CAPILLARY EXTRUSION VISCOMETER FOR THE VISCOSITY MEASUREMENT OF FISH PROTEIN PASTE

To overcome various limitations of conventional viscometers in measuring salted or unsalted surimi paste, a capillary extrusion viscometer was developed. The viscosity of surimi paste was measured as a function of moisture content (MC) (75–80%), salt content (2–4%) and liquid egg white (LEW) content (2–4%). As moisture, salt and LEW contents increased, viscosity gradually decreased. The viscosity values, as affected by MCs, showed a highly negative relationship with fracture properties of surimi gel, especially shear stress from the torsion test, indicating that MC is linearly correlated to the strength of gels at fracture. This easy and quick viscosity measurement can effectively facilitate the production control of comminuted muscle foods, including surimi paste.

PRACTICAL APPLICATIONS

There had been a difficulty to measure the exact viscosity of comminuted muscle food pastes when conventional viscometers were used. This was due to the non-linearity between dilution rates and viscosity of muscle paste, or limited range of shear rate during viscosity measurement. New developed small capillary extrusion viscometer can measure a wide range of comminuted muscle paste viscosity. When using this capillary viscometer, flow behavior of non-Newtonian surimi paste and other comminuted muscle paste can be well defined.     

Simple reactor for the synthesis of silver nanoparticles with the assistance of ethanol by gas–liquid discharge plasma

Atmospheric pressure plasma technology is gaining increasing importance because it is a simple and tunable synthesis process for the production of metallic nanoparticles. In addition to the development of the power supply, improving the reactor is also one of the main strategies to enhance the utility. In this study, a simple reactor for the gas–liquid discharge plasma induced by argon gas was applied to synthesize silver nanoparticles from silver nitrate (AgNO₃) in solution. An AC power supply with a peak voltage of 3.5 kV was used. The frequency and on-time were set to 50 kHz and 2.5 μs, respectively. The oscilloscope showed that the rising time was approximately 2 μs. The ethanol was used as the source for the reactive reducing agent. No more additional components existed in the solution during the discharge and neither of the electrodes was in contact with the treated solution. The temperature increased by 10 °C within 1min without a cooling system. Carbon was the main impurity and was expected to be produced from the decomposition of the organics under the plasma. The elevated temperature decreased the organic by-products by evaporation and could also decrease the production of carbon. Transmission electron microscopy showed that the spherical silver nanoparticles with a size of approximately 10 nm were synthesized with a crystal structure and that a low concentration of ethanol prefers the production of the mono-dispersed colloid.     

Uranium measurements using laser-induced breakdown spectroscopy in lithium chloride-potassium chloride salt of pyroprocessing

In pyroprocessing,uranium(U) is recovered from molten LiCl-KCl salt,and,for safeguard purposes,it is important to analyze the U and Plutonium(Pu) concentrations in a timely manner.In the present work,salt samples containing U were fabricated.The laser used in the present work was an Nd:YAG laser with a wavelength of 532 nm,a laser energy on the sample of11.5 mJ,and a pulse repetition rate of 10 Hz.The plasma emission light was measured with an Echelle spectrometer.A total of 100 points on the sample surface were measured as the laser incident position was changed.The U and potassium(K) peaks in the spectrum were identified.Univariate and multivariate analyzes were conducted to determine the accuracy and limit of detection(LOD) of the laser-induced breakdown spectroscopy.     

Processing, microstructure and mechanical properties of hot-pressed SiC continuous fibre/SiC composites

SiC (SCS-6TM) continuous fibre/SiC composites were fabricated by hot-pressing at 1700°C in vacuum using an Al sintering additive. Analytical transmission electron microscopy was used to investigate the microstructure of the composites. The room-temperature mechanical and high-temperature creep properties of the composites were investigated by four-point bending. The SiC powders used were sintered at a relatively low sintering temperature to high density (97% of theoretical density) with the addition of the Al sintering additive. It is believed that the Al additive is very efficient for the densification of SiC. The SiC fibres maintained their original form and microstructure during fabrication. The SiC matrix reacted with the outermost carbon sublayer in the fibre, forming a thin (1.8–4.8m) interfacial layer, which was composed of Al4C3, Si–Al–C, and Si–Al–O phases. The incorporation of SiC fibre into a dense SiC matrix significantly increased the room-temperature failure strain and improved the high-temperature creep properties. In addition, the incorporation of SiC fibre into a porous SiC matrix increased the room-temperature failure strain, but did not contribute to the high-temperature creep properties.     

Linearization of T-S fuzzy systems and robust H_∞ control

Takagi-Sugeno (T-S) fuzzy model is difficult to be linearized because of membership functions included. So, novel T-S fuzzy state transformation and T-S fuzzy feedback are proposed for the linearization of T-S fuzzy system. The novel T-S fuzzy state transformation is the fuzzy combination of local linear transformation which transforms local linear models in the T-S fuzzy model into the local linear controllable canonical models. The fuzzy combination of local linear controllable canonical model gives controllable canonical T-S fuzzy model and then nonlinear feedback is obtained easily. After the linearization of T-S fuzzy model, a robust H _∞ controller with the robustness of sliding model control (SMC) is designed. As a result, controlled T-S fuzzy system shows the performance of H _∞ control and the robustness of SMC.     

