Characterization of ultrashort optical pulses with third-harmonic-generation based triple autocorrelation

We present a method to obtain complete information of femtosecond pulses. By measuring triple-optical autocorrelation directly with third-harmonic generation, without spectral information, a temporal pulse shape can be obtained by analytical calculation without direction-of-time ambiguity. Combining the resulting optical pulse shape with its corresponding optical spectrum, the exact phase and color variations in time can all be recovered with a Gerchberg-Saxton algorithm through an iterative calculation with an O(n) complexity.     

Automatic generation of boundary conditions using demons nonrigid image registration for use in 3-D modality-independent elastography

Modality-independent elastography (MIE) is a method of elastography that reconstructs the elastic properties of tissue using images acquired under different loading conditions and a biomechanical model. Boundary conditions are a critical input to the algorithm and are often determined by time-consuming point correspondence methods requiring manual user input. This study presents a novel method of automatically generating boundary conditions by nonrigidly registering two image sets with a demons diffusion-based registration algorithm. The use of this method was successfully performed in silico using magnetic resonance and X-ray-computed tomography image data with known boundary conditions. These preliminary results produced boundary conditions with an accuracy of up to 80% compared to the known conditions. Demons-based boundary conditions were utilized within a 3-D MIE reconstruction to determine an elasticity contrast ratio between tumor and normal tissue. Two phantom experiments were then conducted to further test the accuracy of the demons boundary conditions and the MIE reconstruction arising from the use of these conditions. Preliminary results show a reasonable characterization of the material properties on this first attempt and a significant improvement in the automation level and viability of the method.     

Influence of bi-layer period thickness on the residual stress, mechanical and tribological properties of nanolayered TiAlN/CrN multi-layer coatings

TiAlN/CrN nanoscale multi-layered coatings have been deposited using cathodic arc evaporation system. The coatings were deposited using one Ti₅₀Al₅₀ alloy target and one Cr target with a fixed target power in all the processes, while the bi-layer thickness was varied by various rotation speeds of the substrate holder in order to produce different nanoscale multi-layered period thickness. The texture structure, residual stress, and nanoscale multi-layer period thickness of the coatings were determined by X-ray diffraction using both Bragg-Brentano and glancing angle parallel beam geometries. Hardness and adhesion strength of the coatings were measured by Nano-indentation and Rockwell-C indentation methods, respectively. It has been found that the structural and mechanical properties of the films correlate with nano-scaled bi-layer thickness and crystalline texture. The maximum hardness of nano-scaled TiAlN/CrN multi-layered coatings was approximately 36 GPa with highest residual stress of −6.2 GPa, for a bi-layer thickness ranging from 6 to 12 nm.     

Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu₆Sn₅ phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn₂, and AuSn₄, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)₆Sn₅ phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn₄ phase disappeared gradually. The (Au, Cu)Sn and (Cu_,Au)₆Sn₅ layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.     

The display of photographic-quality images on the Web: a comparisonof two technologies

Downloading medical images on the Web creates certain compromises. The tradeoff is between higher resolution and faster download times. As resolution increases, download times increase. High-resolution (photographic quality) electronic images can potentially play a key role in medical education and patient care. On the Internet, images are typically formatted as Graphics Interchange Format (GIF) or the Joint Photographic Experts Group (JPEG) files. However, these formats are associated with considerable data loss in both color depth and image resolution. Furthermore, these images are available in a single resolution and have no capability of allowing the user to adjust resolution as needed. Images in the photo compact disc (PCD) format have higher resolutions than GIF or JPEG, but suffer the disadvantage of large file sizes leading to long download times on the Web. Furthermore, native Web browsers are not currently able to read PCD files. The FlashPix format (FPX) offers distinct advantages over the PCD, GIF, and JPEG formats for display of high-resolution images on the Web. A Java applet can be easily downloaded for viewing FPX images. FPX images are higher resolution than JPEG and GIF images. FPX images offer rich resolutions comparable to PCD images with shorter download times     

Effect of Hydrostatic Pressure on Molecular Conformation of Tilapia (Orechromis niloticus) Myosin

