Green tea polyphenol-reduced graphene oxide: derivatisation, reduction efficiency, reduction mechanism and cytotoxicity

This paper reports on the derivatisation, reduction efficiency, reduction mechanism and cytotoxicity of green tea polyphenol-reduced graphene oxide (GTP-RGO). The reduction of graphene oxide (GO) at 90°C using a weight ratio (WR) of GTP/GO=1 resulted in the production of a stable GTP-RGO dispersion in aqueous media, as indicated by the results of ultravioletvisible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and the measurement of zeta potential and electrophoretic mobility. In addition, the results from UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis indicated the comparable reduction ability of GTP relative to the standard reducing agent, hydrazine (N2H4). The removal mechanism of epoxy group from GO via reduction reaction with GTP was investigated by implementing hybrid functional method of Becke-3-parameters-Lee-Yang-Parr (B3LYP)using Gaussian 09 software. The energy and frequency calculations showed that the GO reduction using GTP was more spontaneous and relatively took place faster than the reduction using N2H4, as evidenced by higher entropy change (ΔS) (0.039 kcal/mol·K) and lower Gibbs free energy (ΔG) barrier (58.880 kcal/mol).The cytotoxicities of GO and GTP-RGO samples were evaluated against human colonic fibroblasts cells (CCD-18Co). The GO sample was determined to be toxic even at low concentration (6.25 μg/mL), while the GTP-RGO sample possesses notably low toxicity at the same concentration. The cell culture experiments revealed that the incorporation of GTP led to a decrease in the toxicity of GTP-RGO samples

The Pedagogy of Teaching English to Young Learners: Implications for Teacher Education

EYL (English for Young Learners) is a global phenomenon, and yet research is laden with reports suggesting teachers' difficulty in developing appropriate EYL pedagogy (e.g. Butler, 2015; Copland, Garton & Burns 2014; Emery, 2012; Garton, Copland & Burns, 2011; Le & Do, 2012; Zein, 2015, 2016a, 2016b). This chapter reports on a study that investigated the perspectives of twenty-six (26) teachers on the appropriate pedagogy needed to teach in the EYL classroom. Data were collected through semi-structured interviews. The findings demonstrate that in the EYL classroom larger emphasis needs to be given to the young learners rather than the language. The findings show that developing a child-friendly pedagogy in the EYL classroom is of vital importance; it is at the core of EYL pedagogy. This brings implications for TESOL teacher education at pre-service and in-service levels in the sense that TESOL teacher educators need to design courses aimed to foster child-friendly pedagogy. The chapter specifically argues for TESOL teacher education to make stronger emphasis on child individual differences (IDs). This is necessary in order to equip teachers with appropriate working knowledge in second language acquisition (SLA) that is prerequisite to the development of EYL teaching expertise

Worldsheet Realization of the Refined Topological String

A worldsheet realization of the refined topological string is proposed in terms of physical string amplitudes that compute generalized N=2 F-terms of the form F_{g,n} W^{2g}Y^{2n} in the effective supergravity action. These terms involve the chiral Weyl superfield W and a superfield Y defined as an N=2 chiral projection of a particular anti-chiral T-bar vector multiplet. In Heterotic and Type I theories, obtained upon compactification on the six-dimensional manifold K3xT2, T is the usual K\"ahler modulus of the T2 torus. These amplitudes are computed exactly at the one-loop level in string theory. They are shown to reproduce the correct perturbative part of the Nekrasov partition function in the field theory limit when expanded around an SU(2) enhancement point of the string moduli space. The two deformation parameters epsilon_- and epsilon_+ of the Omega-supergravity background are then identified with the constant field-strength backgrounds for the anti-self-dual graviphoton and self-dual gauge field of the T-bar vector multiplet, respectively.Comment: 35 pages, typos corrected, published in NP

Local Self-Energy Approach For Electronic Structure Calculations

Using a novel self-consistent implementation of Hedin's GW perturbation theory we calculate space and energy dependent self-energy for a number of materials. We find it to be local in real space and rapidly convergent on second-- to third-- nearest neighbors. Corrections beyond GW are evaluated and shown to be completely localized within a single unit cell. This can be viewed as a fully self consistent implementation of the dynamical mean field theory for electronic structure calculations of real solids using a perturbative impurity solver.Comment: 5 pages, 2 figure

Non-Perturbative Nekrasov Partition Function from String Theory

We calculate gauge instanton corrections to a class of higher derivative string effective couplings introduced in [1]. We work in Type I string theory compactified on K3xT2 and realise gauge instantons in terms of D5-branes wrapping the internal space. In the field theory limit we reproduce the deformed ADHM action on a general {\Omega}-background from which one can compute the non-perturbative gauge theory partition function using localisation. This is a non-perturbative extension of [1] and provides further evidence for our proposal of a string theory realisation of the {\Omega}-background.Comment: 23 page

The inheritance of protein content in the milk of dairy cows

Details are given of the protein and casein yields during the complete lactation of healthy cows maintained under conditions of reasonably uniform management at the experimental farms of the Institute of Animal Genetics.Methods of chemical analysis are stated in detail, with especial reference to the precipitation of the casein at its isoelectric point. The standard errors involved in the chemical work were determined experimentally and two methods for precipitating the casein were compared without finding a substantial difference.An examination is made of the effect of various 'environmental conditions on the secretion of protein. Age of the cow was found to have a definite effect on the amount of protein secreted; it was found to increase with age. Service period also affects the amount, the longer the S.P. the bigger the amount of protein. Cows calving in October and November give the highest yields and those calving in March and April give the lowest. A dry period preceding the lactation has no effect if it exceeds three weeks.Statistical methods used at present to investigate the problems of inheritance of the milk yield and its constituents are discussed in detail. The squared difference method is employed and certain difficulties in its application are noted, requiring an adjustment of one of the raw figures to compensate for the fact that one relationship group is unduly dominated by the progeny of a single bull.The results show that the amounts of protein and casein secreted during lactation are inherited. The effect of the sire was found to be equal to that of the dam in the transmission of the genes governing the inheritance of these two characters. The mean square difference between the yields of unrelated cows was greater than the mean square difference between the yields of any other relationship group. The mean square difference between the yields of dam and daughter was also found. Arising from this study certain correlations between the protein yield of related cows are included

Probing the Moduli Dependence of Refined Topological Amplitudes

With the aim of providing a worldsheet description of the refined topological string, we continue the study of a particular class of higher derivative couplings $F_{g,n}$ in the type II string effective action compactified on a Calabi-Yau threefold. We analyse first order differential equations in the anti-holomorphic moduli of the theory, which relate the $F_{g,n}$ to other component couplings. From the point of view of the topological theory, these equations describe the contribution of non-physical states to twisted correlation functions and encode an obstruction for interpreting the $F_{g,n}$ as the free energy of the refined topological string theory. We investigate possibilities of lifting this obstruction by formulating conditions on the moduli dependence under which the differential equations simplify and take the form of generalised holomorphic anomaly equations. We further test this approach against explicit calculations in the dual heterotic theory.Comment: 30 page