Development of XY scanner with minimized coupling motions for high-speed atomic force microscope

The design and fabrication processes of a novel scanner withminimized coupling motions for a high-speed atomic force microscope (AFM) were addressed.An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program,Recurdyn.Because the scanning speed of each direction may differ,the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes,with one dominan...     

Electrical Properties of Sputter-deposited ZrO2-based Pt/ZrO2/Si Capacitors

Pt/ZrO2/Si sandwich structures where ZrO2 is deposited by radio frequency （r.f.） magnetron sputtering using a Zr target in an atmosphere of O2/Ar gas mixture, were fabricated and the effects of the O2/Ar flow ratio in the reactive sputtering process, the annealing temperature, the ZrO2 film thickness on the structure, the surface roughness of ZrO2 films and the electric properties of Pt/ZrO2/Si metal-oxide-semiconductor （MOS） capacitors were investigated. The optimum process parameters of the Pt/ZrO2/Si capacitor based on reactively sputtered-ZrO2 determined in such a way as the capacitance is maximized and the leakage current, the oxide charge, and the interface trap density are minimized that is the O2/Ar flow ratio of 1.5, the annealing temperature of 800℃, and the film thickness of 10 nm. Also the conduction mechanism in the Pt/ZrO2/Si capacitor has been discussed.     

GEOMETRICALLY NON-LINEAR AND ELASTOPLASTIC THREE-DIMENSIONAL SHEAR FLEXIBLE BEAM ELEMENT OF VON-MISES-TYPE HARDENING MATERIAL

A three-dimensional elastoplastic beam element being capable of incorporating large displacement and large rotation is developed and examined. Elastoplastic constitutive equations are applied to the beam element based upon the assumption of small deformational strain leading to a material formulation which is completely objective for the application of stress update procedures. The continuum-type equations of plastic model of J₂ mixed hardening are transformed into the beam equations by satisfying beam hypotheses. An effective stress update algorithm is proposed to integrate elastoplastic rate equations by means of the so-called multistep method which is a method of successive control of residuals on yield surfaces. It avoids severe divergence when the displacement increments become large which is usual for the continuation methods. Material tangent stiffness matrix is derived by using consistent elastoplastic modulus resulting from the integration algorithm and is combined with geometric tangent stiffness matrix. Different from other elements, the present element is shear flexible and can satisfy the plasticity condition in a pointwise fashion. A great number of numerical examples are analysed and compared with the literature. The proposed beam element is verified to be not only quite accurate but also very effective for the analyses of pre-buckling and large deflection collapse of spatial framed structures.     

ANGIOTENSIN I-CONVERTING ENZYME (ACE) INHIBITORY PEPTIDES FROM WHEY FERMENTED BY LACTOBACILLUS SPECIES

From 2% (w/w) whey powder in growth media, inhibitory peptides against angiotensin I-converting enzyme (ACE) were studied with nine Lactobacillus species. Lb. brevis, Lb. helveticus and Lb. paracasei were proved to be the most effective strains in liberating ACE inhibitory peptides from whey protein. The inhibition rates of these peptides against ACE ranging from 93.3 to 100%. Several distinct peaks were eluted when the whey proteins were fractionated on a Delta Pak C₁₈ column by reversed phase-high performance liquid chromatography (RP-HPLC). Among ACE inhibitory activities of 14 peptides purified by dialysis and by fractionation using RP-HPLC, two peptide fractions (H5 and H7) of Lb. helveticus showing IC₅₀ values of 5.3 and 7.8 were the most potent ACE inhibitors.
All of these peptides including some other peptides (H1 and B1), having strong inhibitory activities against ACE were pentapeptides positioning with Ala at their N-terminal and these petapeptides had mostly hydrophobic (Pro, Val and Leu) or aromatic (Phe) amino acids at the C-terminal.

PRACTICAL APPLICATIONS

There is a significant amount of research and interest in developing and charactering the peptides that inhibit angiotensin I-converting enzyme (ACE) activity as these natural products may have a role in blood pressure control in man. This study revealed that the identification of peptides, mostly composed of pentapeptides following fermentation of whey protein in growth medium with different strains have the ACE inhibitory activities. These peptides may have antihypertensive effect as natural and safe nutraceutical/functional ingredients, though the exact potency of the pentapeptides isolated in this experiment has not been determined.     

Weldability evaluation and tensile strength estimation model for aluminum alloy lap joint welding using hybrid system with laser and scanner head

Aluminum welding using a hybrid system with a laser and scanner welding head was performed under various welding conditions to verify the feasibility of applying an aluminum alloy to a car body.The experimental material was 5J32 aluminum alloy,and the laser power,welding speed,and laser incidence angle were used as the control variables.The weld bead shape and the tensile shear strength were evaluated in order to understand the aluminum lap joint weld characteristics.Analysis of variance (ANOVA) was conducted to identify the effect of the process variables on the tensile shear strength.Tensile strength estimation models using three different regression models were also suggested.The input variables were the laser power,welding speed,and laser incidence angle,and the output was the tensile shear strength.Among the models,the second-order polynomial estimation model had the best estimation performance,and the average error rate of this model was 0.058.