphenated chromatography method, which can greatly facilitate analysis and is much more effective than previously published results.
Hydrogen Bond Induces Hierarchical Self‐Assembly in Liquid‐Crystalline Block Copolymers
Authors: Huang Shuai , Pang Linlin , Chen Yuxuan , Zhou Liming , Fang Shaoming , Yu Haifeng 
Published: February 2018

AbstractMicrophase‐separated structures of block copolymers (BCs) with a size of sub‐10 nm are usually obtained by hydrogen‐bond‐induced self‐assembly of BCs through doping with small molecules as functional additives. Here, fabrication of hierarchically self‐assembled sub‐10 nm structures upon microphase separation of amphiphilic liquid‐crystalline BCs (LCBCs) at the existence of hydrogen bonds but without any dopants is reported. The newly introduced urethane groups in the side chain of the hydrophobic block of LCBCs interact with the ether groups of the hydrophilic poly(ethylene oxide) (PEO) block, leading to imperfect crystallization of the PEO blocks. Both crystalline and amorphous domains coexist in the separated PEO phase, enabling a lamellar structure to appear inside the PEO nanocylinders. This provides an elegant method to fabricate controllable sub‐10 nm microstructures in well‐defined polymer systems without the introduction of any dopants.
Cross‐linked poly(aryl ether sulfone) membranes for direct methanol fuel cell applications
Authors: Yılmaz Esra , Can Erde 
Published: February 2018

ABSTRACTPartially sulfonated poly(aryl ether sulfone) (PESS) was synthesized and methacrylated via reaction with glycidyl methacrylate (PESSGMA) and cross‐linked via radical polymerization with styrene and vinyl‐phosphonic acid (VPA). The chemical structures of the synthesized pre‐polymers were characterized via FTIR and 1H NMR spectroscopic methods and molecular weight was determined via GPC. Membranes of these polymers were prepared via solution casting method. The crosslinking of the PESS polymer reduced IEC, proton conductivity, swelling in water, and methanol permeability of the membranes while increasing the modulus and the glass transition temperature. However, the introduction of the VPA comonomer increased the proton conductivity while maintaining excellent resistance to methanol cross‐over, which was significantly higher as compared with both PESS and the commercial Nafion membranes. Membranes of PESSGMA copolymers incorporating VPA, exhibited proton conductivity values at 60 °C in the range of 16–32 mS cm−1 and methanol permeability values in the range of 6.52 × 10−9 – 1.92 × 10−8 cm2 s−1. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 558–575
Preparation of Macroporous Mn3O4 Microspheres via Thermal Decomposition in Water Vapor
Authors: Kozawa Takahiro 
Published: February 2018

AbstractMacroporous materials are in constant demand for use in environmental purification filters. Although the preparation of porous materials by a thermal decomposition route without templates and surfactants is simple, low‐cost, and scalable, the pore size of the resulting materials is limited to micropore or mesopore regions. Herein, I report the preparation of macroporous Mn3O4 microspheres from MnCO3 spheres via thermal decomposition in water vapor. The accelerated decomposition of MnCO3 by water vapor facilitates vermicular growth of Mn3O4 primary particles at a low temperature, leading to the formation of a maze‐like pore structure. The characteristic microstructure of macroporous Mn3O4 microspheres exhibits nanoparticle capture properties and inherited its pore structure of Mn3O4 during conversion to Mn2O3 by reheating. This study reveals new possibilities for the application of the thermal decomposition method to prepare macroporous particles.
Penne‐Like MoS2/Carbon Nanocomposite as Anode for Sodium‐Ion‐Based Dual‐Ion Battery
Authors: Zhu Haili , Zhang Fan , Li Jinrui , Tang Yongbing 
Published: February 2018

