bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reversible Dihydrogen Activation by Reduced Aryl Boranes as Main‐Group Ambiphiles
Authors: von Grotthuss Esther , Diefenbach Martin , Bolte Michael , Lerner Hans‐Wolfram , Holthausen Max C. , Wagner Matthias 
Published: October 2016

AbstractA new approach to main‐group H2 activation combining concepts of transition‐metal and frustrated Lewis pair chemistry is reported. Ambiphilic, metal‐like reactivity toward H2 can be conferred to 9,10‐dihydro‐9,10‐diboraanthracene (DBA) acceptors by the injection of two electrons. The resulting [DBA]2− ions cleave the H−H bond with the formation of hydridoborates under moderate conditions (T=50–100 °C; p<1 atm). Depending on the boron‐bonded substituents R, the addition is either reversible (R=C≡CtBu) or irreversible (R=H). The reaction rate is strongly influenced by the nature and the coordination behavior of the countercation (Li+ slower than K+). Quantum‐chemical calculations support the experimental observations and suggest a concerted, homolytic addition of H2 across both boron atoms. As proven by the successful conversion of Me3SiCl into Me3SiH, the system Li2[DBA]/H2 appears generally relevant for the hydrogenation of element–halide bonds.
Monitoring ssDNA Binding to the DnaB Helicase from Helicobacter pylori by Solid‐State NMR Spectroscopy
Authors: Wiegand Thomas , Cadalbert Riccardo , Gardiennet Carole , Timmins Joanna , Terradot Laurent , Böckmann Anja , Meier Beat H. 
Published: October 2016

AbstractDnaB helicases are bacterial, ATP‐driven enzymes that unwind double‐stranded DNA during DNA replication. Herein, we study the sequential binding of the “non‐hydrolysable” ATP analogue AMP‐PNP and of single‐stranded (ss) DNA to the dodecameric DnaB helicase from Helicobacter pylori using solid‐state NMR. Phosphorus cross‐polarization experiments monitor the binding of AMP‐PNP and DNA to the helicase. 13C chemical‐shift perturbations (CSPs) are used to detect conformational changes in the protein upon binding. The helicase switches upon AMP‐PNP addition into a conformation apt for ssDNA binding, and AMP‐PNP is hydrolyzed and released upon binding of ssDNA. Our study sheds light on the conformational changes which are triggered by the interaction with AMP‐PNP and are needed for ssDNA binding of H. pylori DnaB in vitro. They also demonstrate the level of detail solid‐state NMR can provide for the characterization of protein–DNA interactions and the interplay with ATP or its analogues.
Environmentally friendly and highly efficient synthesis of benzoxazepine and malonamide derivatives using HPA/TPI‐Fe3O4 nanoparticles as recoverable catalyst in aqueous media
Authors: Vessally Esmail , Hosseinzadeh‐Khanmiri Rahim , Babazadeh Mirzaagha , Ghorbani‐Kalhor Ebrahim , Edjlali Ladan 
Published: October 2016

A magnetic inorganic–organic nanohybrid material (HPA/TPI‐Fe3O4 NPs) was produced as an efficient, highly recyclable and eco‐friendly catalyst for the one‐pot multi‐component synthesis of malonamide and 2,3,4,5‐tetrahydrobenzo[b][1,4]oxazepine derivatives with high yields in short reaction times (25–35 min) in aqueous media at room temperature. The nanohybrid catalyst was prepared by the chemical anchoring of H6P2W18O62 onto the surface of modified Fe3O4 nanoparticles (NPs) with N‐[3‐(triethoxysilyl)propyl]isonicotinamide (TPI) linker. The magnetic recoverable catalyst was easily recycled at least ten times without any loss of catalytic activity.
Effect of fluorinated/non‐fluorinated β‐diketones and side‐chain branching of N‐protected amino acids on the antibacterial potential of new heptacoordinated monobutyltin(IV) complexes
Authors: Maheshwari Karuna , Srivastava Manish Kumar , Saxena Sanjiv , Jain Asha 
Published: October 2016

