No abstract

To evaluate differences among poplar clones of various ploidies, 12 hybrid poplar clones (P. simonii × P. nigra) × (P. nigra × P. simonii) with different ploidies were used to study phenotypic variation in growth traits and photosynthetic characteristics. Analysis of variance showed remarkable differences for each of the investigated traits among these clones (P < 0.01). Coefficients of phenotypic variation (PCV) ranged from 2.38% to 56.71%, and repeatability ranged from 0.656 to 0.987. The Pn (photosynthetic rate) photosynthetic photon flux density (PPFD) curves of the 12 clones were S-shaped, but the Pn-ambient CO2 (Ca) curves were shaped like an inverted “V”. The stomatal conductance (Gs)-PPFD and transpiration rate (Tr)-PPFD curves had an upward tendency; however, with increasing PFFD, the intercellular CO2 concentration (Ci)-PPFD curves had a downward tendency in all of the clones. The Pn-PPFD and Pn-Ca curves followed the pattern of a quadratic equation. The average light saturation point and light compensation point of the triploid clones were the highest and lowest, respectively, among the three types of clones. For Pn-Ca curves, diploid clones had a higher average CO2 saturation point and average CO2 compensation point compared with triploid and tetraploid clones. Correlation analyses indicated that all investigated traits were strongly correlated with each other. In future studies, molecular methods should be used to analyze poplar clones of different ploidies to improve our understanding of the growth and development mechanisms of polyploidy.

The thermal conductive filler/epoxy resin (EP) composites were prepared by a casting method. The effects of the multiwalled carbon nanotubes (MWCNTs), aluminum nitride (AlN) particles, and their compounds on the microstructure and thermal conductivity of the composites were investigated, in addition to the thermal properties. The results indicated that compounds of MWCNTs and AlN particles exhibited a remarkable synergistic effect to improve the thermal conductivity properties of the composites. The one-dimensional MWCNTs with superb thermal conductivity bridged the AlN particles to form an excellent network, which provides a faster and more effective pathway for phonon transport in the composites. The thermal conductivity of the 0.6 vol% MWCNTs/3.4 vol% AlN/EP composite is 0.53 W (m K) À1 . In addition, the thermal conductivity of the MWCNTs/AlN/EP composites with 0.4 vol% MWCNTs and 3.4 vol% AlN is 0.48 W (m K) À1 (which is twice the value of 0.24 W (m K) À1 for the pure EP) which was much higher than the 0.4 vol% MWCNTs/EP composites (0.27 W (m K) À1 ) and the 3.4 vol% AlN/EP composites (0.28 W (m K) À1 ). Bruggeman's equation is identified to fit quite well to the experimental results of the AlN/EP composites in the entire range of volume percentage of AlN; however, the MWCNTs/EP composites coincided better to the Russell equation. The volume resistivity of the MWCNTs/AlN/EP composites (approximately 1.8-2.6 Â 10 12 m) exhibited only a slight compromise in comparison to the pure EP (2.5 Â 10 14 m), which manifested the excellent insulation characteristic of these composites.

The gut microbiota of insects has a wide range of effects on host nutrition, physiology, and behavior. The structure of gut microbiota may also be shaped by their environment, causing them to adjust to their hosts; thus, the objective of this study was to examine variations in the morphological traits and gut microbiota of Lymantria xylina in response to natural and artificial diets using high-throughput sequencing. Regarding morphology, the head widths for larvae fed on a sterilized artificial diet were smaller than for larvae fed on a non-sterilized host-plant diet in the early instars. The gut microbiota diversity of L. xylina fed on different diets varied significantly, but did not change during different development periods. This seemed to indicate that vertical inheritance occurred in L. xylina mutualistic symbionts. Acinetobacter and Enterococcus were dominant in/on eggs. In the first instar larvae, Acinetobacter accounted for 33.52% of the sterilized artificial diet treatment, while Enterococcus (67.88%) was the predominant bacteria for the non-sterilized host-plant diet treatment. Gut microbe structures were adapted to both diets through vertical inheritance and self-regulation. This study clarified the impacts of microbial symbiosis on L. xylina and might provide new possibilities for improving the control of these bacteria.

