Room-temperature ferromagnetism in graphitic petal arrays

We report room-temperature ferromagnetism of graphitic petal arrays grown on Si substrates by microwave plasma chemical vapor deposition without catalyst. The samples have been characterized by Raman and X-ray photoelectron spectroscopy to confirm the absence of possible ferromagnetic impurities. The petals exhibit ferromagnetic hysteresis with saturation magnetization of ～4.67 emu cm(-3) and coercivity of ～105 Oe at 300 K, comparable to the reported behavior of few-layer graphene. Upon O2 annealing the saturation magnetization and coercivity decreased to 2.1 emu cm(-3) and ～75 Oe respectively. The origin of ferromagnetism is believed to arise from the edge defects and vacancies in the petals.     

Modification of nylon 66 by electron beam irradiation for improved properties and superior performances

Nylon 66 has been transformed into a material with significantly improved properties like hardness, tensile strength, and flexural modulus by processing it under the optimized dose rate of electron beam in the presence of suitable crosslinkers. Furthermore, percent water absorption of nylon 66 was reduced substantially on irradiation. Thermogravimetric analysis revealed that thermal stability of nylon 66 improved with increasing dose of radiation. Improvement of mechanical and thermal properties and reduction of water absorption of nylon 66 were due to the crosslinking of polyamide molecules made possible by the high energy radiation. Increase of crosslinking with increasing radiation dose was verified by the increase of gel content at higher doses. Differential scanning calorimetry showed that both melting and crystallization temperatures along with percent crystallinity of nylon 66 were decreased with the increasing dose of radiation leading to the development of more amorphous character in this semicrystalline polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Fabrication of dense Ce0.9Mg0.1P2O7-PmOn composites by microwave heating for application as electrolyte in intermediate-temperature fuel cells

In the present work, we report a method of fabrication of dense 10 mol% Mg²⁺-doped cerium pyrophosphate-phosphate (Ce_0.9Mg_0.1P₂O₇-P_mO_n; CMP-P) composites by microwave heat-treatment of the preformed Ce_0.9Mg_0.1P₂O₇ substrates in the presence of phosphoric acid. The composite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The microwave heating at 375 °C for 5 min resulted in the formation of dense CMP-P composites which retained most of the pyrophosphate phase. The electrical conductivity was extracted from the EIS data and for the CMP-P composite prepared by H₃PO₄ loading for 10 h and microwave heat-treatment for 5 min it was found to be >10^?2 S m^?1 in 100–250 °C range with a maximum of 0.062 S cm^?1 at 190 °C, which was significant for its application as electrolyte in intermediate temperature fuel cells.     

Chemically clean synthesis and characterization of graphene oxide‐poly(acrylic acid–sodium styrene sulfonate) composite thermostable elastic gel encapsulating copper nanoparticles for efficient catalytic reduction of 4‐nitrophenol

The thermostable chemically blended elastic poly‐(acrylic acid–sodium‐styrene‐sulfonate–graphene oxide) super‐absorbent hydrogel was synthesized by additive‐free gamma‐radiation induced polymerization followed by crosslinking method. It showed the best swelling ratio in water due to its porous nature. The composite material adsorbed 98 mg/g Cu(II) at room temperature from the aqueous solution of Cu(II) at pH 5 by the chemi‐adsorption of Cu(II) ions at several energetically heterogeneous functional groups. The copper nanoparticles (CuNPs) of size 12 ± 8 nm had been synthesized in situ by chemical reduction of the pre‐adsorbed Cu(II) ions. The functional groups of composite hydrogel served as complexing agent and nano‐reaction sites. Avoiding any pre‐reduction induction time, the inexpensive CuNPs catalytically completely decolorized the aqueous solution of 4‐nitrophenol (4‐NP) within 60 s in the presence of NaBH₄ at a promising calculated rate constant (9.0 × 10^?2/s) ever reported in the literatures. It is in contrast to the commonly noticeable phenomenon for other CuNPs‐based catalysis of 4‐NP. The composite hydrogel matrix helped to retain the catalytic activity of CuNPs and simultaneously it helped in the osmotic inclusion of 4‐NP into the reaction cites. This composite hydrogel synthesized through a chemically clean method could be utilized for efficient conversion of hazardous chemical 4‐NP to industrially important chemical 4‐aminophenol. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46200.     

Fatty Acids in Vernonia Produced in the Mid-Atlantic Region of the United States

Vernonia galamensis [(Cass.) Less.] is a native of Ethiopia and Eritrea. Seed of vernonia contain substantial quantities of naturally epoxidized oil, which is used in the paint industry to reduce emissions of volatile organic compounds that produce smog resulting from the use of petroleum-based (alkyd-resin) paint. Epoxidized oil is also used in the manufacture of plasticizers, additives to polyvinyl chloride, polymer blends and coatings, and cosmetic and pharmaceutical applications. Previous research has indicated that vernonia has potential for commercialization in the mid-Atlantic region of the United States. This study characterized fatty acids in oil from vernonia grown in this latter region. Vernonia oil, from 14 vernonia lines grown during 1995 and 1996 under field conditions in Virginia, contained 3.3, 3.0, 5.0, 15.0, 0.2, 0.5, 0.4, and 72.7%, respectively, of C16:0, C18:0, C18:1, C18:2, C18:3, C20:0, C20:1, and vernolic (C18:1 epoxy) fatty acids. Effects of genotypes on vernonia oil quality were generally not significant whereas the effects of years were significant. The concentration of vernolic acid was positively correlated with oil concentration but negatively correlated with concentrations of all individual fatty acids, except for C18:3. Contribution of Virginia State University Agricultural Research Station, journal article series number 253. The use of any trade names or vendors does not imply approval to the exclusion of other products or vendors that may also be suitable.     