The effect of fluorinated/non‐fluorinated β‐diketones and side‐chain branching of N‐protected amino acids on the antibacterial potential of new heptacoordinated monobutyltin(IV) complexes was investigated. New heptacoordinated monobutyltin(IV) complexes having the general formulae BuSn(A)2B and BuSnA(B)2 [where AH = (1,3‐dihydro‐1,3‐dioxo‐α‐(substituted)‐2H‐isoindole‐2‐acetic acids, N‐protected amino acids), R = CH(CH3)CH2CH3: A1H; R = CH(CH3)2: A2H; and BH = R'COCH2COR″ (β‐diketones), R′ = R″ = CH3: B1H; R′ = CH3, R″ = C6H5: B2H; R′ = CF3, R″ = C6H5: B3H] were synthesized. Complexes BuSn(A)2B and BuSnA(B)2 were generated by the reaction of sodium salts of the ligands AH and BH with BuSnCl3 in 2:1:1 and 1:2:1 molar ratios, respectively. These newly generated complexes were characterized in physicochemical and spectroscopic studies. These complexes contain heptacoordinated tin centres as revealed by 119Sn NMR chemical shift values. Some of the newly generated complexes and their corresponding ligands were screened for their antibacterial activity to study the structure–activity relationship.
Development and material properties of poly(lactic acid)/poly(3‐hydroxybutyrate‐co−3‐hydroxyvalerate)‐based nanocrystalline cellulose nanocomposites
Authors: Dasan Y. K. , Bhat A. H. , Faiz A. 
Published: October 2016

ABSTRACTThis study is focused on the development and analysis of the thermal and structural behavior of nanocrystalline cellulose (NCC)‐based bionanocomposites (BCs). Nanocrystalline cellulose was prepared by controlled acid hydrolysis of oil palm empty fruit bunch fibers. The resulting NCC was surface modified using TEMPO‐mediated oxidation and solvent exchange methods for surface functionalization and also to improve dispersion of fillers. Solvent exchange NCC reinforced polymer blend containing poly(lactic acid)/poly‐(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) was prepared by using solution casting technique at various NCC loading percentages. The addition of NCC resulted in the improvement of structural, thermal, and mechanical properties of BCs as compared to that of the polymer blend. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44328.
The grafting reaction of epoxycyclohexyl polyhedral oligomeric silsesquioxanes with carboxylic methoxypolyethylene glycols and the properties of composite solid polymer electrolytes with the graftomer
Authors: Mei Hua , Wang Ran , Ren Wentan , Zhang Yong 
Published: October 2016

ABSTRACTA novel organic–inorganic hybrid of epoxycyclohexyl polyhedral oligomeric silsesquioxane (e‐POSS)–grafted carboxylic methoxypolyethylene glycols (mPEG‐COOH), that is, a POSS‐mPEG graftomer, was synthesized. The grafting reaction of e‐POSS and mPEG‐COOH was characterized by Fourier transform infrared (FTIR) and 1H‐NMR spectroscopy. Then the graftomer was used to develop new composite solid polymer electrolyte (SPE) films with a carboxylated nitrile rubber–epoxidized natural rubber (XNBR‐ENR) self‐crosslinked blend system as a dual‐phase polymer matrix. The self‐crosslinked reaction of the XNBR‐ENR matrix was investigated using ATR‐FTIR. The morphology of the SPE films and the distribution of lithium salt were investigated using field emission scanning electron microscopy and X‐ray diffraction, and the result illustrated that the addition of POSS‐mPEG could promote and accelerate the dissociation of LiClO4. The best effect within the range of this study was achieved when 25 phr POSS‐mPEG was involved. The differential scanning calorimetry analysis proved that the glass‐transition temperature of the composite SPE films was reduced with the increase of POSS‐mPEG. The ionic conductivity of the composite SPE films was investigated by electrochemical impedance spectroscopy. The highest ionic conductivity in this study of 2.57 × 10−5 S cm−1 was obtained with 25 phr POSS‐mPEG loading. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44460.
Electropolymerization and energy storage of poly[Ni(salphen)]/MWCNT composite materials for supercapacitors
Authors: Chen Cheng , Zhu Zhixun , Li Xinping , Li Jianling 
Published: October 2016