Tetraethylenepentamine (TEPA) was employed to functionalize the large-pore mesoporous silica (denoted MSU-J) with 3D worm-hole framework structures which was prepared through a supramolecular hydrogen-bonding assembly pathway from low-cost H 2 NCH(CH 3 )CH 2 [OCH 2 CH(CH 3 )] 33 NH 2 (D2000) as structure-directing porogens and tetraethylorthosilioate as the silica source for capturing CO 2 . The resultant adsorbents were characterized by FT-IR, Transmission electron microscopy (TEM), N 2 adsorption/desorption and thermogravimetric analysis. Textural properties, elemental analysis and TEM measurement of the samples showed a severe pore filling of MSU-J as TEPA loading was increased to 70 wt%. CO 2 adsorption isotherms measured at different temperatures revealed the optimal adsorption temperature is 25°C. The adsorption capacity of MSU-J with different TEPA loading contents was calculated. As a result, 50 wt% of TEPA supported on as-synthesized MSU-J achieved the highest capacity with the value of 164.3 mg/g under the conditions of 99.99 % CO 2 at 25°C and 0.1 MPa. Repeated adsorption/desorption cycles revealed that amine-impregnated materials was very efficient for less apparent decrease in CO 2 adsorption capacity even after 6 adsorption-regeneration cycles.

Mesoporous silicas (MPSs) with two-dimensional (2D) hexagonal framework (SBA-15) and worm-hole framework (MSU-J) were synthesized with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (P123) and a,o-polyoxypropylene diamine (D2000) as templates, respectively. Both SBA-15 and MSU-J were further modified with g-(methacryloyloxy) propyl trimethoxy silane (MAPTS) via post-grafting to prepare organic mesoporous silicas (denoted SBA-15-G and MSU-J-G, respectively) with -C ¼ C groups on the surface of mesopores. All mesoporous silicas were employed as filler to prepare improved poly(methyl methacrylate) (PMMA) composites with lower dielectric constant, higher thermal, and mechanical properties. It was found that all mesoporous silicas retained their mesostructure in MPS/PMMA composites to introduce a lot of voids into the composites. So, the dielectric constant of composites decreased with the loading of mesoporous silica and their organic derivatives increased. Also, all composites exhibited stabilized dielectric constant with lower value in comparison to pure PMMA over the whole frequency from 1 to 160 MHz. Specifically, with the addition of MPS to PMMA, the dielectric constants of the composite can be reduced from 2.91 of the pure PMMA to 2.73 and 2.64 by incorporating 4 wt% SBA-15 and 7 wt% MSU-J, respectively. All the composites exhibited improved mechanical properties, glass transmission temperature (T g ), and thermal stability in comparison to PMMA. All these differences in macro-properties are attributed to the different structure between MPS/PMMA composites and PMMA. MSU-J silica with the larger framework pore size provides the composite with the best improvement in dielectric, thermal, and mechanical properties.

A novel hybrid functional nanoparticle (denoted POSS‐MPS) was synthesized by aminopropyl‐functionalized mesoporous silica (AP‐MPS) with glycidyl polyhedral oligomeric silsesquioxane (G‐POSS). The G‐POSS was employed as molecular caps to envelop the MPS and improve the interaction with the polymer matrix. The POSS‐MPS hybrids were designed to improve the properties of cyanate ester (CE) without affecting its inherent properties. The POSS‐MPS/CE composites exhibited excellent improvement in dielectric properties, mechanical properties, and thermal properties due to increase of voids volume in the composites and reinforcement of interface interaction between organic and inorganic phase. The dielectric constant (κ) and loss factor (tan δ) of composites with 4 phr of POSS‐MPS reduced to 2.78 and 0.008 in comparison to pure CE with the value of 3.27 and 0.012, respectively. Moreover, the composites exhibited 14.3, 4.9, 57.5, and 8.7% enhancement in flexural strength, flexural modulus, impact strength, and glass transition temperature (Tg) in comparison to pure CE, respectively. The results manifested that introduction of POSS‐MPS into CE exhibited toughening and reinforcing effects on the composites. POLYM. COMPOS., 37:2142–2151, 2016. © 2015 Society of Plastics Engineers

Interpenetrating polymer networks (IPNs) based on triisocyanate-terminated poly(urethane-imide)s (PUIs) were prepared by in situ interpenetrating reactions between modified polyurethane (PU) with different ratios of polyimide (PI). The effects of PU, which was made from hydroxyl-terminated polybutadiene modified with triisocyanate, and the amounts of PI on the mechanical properties, thermal properties, and crystalline character of the IPNs were discussed. Triisocyanate-terminated PUI showed that the highest tensile strength was 38 times that of the diisocyanate-terminated materials. Supramolecular cross-linking from an additional hydrogen-bonding network of modified PU and the degree of interpenetration with a regular imide structure of PI were introduced, which accounted for the remarkable improvement in mechanical properties of IPNs. Preferable thermal stability and glass transition temperature for the hard segment of IPNs were rewarded with increasing PI content. X-ray diffraction revealed vigorous segmental mixing between the soft and hard segments of modified PUI. Scanning electron micrographs showed the "fibrous assembly" morphology and short-range-ordered structure of modified PUI.