bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal and mechanical evaluation of cyanate ester resin catalyzed by nonylphenol and stannous octoate
Authors: Liu Ting , Li Jinhuan , Xiao Jun , Tian Wenping 
Published: July 2016

ABSTRACTNonylphenol (NP), stannous octoate [Sn(Otc)2], and a mixture of NP and Sn(Otc)2 were employed for catalyzing cyanate ester resin. The curing reaction was studied by differential scanning calorimetry. A water‐absorption test at 85 °C was utilized to study the resistance to warm and humid conditions. The thermal properties were evaluated through measuring thermal weight loss and the glass‐transition temperature (Tg), and the mechanical properties were evaluated through three‐point bending tests and tensile tests. The results show that the mixture of NP and Sn(Otc)2 exhibits the best catalytic efficiency by decreasing the exothermic peak temperature by almost 148 °C. The mixture of NP and Sn(Otc)2 has unfavorable effects on the thermal stability. Nevertheless, all catalyst systems have good water‐absorption resistance. The mechanical investigation confirms that the tensile properties show a little reduction that is due to the plasticization of the catalyst, while the excellent flexural properties are maintained. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43959.
Tunable multifunctional tissue engineering scaffolds composed of three‐component polyampholyte polymers
Authors: Cao Siyu , Barcellona Marcos N. , Pfeiffer Ferris , Bernards Matthew T. 
Published: July 2016

ABSTRACTResistance to nonspecific protein adsorption and the capability to provide targeted bioactive signals are essential qualities for implantable biomaterials. The development of materials that combine these multifunctional characteristics and tunable mechanical properties has been a target in the tissue engineering field over the last decade. This study is the first to demonstrate that polyampholyte hydrogels prepared with equimolar quantities of positively charged and negatively charged monomer subunits from multiple monomer compositions have great potential to address these needs. The hydrogels were synthesized with positively charged [2‐(acryloyloxy)ethyl] trimethylammonium chloride and different monomer ratios of the negatively charged 2‐carboxyethyl acrylate and 3‐sulfopropyl methacrylate monomers. The physical and chemical properties of the hydrogels were fully characterized, including swelling, hydration, mechanical strength, and chemical composition, and the fouling resistance of the hydrogels was demonstrated using enzyme‐linked immunosorbent assays. Additionally, the capability of the hydrogels to facilitate protein conjugation via EDC/NHS conjugation chemistry was assessed. The results clearly demonstrate that the polyampholyte hydrogels have a range of tunable mechanical strength based on the monomer subunits, while maintaining their excellent nonfouling properties. Additionally, high levels of conjugated protein were achieved for all of the monomer combinations investigated. Therefore, the broadly applicable multifunctional properties of polyampholyte hydrogels and their tunable mechanical properties clearly demonstrate the potential of these materials for tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43985.
Liquid‐phase catalytic thermal cleavage of thiocarbonylthio end‐groups for polymers synthesized by RAFT polymerization: Influences of different solvents
Authors: Zhang Xiaolei , Jiang Junqing , Zhang Yanwu 
Published: July 2016

ABSTRACTCatalytic thermal cleavage of thiocarbonylthio end‐groups for RAFT synthesized polymers is usually accompanied by other side reactions such as chain‐scission and crosslinking. Occurrence of these side reactions depends on polymers, end‐groups, and oxidation–reduction property of reaction media in a liquid phase. Herein, well‐defined hydrophilic poly(4‐vinylpridine) (P4VP) and hydrophobic polystyrene (PS) are synthesized via a controlled RAFT polymerization in the presence of S‐1‐Dodecyl‐S′‐(R,R′‐dimethyl‐R″‐acetic acid) trithiocarbonates (DDMAT). Then their thiocarbonylthio end‐groups are cleaved through catalytic thermolysis in a liquid phase. Under the catalysis of Cu(0), all S‐containing groups can be removed at 165 °C in 3 h. To study the effect of solvent on thermolysis and microstructure of polymer, nitrobenzene of oxidation property and diethylene glycol of reduction property are chosen as solvents. Because of oxidizing property of nitrobenzene, Z groups of RAFT agent are eliminated at the same time that thiocarbonylthio end‐groups are removed. Therefore crosslinking among multipolymer chains occurs. While diethylene glycol is used as a solvent, no crosslinking occurs. Diethylene glycol is superior to nitrobenzene for synthesis of well‐defined polymer without S‐containing groups. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43992.
Biodegradable and temperature‐responsive thermoset polyesters with renewable monomers
Authors: Lee XiauYeen , Wahit Mat Uzir , Adrus Nadia 
Published: July 2016

