Quantitative analysis of tea using ytterbium‐based internal standard near‐infrared spectroscopy coupled with boosting least‐squares support vector regression

The present study demonstrated the possibility of utilizing the ytterbium (Yb)‐based internal standard near‐infrared (NIR) spectroscopic measurement technique coupled with multivariate calibration for quantitative analysis of tea, including total free amino acids and total polyphenols in tea. Yb is a rare earth element aimed to compensate for the spectral variation induced by the alteration of sample quantity during the spectral measurement of the powdered samples. Boosting was invoked to be combined with least‐squares support vector regression (LS‐SVR), forming boosting least‐squares support vector regression (BLS‐SVR) for the multivariate calibration task. The results showed that the tea quality could be accurately and rapidly determined via the Yb‐based internal standard NIR spectroscopy combined with BLS‐SVR method. Moreover, the introduction of boosting drastically enhanced the performance of individual LS‐SVR, and BLS‐SVR compared favorably with partial least‐squares regression. Copyright © 2013 John Wiley & Sons, Ltd.     

Toughening of Propylene‐ethylene Copolymer/Calcium Carbonate Composites with High‐Density Polyethylene

Propylene‐ethylene copolymer/calcium carbonate (CaCO₃) composites (weight ratio=50/50) toughened with high density polyethylene (HDPE) were prepared using a twin‐screw extruder; the HDPE content in composites was in the range of 0–4 wt.%. The notched impact strength of propylene‐ethylene copolymer/CaCO₃ composites with 1.5 wt.% HDPE was 46% higher than that of propylene‐ethylene copolymer/CaCO₃ composites. Differential scanning calorimetry (DSC) experiments showed that good miscibility between propylene‐ethylene copolymer and HDPE enhanced the interpenetration of the macromolecules located in the interface. It was shown that debonding of the small HDPE particles within the propylene‐ethylene copolymer matrix resulted in the formation of small voids; the subsequent plastic deformation of the propylene‐ethylene copolymer matrix next to the voids thinned the ligaments and led to large energy consumption.     

Electrostatic potential in cylindrical dielectric media using the image charge method

We derive a simple analytical expression for the electric potential produced by a point charge in a cylindrical pore with relative permittivity different from that of the surrounding medium. The interface between the pore and the surrounding media may contain electric charge or be electrically neutral. The expression reduces to the known solutions when the surrounding dielectric medium is identical to the pore or an electric conductor. We discuss the convergence of the series expansion and numerically evaluate the electrostatic potential inside the cylindrical pore. The calculated potential shows the effect of the dielectric permittivity difference of the media. The results demonstrate that the expression can be implemented in a numerical dynamic simulation of charged systems in cylindrical geometry. We also give an expression for the case when the source charge is in the medium outside the cylinder.     

Laser-induced changes in titanium by femtosecond,picosecond and millisecond laser ablation

In order to realize the qualitative control of the laser-induced changes trend and the quantitative control of the laser-induced changes range in titanium upon laser irradiation with different pulse duration, comparative ablation experiments by femtosecond, picosecond and millisecond pulsed lasers were carried out on titanium in this study. Then the final surface morphology, aspect ratio, chemical composition and microstructural state of the ablated titanium were analyzed by laser scanning confocal microscopy, X-ray photoelectron spectroscopy and transmission electron microscopy, respectively. The dependency of the morphology, size, composition and microstructure of ablated titanium on laser pulse duration variation were emphatically discussed. It is found that, as the laser pulse duration increases from femtosecond to millisecond scale, surface morphology quality of ablated titanium gets worse, aspect ratio of microgroove decreases, proportion of titanium oxides in final ablation products becomes larger and the microstructural state of ablated titanium has a higher amorphization degree, which can be attributed to the decreased laser intensity per pulse and enhanced heat conduction effect in titanium with the pulse duration increasing.     

Comprehensive study on hot carrier reliability of radiation hardened H-gate PD SOI NMOSFET after gamma radiation

ABSTRACT

The authors perform gamma ray irradiation and hot carrier stress on RH H-Gate PD (partially depleted) SOI NMOSFETs as the experimental group and commercial strip-shaped gate PD SOI NMOSFETs as the control group. They analyse HCI degradation in samples and conclude that radiation could enhance HCI degradation in RH H-gate samples. Moreover, the mechanism is explained as the coupling effect between the front gate and back gate caused by TID radiation-induced trap charges in the buried oxide.     

A Straightforward Immunoassay Applicable to a Wide Range of Antibodies Based on Surface Enhanced Fluorescence

A straightforward immunoassay based on surface enhanced fluorescence (SEF) has been demonstrated using a fluorescent immune substrate and antibody functionalized-silver nanoparticles. Unlike the conventional SEF-based immunoassay, which usually uses the dye-labeled antibodies and the metallic nanostructured-substrates, the presented immune system does not need the antibodies to be labeled with dye molecules. Thus, this immunoassay can be easily applied to the detection of a wide range of target antigens, which is of great importance for its practical application. The experimental results show that this immunoassay has a good specificity as well as the capacity of quantitative detection. Basically, the surface density of the immuno-adsorbed silver nanoparticles increases with the increased amount of target antigens, resulting in a fluorescence enhancement up to around 7 fold. The dose-responsive performance of the immunoassay has been investigated and the limit of detection (LOD) is 1 ng/mL. Due to its simple preparation method and the wide range of detectable antigens, this presented immunoassay is expected to be helpful for extending the SEF-based application.     

Critical curves for fast diffusive polytropic filtration equations coupled through boundary

This article deals with the critical curve of a fast diffusive polytropic filtration system coupled at the boundary condition. By constructing the self-similar supersolution and subsolution, we obtain the critical global existence curve. The critical curve of Fujita type is conjectured with the aid of some new results.     

The Stage-structured Predator-Prey System with Delay and Harvesting

In this article, we establish a mathematical model of two species with stage structure and the relation of predator-prey, obtain the necessary and sufficient condition for the permanence of two species and the extinction of one species or two species. We also obtain the optimal harvesting and the threshold of harvesting for the sustainable development and increasing delays can cause a bifurcation into periodic solutions. Finally, we give some numerical results and graphs.     

Some researches on multivariate Lagrange interpolation along the sufficiently intersected algebraic manifold

In this article, Lagrange interpolation by polynomials in several variables is studied. Particularly on the sufficiently intersected algebraic manifolds, we discuss the dimension about the interpolation space of polynomials. After defining properly posed set of nodes (or PPSN for short) along the sufficiently intersected algebraic manifolds, we prove the existence of PPSN and give the number of points in PPSN of any degree. Moreover, in order to compute the number of points in PPSN concretely, we propose the operator ? _k with reciprocal difference.     

Gelfand-Kirillov dimension of some primitive abundant semigroups

In this paper, the growth and Gelfand-Kirillov dimension of some primitive abundant semigroups are investigated. It is shown that for certain primitive abundant (regular) semigroup S, S as well as the semigroup algebra K [S] has polynomial growth if and only if all of its cancellative submonoids (subgroups) T as well as K[T] have polynomial growth. As applications, it is shown that if S is a finitely generated primitive inverse monoid having the permutational property, then clK dim K[S] = GK dim K[S] = rk(S).