Hierarchical simulations of hybrid polymer-solid materials

Complex polymer-solid materials have gained a lot of attention during the last 2-3 decades due to the fundamental physical problems and the broad spectrum of technological applications in which they are involved. Therefore, significant progress concerning the simulations of such hybrid soft-hard nanostructured systems has been made in the last few years. Simulation techniques vary from quantum to microscopic (atomistic) up to mesoscopic (coarse-grained) level. Here we give a short overview of simulation approaches on model polymer-solid interfacial systems for all different levels of description. In addition, we also present a brief outlook concerning the open questions in this field, from the point of view of both physical problems and computational methodologies

A particle swarm optimisation-based Grey prediction model for thermal error compensation on CNC machine tools

Thermal errors can have a significant effect on CNC machine tool accuracy. The thermal error compensation system has become a cost-effective method of improving machine tool accuracy in recent years. In the presented paper, the Grey relational analysis (GRA) was employed to obtain the similarity degrees between fixed temperature sensors and the thermal response of the CNC machine tool structure. Subsequently, a new Grey model with convolution integral GMC(1, N) is used to design a thermal prediction model. To improve the accuracy of the proposed model, the generation coefficients of GMC(1, N) are calibrated using an adaptive Particle Swarm Optimisation (PSO) algorithm. The results demonstrate good agreement between the experimental and predicted thermal error. Finally, the capabilities and the limitations of the model for thermal error compensation have been discussed. Keywords: CNC machine tool, Thermal error modelling, ANFIS, Fuzzy logic, Grey system theory

Graduate teaching assistant (GTA) development in the college classroom

The graduate student population has been traditionally overlooked within higher education. However, within recent decades, much research has been devoted to addressing the multiple facets of the graduate student experience, including that of the graduate teaching assistant (GTA) position. This thesis seeks to explore in depth the experiences of GTAs in the classroom. A summary and critique of the literature that exists surrounding GTAs is provided, including literature related to national graduate student demographics, the history of GTA/GRA positions, salient issues surrounding the GTA position, and models of GTA development. The goal of this thesis is to share results from a quantitative study that analyzes how graduate students self-identify into a three-stage model of GTA development proposed by Nyquist and Sprague (1998). Within this particular study, an online survey questionnaire was developed to support a quantitative research design. An independent chi-square analysis was conducted on the data derived from this questionnaire. The results from this study will be discussed, and further implications of this research for both researchers and practitioners will be explored

Serious mortality: the date of the Fussell's Lodge long barrow

Twenty-seven radiocarbon results are now available from the Fussell’s Lodge long barrow, and are presented within an interpretive Bayesian statistical framework. Three alternative archaeological interpretations of the sequence are given, each with a separate Bayesian model. It is hard to decide between these, though we prefer the third. In the first (following the excavator), the construction is a unitary one, and the human remains included are by definition already old. In the second, the primary mortuary structure is seen as having two phases, and is set within a timber enclosure; these are later closed by the construction of a long barrow. In that model of the sequence, deposition began in the 38th century cal BC and the mortuary structure was extended probably in the 3660s–3650s cal BC; the long barrow was probably built in the 3630s–3620s cal BC; ancestral remains are not in question; and the use of the primary structure may have lasted for a century or so. In the third, preferred model, a variant of the second, we envisage the inclusion of some ancestral remains in the primary mortuary structure alongside fresh remains. This provides different estimates of the date of initial construction (probably in the last quarter of the 38th century cal BC or the first half of the 37th century cal BC) and the duration of primary use, but agrees in setting the date of the long barrow probably in the 3630s–3620s cal BC. These results are discussed in relation to the development and meanings of long barrows at both national and local scales

A Dual-Fluorescent Composite of Graphene Oxide and Poly(3-Hexylthiophene) Enables the Ratiometric Detection of Amines

A composite prepared by grafting a conjugated polymer, poly(3-hexylthiophene) (P3HT), to the surface of graphene oxide was shown to result in a dual-fluorescent material with tunable photoluminescent properties. Capitalizing on these unique features, a new class of graphene-based sensors that enables the ratiometric fluorescence detection of amine-based pollutants was developed. Moreover, through a detailed spectroscopic study, the origin of the optical properties of the aforementioned composite was studied and was found to be due to electronic decoupling of the conjugated polymer from the GO. The methodology described herein effectively overcomes a long-standing challenge that has prevented graphene based composites from finding utility in sensing and related applications.Meng, Dongli, Shaojun Yang, Dianming Sun, Yi Zeng, Jinhua Sun, Yi Li, Shouke Yan, Yong Huang, Christopher W. Bielawski, and Jianxin Geng. "A dual-fluorescent composite of graphene oxide and poly (3-hexylthiophene) enables the ratiometric detection of amines." Chemical Science 5, no. 8 (Apr., 2014): 3130-3134.Chemistr