Algebraic, geometric, and stochastic aspects of genetic operators

Genetic algorithms for function optimization employ genetic operators patterned after those observed in search strategies employed in natural adaptation. Two of these operators, crossover and inversion, are interpreted in terms of their algebraic and geometric properties. Stochastic models of the operators are developed which are employed in Monte Carlo simulations of their behavior

Retrofit of water network with regeneration using water pinch analysis

This paper presents the development of a new systematic technique for the retrofit of water network with regeneration based on water pinch analysis. The procedure consists of two parts: retrofit targeting and design for a water network with regeneration unit(s). In the targeting stage, retrofit targets (utility savings and capital investment) were determined for a range of process parameters (total flowrate and/or outlet concentration of the regeneration unit) to obtain a savings versus investment curve. Next, the existing water network was re-designed to meet the chosen targets. A case study on paper making process was used to demonstrate the new methodology

Magnetic and Metal-Insulator Transitions in beta-Na0.5CoO2 and gamma-K0.5CoO2 -NMR and Neutron Diffraction Studies-

Co-oxides beta-Na0.5CoO2 and gamma-K0.5CoO2 have been prepared by the Na de-intercalation from alpha-NaCoO2 and by the floating-zone method, respectively. It has been found that successive phase transitions take place at temperatures Tc1 and Tc2 in both systems. The appearance of the internal magnetic field at Tc1 with decreasing temperature T indicates that the antiferromagnetic order exists at T < Tc1, as in gamma-Na0.5CoO2. For beta-Na0.5CoO2, the transition temperatures and the NMR parameters determined from the data taken for magnetically ordered state are similar to those of gamma-Na0.5CoO2, indicating that the difference of the stacking ways of the CoO2 layers between these systems do not significantly affect their physical properties. For gamma-K0.5CoO2, the quantitative difference of the physical quantities are found from those of beta- and gamma-Na0.5CoO2. The difference between the values of Tci (i = 1 and 2) of these systems might be explained by considering the distance between CoO2 layers.Comment: 8 pages, 14 figures, 1 Tabl

Possible singlet to triplet pairing transition in NaxCoO2 H2O

We present precise measurements of the upper critical field (Hc2) in the recently discovered cobalt oxide superconductor. We have found that the critical field has an unusual temperature dependence; namely, there is an abrupt change of the slope of Hc2(T) in a weak field regime. In order to explain this result we have derived and solved Gor'kov equations on a triangular lattice. Our experimental results may be interpreted in terms of the field-induced transition from singlet to triplet superconductivity.Comment: 6 pages, 5 figures, revte

A novel route to phase formation of cobalt oxyhydrates using KMnO4 as an oxidizing agent

We have first succeefully synthesized the sodium cobalt oxyhydrate superconductors using KMnO4 as a de-intercalating and oxidizing agent. It is a novel route to form the superconductive phase of NaxCoO2.yH2O without resorting to the commonly used Br2/CH3CN solution. The role of the KMnO4 is to de-intercalate the Na+ from the parent compound Na0.7CoO2 and oxidize the Co ion as a result. The higher molar ratio of KMnO4 relative to the sodium content tends to remove more Na+ from the parent compound and results in a slight expansion of the c-axis in the unit cell. The superconducting transition temperature is 4.6-3.8 K for samples treated by the aqueous KMnO4 solution with the molar ratio of KMnO4 relative to the sodium content in the range of 0.3 and 2.29.Comment: 10 pages, 3 figure

MicroRNA29a regulates IL-33-mediated tissue remodelling in tendon disease

MicroRNA (miRNA) has the potential for cross-regulation and functional integration of discrete biological processes during complex physiological events. Utilizing the common human condition tendinopathy as a model system to explore the cross-regulation of immediate inflammation and matrix synthesis by miRNA we observed that elevated IL-33 expression is a characteristic of early tendinopathy. Using in vitro tenocyte cultures and in vivo models of tendon damage, we demonstrate that such IL-33 expression plays a pivotal role in the transition from type 1 to type 3 collagen (Col3) synthesis and thus early tendon remodelling. Both IL-33 effector function, via its decoy receptor sST2, and Col3 synthesis are regulated by miRNA29a. Downregulation of miRNA29a in human tenocytes is sufficient to induce an increase in Col3 expression. These data provide a molecular mechanism of miRNA-mediated integration of the early pathophysiologic events that facilitate tissue remodelling in human tendon after injury

