Scanning probe-based frequency-dependent microrheology of polymer gels and biological cells

A new scanning probe-based microrheology approach is used to quantify the frequency-dependent viscoelastic behavior of both fibroblast cells and polymer gels. The scanning probe shape was modified using polystyrene beads for a defined surface area nondestructively deforming the sample. An extended Hertz model is introduced to measure the frequency-dependent storage and loss moduli even for thin cell samples. Control measurements of the polyacrylamide gels compare well with conventional rheological data. The cells show a viscoelastic signature similar to in vitro actin gels.     

Mean-field HP model, designability and alpha-helices in protein structures

Analysis of the geometric properties of a mean-field HP model on a square lattice for protein structure shows that structures with a large number of switchbacks between surface and core sites are chosen favorably by peptides as unique ground states. Global comparison of model (binary) peptide sequences with concatenated (binary) protein sequences listed in the Protein Data Bank and the Dali Domain Dictionary indicates that the highest correlation occurs between model peptides choosing the favored structures and those portions of protein sequences containing alpha helices.     

An investigation of surface state capture cross-sections for metal–oxide–semiconductor field-effect transistors using HfO2 gate dielectrics

MOSFETs and MOSCs incorporating HfO₂ gate dielectrics were fabricated. The I_DS–V_DS, I_DS–V_GS, gated-diode and C–V characteristics were investigated. The subthreshold swing and the interface trap density were obtained. The surface recombination velocity and the minority carrier lifetime in the field-induced depletion region measured from the gated diodes were about 2.73 × 10³ cm/s and 1.63 × 10⁻⁶ s, respectively. The effective capture cross section of surface state was determined to be 1.6 × 10⁻¹⁵ cm² using the gated-diode technique in comparison with the subthreshold swing measurement. A comparison with conventional MOSFETs using SiO₂ gate oxide was also made.     

Background removal of multiview images by learning shape priors.

Image-based rendering has been successfully used to display 3-D objects for many applications. A well-known example is the object movie, which is an image-based 3-D object composed of a collection of 2-D images taken from many different viewpoints of a 3-D object. In order to integrate image-based 3-D objects into a chosen scene (e.g., a panorama), one has to meet a hard challenge--to efficiently and effectively remove the background from the foreground object. This problem is referred to as multiview images (MVIs) segmentation. Another task requires MVI segmentation is image-based 3-D reconstruction using multiview images. In this paper, we propose a new method for segmenting MVI, which integrates some useful algorithms, including the well-known graph-cut image segmentation and volumetric graph-cut. The main idea is to incorporate the shape prior into the image segmentation process. The shape prior introduced into every image of the MVI is extracted from the 3-D model reconstructed by using the volumetric graph cuts algorithm. Here, the constraint obtained from the discrete medial axis is adopted to improve the reconstruction algorithm. The proposed MVI segmentation process requires only a small amount of user intervention, which is to select a subset of acceptable segmentations of the MVI after the initial segmentation process. According to our experiments, the proposed method can provide not only good MVI segmentation, but also provide acceptable 3-D reconstructed models for certain less-demanding applications.     

In-Situ monitoring of temperature and alloy composition of Hg1−xCdxTe using FTIR spectroscopic techniques

Optical real-time in-situ sensors play a very important role in the processing of semiconductor devices because of their noncontact remote nature and excellent compatibility with UHV systems. In this work, we report on progress in developing an in-situ temperature sensor for HgCdTe structures grown by molecular beam epitaxy (MBE). Based on the Fourier transform infrared (FTIR) spectrometer, this sensor is capable of continuous real-time monitoring of the surface temperature, thickness and alloy composition of HgCdTe epilayers. The accuracy and sensitivity of this FTIR technique were studied in all temperature ranges of interest. Also compared are two different methods of temperature determination obtained from the normalized spectral radiance. The influence of stray radiation and of sample holder rotation on the measurement accuracy have been studied. Reflectivity spectra for HgCdTe/CdZnTe(211) and HgCdTe/CdTe(211)/Si(211) structures have been analyzed in real time in order to determine the layer thickness and alloy composition for growing layers. Also discussed is a multilayer-structure optical model developed to solve the problem of composition determination at early stages of growth. The application of this model for fitting the transmission spectra is demonstrated.     

Gibbs energy of activation for thermal isomerization of (1Z)‐acetaldehyde hydrazone and (1Z)‐acetaldehyde N,N‐dimethylhydrazone by Gaussian‐4 theory and CCSD(T)/CBS computations

In this article, we examined the Gibbs energy of activation for the Z/E thermal isomerization reaction of (1Z)‐acetaldehyde hydrazone and (1Z)‐acetaldehyde N,N‐dimethylhydrazone, at 298.15 K in the solvent of cyclohexane. We carried out computations employing both the Gaussian‐4 (G4) theory and the coupled cluster method using both single and double substitutions and triple excitations noniteratively, CCSD(T). The CCSD(T) energy is extrapolated to the complete basis set (CBS). We compared the calculated results to the available experimental observation. It appeared that both G4 and CCSD(T)/CBS computations overestimated the experimental value by as much as about 6 and 12 kcal/mol in the present two cases. We discussed possible sources of error and proposed the experimental kinetic data could be questionable. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009     

Numerical solution of reaction–diffusion equations by compact operators and modified equation methods

A system of reaction–diffusion equations which governs the propagation of an ozone decomposition laminar flame in Lagrangian co-ordinates is analysed by means of compact operators and modified equation methods. It is shown that the use of fourth-order accurate compact operators yields very accurate solutions if sufficient numbers of grid points are located at the flame front, where very steep gradients of temperature and species concentrations exist. Modified equation methods are shown to impose a restriction on the time step under certain conditions. The solutions obtained by means of compact operators and modified equation methods are compared with solutions obtained by other methods; good agreement is obtained.     

In-situ synchrotron X-ray absorption studies of LiMn0.25Fe0.75PO4 as a cathode material for lithium ion batteries

Recently, lithium bi-metal phosphates (LiM′M″PO₄) have been synthesized for use as cathode materials in order to increase cell voltages and electrical performances. In this work, we have substituted Mn²⁺ at the 4c site of LiFePO₄ to prepare the lithium bi-metal phosphate LiMn_0.25Fe_0.75PO₄ and have found that it greatly enhances the cell voltage. At a 0.05 C discharge rate, the cell capacity was about 153 mAhg^− 1 and the average working voltage rose to 3.53 V due to the Mn substitution. However, the capacity and working voltage both decrease as the discharge rate increases. By in-situ metal K-edge absorption analysis, it reveals that the substituted metal Mn²⁺ does not work completely at a higher discharge rate, due to poor electrical conductivity and a serious Jahn–Teller effect.     

Image Processing-Based Methodology for Optimizing Automotive Ignition Timing

Modern fuel-injected automobiles use an electronic engine control unit (ECU) that is programmed to ignite the air-fuel mixture in a way that maximizes the torque (TQ) and power output of the engine without compromising its reliability. The ECU achieves this by reading a base value from the primary ignition map (PIM) and then manipulating various other parameters to come up with the final solution. Each input into the final solution comes from a so-called map, which is a 3-D image that represents a set of all the possible values that each parameter can take on. In this paper, we develop a robust methodology using image processing techniques to optimize the PIM for automobiles. The techniques are used to compare, combine, manipulate, and reconstruct various maps. Experiments show that the process yields a gain of about 7 hp and a TQ of 15 ft middotlb measured at the wheels.