bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hiatus‐like decades in the absence of equatorial Pacific cooling and accelerated global ocean heat uptake
Authors: von Känel Lukas , Frölicher Thomas L. , Gruber Nicolas 
Published: June 2017

AbstractA surface cooling pattern in the equatorial Pacific associated with a negative phase of the Interdecadal Pacific Oscillation is the leading hypothesis to explain the smaller rate of global warming during 1998–2012, with these cooler than normal conditions thought to have accelerated the oceanic heat uptake. Here using a 30‐member ensemble simulation of a global Earth system model, we show that in 10% of all simulated decades with a global cooling trend, the eastern equatorial Pacific actually warms. This implies that there is a 1 in 10 chance that decadal hiatus periods may occur without the equatorial Pacific being the dominant pacemaker. In addition, the global ocean heat uptake tends to slow down during hiatus decades implying a fundamentally different global climate feedback factor on decadal time scales than on centennial time scales and calling for caution inferring climate sensitivity from decadal‐scale variability.
Dependence of model‐simulated response to ozone depletion on stratospheric polar vortex climatology
Authors: Lin Pu , Paynter David , Polvani Lorenzo , Correa Gustavo J. P. , Ming Yi , Ramaswamy V. 
Published: June 2017

AbstractWe contrast the responses to ozone depletion in two climate models: Community Atmospheric Model version 3 (CAM3) and Geophysical Fuild Dynamics Laboratory (GFDL) AM3. Although both models are forced with identical ozone concentration changes, the stratospheric cooling simulated in CAM3 is 30% stronger than in AM3 in annual mean, and twice as strong in December. We find that this difference originates from the dynamical response to ozone depletion, and its strength can be linked to the timing of the climatological springtime polar vortex breakdown. This mechanism is further supported by a variant of the AM3 simulation in which the southern stratospheric zonal wind climatology is nudged to be CAM3‐like. Given that the delayed breakdown of the southern polar vortex is a common bias among many climate models, previous model‐based assessments of the forced responses to ozone depletion may have been somewhat overestimated.
Holocene black carbon in Antarctica paralleled Southern Hemisphere climate
Authors: Arienzo M. M. , McConnell J. R. , Murphy L. N. , Chellman N. , Das S. , Kipfstuhl S. , Mulvaney R. 
Published: June 2017

AbstractBlack carbon (BC) and other biomass‐burning (BB) aerosols are critical components of climate forcing, but quantification, predictive climate modeling, and policy decisions have been hampered by limited understanding of the climate drivers of BB and by the lack of long‐term records. Prior modeling studies suggested that increased Northern Hemisphere anthropogenic BC emissions increased recent temperatures and regional precipitation, including a northward shift in the Intertropical Convergence Zone (ITCZ). Two Antarctic ice cores were analyzed for BC, and the longest record shows that the highest BC deposition during the Holocene occurred ~8–6 k years before present in a period of relatively high austral burning season and low growing season insolation. Atmospheric transport modeling suggests South America (SA) as the dominant source of modern Antarctic BC and, consistent with the ice core record, climate model experiments using mid‐Holocene and preindustrial insolation simulate comparable increases in carbon loss due to fires in SA during the mid‐Holocene. SA climate proxies document a northward shifted ITCZ and weakened SA Summer Monsoon (SASM) during this period, with associated impacts on hydroclimate and burning. A second Antarctic ice core spanning the last 2.5 k years documents similar linkages between hydroclimate and BC, with the lowest deposition during the Little Ice Age characterized by a southerly shifted ITCZ and strengthened SASM. These new results indicate that insolation‐driven changes in SA hydroclimate and BB, likely linked to the position of the ITCZ, modulated Antarctic BC deposition during most of the Holocene and suggests connections and feedbacks between future BC emissions and hydroclimate.
Bis(dibenzylideneacetone)palladium(0)/tert‐Butyl Nitrite‐ Catalyzed Cyclization of o‐Alkynylanilines with tert‐Butyl Nitrite: Synthesis and Applications of Indazole 2‐Oxides
Authors: Senadi Gopal Chandru , Wang Ji‐Qi , Gore Babasaheb Sopan , Wang Jeh‐Jeng 
Published: June 2017

