Effect of compositional gradient on thermal behavior of synthetic graphite-phenolic nanocomposites

Synthetic graphite–phenolic nanocomposites were designed and synthesized with a compositional gradient which is shown to influence transient temperature fields during rapid temperature changes. Such nanocomposites were fabricated using a compression moulding technique, and thermal conductivity and heat capacity of nanocomposites were experimentally determined using a modified transient plane source technique over a wide temperature range from 253.15 to 373.15 K. The effects of four compositional gradient configurations on the transient temperature field across the thickness of a nanocomposite plate, at a high imposed temperature, was investigated. The transient time and temperature fields in nanocomposite structures were highly affected by the compositional gradient configurations.

Synthetic evaluation method for bridge priority ranking

In order to maintain the transportation operation, proper monitoring systems should be established on road structures, especially bridges. Since these systems need enormous investments, only a part of bridges should be equipped. Thus, the priorities of the bridges should be ranked. In this paper, a method based on two-level synthetic evaluation is proposed. First, the importance of each bridge is analyzed through the economic analysis. Six factors are considered for the bridges in a network, including construction cost, service duration, length, location importance coefficient, traffic volume, and reconstruction time. Second, the safety condition of the bridge is evaluated by using improved entropy method (IEM) which combines subjective weight with objective entropy weight. Five indices are incorporated in this step, i.e., design and construction condition, technical condition, level of overloading, hazard of wind and earthquake and environmental factors. Finally, the priorities of all the bridge in one network can be ranked and classified through a judge matrix. To demonstrate the effectiveness of the proposed method, a main highway including 16 bridges is taken as an illustrative example. The results show that the bridges can be ranked and classified quickly by using the proposed method.

Composition-optimized synthetic graphite/polymer nanocomposites

In this study the optimization design, fabrication and characterization of synthetic graphite/phenolic nanocomposites are performed. The composition of synthetic graphite/phenolic nanocomposites was controlled across the thickness by stacking eight homogeneous layers containing 0, 5, 10, and 20wt% synthetic graphite in different sequences. Four compositional gradient patterns, as well as a homogenous nanocomposite, with the same geometry and synthetic graphite content, were fabricated to investigate the optimized design for thermomechanical properties. Results show that nanocomposites with a high concentration of synthetic graphite on the surfaces and neat resin at the center have the best thermomechanical and viscoelastic properties.

Controlled modification of the inorganic and organic bricks in an Al-based MOF by direct and post-synthetic synthesis routes

Four new porous CAU-1 derivatives CAU-1–NH2 ([Al4(OH)2(OCH3)4(BDC–NH2)3]·xH2O, BDC–NH22− = aminoterephthalate), CAU-1–NH2(OH) ([Al4(OH)6(BDC–NH2)3]·xH2O), CAU-1–NHCH3 ([Al4(OH)2(OCH3)4(BDC–NHCH3)3]·xH2O) and CAU-1–NHCOCH3 ([Al4(OH)2(OCH3)4(BDC–NHCOCH3)3]·xH2O) all containing an octameric [Al8(OH)4+y(OCH3)8−y]12+ cluster, with y = 0–8, have been obtained by MW-assisted synthesis and post-synthetic modification. The inorganic as well as the organic unit can be modified. Heteronuclear 1H–15N, 1H–13C and homonuclear 1H–1H connectivities determined by solid-state NMR spectroscopy prove the methylation of the NH2 groups when conventional heating is used. Varying reaction times and temperatures allow controlling the degree of methylation of the amino groups. Short reaction times lead to non-methylated CAU-1 (CAU-1–NH2), while longer reaction times result in CAU-1–NHCH3. CAU-1–NH2 can be modified chemically by using acetic anhydride, and the acetamide derivative CAU-1–NHCOCH3 is obtained. Thermal treatment permits us to change the composition of the Al-containing unit. Methoxy groups are gradually exchanged by hydroxy groups at 190 °C in air. Solid-state NMR spectra unequivocally demonstrate the presence of the amino groups, as well as the successful post-synthetic modification. Furthermore 1H–1H correlation spectra using homonuclear decoupling allow the orientation of the NHCOCH3 groups within the pores to be unravelled. The influence of time and temperature on the synthesis of CAU-1 was studied by X-ray powder diffraction, elemental analyses, and 1H liquid-state NMR and IR spectroscopy.

