Molecular dynamic study for nanopatterning using atomic force microscopy

The atomic force microscopy (AFM)-based nanolithographic technique is currently used to directly machine material surfaces and fabricate nanocomponents for microelectromechanical systems (MEMS) devices. In the current study, three-dimensional molecular dynamic (MD) simulations with potentials based on the Morse function were performed to evaluate the effect of crystallographic factors and process variables on the nanodeformation characteristics of the nanolithography processing of monocrystalline copper. Moreover, the effects of process variables (tool shape, cutting speed, and ploughing depth) on the nanostructural pattern are investigated. The simulation results revealed that the crystal orientation and ploughing direction had a significant influence on varying the forces (cutting force, thrust force, and width-direction force); the nature of the nanodeformation ahead of the tool; and the surface quality of the machined material.     

Interlingua-based English–Korean Two-way Speech Translation of Doctor–Patient Dialogues with CCLINC

Development of a robust two-way real-time speech translationsystem exposes researchers and system developers to various challenges of machine translation(MT) and spoken language dialogues. The need for communicating in at least two differentlanguages poses problems not present for a monolingual spoken language dialogue system,where no MT engine is embedded within the process flow. Integration of various componentmodules for real-time operation poses challenges not present for text translation. In this paper,we present the CCLINC (Common Coalition Language System at Lincoln Laboratory) English–Koreantwo-way speech translation system prototype trained on doctor–patient dialogues,which integrates various techniques to tackle the challenges of automatic real-time speechtranslation. Key features of the system include (i) language–independent meaning representation which preserves the hierarchicalpredicate–argument structure of an input utterance, providing a powerful mechanism for discourse understanding of utterances originating from different languages,word-sense disambiguation and generation of various word orders of many languages, (ii) adoptionof the DARPA Communicator architecture, a plug-and-play distributed system architecturewhich facilitates integration of component modules and system operation in real time, and (iii)automatic acquisition of grammar rules and lexicons for easy porting of the system to differentlanguages and domains. We describe these features in detail and present experimental results.     

Ductile Fracture Prediction in Rotational Incremental Forming for Magnesium Alloy Sheets Using Combined Kinematic/Isotropic Hardening Model

To predict the ductile fracture of a magnesium alloy sheet when using rotational incremental forming, a combined kinematic and isotropic hardening law is implemented and evaluated from the histories of the ductile fracture value (I) using a finite element analysis. Here, the criterion for a ductile fracture, as developed by Oyane (J. Mech. Work. Technol., 1980, vol. 4, pp. 65–81), is applied via a user material based on a finite element analysis. To simulate the effect of the large amount of heat generation at elements in the contact area due to the friction energy of the rotational tool-specimen interface on the equivalent stress-strain evolution in incremental forming, the Johnson–Cook (JC) model was applied and the results compared with equivalent stress-strain curves obtained from tensile tests at elevated temperatures. The finite element (FE) simulation results for a ductile fracture were compared with the experimental results for a (80 mm × 80 mm × 25 mm) square shape with a 45 and 60 deg wall angle, respectively, and a (80 mm × 80 mm × 20 mm) square shape with a 70 deg wall angle. The trends of the FE simulation results agreed quite well with the experimental results. Finally, the effects of the process parameters, i.e., the tool down-step and tool radius, on the ductile fracture value and FLC at fracture (FLCF) were also investigated using the FE simulation results.     

Effect of material damage on forming limits of voided anisotropic sheet metals

Most failures of ductile materials in metal-forming processes occur due to material damage evolution (void nucleation, growth, and coalescence). The current article examines the modified yield function of Liao et al., in conjunction with Hosford’s yield criterion, to clarify the plastic-deformation characteristic of voided anisotropic sheet metals. As such, the void growth of an anisotropic sheet under biaxial tensile loading and the damage effect of void growth on the forming limits of sheet metals are investigated. Plus, the process length defining the neck geometry is included in the Marciniak and Kuczynski (M-K) model to incorporate the effect of triaxial stress in a necked region on the forming limits. The predicted forming limits were compared with experimental data, and a satisfactory agreement was obtained.     