ABSTRACTNi(salphen), a Schiff base ligand compound, was synthesized and electropolymerized on multiwalled carbon nanotube (MWCNT) electrodes in an acetonitrile solution via the pulse potentiostatic method and then applied as a supercapacitor electrode material. The polymerization mode was investigated through methyl replacement in the para‐position of phenyl rings in the Ni(salphen) monomer, and it was found that the Ni(salphen) monomers would polymerize by the generation of CC bonds between the phenyl rings in the para‐position of the phenol moieties. The optimum condition for polymerization was evaluated, and when the polymerization time was 8 min, poly[Ni(salphen)] exhibited a specific capacitance up to 200 F g−1 at a current density of 0.1 mA cm−2, and the capacitance remains at 164 F g−1 at 20 mA cm−2. The energy density of the poly[Ni(salphen)] electrode reached 40 Wh kg−1 at 0.1 mA cm−2, about eight times greater than for a pure MWCNT electrode. Electrochemical performances were investigated, and the composites showed good redox property and ion transfer capability. This work showed that Ni(salphen) may be an attractive material in supercapacitors© 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44464.
Preparation and properties of gel‐filled PVDF separators for lithium ion cells
Authors: Li Hao , Chao Chun‐Ying , Han Pei‐Lin , Yan Xiao‐Ran , Zhang Hong‐Hao 
Published: October 2016

ABSTRACTPolyether gel‐filled poly(vinylidene fluoride) separators (GF‐PVDF separators) were prepared by means of thermal crosslinking of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GF‐PVDF and their corresponding gel polymer electrolyte (GPE) were characterized by SEM, DSC, and electrochemical methods. It was found a relatively better GPE could be got when the filled polyether content no more than 60 wt % and its ion conductivity could reach 1.3 × 10−3 S cm−1. The GPE is compatible with anode and cathode of lithium ion battery at high voltage and its electrochemical window is 4.6 V (vs. Li/Li+). The coulombic efficiency could reach 94% after 100 cycles for the cells using such GPE. The results reveal that the composite polymer electrolyte qualifies as a potential application in lithium cells. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44473.
Effects of styrene–acrylonitrile contents on the properties of ABS/SAN blends for fused deposition modeling
Authors: Zhu Jin , Hu Yufei , Tang Yijing , Wang Biao 
Published: October 2016

ABSTRACTThis paper was to assess the effects of styrene–acrylonitrile (SAN) contents on the glass transition temperature (Tg), melt flow index (MFI), and mechanical properties of acrylonitrile–butadiene–styrene (ABS)/SAN blends for fused deposition modeling (FDM) process. The addition of SAN had little effects on Tg but could decrease the MFI and elongation at break while improving the tensile strength and modulus of ABS/SAN blends. For both longitudinal direction and transverse direction FDM printed specimens, the incorporation of SAN improved mechanical properties without sacrificing dimensional stability. This result was mainly attributed to the increasing content of continuous phase (SAN phase) and improvement in adhesion quality. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44477.
Influence of ionic liquid on the polymer–filler coupling and mechanical properties of nano‐silica filled elastomer
Authors: Zhang Xumin , Xue Xiaodong , Jia Hongbing , Wang Jingyi , Ji Qingmin , Xu Zhaodong 
Published: October 2016

ABSTRACTThe natural rubber (NR) nanocomposites were fabricated by filling ionic liquid (1‐allyl‐3‐methyl‐imidazolium chloride, AMI) modified nano‐silica (nSiO2) in NR matrix through mechanical mixing and followed by a cure process. Based on the measurements of differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), solid state nuclear magnetic resonance spectroscopy, and Raman spectroscopy, it was proved that AMI could interact with nSiO2 through hydrogen bonds. With the increase of AMI content, the curing rate of nSiO2/NR increased. The results of bound rubber and dynamic mechanical properties showed that polymer–filler interaction increased with the modification of nSiO2. Morphology studies revealed that modification of nSiO2 resulted in a homogenous dispersion of nSiO2 in NR matrix. AMI modified nSiO2 could greatly enhance the tensile strength and tear strength of nSiO2/NR nanocomposites. Compared to unmodified nSiO2/NR nanocomposite, the tensile strength of AMI modified nSiO2/NR nanocomposite increased by 102%. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44478.
Continuous dosing of fast initiator during vinyl chloride suspension polymerization: Thermal stability of PVC resin
Authors: Bijhanmanesh Mohammad Javad , Etesami Nasrin , Darvishi Reza 
Published: October 2016