High N-content holey few-layered graphene electrocatalysts: Scalable solvent-less production

Few layered nitrogen doped graphene (NG) attracts great interest in energy storage and conversion applications due to its electronic and catalytic properties. However, its bulk production cannot be envisioned by the current synthetic methods. Here we report a facile, solvent-less, low cost and high yield process for the synthesis of NG. Mechanochemical solid-state exfoliation allows scalable synthesis of holey and crumple nitrogen-doped few-layered graphene from graphite with controlled high concentration N doping and a high surface area through ball-milling. By adjusting the ratio of starting materials, the nitrogen content can be modulated from 4.87 to 17.83 at.%. Furthermore, the types of nitrogen-containing species in few-layered graphene can also be controlled. The resultant NG exhibits superior oxygen reduction reaction performance and more reliable stability than commercial Pt/C catalysts. This journal is

Deficient cognitive control fuels children's exuberant false allegations.

In eyewitness studies as in actual investigations, a minority of children generate numerous false (and sometimes incredulous) allegations. To explore the characteristics of these children, we reinterviewed and administered a battery of tasks to 61 children (ages 4-9 years) who had previously participated in an eyewitness study where a man broke a "germ rule" twice when he tried to touch them. Performance on utilization, response conflict (Luria tapping), and theory of mind tasks predicted the number of false reports of touching (with age and time since the event controlled) and correctly classified 90.16% of the children as typical witnesses or exuberant (more than 3) false reporters. Results of a factor analysis pointed to a common process underlying performance on these tasks that accounted for 49% of the variability in false reports. Relations between task performance and testimony confirmed that the mechanisms underlying occasional intrusions are different from those that drive persistent confabulation and that deficient cognitive control fuels young children's exuberant false reports.

Synthetic biology based metabolic engineering of saccharomyces cerevisiae for omega 6 and 3 PUFA production

Metabolic engineering of PUFA biosynthesis pathway using codon optimized DGA1 (Diacylglycerol acyltransferase), FAA3 (Acyl-CoA synthetase), desaturase genes named D9D, D12D, D5D, D6D, D17D and D6E elongase gene was studied in S. cerevisiae. Engineered yeast strains successfully demonstrated increase in lipid accumulation, and heterologous biosynthesis of linoleic, γ-linolenic, dihomo γ-linolenic, arachidonic and eicosapentaenoic acid.

Sequence-dependent structure/function relationships of catalytic peptide-enabled gold nanoparticles generated under ambient synthetic conditions

Peptide-enabled nanoparticle (NP) synthesis routes can create and/or assemble functional nanomaterials under environmentally friendly conditions, with properties dictated by complex interactions at the biotic/abiotic interface. Manipulation of this interface through sequence modification can provide the capability for material properties to be tailored to create enhanced materials for energy, catalysis, and sensing applications. Fully realizing the potential of these materials requires a comprehensive understanding of sequence-dependent structure/function relationships that is presently lacking. In this work, the atomic-scale structures of a series of peptide-capped Au NPs are determined using a combination of atomic pair distribution function analysis of high-energy X-ray diffraction data and advanced molecular dynamics (MD) simulations. The Au NPs produced with different peptide sequences exhibit varying degrees of catalytic activity for the exemplar reaction 4-nitrophenol reduction. The experimentally derived atomic-scale NP configurations reveal sequence-dependent differences in structural order at the NP surface. Replica exchange with solute-tempering MD simulations are then used to predict the morphology of the peptide overlayer on these Au NPs and identify factors determining the structure/catalytic properties relationship. We show that the amount of exposed Au surface, the underlying surface structural disorder, and the interaction strength of the peptide with the Au surface all influence catalytic performance. A simplified computational prediction of catalytic performance is developed that can potentially serve as a screening tool for future studies. Our approach provides a platform for broadening the analysis of catalytic peptide-enabled metallic NP systems, potentially allowing for the development of rational design rules for property enhancement.