ABSTRACTA series of biodegradable thermoset polyesters, poly(1,8‐octanediol–glycerol–dodecanediaote)s (POGDAs), were synthesized with the polycondensation polymerization method without a catalyst and with different monomer molar ratios. Synthesis was confirmed with structural analysis via Fourier transform infrared spectroscopy. The effect of varying the monomer molar ratio on the material properties was illustrated in the gel content and swelling analysis, ultraviolet–visible spectroscopy, differential scanning calorimetry, X‐ray diffraction, and degradation tests. Degradation tests were performed in phosphate‐buffered solution at 37 °C for 60 days. Temperature‐responsive behavior was revealed with POGDA (0.5 glycerol), and bending tests were performed to study the shape‐memory effect. In vitro cytotoxicity tests and cell proliferation tests suggested that these POGDAs have potential applications in biomedical fields such as tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44007.
Form birefringence and turbidity of polystyrene/poly(methyl methacrylate) blends in slit dies and planar contractions
Authors: Silva Jorge , Canevarolo Sebastião V. 
Published: July 2016

ABSTRACTThe birefringence and turbidity of a polystyrene/poly(methyl methacrylate) (PMMA) blend, with the concentration of the PMMA dispersed phase ranging up to 1%, were measured in both a slit channel with a constant cross section and a planar hyperbolic contraction/expansion (8:1:8). The measurements were performed by the attachment of a modular rheo‐optical die to a twin‐screw extruder. The optical arrangement had a red light‐emitting diode as the source and two photoresistors, with one of them measuring the turbidity and the other one measuring the transmitted intensity between cross‐polarizers. The experimental procedure consisted of the stopping of the extruder feeding, while the screw rotation was kept constant. Because the form birefringence could be associated with the shape of the droplets, these measurements were used to infer information about the PMMA droplet deformation and breakup. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016,133, 44066.
Development and characteristics of biodegradable Aloe‐gel/egg white films
Authors: López‐Mata Marco Antonio , García‐González Gerardo , Valbuena‐Gregorio Edith , Ruiz‐Cruz Saúl , Zamudio‐Flores Paul Baruk , Burruel‐Ibarra Silvia Elena , Morales‐Figueroa Gloria Guadalupe , Quihui‐Cota Luis 
Published: July 2016

ABSTRACTThe use of synthetic nonbiodegradable polymers has led to environmental damage. This has encouraged the interest to the development of new renewable and biodegradable matrices. The potential of egg white (EW) protein for the development of bioplastic materials has been published. However, the mixture of EW with Aloe‐gel (AG) for film formation has not been documented. In this study, films with different EW and AG combinations are manufactured and their properties are analyzed. In general, the AG/EW films are homogeneous, smooth, with no pores and with cumulus of protein on the surface with better extensibility, plasticity, and low tensile strength. In addition, they are yellow colored, UV‐light blocker, with high solubility (2.2 times) and high Water Vapor Permeability (4.17 times) compared with the control (EW film). The AG/EW films showed higher percentage of soluble protein and antibacterial activity than the control. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44067.
Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Polymerization rate and PVC properties
Authors: Bijhanmanesh Mohammad Javad , Etesami Nasrin 
Published: July 2016

ABSTRACTContinuous dosing of a fast initiator during the suspension polymerization of vinyl chloride has been carried out in a pilot‐scale reactor. The kinetics course of this polymerization and the particle features of the resulting grains were discussed and compared to the conventional polymerization with the same conversion and maximum reaction rate. It was found for the system used that a suitable dosage trajectory allows the reaction rate to remain constant during polymerization. This decreases the polymerization time up to 53% compared with the conventional suspension polymerization, while the molecular weight distribution and molecular weight of the final grains remained almost unchanged. SEM micrographs revealed that PVC grains prepared using this polymerization process had irregularly shaped, uneven particle surfaces and larger particle sizes. The grains also featured high porosity with loosely aggregated smaller primary particles that led to low levels of residual unreacted monomer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44079.
A kidney‐shaped polycystic mass on the back of a hemodialysis patient
Authors: Volkmann Julia , Nordlohne Johannes , Schmitt Roland , von Vietinghoff Sibylle 
Published: July 2016