AbstractAn efficient method for the synthesis of 1‐benzyl/arylindazole 2‐oxides via a bis(dibenzylideneacetone)palladium(0) [Pd(dba)2]/tert‐butyl nitrite (TBN)‐catalyzed reaction of o‐alkynylaniline derivatives with TBN is reported. The overall transformation involves the formation of three new bonds via N‐nitrosation (N–NO), 5‐exo‐dig cyclization (C–N) and oxidation (C=O). The notable features are the mild reaction conditions, broad substrate scope and dual role of TBN as an NO source and redox co‐catalyst. This strategy was implemented for the synthesis of indazole‐3‐carbaldehyde derivatives and the formal syntheses of pharmaceutically active YC‐1, an anticancer agent (lonidamine), and the male contraceptive experimental drugs AF‐2785 and adjudin (AF‐2364).magnified image
How nano‐scale roughness impacts the flow of grains influenced by capillary cohesion
Authors: LaMarche Casey Q. , Miller Andrew W. , Liu Peiyuan , Leadley Stuart , Hrenya Christine M. 
Published: June 2017

SignificanceWe show that nano‐scale changes in surface roughness affect the macro‐scale (many‐particle) behavior of granular materials influenced by cohesion. Macro‐scale effects of roughness are investigated for conditions where cohesion is dominated by either humidity‐induced or van der Waals‐induced forces. Surface‐topography measurements are used to calculate the relevant interparticle cohesive forces. The (force‐dominated) macro‐scale cohesion measurements are explained via the ratio of the predicted interparticle cohesive force to gravity, thus reinforcing the importance of roughness to cohesion. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5250–5257, 2017
Highly Stable, Low Gas Crossover, Proton‐Conducting Phenylated Polyphenylenes
Authors: Adamski Michael , Skalski Thomas J. G. , Britton Benjamin , Peckham Timothy J. , Metzler Lukas , Holdcroft Steven 
Published: June 2017

AbstractTwo classes of novel sulfonated phenylated polyphenylene ionomers are investigated as polyaromatic‐based proton exchange membranes. Both types of ionomer possess high ion exchange capacities yet are insoluble in water at elevated temperatures. They exhibit high proton conductivity under both fully hydrated conditions and reduced relative humidity, and are markedly resilient to free radical attack. Fuel cells constructed with membrane‐electrode assemblies containing each ionomer membrane yield high in situ proton conductivity and peak power densities that are greater than obtained using Nafion reference membranes. In situ chemical stability accelerated stress tests reveal that this class of the polyaromatic membranes allow significantly lower gas crossover and lower rates of degradation than Nafion benchmark systems. These results point to a promising future for molecularly designed sulfonated phenylated polyphenylenes as proton‐conducting media in electrochemical technologies.
The Structure of the Diatom Silaffin Peptide R5 within Freestanding Two‐Dimensional Biosilica Sheets
Authors: Lutz Helmut , Jaeger Vance , Schmüser Lars , Bonn Mischa , Pfaendtner Jim , Weidner Tobias 
Published: June 2017

AbstractThe silaffin peptide R5 is instrumental to the mineralization of silica cell walls of diatom organisms. The peptide is also widely employed in biotechnology, for example, in the encapsulation of enzymes and for fusion proteins in tissue regeneration. Despite its scientific and technological importance, the interfacial structure of R5 during silica precipitation remains poorly understood. We herein elucidate the conformation of the peptide in its active form within silica sheets by interface‐specific vibrational spectroscopy in combination with molecular dynamics simulations. Contrary to previous solution‐state NMR studies, our data confirm that R5 maintains a defined structure when interacting with extended silica sheets. We show that the entire amino acid sequence of R5 interacts with silica during silica formation, leading to the intercalation of silica into the assembled peptide film.
Pentagon‐Embedded Cycloarylenes with Cylindrical Shapes
Authors: Hitosugi Shunpei , Sato Sota , Matsuno Taisuke , Koretsune Takashi , Arita Ryotaro , Isobe Hiroyuki 
Published: June 2017

AbstractCylinder‐shaped graphitic networks in carbon nanotubes have attracted interest from scientists in various disciplines. The chemical synthesis of segments thereof is considered as a challenging and appealing subject in chemistry, and deepens our understanding of curved and conjugated arrays of hexagons. We herein report the synthesis of cylinder‐shaped molecules containing non‐hexagon bridges in their conjugated systems. Multiple pentagon units were embedded in the cylinder‐shaped discrete molecules, and the stereoisomerism originating from their helical carbon arrangements was studied. Structural analysis by NMR, UV/Vis absorption spectroscopy, and single‐crystal X‐ray diffraction provided fundamental experimental information on the curved systems with conjugation across the pentagons. This study provides the first experimental guide for further explorations of anomalous non‐hexagon arrays of graphitic carbon materials with cylindrical shapes.
Frustrated Lewis Pair Mediated 1,2‐Hydrocarbation of Alkynes
Authors: Fasano Valerio , Curless Liam D. , Radcliffe James E. , Ingleson Michael J. 
Published: June 2017