Formation and evolution of epitaxial Co5Ge7Co5Ge7 film on Ge (001) surface by solid-state reaction in an in situ ultrahigh-vacuum transmission electron microscope

A thin metallic cobalt (Co) layer was deposited on a single-crystal Ge (001) surface at room temperature by the electron-beam evaporation of a pure Co metal source in an ultrahigh-vacuum transmission electron microscope. The formation and epitaxial growth of a cobalt germanide Co5Ge7Co5Ge7 phase on the Ge (001) surface was studied in situ by gradually heating the sample from room temperature to ∼ 350 °C∼350°C. The occurrence of an epitaxial hexagonal-close-packed Co and the reaction between Co and Ge were observed at ∼ 225 °C∼225°C. After annealing at ∼ 300 °C∼300°C for 26.5 h, a continuous epitaxial Co5Ge7Co5Ge7 film formed on the Ge (001) substrate. With further annealing at a higher temperature, the continuous Co5Ge7Co5Ge7 layer broke up and formed three-dimensional islands in order to relieve the strain energy in the epitaxial Co5Ge7Co5Ge7 layer. Two epitaxial relationships between Co5Ge7Co5Ge7 and Ge, i.e., Co5Ge7〈110〉(001)//Ge〈100〉(001)Co5Ge7〈110〉(001)∕∕Ge〈100〉(001) and Co5Ge7〈001〉(110)//Ge〈100〉(001)Co5Ge7〈001〉(110)∕∕Ge〈100〉(001) were found by electron diffraction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87837/2/211909_1.pd

Large enhancement of the thermopower in Nax_xCoO2_2 at high Na doping

Research on the oxide perovskites has uncovered electronic properties that are strikingly enhanced compared with those in conventional metals. Examples are the high critical temperatures of the cuprate superconductors and the colossal magnetoresistance in the manganites. The conducting layered cobaltate $\rm Na_xCoO_2$ displays several interesting electronic phases as $x$ is varied including water-induced superconductivity and an insulating state that is destroyed by field. Initial measurements showed that, in the as-grown composition, $\rm Na_xCoO_2$ displays moderately large thermopower $S$ and conductivity $\sigma$. However, the prospects for thermoelectric cooling applications faded when the figure of merit $Z$ was found to be small at this composition (0.6$<x<$0.7). Here we report that, in the poorly-explored high-doping region $x>$0.75, $S$ undergoes an even steeper enhancement. At the critical doping $x_p\sim$ 0.85, $Z$ (at 80 K) reaches values $\sim$40 times larger than in the as-grown crystals. We discuss prospects for low-temperature thermoelectric applications.Comment: 6 pages, 7 figure

59Co-NMR Knight Shift of Superconducting Three-Layer NaxCoO2.yH2O

The superconducting state of NaxCoO2.yH2O with three CoO2 layers in a unit cell has been studied by 59Co-NMR. The Knight shift measured for a peak of the NMR spectra corresponding to the external magnetic field H along one of the principal directions within the CoO2 plane, exhibits a rapid decrease with decreasing temperature T below the superconducting transition temperature Tc, indicating that the spin susceptibility is suppressed in the superconducting phase, at least, for this field direction. Because differences of the superconducting properties are rather small between this three-layer NaxCoO2.yH2O and previously reported NaxCoO2.yH2O with two CoO2 layers within a unit cell, the present result of the Knight shift studies indicates that the Cooper pairs of the former system are in the singlet state as in the latter, for which the spin susceptibility is suppressed for both directions of H parallel and perpendicular to the CoO2 plane.Comment: 5 page