ABSTRACTThermal stability of poly(vinyl chloride) (PVC) produced using continuous dosages of a fast initiator method was investigated in terms of morphological and microstructural characteristics. The results were compared with the properties of the PVC prepared by conventional polymerization method. The Brabender® Plastograph and DSC results showed a lower fusion time, higher stable time, and greater degree of fusion for PVC obtained by polymerization using initiator continuous dosage method. Also, chemical analysis indicated that the PVC produced under an initiator continuous dosage system have lower structural defects, that is, branch numbers, internal double bonds, labile chlorine, and tacticity index, thereby improving the thermal stability of PVC resin. The results obtained from dehydrochlorination and thermogravimetry analysis confirm the improvement of thermal stability of PVC chains synthesized with continuous dosages of a fast initiator. Moreover, it was found that the concentration of microstructural defects and the dehydrochlorination rates of the PVC samples prepared by both processes increase with monomer conversion, particularly after critical conversion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44480.
Polyurethane‐acrylic hybrid emulsions with high acrylic/polyurethane ratios: Synthesis, characterization, and properties
Authors: Yi Tingfa , Ma Guozhang , Hou Caiying , Li Shasha , Zhang Ruofei , Wu Jianbing , Hao Xiaogang , Zhang Hui 
Published: October 2016

ABSTRACTAllyl polyoxyethylene ether (APEE) was used as coupling agent between polyurethane (PU) and acrylic polymer (AC) to synthesize stable waterborne polyurethane‐acrylic (PU‐AC) hybrid emulsions with high AC/PU weight ratio ranged from 45/55 to 70/30. The effect of the AC/PU weight ratio and the acrylate type including methyl methacrylate (MMA), butyl acrylate (BA) and mixture of them on the properties of the synthesized emulsions and resultant films were investigated. The research results showed that the colloidal particle of the emulsions behaved core‐shell structure, and the copolymers were not crosslinked. An increase in the AC/PU weight ratio led to an increase in the average particles size and the particle size distribution, but decrease in the viscosity of the emulsions. Meanwhile, the molecular weight distribution of the copolymers became wide, and the tensile stress, shore A hardness, storage modulus, glass transfer temperature, water resistance, and water contact angle of the resultant films increased, except that the films of PU‐BA were too soft to determine their mechanical properties. MMA and BA can provide the PU‐AC hybrid emulsions with very different properties, and which can be adjusted according to the special application. It was suggested that APEE can not only built up chemical bonds between PU and AC, but also increase the self‐emulsifying ability in the emulsion polymerization due to its hydrophilic ethylene oxide and carboxylic groups, resulting in that PU‐AC hybrid emulsions with high AC/PU ratio can be obtained by this method. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44488.
Thermal properties and crystallinity of PCL/PBSA/cellulose nanocrystals grafted with PCL chains
Authors: Simão José Alexandre , Bellani Caroline Faria , Branciforti Marcia Cristina 
Published: October 2016

ABSTRACTBionanocomposite films of poly(ɛ‐caprolactone) (PCL) and poly(butilene succinate‐co‐adipate) (PBSA) blends with cellulose nanocrystals (CNW) grafted with PCL chains (CNW‐g‐PCL) were prepared by solution casting and their thermal properties and crystallinity were studied. The CNW surface was modified with PCL chains by grafting “from” approaches, in an effort to improve their compatibility with the polymer blends. The grafting efficiency was evidenced by FTIR and TGA analysis. The acicular morphology of CNW‐g‐PCL was characterized by SEM. The TGA results showed an increase in the thermal stability of the CNW grafted with PCL chains. The PCL/PBSA blends showed higher thermal stability in comparison with the neat polymers and PCL/PBSA/CNW‐g‐PCL bionanocomposites. DSC results showed the CNW‐g‐PCL act as a nucleating agent in the bionanocomposites. Additionally, a better interaction of the CNW‐g‐PCL in the blends of 30/70 composition in comparison with the blends of 50/50 composition was characterized. The results obtained for aforementioned films prepared by solution casting encourage the production of such bionanocomposites by melt compounding (extrusion), aiming the achievement of new bionanocomposites materials with improved thermal and mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44493.
Enhancing mechanical strength of hydrogels via IPN structure
Authors: Yu Zhe , Zhang Ying , Gao Zi Jian , Ren Xiu Yan , Gao Guang Hui 
Published: October 2016