AbstractFrustrated Lewis pair (FLP) chemistry enables a rare example of alkyne 1,2‐hydrocarbation with N‐methylacridinium salts as the carbon Lewis acid. This 1,2‐hydrocarbation process does not proceed through a concerted mechanism as in alkyne syn‐hydroboration, or through an intramolecular 1,3‐hydride migration as operates in the only other reported alkyne 1,2‐hydrocarbation reaction. Instead, in this study, alkyne 1,2‐hydrocarbation proceeds by a novel mechanism involving alkyne dehydrocarbation with a carbon Lewis acid based FLP to form the new C−C bond. Subsequently, intermolecular hydride transfer occurs, with the Lewis acid component of the FLP acting as a hydride shuttle that enables alkyne 1,2‐hydrocarbation.
Ultrasonic‐assisted synthesis and biological evaluation of a nano‐rod diorganotin phosphonic diamide: Precursor for the fabrication of SnP2O7 nano‐structure
Authors: Dorosti Niloufar , Delfan Bahram , Khodadadi Marzieh 
Published: June 2017

Nanorods of a diorganotin phosphonic diamide with formula [Sn(CH3)2(Cl)2(L)2]{L = C6H5(O)P(NHC6H11)2} have been synthesized by sonochemical processes at different concentrations without any surfactant or capping agent. The structure and morphology of the prepared complex were investigated by using SEM‐EDAX, XRD, DLS, UV–Vis and FT‐IR spectroscopy. Nanoparticles with well‐defined rod shapes and sizes in the range 30–40 nm have been obtained. Also bulk form of the titled complex was synthesized and characterized by 1H, 13C, 31P, 119Sn NMR, UV–Vis and FT‐IR spectroscopy and compared with its nano‐size. The thermal stabilities at bulk and nano‐size scale have been studied by thermal gravimetric (TG) and differential thermal analysis (DTA). Further, SnP2O7 nanoparticles were synthesized by direct calcination at 730 °C under air atmosphere and characterized using XRD, SEM, and TEM. From XRD measurements, we determined the mean size of the crystallites about 27.4 nm. It is found that the size and morphology of the tin pyrophosphate nano‐structures are dependent upon the particles size of precursor compound as well. Two different forms of metal coordination compound (1a, 1b) and the corresponding ligand (L) were screened for their antibacterial activity against the selected Gram‐positive and Gram‐negative bacteria, showing bactericidal activity for complexes 1a and 1b. In vitro cytotoxicity of compounds was studied against human carcinoma cell lines, A2780 (ovarian cancer) and PC‐3 (prostate cancer). Results indicated that 1a and 1b possess relatively strong cytotoxic activity against cancer cells with IC50 values ranging from 93.2 to 376.2 μM for two exposure time (24 and 48 h).
To prepare the collagen‐based artificial cornea with improved mechanical and biological property by ultraviolet‐A/riboflavin crosslinking
Authors: Zhao Xuan , Long Kai , Liu Yang , Li Weichang , Liu Sa , Wang Lin , Ren Li 
Published: June 2017

ABSTRACTIn the present study, we optimized the ultraviolet‐A (UVA)/riboflavin crosslinking for the collagen‐based artificial cornea for the first time to resolve the lack of donor cornea for corneal disease. We found that the crosslinking conditions, including irradiation time and irradiation intensity, played important roles on the property of the sample. At the optimal condition (with the irradiation time of 30 min and the irradiation intensity of 5 mW/cm2), the sample exhibited excellent crosslink degree and mechanical property while keeping good light transmittance. Meanwhile, the sample showed improved enzyme tolerance capacity and thermal stability. This developed artificial cornea also had good biocompatibility to human corneal epithelial cells in vitro. In vivo lamellar keratoplasty results showed that the developed sample could promote complete epithelialization in about 4 weeks, and the transparency is restored quickly in the first 6 weeks. Corneal rejection reaction and keratoconus are not observed. This optimized UVA/riboflavin crosslinking method would have great potential for collagen‐based artificial cornea in clinic. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45226.
Isotactic polypropylene–vapor grown carbon nanofibers composites: Electrical properties
Authors: Aldica Gheorghe Virgil , Ciurea Magdalena Lidia , Chipara Dorina Magdalena , Lepadatu Ana Maria , Lozano Karen , Stavarache Ionel , Popa Stelian , Chipara Mircea 
Published: June 2017