Key Clinical MessageMulticystic back masses can be of infectious, metastatic, or local pre‐ or malignant origin. We present a case of a rapidly evolving mass in a hemodialysis patient with severe “chronic kidney disease‐associated mineral bone disease” (CKD‐MBD), that also highlights limitations of chest x‐ray for diagnosis of bone disease.
CdS‐Nanoparticles‐Decorated Perpendicular Hybrid of MoS2 and N‐Doped Graphene Nanosheets for Omnidirectional Enhancement of Photocatalytic Hydrogen Evolution
Authors: Zhang Shuqu , Wang Longlu , Zeng Yunxiong , Xu Yuzi , Tang Yanhong , Luo Shenglian , Liu Yutang , Liu Chengbin 
Published: July 2016

AbstractA new hierarchical nanoarchitecture with integration of multiple active materials has been developed for highly efficient hydrogen evolution reaction (HER), by decorating a perpendicular hybrid of MoS2 and N‐doped graphene nanosheets with CdS nanoparticles. The unique architecture promoted light trapping and absorption for highly efficient light harvesting and photocarrier generation, and offered an unblocked electron transport pathway for rapid charge separation/transport to suppress charge recombination. Its high surface area and high density of active sites result in highly efficient utilization of photogenerated carriers for productive HER. Significantly, without using noble metals as co‐catalysts, the photocatalysts demonstrated rapid HER rates as high as 5.01 mmol h−1 g−1 under visible‐light irradiation, which was approximately 25 times that of pure CdS. The hydrogen production remained stable after a continued test for 30 h, showing an exceedingly high performance and superior stability.
Particle‐Scale Investigation of Heat Transfer in Radiation‐Driven Char Gasification
Authors: Lu Zhao , Jafarian Mehdi , Arjomandi Maziar , Nathan Graham J. 
Published: July 2016

AbstractA model of the steam gasification of a single char particle driven by high‐intensity radiation was developed and experimentally verified with available measurements in the literature. This was used to explore the sensitivity of the particle surface temperature and heat‐transfer mechanisms to variations in particle diameters, radiative heat flux, and the concentration of the gasification agent H2O under typical conditions for solar gasification reactors. The results highlight the importance of the particle diameter in influencing solar‐to‐chemical energy conversion efficiency and assist in the selection of appropriate feedstock particles to match the conditions in specific solar gasification reactors.
Catalytic Upgrading of Phenolic Oil by Etherification with Methanol
Authors: Wang Ze , Dang Dan , Lin Weigang , Song Wenli 
Published: July 2016

AbstractCatalytic etherification of phenolic oil with methanol was investigated to decrease the polarity and acidity of the product oil. The catalyst KH2PO4/activated alumina (AA) provided the best performance due to its excellent dehydration and anti‐coking property. When catalyzed by KH2PO4‐AA, the content of aryl ethers increased with rising temperature during the early stage but decreased at 500 °C. Alkoxy phenols had an inhibiting effect on etherification of alkyl phenols due to adsorption competition. Aryl ethers were mostly generated from alkyl phenols, while alkoxy phenols also contributed by simultaneous conversion to dialkoxybenzenes and diphenols, with a higher selectivity to diphenols. This explained the reduced alkoxy phenols and more generated alkyl phenols and aryl ethers at 350 °C.
Photoreactions with a Twist: Atropisomerism‐Driven Divergent Reactivity of Enones with UV and Visible Light
Authors: Vallavoju Nandini , Sreenithya Avadakkam , Ayitou Anoklase J.‐L. , Jockusch Steffen , Sunoj Raghavan B. , Sivaguru Jayaraman 
Published: July 2016

AbstractLight‐induced transformation of atropisomeric and achiral enones displays divergent reactivity. Photocyclization leading to 3,4‐dihydroquinolin‐2‐one was observed with achiral enone carboxamide, whereas the atropisomeric enone carboxamides underwent hydrogen abstraction leading to spiro‐β‐lactams. Detailed photochemical, photophysical, and theoretical investigations have provided insight into this divergent reactivity and selectivity.
Towards a General Understanding of Carbonyl‐Stabilised Ammonium Ylide‐Mediated Epoxidation Reactions
Authors: Novacek Johanna , Roiser Lukas , Zielke Katharina , Robiette Raphaël , Waser Mario 
Published: July 2016