AbstractThe dual‐ion battery (DIB) system has attracted great attention owing to its merits of low cost, high energy, and environmental friendliness. However, the DIBs based on sodium‐ion electrolytes are seldom reported due to the lack of appropriate anode materials for reversible Na+ insertion/extraction. Herein, a new sodium‐ion based DIB named as MoS2/C‐G DIB using penne‐like MoS2/C nanotube as anode and expanded graphite as cathode is constructed and optimized for the first time. The hierarchical MoS2/C nanotube provides expanded (002) interlayer spacing of 2H‐MoS2, which facilitates fast Na+ insertion/extraction reaction kinetics, thus contributing to improved DIB performance. The MoS2/C‐G DIB delivers a reversible capacity of 65 mA h g−1 at 2 C in the voltage window of 1.0–4.0 V, with good cycling performance for 200 cycles and 85% capacity retention, indicating the feasibility of potential applications for sodium‐ion based DIBs.
Fine Tuning of Canonical Wnt Stimulation Enhances Differentiation of Pluripotent Stem Cells Independent of β-Catenin-Mediated T-Cell Factor Signaling
Authors: Chen Joseph , Nefzger Christian M. , Rossello Fernando J. , Sun Yu B.Y. , Lim Sue Mei , Liu Xiaodong , de Boer Suzan , Knaupp Anja S. , Li Jinhua , Davidson Kathryn C. , Polo Jose M. , Barberi Tiziano 
Published: February 2018

Abstract
The canonical Wnt/β-catenin pathway is crucial for early embryonic patterning, tissue homeostasis, and regeneration. While canonical Wnt/β-catenin stimulation has been used extensively to modulate pluripotency and differentiation of pluripotent stem cells (PSCs), the mechanism of these two seemingly opposing roles has not been fully characterized and is currently largely attributed to activation of nuclear Wnt target genes. Here, we show that low levels of Wnt stimulation via ectopic expression of Wnt1 or administration of glycogen synthase kinase-3 inhibitor CHIR99021 significantly increases PSC differentiation into neurons, cardiomyocytes and early endodermal intermediates. Our data indicate that enhanced differentiation outcomes are not mediated through activation of traditional Wnt target genes but by β-catenin's secondary role as a binding partner of membrane bound cadherins ultimately leading to the activation of developmental genes. In summary, fine-tuning of Wnt signaling to subthreshold levels for detectable nuclear β-catenin function appears to act as a switch to enhance differentiation of PSCs into multiple lineages. Our observations highlight a mechanism by which Wnt/β-catenin signaling can achieve dosage dependent dual roles in regulating self-renewal and differentiation.
Acute Limb Ischemia Secondary to Native Artery Occlusion: Results of a Contemporary Case Series
Authors: Seguí Nuria , Ruiz‐Carmona Carlos , Velescu Alina , Mateos Eduardo , Elosua Roberto , Clará Albert 
Published: February 2018

AbstractBackgroundThe treatment of acute limb ischemia (ALI) has barely changed over the last years. However, the progressive implementation of anticoagulants, antiplatelet agents or statins within the population might have modified the profile and prognosis of patients suffering an ALI. The aim of this study was to evaluate the current results of the management of ALI secondary to a native artery occlusion.MethodsRetrospective study of 220 consecutive patients (mean age 78 years; 49% male) was conducted between 2007 and 2015. ALI secondary to trauma or grafts/stents occlusions were excluded. Statistical analysis was performed with logistic regression.ResultsA total of 141 cases (64.1%) were attributed to embolism and 79 (35.9%) to acute arterial thrombosis. Peripheral neuro‐ischemic impairment occurred in 135 patients (61.4%), being severe in 42 (19.1%). ALI treatment included anticoagulation (n = 27; 12.3%), regional fibrinolysis (n = 2; 1%), embolectomy/thrombectomy (n = 129; 58.6%), angioplasty/stenting (n = 8; 3.6%), bypass (n = 47; 21.3%) or direct major limb amputation (n = 7; 3.2%). Limb salvage and survival rates at 30/90 days were 95%/95% and 82.3%/74.1%, respectively. Independent risk factors for major amputation were diabetes, severe neuro‐ischemic impairment, acute arterial thrombosis and treatment delay >1 day after vascular consultation. In addition, age, chronic peripheral arterial disease, any neuro‐ischemic impairment and a hospitalization for any other reason simultaneous to the ALI were independently associated with mortality.ConclusionsRegardless of excellent limb salvage rates, patients currently suffering from an ALI are, when compared to previous studies, older than before and with an increased rate of mortality. Risk factors do not appear to be modifiable once the ALI appears so prevention strategies should be aimed to avoid the episode.