Effect of particle size of magnesium silicate filler on physical properties of paper

Fillers are essential component of printing papers to increase the opacity, brightness, and to improve formation and printing properties. As a very little work has been reported so far on magnesium silicate (talc), the study was conducted with the filler of different particle size for papermaking. The sheets were made in the laboratory with refined mixed hardwood chemical pulp with five grades of talc, ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) fillers with 15–24% ash level. Apparent density along with tensile, burst, tear index, Z‐direction tensile strength (ZDTS) and bending stiffness index were evaluated for talc filled sheets, and compared with GCC and PCC. Physical strength properties of talc filled sheets were decreased at a faster rate on increasing filler loading in paper and decreasing the particle size of the filler. With same type of filler its particle size determines the physical properties of paper. The postulate was not found to be valid for all the three varieties of fillers viz., talc, PCC and GCC. Shape and geometry of the PCC and GCC fillers determine the individual property. © 2012 Canadian Society for Chemical Engineering     

A Genetically-Based Latitudinal Cline in the Emission of Herbivore-Induced Plant Volatile Organic Compounds

The existence of predictable latitudinal variation in plant defense against herbivores remains controversial. A prevailing view holds that higher levels of plant defense evolve at low latitudes compared to high latitudes as an adaptive plant response to higher herbivore pressure on low-latitude plants. To date, this prediction has not been examined with respect to volatile organic compounds (VOCs) that many plants emit, often thus attracting the natural enemies of herbivores. Here, we compared genetically-based constitutive and herbivore-induced aboveground vegetative VOC emissions from plants originating across a gradient of more than 10° of latitude (>1,500 km). We collected headspace VOCs from Asclepias syriaca (common milkweed) originating from 20 populations across its natural range and grown in a common garden near the range center. Feeding by specialist Danaus plexippus (monarch) larvae induced VOCs, and field environmental conditions (temperature, light, and humidity) also influenced emissions. Monarch damage increased plant VOC concentrations and altered VOC blends. We found that genetically-based induced VOC emissions varied with the latitude of plant population origin, although the pattern followed the reverse of that predicted—induced VOC concentration increased with increasing latitude. This pattern appeared to be driven by a greater induction of sesquiterpenoids at higher latitudes. In contrast, constitutive VOC emission did not vary systematically with latitude, and the induction of green leafy volatiles declined with latitude. Our results do not support the prevailing view that plant defense is greater at lower than at higher latitudes. That the pattern holds only for herbivore-induced VOC emission, and not constitutive emission, suggests that latitudinal variation in VOCs is not a simple adaptive response to climatic factors.     

Numerical Modeling of Viscoelastic Stress Relaxation During Glass Lens Forming Process

With the recent advances in numerical simulation capabilities and computing technology, finite element method (FEM) can be applied to predict the performance of a precision aspherical lens molding process. In this paper, various stages of the lens molding process have been modeled using a commercial FEM code MSC MARC. Stress relaxation effect during the forming stage has been incorporated into the numerical model by using a generalized Maxwell model. Successful comparison of the predicted results has been made with the experimental data. The various aspects of the simulation that would enable a more realistic modeling of the process have been identified for future research.     

Effect of accelerated aging on the tensile index of a synthetic insulation paper

This paper explores the possibility of using tensile index as one of the appropriate end point parameters to determine the thermal index of a synthetic insulation paper. The paper samples were aged at three different times and temperatures. The tensile index of fresh as well as aged samples was determined experimentally. The study showed that tensile index could be considered as an appropriate parameter to find the thermal index of the chosen synthetic insulation paper.     

Tuning of shear thickening behavior and elastic strength of polyvinylidene fluoride via doping of ZnO-graphene

ZnO rice like nonarchitects are grafted on the graphene carbon core via a rapid microwave synthesis route. The prepared grafted systems are characterized via XRD, SEM, RAMAN, and XPS to examined the structural and morphological parameters. Zinc oxide grafted graphene sheets (ZnO-G) are further doped in β-phase of polyvinylidene fluoride (PVDF) to prepare the polymer nanocomposites (PNCs) via mixed solvent approach (THF/DMF). β-phase confirmation of PVDF PNCs is done by FTIR studies. It is observed that ZnO-G filler enhances the β-phase content in the PNCs. Non-doped PVDF and PNCs are further studied for rheological behavior under the shear rate of 1–100 s⁻¹. Doping of ZnO-G dopant to the PVDF matrix changes its discontinuous shear thickening (DST) behavior to continues shear thickening behavior (CST). Hydrocluster formation and their interaction with the dopant could be the reason for this striking DST to CST behavioral change. Strain amplitude sweep (10⁻³% -10%) oscillatory test reveals that the PNCs shows extended linear viscoelastic region with high elastic modulus and lower viscous modulus. Effective shear thickening behavior and strong elastic strength of these PNCs present their candidature for various fields including mechanical and soft body armor applications.