AbstractThe key factors for carbonyl‐stabilised ammonium ylide‐mediated epoxidation reactions were systematically investigated by experimental and computational means and the hereby obtained energy profiles provide explanations for the observed experimental results. In addition, we were able to identify the first tertiary amine‐based chiral auxiliary that allows for high enantioselectivities and high yields for such epoxidation reactions.
Tetrahydropyrrolization of Resveratrol and Other Stilbenes Improves Inhibitory Effects on DNA Oxidation
Authors: Bao Liang‐Liang , Liu Zai‐Qun 
Published: July 2016

AbstractThe inhibitory effect of resveratrol on DNA oxidation caused by 2,2′‐azobis(2‐amidinopropane hydrochloride) (AAPH) was found to be enhanced if the C=C bond in resveratrol was converted into tetrahydropyrrole by reaction with azomethine ylide (CH2=N+(CH3)CH2−). This encouraged us to explore whether the inhibitory activities of other stilbenes could also be increased by the same method. We found that the inhibitory effects of the tetrahydropyrrole derivatives on AAPH‐induced oxidation of DNA were higher than those of the corresponding stilbenes, because the tetrahydropyrrole motif can provide hydrogen atoms to be abstracted by radicals. Therefore, the tetrahydropyrrolization offered an advantage for enhancing the antioxidant effects of stilbenes. Notably, (CH3)3SiCH2N(CH3)CH2OCH3 (in the presence of CF3COOH) and (CH3)3NO (in the presence of LiN(iPr)2) can be used to generate azomethine ylide for the tetrahydropyrrolization of stilbenes containing electron‐withdrawing and ‐donating groups, respectively.
Commercially Available WO3 Nanopowders for Photoelectrochemical Water Splitting: Photocurrent versus Oxygen Evolution
Authors: Reinhard Sandra , Rechberger Felix , Niederberger Markus 
Published: July 2016

AbstractWO3 photoanodes with remarkable photocurrent densities are presented. These photoanodes were prepared from three different commercially available WO3 nanopowders. Doctor blading of the nanopowders followed by a short annealing in air led to nanostructured films. The best photoanode showed a photocurrent density of 3.5 mA cm−2 at 1.23 V vs. RHE in 1 m CH3SO3H under AM 1.5 G illumination (100 mW cm−2), surpassing values reported so far for bare WO3 photoanodes. The study also showed that the photocurrent was strongly dependent on the electrolyte, indicating oxidation of the electrolyte rather than of water. Oxygen evolution measurements performed in different electrolytes revealed that the amounts of oxygen were highly dependent on the electrolyte. By comparing the photocurrent values in the different electrolytes with the amount of evolving oxygen, it was found that the electrolyte producing the highest photocurrent was the electrolyte with the lowest oxygen evolution. Stability measurements showed that the more oxygen is produced, the less stable is the photoanode. These results clearly underline the difficulty to correlate the photocurrent values with oxygen evolution, drawing the attention to one of the major limitations of photoelectrochemical water splitting.
Thermodynamically Favorable Synthesis of 2‐Oxazolidinones through Silver‐Catalyzed Reaction of Propargylic Alcohols, CO2, and 2‐Aminoethanols
Authors: Song Qing‐Wen , Zhou Zhi‐Hua , Wang Mei‐Yan , Zhang Kan , Liu Ping , Xun Jia‐Yao , He Liang‐Nian 
Published: July 2016

AbstractDevelopment of catalytic routes to incorporate CO2 into carbonyl compounds at mild conditions remains attractive and challenging. Herein, a one‐pot three‐component cascade reaction of terminal propargylic alcohols, CO2, and 2‐aminoethanols through AgI‐based catalysis is reported for the synthesis of carbonyl compounds through C−O/C−N bond formation. This thermodynamically favorable route can be ingeniously regulated to afford a wide range of 2‐oxazolidinones along with concurrent production of α‐hydroxyl ketone derivatives in excellent yields and selectivity. Preliminary mechanistic studies indicate that such a process proceeds through successive formation of α‐alkylidene cyclic carbonate, β‐oxopropylcarbamate, and 2‐oxazolidinones.
Detecting the small island effect and nestedness of herpetofauna of the West Indies
Authors: Gao De , Perry Gad 
Published: July 2016