ABSTRACTNanocomposites have been obtained by dispersing various amounts of vapor grown carbon nanofibers within isotactic polypropylene. Thermal investigations done by differential scanning calorimetry and dynamic mechanical analysis revealed the effect of the vapor grown carbon nanofibers on the melting, crystallization, α, and β relaxations. Direct current electrical features of these nanocomposites have been investigated and related to the thermal features of these nanocomposites. The effect of the loading with carbon nanofibers on the electrical properties of these nanocomposites is discussed within the percolation theory. The percolation threshold was estimated at about 5.5% wt carbon nanofibers. The temperature dependence of the direct current conductivity is analyzed in detail and it is concluded that the electronic hopping is the dominant transport mechanism. A transition from one‐dimensional hopping towards a three‐dimensional hopping was noticed as the concentration of carbon nanofibers was increased from 10% wt to 20% wt carbon nanofiber. The possibility of a differential negative resistivity is suggested. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45297.
Microporous PDMAEMA‐based stimuli‐responsive hydrogel and its application in drug release
Authors: Chen Yi , Liu Wenyong , Zeng Guangsheng , Liu YueJun 
Published: June 2017

ABSTRACTThe microporous hydrogels (Pn‐Cm gels) composed of poly(dimethylaminoethyl methacrylate) and carboxymethylchitosan were synthesized in situ radical polymerization by using nano γ‐Fe2O3 particles as pore‐agent. The microporous structure formed through eliminating the Fe2O3 particles was designed to achieve a faster response rate and better drug loading effect. Comparing to the neat gels, Pn‐Cm gels exhibit deteriorative mechanical properties with the increased pores, while the gels still keep the elastic network structure which could bear some degree of tensile and compression deformation. Meantime, Pn‐Cm gels show similar temperature and pH double responsiveness with same isoelectric point shrink as that of neat gels, the swelling ability decreases slightly, and the deswelling rate increases with the increase of pores. Moreover, the 5‐fluorouracil was used as a target drug to explore the potential of this gel applied as drug‐release system. For Pn‐Cm gels, the more pores and carboxymethyl chitosan inside the gels are beneficial to the drug loading, all gels show a burst release of drug, being followed by a slow and sustained release with different rate. Comprehensively, the Pn‐Cm gels exhibit a better sustained release effect in the simulated stomach condition (pH = 2.1), the related release mechanism could be interpreted by the superposition of Fickian diffusion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45326.
Ionic‐liquid‐assisted three‐dimensional caged silica ablative nanocomposites
Authors: Kumar Vijay , Kandasubramanian Balasubramanian 
Published: June 2017

ABSTRACTIn this study, we demonstrated a novel three‐dimensional network of thermally stable fumed silica (FS)–resorcinol formaldehyde (RF) nanocomposites via an ionic‐liquid (IL)‐assisted in situ polycondensation process. The study involved subjecting the tailored nanocomposites to thermogravimetric analysis and oxyacetylene flame environment as per ASTM test standards for thermal ablative performance. X‐ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high‐resolution transmission electron microscopy, Raman spectroscopy, and wettability studies were undertaken to underline the improvement correlation in the microstructure and material properties. Significant reductions in the linear ablation rate (66%) and mass ablation rate (26.6%), along with lower back‐face temperature profiles, marked enhanced ablative properties. The increased char yield (33.3%) and higher temperatures for weight losses evinced the improved thermal stability of the modified RF resin. The uniformly dispersed fused nanosilica with a glassy coating morphology on the ablative surface acted as barrier to oxidation. The results signify that the IL‐assisted modification of the RF resin with FS significantly enhanced ablative performance. A viable replacement to the conventional phenolic nanocomposites for thermal ablative applications to buy critical time for the containment and suppression of thermal‐heat‐flux threats is of paramount importance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45328.
A new sulfonated poly(ether sulfone) hybrid with low humidity dependence for high‐temperature proton exchange membrane fuel cell applications
Authors: Molavian Mohammad Reza , Abdolmaleki Amir , Firouz Tadavani Koorosh , Zhiani Mohammad 
Published: June 2017