Cobalt and cerium coated Ni powder as a new candidate cathode material for MCFC

The dissolution of nickel oxide cathode in the electrolyte is one of the major technical obstacles to the commercialization of molten carbonate fuel cell (MCFC). To improve the MCFC cathode stability, the alternative cathode material for MCFC was prepared, which was made of Co/Ce-coated on the surface of Ni powder using a polymeric precursor based on the Pechini method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX) were employed in characterization of the alternative cathode materials. The Co/Ce-coated Ni cathode prepared by the tape-casting technique. The solubility of the Co/Ce-coated Ni cathode was about 80% lower when compare to that of pure Ni cathode under CO₂:O₂ (66.7:33.3%) atmosphere at 650 °C. Consequently, the fine Co/Ce-coated Ni powder could be confirmed as a new alternative cathode material for MCFC.     

Hedgehog Signaling Regulates the Survival of Gastric Cancer Cells by Regulating the Expression of Bcl-2

Gastric cancer is the second most common cause of cancer deaths worldwide. The underlying molecular mechanisms of its carcinogenesis are relatively poorly characterized. Hedgehog (Hh) signaling, which is critical for development of various organs including the gastrointestinal tract, has been associated with gastric cancer. The present study was undertaken to reveal the underlying mechanism by which Hh signaling controls gastric cancer cell proliferation. Treatment of gastric cancer cells with cyclopamine, a specific inhibitor of Hh signaling pathway, reduced proliferation and induced apoptosis of gastric cancer cells. Cyclopamine treatment induced cytochrome c release from mitochondria and cleavage of caspase 9. Moreover, Bcl-2 expression was significantly reduced by cyclopamine treatment. These results suggest that Hh signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2.     

Formability and forming force in incremental sheet forming of AA7075-T6 at different temperatures

Journal of Mechanical Science and Technology - The AA7075-T6 sheet recently received attention, owing to its low weight and strength for use fabricating automotive parts (e.g., body, motor case)....     

Stiffness matrix of thin-walled curved beam for spatially coupled stability analysis

The exact stiffness matrix for the spatially coupled stability analysis of thin-walled curved beam with non-symmetric cross-section subjected to uniform compression is newly presented. For this, the elastic strain energy including the axially/flexurally/torsionally coupled terms and the potential energy due to the initial stress resultant are introduced. Then, equilibrium equations and force–deformation relationship are derived from the energy principle and explicit expressions for displacement parameters are derived based on power series expansions of displacement components. Next, the exact element stiffness matrix is determined using force–deformation relationships. In order to verify the accuracy of this study, the numerical solutions are presented and compared with the finite element solutions using the Hermitian curved beam elements. In addition, the coupling of symmetric and anti-symmetric modes at the buckling load crossover with change in curvature of beam is investigated.     

Effects of enzymatic modification of wheat protein on the formation of pyrazines and other volatile components in the Maillard reaction

Enzymatically hydrolysed wheat gluten hydrolysate (WGH) was deamidated using glutaminase to produce deamidated wheat gluten hydrolysate (DWGH). Volatile components were analysed in WGH and DWGH thermally reacted with glucose or fructose. In the reaction system containing glucose, 19 pyrazines, 2 furans, and 5 sulphur-containing components were detected in WGH, while 34 pyrazines, 4 furans, and 7 sulphur-containing components were found in DWGH. In the system containing fructose, 24 pyrazines, 3 furans, and 6 sulphur-containing components were identified in the thermal reaction of WGH, whereas 36 pyrazines, 4 furans, and 8 sulphur-containing components were found in DWGH. The volatile components increased in DWGH, both qualitatively and quantitatively, mainly due to free ammonia released by deamidation. More volatiles were also developed in WGH and DWGH with fructose than with glucose. It was found that ammonia released from wheat protein via deamidation participated in the generation of diverse volatile components including pyrazines in the Maillard reaction.     

Free radical-scavenging and inhibition of nitric oxide production by four grades of pine mushroom (Tricholoma matsutake Sing.)

Fractions from methanol extracts of four grades of pine mushroom (Tricholoma matsutake Sing.) were evaluated for their free radical-scavenging and inhibition of nitric oxide production, and the underlying mechanisms were elucidated. The fractions from first-grade pine mushroom exhibited the highest degree of free radical-scavenging and inhibition of nitric oxide production among the various grades of mushroom tested, and free radical-scavenging and inhibition of nitric oxide production by the second-, third-, and fourth-grade mushroom fractions were successively lower. The degree of free radical-scavenging by each fraction decreased in the order ethyl acetate > butanol > diethyl ether > water. Inhibition of nitric oxide production by each fraction decreased in the order ethyl acetate > butanol > water. The ethyl acetate and butanol fractions of methanol-extracted pine mushroom samples exhibited potential anti-oxidative and anti-inflammatory effects that might be attributable to phenolics or flavonoids.