ABSTRACTIn this investigation, polyacrylamide (PAAm) as the flexible network is introduced to enhance the mechanical strength of hyaluronic acid–gelatin (HA–Gel) hydrogels by interpenetrating polymer network (IPN). The structure, mechanical property, and rheology property of the IPN hydrogels are investigated. It is found that the compressive strength of the HA–Gel/PAAm IPN hydrogels has increased five times higher than that of HA–Gel hydrogels. Rheological test demonstrates that elastic moduli (G′) and viscous moduli (G″) of HA–Gel/PAAm IPN hydrogels increase 100 times higher than those of HA–Gel hydrogels. Moreover, the HA–Gel hydrogels are fractured under the low compressive stress, whereas HA–Gel/PAAm IPN hydrogels are not broken under the high compressive stress. It is envisioned that the IPN hydrogels will be an effective approach to enhance the mechanical strength and broaden the range of hydrogels' applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44503.
Preparation and performance of waterborne UV‐curable polyurethane containing long fluorinated side chains
Authors: Tan Jianquan , Liu Weiqu , Wang Zhengfang 
Published: October 2016

ABSTRACTNovel waterborne UV‐curable polyurethane containing long fluorinated side chains (WUVFPU) was prepared and the fluorinated component was incorporated by two novel fluorinated macromolecular diols (FDO) with different chain length as chain extender. FDO was synthesized via free radical polymerization of hexafluorobutyl methacrylate (HFBMA) using 1‐thioglycerol (TG) as chain transfer agent. Extremely low dosage of FDO incorporated could change the surface property significantly. The influence of both the content and chain length of FDO on the surface energy, surface composition and morphology were investigated by contact angle measurement, XPS and AFM. Surface energy significantly decreased at extremely low concentration of FDO. The hydrophobicity was enhanced with increasing both the content and the chain length of FDO. XPS and AFM results revealed the enhancing hydrophobicity was attributed to the enrichment of F atoms and rougher surface morphology. Gel content, pencil hardness, adhesion, and optical transmittance tests were employed to investigate the coating properties of the UV‐cured films. The preparation and investigation of WUVFPU might provide better understanding of the influence of fluorinated chain length on the properties of polyurethane for theory. Moreover, it might provide a facile and effective route to prepare polyurethane materials with low surface energy for engineering and industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44506.
A renewed archaeological and archaeobotanical assessment of house sites at Kuk Swamp in the highlands of Papua New Guinea
Authors: LEWIS TARA , DENHAM TIM , GOLSON JACK 
Published: October 2016

ABSTRACTHouse sites located on the wetland margin at Kuk Swamp in the Upper Wahgi Valley of Papua New Guinea were excavated in 1972 and 1973. Macrobotanical remains collected during excavation of domestic contexts were collected and subject to preliminary identification. Renewed macrobotanical analysis of these remains provides a more reliable foundation for their taxonomic identification to species or genus level. Plant remains include sugar cane (Saccharum officinarum) and probable sweet potato (Ipomoea batatas). Direct accelerator mass spectrometry (AMS) dating of macrobotanical remains provides a reliable basis for determining the antiquity of the house sites and differentiates at least two periods of settlement.
Susan Bulmer, an archaeological pioneer
Authors: GOLSON JACK 
Published: October 2016

ABSTRACTThis is the story of how a young American woman with a degree in anthropology, but not including archaeology, became a pioneer of archaeological research in the New Guinea Highlands from a base in New Zealand; active archaeologically in the Port Moresby region as the wife of the Professor of Anthropology at the University of Papua New Guinea; and finally, back in New Zealand, employed for some years by the New Zealand Historic Places Trust, but surrounded at all times by her New Guinea papers and collections that called for her attention. The approach is to follow her progress, note the people she met and the literature she read and discover the qualities that she brought to the tasks that she undertook.
Chloroacetate Promotes and Participates in the Oxidative Annulation of Pyridines/Isoquinoline by Using Oxygen as the Oxidant
Authors: Yue Yuanyuan , Sun Yangyang , Zhao Shufang , Yan Xuyang , Li Rong , Shi Yaru , Zhuo Kelei , Liu Jianming 
Published: October 2016

AbstractThe aerobic oxidative annulation of chalcones, pyridines/isoquinoline and ethyl chloroacetate to indolizines was achieved by cascade reaction. Various functional groups on chalcones were tolerated. And different pyridines derivatives could also be suitable substrates. Ethyl chloroacetate is an essential component in participating of the oxidative annulation process. Overall, this protocol is very practical and efficient by using molecular oxygen as oxidant with high selectivity for the annulation product.