Fractionation of transgenic corn for recovery of recombinant enzymes

Two germ-separation methods, dry-milling and density separation by flotation, were evaluated for recovering recombinant β-glucuronidase (rGUS) that accumulated primarily in the germ of transgenic corn. The dry-milling process consisted of (i) seed tempering, (ii) degerming with a horizontal-drum degermer/dehuller, (iii) particle size fractionation with standard sieves, (iv) germ and endosperm separation by roller milling and sifting, and (v) removal of hulls by aspiration. Sieves nos. 5, 6, and 7 retained the majority of germ, and subfractions from these sieves were pooled as a germ-rich fraction. Mass balances showed that the germ-rich fraction, which constituted 17% of the total dry-milled corn weight, contained 49% of rGUS activity and 64% of the total recoverable oil. Germ fractionation by flotation was tested as a proof-of-concept method aimed at separating corn fractions based on their difference in specific gravity (sp gr). The process consisted of impact-grinding of corn kernels followed by density separation using 1.15 or 1.3 specific gravity sodium nitrate solution. The oil-containing germ fraction floated, whereas the heavier endosperm fraction sedimented. The flotation method was simpler and resulted in higher enzyme recovery, that is, the germ-rich fraction was 20% (w/w) of the initial corn weight, and accounted for 80% of rGUS activity and 77% of total oil. The sodium nitrate solution did not have an adverse effect on the enzyme activity.     

Noise analysis of robot manipulator using neural networks

Due to a lot of robot manipulators application in industry, low noise degree is very important criteria for robot manipulator's joints. In this paper, joint noise problem of a robot manipulator with five joints is investigated both theoretically and experimentally. The investigation is consisted of two steps. First step is to analyze the noise of joints using a hardware and software. The hardware is a part of noise sensors. The second step; according to experimental results, some neural networks are employed for finding robust neural noise analyzer. Five types of neural networks are used to compare each other. From the results, it is noted that the proposed RBFNN gives the best results for analyzing joint noise of the robot manipulator.     

Approximate periodic solutions for the Helmholtz-Duffing equation

Approximate periodic solutions for the Helmholtz-Duffing oscillator are obtained in this paper. He’s Energy Balance Method (HEBM) and He’s Frequency Amplitude Formulation (HFAF) are adopted as the solution methods. Oscillation natural frequencies are analytically analyzed. Error analysis is carried out and accuracy of the solution methods is evaluated.     

Dielectric properties of sol-gel derived Ta2O5 thin films

The dielectric constant and the dielectric loss of tantalum pentoxide (Ta₂O₅) thin films, produced by sol-gel spin-coated process on Corning glass substrates, have been investigated in the frequency range of 20-10⁵ Hz and the temperature range of 183-403 K, using ohmic Al electrodes. The frequency and temperature dependence of relaxation time has also been determined. The capacitance and loss factor were found to decrease with increasing frequency and increase with increasing temperature. The activation energy values were evaluated and a good agreement between the activation energy values obtained from capacitance and dielectric loss factor measurements were observed.     

Investigation of Al-O-Al sites in an Na-aluminosilicate glass

This paper reports the presence of Al- O- Al linkages in an aluminosilicate glass where Si/Al = 1 by using 2D¹⁷O triple quantum MAS NMR technique (3Q MASNMR). The experiments were performed at external magnetic fields of 8.4 and 14.4T. Despite¹⁷OMAS NMR spectra of the sample in both fields do not give much information about the different kinds of linkages in the sample, 3Q MAS NMR spectrum shows clear evidence that there are some amounts of Al-O-Al linkages in the sample giving two completely resolved peaks. These two peaks were attributed to the Si-O-Al and Al-O-Al linkages on the basis of their chemical shifts and, quadrupolar coupling constants which are quite sensitive to the local structure.     

Role of diffusion-annealing time on the superconducting, microstructural and mechanical properties of Cu-diffused bulk MgB2 superconductor

In this study, the effect of various annealing time (0.5, 1, 1.5 and 2 h) on microstructural, mechanical and superconducting properties of the Cu-diffused bulk MgB₂ superconducting samples is investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers microhardness (H _v ) and dc resistivity measurements for the first time. The critical transition temperature, grain size, phase purity, lattice parameter, surface morphology, crystallinity and room temperature resistivity values of the bulk samples prepared are compared with each other. Electrical-resistivity measurements show that the sample (annealed at 850 °C for 1 h), exhibiting the highest room temperature resistivity, obtains the maximum zero resistivity transition temperature (T _c ). From the XRD results, all the samples contain MgB₂ as the main phase with a very small amount of Mg₂Cu phase. Moreover, SEM investigations conducted for the microstructural characterization illustrate that not only does the grain size of the samples studied enhance gradually, but the surface morphology and grain connectivity also improve with the increase in the diffusion-annealing time up to 1 h beyond which all the properties obtained start to degrade. Indeed, the worst surface morphology is observed for the Cu-diffused bulk MgB₂ superconductor exposed to 2 h annealing duration. At the same time, Vickers microhardness, elastic modulus, load independent hardness, yield strength, fracture toughness and brittleness index values are calculated separately for the pure and Cu-diffused samples. It is found that the microhardness values depend strongly on the diffusion-annealing time. Furthermore, the diffusion coefficient of the Cu ion in the bulk MgB₂ superconductor is obtained to change from 1.63 × 10^?7 to 2.58 × 10^?7 cm² s^?1. The maximum diffusion coefficient is observed for the sample prepared at 850 °C for 1 h whereas the minimum one is noted for the sample annealed at 850 °C for 2 h, confirming that the annealing-time of 1 h is the best ambient to improve the mechanical, microstructural and superconducting properties of the samples produced.     

