Modeling the underlying mechanisms for organic memory devices: Tunneling, electron emission and oxygen adsorbing

We present a combined experimental and theoretical study to get insight into both memory and negative differential resistance (NDR) effect in organic memory devices. The theoretical model we propose is simply a one-dimensional metallic island array embedding within two electrodes. We use scattering operator method to evaluate the tunneling current among the electrode and islands to establish the basic bistable I-V curves for several devices. The theoretical results match the experiments very well, and both memory and NDR effect could be understood comprehensively. The experimental correspondence, say, the experiment of changing the pressure of oxygen, is addressed as well.Comment: 5 pages, 3 figure

Experimental Study on the Effect of Nano-silica on Mud Density in Synthetic Based Mud

Drilling fluids play important roles in drilling operations to suspend cuttings, counter high formation pressure and to ensure wellbore stability. Amongst the different types of drilling fluids, currently synthetic based muds are the choice drilling fluid due to its high performance in HPHT wells in terms of wellbore stability and high penetration rates. However, under HPHT conditions, the well will encounter thermal degradation of mud properties, which will affect the performance of the mud, such as fluid loss, unstable rheology and barite sag. Barite sag is an effect of high density and high solid content in muds, in which the heavy solids in the mud settle at the bottom of the wellbore causing pipe sticking and lost of circulation. The experiment was carried out at LPLT, starting of HPHT and extreme HPHT conditions with a varying nano-silica concentration of 0%(base case) to 40%. At different mud weights, the formulated drilling fluid will be tested for HPHT filtrate loss, stable rheology and static sag at a 45° tilt. Nano-silica has been proven in this project to be only effective for fluid loss and improve mud rheology due to the nature of nano-silica as a plugging agent. The nano-silica had no effect on barite sag as proven in this experiment. Nevertheless, the newly formulated mud is still effective for solving and preventing downhole problems

Natural constraints on the gluon-quark vertex

In principle, the strong-interaction sector of the Standard Model is characterised by a unique renormalisation-group-invariant (RGI) running interaction and a unique form for the dressed--gluon-quark vertex, $\Gamma_\mu$; but, whilst much has been learnt about the former, the latter is still obscure. In order to improve this situation, we use a RGI running-interaction that reconciles both top-down and bottom-up analyses of the gauge sector in quantum chromodynamics (QCD) to compute dressed-quark gap equation solutions with 1,660,000 distinct Ansaetze for $\Gamma_\mu$. Each one of the solutions is then tested for compatibility with three physical criteria and, remarkably, we find that merely 0.55% of the solutions survive the test. Plainly, therefore, even a small selection of observables places extremely tight bounds on the domain of realistic vertex Ansaetze. This analysis and its results should prove useful in constraining insightful contemporary studies of QCD and hadronic phenomena.Comment: 6 pages, 7 figure

Phase diagram and critical endpoint for strongly-interacting quarks

We introduce a method based on the chiral susceptibility, which enables one to draw a phase diagram in the chemical-potential/temperature plane for strongly-interacting quarks whose interactions are described by any reasonable gap equation, even if the diagrammatic content of the quark-gluon vertex is unknown. We locate a critical endpoint (CEP) at (\mu^E,T^E) ~ (1.0,0.9)T_c, where T_c is the critical temperature for chiral symmetry restoration at \mu=0; and find that a domain of phase coexistence opens at the CEP whose area increases as a confinement length-scale grows.Comment: 4 pages, 3 figure

Quark spectral density and a strongly-coupled QGP

The maximum entropy method is used to compute the dressed-quark spectral density from the self-consistent numerical solution of a rainbow truncation of QCD's gap equation at temperatures above that for which chiral symmetry is restored. In addition to the normal and plasmino modes, the spectral function also exhibits an essentially nonperturbative zero mode for temperatures extending to 1.4-1.8-times the critical temperature, T_c. In the neighbourhood of T_c, this long-wavelength mode contains the bulk of the spectral strength and so long as this mode persists, the system may fairly be described as a strongly-coupled state of matter.Comment: 4 pages, 2 figure