ABSTRACT: Change in tilapia myosin molecular conformation due to pressurization at 50 to 200 MPa for 0 to 60 min was investigated. After a 50-MPa treatment, tilapia myosins slightly decreased their total sulfhydryl contents and exposed their hydrophobic residues. Experimental results indicated that 100- and 150-MPa treatments caused an apparent unfolding of myosins and a 1-fold increase of their surface hydrophobicity ( S _o). Myosins mainly formed intermolecular disulfide bonds with pressures of 100 to 200 MPa. In addition, increasing pressures altered the myosin conformation and decreased its Ca-ATPase activity. Myosin apparently unfolded and formed disulfide bonds and hydrophobic interactions with pressurizing at 150 MPa.     

Antiproliferative activity of peptides prepared from enzymatic hydrolysates of tuna dark muscle on human breast cancer cell line MCF-7

To produce and identify antiproliferative peptides, two commercial enzymes, papain (PA) and Protease XXIII (PR) were used to hydrolyse tuna dark muscle byproduct, and the protein hydrolysates were purified, before being evaluated for antiproliferative activities against human breast cancer cell line MCF-7. The results showed that the peptide fractions with the molecular weight ranging from 390 to 1400 Da possessed the greatest antiproliferative activity. The amino acid sequences of the two antiproliferative peptides isolated from PA and PR hydrolysates were Leu-Pro-His-Val-Leu-Thr-Pro-Glu-Ala-Gly-Ala-Thr (1206 Da) and Pro-Thr-Ala-Glu-Gly-Gly-Val-Tyr-Met-Val-Thr (1124 Da), whilst they show the dose-dependent inhibition effect of the MCF-7 cells with IC₅₀ values of 8.1 and 8.8 μM, respectively. We thus conclude that antiproliferative hydrolysates from tuna dark muscle byproduct may be useful ingredients in food and nutraceutical applications.     

Diagnosis of PTFE‐Nafion MEA degradation modes by an accelerated degradation technique

Cost and durability are central issues in the commercialization of proton‐exchange membrane fuel cells. This study used complex accelerated‐degradation protocols to diagnose the degradation modes of low‐cost polytetrafluoroethylene–Nafion membrane electrode assemblies (MEAs). Acceleration protocols included open‐circuit voltage, relative humidity cycling, and load cycling. Failure modes included measurements of cyclic voltammetry, linear sweep voltammetry, polarization curve, and AC impedance. The four modes (stages) of degradation were determined to be (i) catalyst aging, (ii) creep deformation, (iii) pinhole formation, and (iv) membrane failure. During catalyst aging, the maximum power density decreased by 0.117 mW cm^?2 cycle^?1. After the 280th cycle, creep deformation occurred, and the maximum power density decreased by 0.227 mW cm^?2 cycle^?1. Pinholes led to membrane failure and a final dramatic loss of performance (?0.453 mW cm^?2 cycle^?1). Therefore, membrane failure is the major factor in the failure of MEAs. Copyright © 2010 John Wiley & Sons, Ltd.     

Interfacial Reactions of Sn, Sn-3.0Ag-0.5Cu, and Sn-9Zn Lead-Free Solders with Fe-42Ni Substrates

Interfacial reactions between Sn, Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC), and Sn-9 wt.%Zn (SZ) lead-free solders and Fe-42 wt.%Ni (alloy 42) substrates at 240°C, 255°C, and 270°C were investigated in this study. FeSn₂, (Fe,Ni, Cu)Sn₂, and (Ni,Fe)₅Zn₂₁ phases were formed, respectively, at the interface in the Sn/alloy 42, SAC/alloy 42, and SZ/alloy 42 couples. As the reaction time and temperature were increased, the layered intermetallic compound (IMC) assumed two distinct structures, i.e., a thicker layer and a pillar-shaped IMC, in all couples. The IMC thickness of these couples increased with the increase of reaction time and temperature. The IMC thickness was also proportional to the square root of the reaction time. The interfacial reaction mechanism of these couples was diffusion controlled.