An upgraded artificial bee colony (ABC) algorithm for constrained optimization problems

Artificial bee colony (ABC) algorithm developed by Karaboga is a nature inspired metaheuristic based on honey bee foraging behavior. It was successfully applied to continuous unconstrained optimization problems and later it was extended to constrained design problems as well. This paper introduces an upgraded artificial bee colony (UABC) algorithm for constrained optimization problems. Our UABC algorithm enhances fine-tuning characteristics of the modification rate parameter and employs modified scout bee phase of the ABC algorithm. This upgraded algorithm has been implemented and tested on standard engineering benchmark problems and the performance was compared to the performance of the latest Akay and Karaboga’s ABC algorithm. Our numerical results show that the proposed UABC algorithm produces better or equal best and average solutions in less evaluations in all cases.     

Coal consumption and industrial production nexus in USA: Cointegration with two unknown structural breaks and causality approaches

The paper investigates the causality relationships among industrial production index, coal consumption and employment in industrial sector for the period of 1973:1–2011:10 in USA. After noticing that there are breaks in the regression model, the Hatemi-J test for cointegration is employed to the cases that take into account two possible regime shifts. It is concluded that there is a long run relationship between industrial production and industrial coal consumption with the breaks at 1983:4 and 1998:4. We found a negative relationship between coal consumption and industrial production for the period of 1973:1–1983:4 and positive relationship for 1983:5–1998:4 period. For the last period that covers 1983:5–2011:10, the cointegration relationship turned to negative. In addition, the results show that causal relationship between coal consumption and industrial production changes over time.     

Investigation of Lu effect on YBa2Cu3O7−δ superconducting compounds

This study reports the effect of Lu addition on the microstructural and superconducting properties of YBa₂Lu_xCu₃O_7?δ (Y123) superconducting samples with x = 0, 0.1, 0.3, 0.5 and 0.7 by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), electron dispersive X-ray (EDX), electrical resistivity and transport critical current density (J_c) measurements. The samples prepared by the liquid ammonium nitrate and derivatives are exposed to various annealing time (20, 40 and 60 h) and temperature (950, 960 and 970 °C), and the best ambient for the sample fabrication is determined to be 970 °C for 20 h. Zero resistivity transition temperatures (T_c), critical current densities (J_c), variation of transition temperatures, hole-carrier concentration, grain size, lattice parameter, surface morphology, element distribution, crystallinity and resistivity (at room temperature) values of the bulk superconducting samples prepared at 970 °C for 20 h are compared with each other. T_c and J_c values of the samples are inferred from the dc resistivity and the critical current measurements, respectively. The results show that the T_c value of the pure sample is about 90.6 K while the sample doped with 0.1 wt% Lu has the maximum T_c value (92.5 K). However, beyond x = 0.1, the T_c value is observed to decrease toward to 83.5 K with increment in the Lu addition. Similarly, the J_c values measured are found to reduce from 142 to 76 A/cm² with the addition. Moreover, XRD measurements show that both pure and Lu-doped samples exhibit the polycrystalline superconducting phase with the changing intensity of diffraction lines and contain Y123 and Y211 phase, confirming the incorporation of Lu atoms into the crystalline structure of the samples studied. At the same time, comparing of the XRD patterns of samples, the intensity ratio of the characteristic (110) and (013) peaks on the sample doped with 0.1 wt% Lu is more than that on the other samples prepared. Additionally, SEM images display that the sample doped with 0.1 wt% Lu obtains the best crystallinity, grain connectivity and largest grain size whereas the worst surface morphology is observed for the maximum doped sample (x = 0.7). Further, EDX results demonstrate that the Lu atoms doped are successfully introduced into the microstructure of the Y123 samples studied and the maximum Cu element level is observed for the sample doped with 0.1 wt%, explaining that why this sample obtains the best superconducting properties compared to others. According to all the results obtained, it is concluded that the 0.1 wt% Lu addition into the Y123 system improves the microstructural and superconducting properties of the samples studied.