AbstractTo detect the small island effect (SIE) and nestedness patterns of herpetofauna of the West Indies, we derived and updated data on the presence/absence of herpetofauna in this region from recently published reviews. We applied regression‐based analyses, including linear regression and piecewise regressions with two and three segments, to detect the SIE and then used the Akaike's information criterion (AIC) as a criterion to select the best model. We used the NODF (a nestedness metric based on overlap and decreasing fill) to quantify nestedness and employed two null models to determine significance. Moreover, a random sampling effort was made to infer about the degree of nestedness at portions of the entire community. We found piecewise regression with three segments performed best, suggesting the species–area relationships possess three different patterns that resulted from two area thresholds: a first one, delimiting the SIE, and a second one, delimiting evolutionary processes. We also found that taxa with lower resource requirement, higher dispersal ability, and stronger adaptation to the environment generally displayed lower corresponding threshold values, indicating superior taxonomic groups could earlier end the SIE period and start in situ speciation as the increase of island size. Moreover, the traditional two‐segment piecewise regression method may cause poor estimations for both slope and threshold value of the SIE. Therefore, we suggest previous SIE detection works that conducted by two‐segment piecewise regression method, ignoring the possibility of three segments, need to be reanalyzed. Antinestedness occurred in the entire system, whereas high degree of nestedness could still occur in portions within the region. Nestedness may still be applicable to conservation planning at portions even if it is antinested at the regional scale. However, nestedness may not be applicable to conservation planning at the regional scale even if nestedness does exist among sampling islands from a portion.
Photoelectrochemical versus Electrochemical Detection of H2O2 Using an All‐inorganic Sensor Based on Nanostructured Copper Oxide
Authors: Rehosek Marco , Mitoraj Dariusz , Bledowski Michal , Beranek Radim 
Published: July 2016

AbstractAll‐inorganic nanostructured CuO sensors for both electrochemical and photolectrochemical detection of H2O2 were fabricated by electrodeposition and annealing, and compared in terms of their sensing properties. The calibration curves showed an excellent linearity in the H2O2 concentration range of 0.1–1.0 mM, with strong correlation in both electrochemical (R2>0.999) and photolectrochemical (R2>0.990) mode. The higher quality of the linear correlation in the electrochemical mode resulted in the lower limit of detection (LOD) of 0.06 mM, as compared to 0.18 mM in the photoelectrochemical mode. The sensitivity in the electrochemical and photoelectrochemical mode was −73.7 µA cm−2 mM−1 and −46.4 µA cm−2 mM−1, respectively. The signal‐to‐noise ratio, performance stability, and selectivity in the presence of various interference compounds (catechol, cysteine, dopamine, nitrate, and uric acid) were found to be better in the photoelectrochemical mode. The photoaction spectra of the photoelectrochemical CuO sensor revealed a maximum in visible light (λ∼450 nm) which is advantageous in terms of the possibility to use low‐cost and highly stable light sources (LEDs). The demonstrated differences of sensor operation in different modes show that a careful analysis is necessary for realistic evaluation of distinct advantages associated with operation of sensors based on nanostructured semiconductors in either electrochemical or photoelectrochemical mode.
A force‐balanced control volume finite element method for multi‐phase porous media flow modelling
Authors: Gomes J. L. M. A. , Pavlidis D. , Salinas P. , Xie Z. , Percival J. R. , Melnikova Y. , Pain C. C. , Jackson M. D. 
Published: July 2016

SummaryA novel method for simulating multi‐phase flow in porous media is presented. The approach is based on a control volume finite element mixed formulation and new force‐balanced finite element pairs. The novelty of the method lies in (i) permitting both continuous and discontinuous description of pressure and saturation between elements; (ii) the use of arbitrarily high‐order polynomial representation for pressure and velocity and (iii) the use of high‐order flux‐limited methods in space and time to avoid introducing non‐physical oscillations while achieving high‐order accuracy where and when possible. The model is initially validated for two‐phase flow. Results are in good agreement with analytically obtained solutions and experimental results. The potential of this method is demonstrated by simulating flow in a realistic geometry composed of highly permeable meandering channels. © 2016 The Authors International Journal for Numerical Methods in Fluids Published by John Wiley & Sons Ltd