ABSTRACTA new sulfonated poly(ether sulfone) (PES) hybrid with low humidity dependence was prepared based on a new synthesized PES and Udel as a commercial PES. The PES was synthesized based on a pyridine containing diol which is able to change between pyridine and pyridinium salt forms during the cell performance (acidic condition) and facilitate proton transfer. The presence of nitrogen group increases inter and intramolecular interactions in the membrane and enhance proton hopping mechanism. Thermogravimetrical analysis of PES hybrid shows good thermal stability. Proton conductivity measurements were evaluated on a fuel cell test station, showing that the membrane has better performance under lower humidity (relative humidity = 60%) compare to the fully hydrated condition (relative humidity = 100%). The results reveal that proton transfer might be mainly accomplished through proton hopping mechanism at higher temperatures. The membrane also shows significant proton conductivity at 120 °C (about 6.6 mS cm−1 at RH = 30%). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45342.
Alkylated pectin hydrogels as potential protein drug carriers
Authors: He Xiao‐hong , Liang Rui‐hong , Liu Cheng‐mei , Liu Wei , Chen Rui‐yun , Hu Xiao‐xue , Chen Jun 
Published: June 2017

ABSTRACTPectin has been used in the development of safe and effective drug delivery systems because of its unique physicochemical and biological characteristics. However, it still needs to be modified to overcome some inherent drawbacks. In the present study, pectin was alkylated by bromododecane. The C12‐alkylated pectin (PC12) can form strong hydrogels in the presence of Ca2+. Such hydrogels were explored to prepare bovine serum albumin (BSA)‐loaded microspheres (PC12‐MS). The BSA encapsulation yield of PC12‐MS was significantly higher than that of microspheres prepared with the original pectin (PC‐MS). Differential scanning calorimetry analysis indicated that interactions existed between BSA and pectin during the preparation of microspheres. Release tests showed that PC12‐MS almost avoided BSA release in simulated gastric fluids, which was verified by environmental scanning electron microscopy analysis, and exhibited an effective controlled release throughout the simulated gastrointestinal tract compared to PC‐MS. In addition, an MTT assay showed the biocompatibility of C12‐alkylated pectin. Thus alkylated pectin may serve as a potential protein drug carrier. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45344.
Fabrication and characteristics of graphene oxide/nanocellulose fiber/poly(vinyl alcohol) film
Authors: Xu Changyan , Shi Lina , Guo Lu , Wang Xi , Wang Xinyi , Lian Hailan 
Published: June 2017

ABSTRACTPoly(vinyl alcohol) (PVA), PVA/nanocellulose fiber (CNF), and PVA/CNF/graphene oxide (GO) films were prepared simply by casting stable aqueous mixed solutions. FTIR investigation indicated that hydrogen bonding existed between the interface of GO and PVA‐CNF. Scanning electron microscopy and X‐ray diffraction analysis showed that GO was uniformly dispersed in PVA‐CNF matrix. Introducing CNF into PVA caused a significant improvement in tensile strength, and further incorporating GO into PVA/CNF matrix led to a further increase. The tensile strength of the neat PVA film, PVA/CNF composite, and PVA/CNF/GO film (0.6 wt % GO) was 43, 69, and 80 MPa, respectively. Moreover, when incorporating 8 wt % CNF into PVA matrix, O2 permeability and water absorption decreased from 13.36 to 11.66 cm3/m2/day and from 164.2% to 98.8%, respectively. Further adding 0.6 wt % GO into PVA/CNF matrix resulted in a further decrease of permeability and water absorption to 3.19 cm3/m2/day and 91.2%, respectively. Furthermore, for all composite samples, the transmittance of visible light was higher than 67% at 800 nm. CNF and GO‐reinforced PVA with high mechanical and barrier properties are potential candidates for packaging industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45345.
On horizontal distribution of vertical gradient of atmospheric refractivity
Authors: Grabner Martin , Pechac Pavel , Valtr Pavel 
Published: June 2017

AbstractThe horizontal distribution of the vertical gradient of atmospheric refractivity is important for the assessment of the propagation of electromagnetic waves on nearly horizontal paths. A 5‐year set of meteorological data, obtained from the ERA‐Interim numerical weather product, has been used to analyze this distribution statistically. Vertical gradient maps of the Central European region have been processed to derive empirical probability distributions of the difference between local point gradient values at two locations. The difference of the effective (path‐averaged) gradient along the path and the local gradient is shown to be statistically distributed so that the quantiles increase linearly with distance in the interval from 100 to 1000 km. Finally, a spatial correlation function is obtained and described by an exponential model with correlation distances determined in the range of 400–700 km.