A four‐node corotational quadrilateral elastoplastic shell element using vectorial rotational variables

A four‐node corotational quadrilateral elastoplastic shell element is presented. The local coordinate system of the element is defined by the two bisectors of the diagonal vectors generated from the four corner nodes and their cross product. This local coordinate system rotates rigidly with the element but does not deform with the element. As a result, the element rigid‐body rotations are excluded in calculating the local nodal variables from the global nodal variables. The two smallest components of each nodal orientation vector are defined as rotational variables, leading to the desired additive property for all nodal variables in a nonlinear incremental solution procedure. Different from other existing corotational finite‐element formulations, the resulting element tangent stiffness matrix is symmetric owing to the commutativity of the local nodal variables in calculating the second derivative of strains with respect to these variables. For elastoplastic analyses, the Maxwell–Huber–Hencky–von Mises yield criterion is employed, together with the backward‐Euler return‐mapping method, for the evaluation of the elastoplastic stress state; the consistent tangent modulus matrix is derived. To eliminate locking problems, we use the assumed strain method. Several elastic patch tests and elastoplastic plate/shell problems undergoing large deformation are solved to demonstrate the computational efficiency and accuracy of the proposed formulation. Copyright © 2013 John Wiley & Sons, Ltd.     

Fractional wavelet transform

The wavelet transform, which has had a growing importance in signal and image processing, has been generalized by association with both the wavelet transform and the fractional Fourier transform. Possible implementations of the new transformation are in image compression, image transmission, transient signal processing, etc. Computer simulations demonstrate the abilities of the novel transform. Optical implementation of this transform is briefly discussed.     

Instrumentation for chemical cytometry

Capillary electrophoresis is ideally suited to chemical analysis of individual cells. Small mammalian somatic cells (approximately 15 microns in diameter) can be analyzed by injecting the intact cell into a capillary, lysing the cell, separating and detecting the cellular components, and reconditioning the capillary prior to the next injection. In this paper, we report on technical improvements to single-cell analysis. We designed an inexpensive multipurpose single-cell injector that facilitates the following: (i) monitoring of injection, (ii) reproducible pressure- or electrokinetic-driven injection of the cell, (iii) complete cell lysis by SDS within 30 s of injection, and (iv) pressure-driven capillary reconditioning. Furthermore, we report on the analysis of glycosylation and glycolysis in single human carcinoma cells (HT29 cell line). The reliability and quality of the analysis is confirmed by comparing electropherograms from single cells and those from purified cell extracts.     

Protein crystallization in space

The microgravity environment of space is an ideal place to study the complicated protein crystallization process and to grow good-quality protein crystals. A series of crystal growth experiments of 10 different proteins was carried out in space on a Chinese re-entry satellite FSW-2 in August, 1992. The experiments were performed for about two weeks at a temperature of 18.5 +/- 0.5 degrees C using a tube-like crystallization apparatus made in the Shanghai Institute of Technical Physics, Academia Sinica. More than half of 48 samples from 6 proteins produced crystals, and the effects of microgravity on protein crystal growth were observed, especially for hen-egg white lysozyme and an acidic phospholipase A2 from the venom of Agkistrodon halys Pallas. Analyses of the crystallization of these two enzymes in this mission showed that the microgravity environment in space may be beneficial to improve size, external perfection, morphology, internal order, and nucleation of protein crystals. Some of these positive microgravity effects were also demonstrated by the growth of protein crystals in gelled solution with the above two enzymes. A structural analysis of the tetragonal lysozyme crystal grown in space is in progress.     

Microstructure and photoluminescence studies of Sb-doped SnO2 zigzag nanobelts

SnO2 zigzag nanobelts were successfully Sb-doped by a simple vapor deposition method. Field emission scanning electron microscope (FESEM), high resolution transmission electron microscope (HRTEM), and X-ray diffraction (XRD) were used to characterize these Sb-doped nanobelts. The Sb doping in SnO2 nanobelts was confirmed by Energy Dispersive X-ray spectrum (EDS) and X-ray photoelectron spectroscopy (XPS). It is found that there is no apparent lattice distance difference between the pure SnO2 and the 0.705 at% Sb doped SnO2 nanobelts. A slight blue-shift in the photoluminescence (PL) spectra was shown with the increase of Sb doping concentration and a reasonable explanation was given.     

Miniaturization and geometry optimization of a polymer-based rectilinear ion trap

The fabrication, operation, and characterization of a polymer-based rectilinear ion trap mass analyzer is discussed. A novel, fast prototyping technique, stereolithography (SLA)-based fabrication, traditionally reserved for end use production parts and to fabricate master molds for rubber products, is applied here as a tool to create precise, arbitrary geometries. Taking full advantage of the SLA methodology, an open corner, polymer-based ion trap has been fabricated and tested. The use of a custom resin, Nanoform 15120 (DSM Somos, New Castle, DE), has resulted in a polymer with high heat deflection temperature and greater structural stability at higher temperatures and lower capacitance. The mass analyzer was mounted in a polymer holder and tested in a custom vacuum system using modified LCQ Duo (Thermo Fisher Corp.) electronics. The resolution, mass/charge range, and MS/MS capabilities were examined using electrospray ionization as well as atmospheric pressure chemical ionization. In the course of this study, three traps of different sizes were fabricated, beginning with a "full size" device measuring 10 x 8 x 50 mm. The next two traps were scaled down by linear factors of a half and a third. SLA is shown to allow fabrication of light, small rectilinear ion traps, which are less expensive and have the same performance as traditional machined devices of the same size. In addition, smaller traps can be built just as easily, and they show unit mass resolution to mass 300, tandem mass spectrometry capabilities, and low power consumption.     

Sideband analysis and seismic detection in a large ring laser

Aring laser unlocked by the Earth's Sagnac effect has attained a frequency resolution of 1 part in 3 × 10(21) and a rotational resolution of 300 prad. We discuss both theoretically and experimentally the sideband structure of the Earth rotation-induced spectral line induced in the microhertz-hertz region by frequency modulation associated with extra mechanical motion, such as seismic events. The relative sideband height is an absolute measure of the rotational amplitude of that Fourier component. An initial analysis is given of the ring laser record from the Arthur's Pass-Coleridge seismic event of 18 June 1994.     

Scattering characteristics of a chiral-coated cylindrical reflector embedded in a double-negative metamaterial

The scattering characteristics of a cylindrical reflector coated with a chiral material and embedded in a double-negative metamaterial have been studied using numerical simulation. The effects of double-negative metamaterial background media and chiral admittances of a chiral coating layer upon the co- and cross-polarized echo widths have been investigated. It is shown that a double-negative metamaterial background with relatively larger negative values of the permittivity and the permeability enhances the co-polarized echo width in the forward scattering direction and reduces this echo width in the backward scattering direction as compared to the free space background. It is further shown that by increasing the chiral admittance of a chiral-coated cylindrical reflector embedded in a double-negative metamaterial with fixed background parameters increases the co-polarized echo width in the forward and the backward scattering directions as compared to an achiral-coated cylindrical reflector embedded in the same double-negative metamaterial background.