Conceptual damage-sensitive features for structural health monitoring: Laboratory and field demonstrations

The use of damage-sensitive features to evaluate structural condition or health is a very critical aspect of structural health monitoring. The purpose of this paper is to investigate the potential of two different damage-sensitive features for detecting damage. Different damage scenarios are simulated on a large-scale laboratory structure and a three-span highway bridge for demonstration. The features presented in this paper are the modal flexibility-based deflection and curvature both of which are obtained directly from dynamic properties. In the literature, flexibility associated with mode shapes and mode shapes curvatures have been mostly explored. In this study, multi-input–multi-output dynamic data are used to obtain modal flexibility, which is a close approximation to the actual flexibility. A main novelty is that the curvature is calculated from the deflected shapes using the modal flexibility as opposed to using modal vectors. In this paper, the theory of the methodology is explained and then experimental studies and results are presented. For the experimental studies, the laboratory specimen and the three-span bridge were gradually damaged. It is shown that both deflection and curvature are conceptual and physically meaningful features for damage detection and localization. The issues and the requirements for these features to perform successfully are also presented.     

Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO2 for no reduction by NH3

Deactivation of copper-ion-exchanged hydrogen-mordenite-type zeolite catalyst by SO₂ for NO reduction by NH₃ was examined in a fixed-bed flow reactor. The deactivation of the catalyst was strongly dependent on reaction temperature. At high reaction temperatures over 300°C, the catalyst did not lose its initial activity up to 50 h of operation, regardless of SO₂ feed concentration from 500 to 20,000 ppm. However, at low reaction temperatures near 250°C, apparent deactivation did occur. Changes in the physicochemical properties such as surface area and sulfur content of deactivated catalyst well correlated with catalyst activity, depending upon reaction temperatures. The deactivation was due to pore blocking and/or filling by deactivating agents, which plugged and/or filled the pores of catalyst. The deactivating agents deposited on the catalyst surface were presumed to be (NH₄)₂SO₄ and/or (NH₄)HSO₄ from the results of TGA and ion-chromatography measurement.     

Ultrahigh molecular weight polyethylene with improved crosslink density,oxidation stability,and microbial inhibition by chemical crosslinking and tea polyphenols for total joint replacements

Highly crosslinked ultrahigh molecular weight polyethylene (UHMWPE) stabilized by vitamin E (VE) is widely applied in artificial joints as the bearings. Despite the approval, there is a discord that VE lowers the crosslinking efficiency, limiting its use at high concentration. In this work, we aim to obtain highly crosslinked and oxidation resistant UHMWPE through the conjunction of tea polyphenol and chemical crosslinking. We hypothesized that highly incorporated tea polyphenol with multiple reactive sites can ameliorate crosslinking efficiency of chemical crosslinked UHMWPE in comparison to VE. Epigallocatechin gallate (EGCG) as representative tea polyphenol was incorporated into UHMWPE at high concentration (2–8 wt%), followed by chemical crosslinking with 2 wt% organic peroxide. Unlike VE/UHMWPE blends as the control, chemical crosslinking achieved an increasing trend in crosslink density of EGCG/UHMWPE blends with increasing antioxidant concentration. High concentration of EGCG also enhanced the oxidation stability of UHMWPE. Intriguingly, EGCG endowed UHMWPE with an excellent antimicrobial property, which was inefficient in VE/UHMWPE. Cell viability was hardly affected by the high loaded antioxidant and peroxide. The chemically crosslinked UHMWPE blended with EGCG is proved to be a reasonable, cost effective and realistic alternative for use in artificial joints.     

Three-dimensional macroscale assembly of Pd nanoclusters

Construction of macro-materials with highly oriented microstructures and well-connected interfaces between building blocks is significant for a variety of applications. However, it is still challenging to confine the desired structures. Thus, well-defined building blocks would be crucial to address this issue. Herein, we present a facile process based on 1.8 nm Pd nanoclusters (NCs) to achieve centimeter-size assemblages with aligned honeycomb structures, where the diameter of a single tubular moiety is ～4 μm. Layered and disordered porous assemblages were also obtained by modulating the temperature in this system. The reconciled interactions between the NCs were crucial to the assemblages. As a comparison, 14 nm Pd nanoparticles formed only aggregates. This work highlights the approach of confining the size of the building blocks in order to better control the assembly process and improve the stability of the structures.

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Therapeutic Effects of Saponins for the Prevention and Treatment of Cancer by Ameliorating Inflammation and Angiogenesis and Inducing Antioxidant and Apoptotic Effects in Human Cells

Saponins are natural compounds found in plants and have a diverse range of applications. However, the therapeutic potential of saponins in regulating cytotoxicity, angiogenesis, and inflammation in mammalian cells is yet to be explored. Here, we investigated the therapeutic effects of saponins from green tea by exploring the cytotoxic effects of saponins by inducing apoptosis in the human cancer cell lines hepatocellular carcinoma (HEPG2) and colorectal adenocarcinoma (HT29). The anti-angiogenesis effect of saponins was also investigated in human umbilical vein endothelial cells (HUVEC). We explored the ability of saponins to attenuate inflammation in a dose-dependent manner in normal human cells. It was found that saponins exhibit cytotoxic effects in cancer cells and not in normal cells at the same concentration. Cytotoxicity was measured by inducing apoptosis by enhancing caspase-3 (cas-3) activation and B-cell lymphoma-2 (Bcl-2)-associated X protein (BAX) gene expression and suppressing the antiapoptotic protein, Bcl-2. The inhibition of HUVEC proliferation was due to the suppression of the phosphoinositide 3-kinase (PI3K), protein kinase B (AKT), vascular endothelial growth factor receptor-2 (VEGFR-2), and nuclear factor kappa B (NF-κB). We also observed the antioxidant potential of green tea-derived saponins against free radicals in reactive oxygen species (ROS)-induced cells. Here we observed that the saponins exhibited free radical scavenging activities and activated nuclear factorerythroid 2-related factor 2 (NRF-2) leading to the upregulation of antioxidant-related genes in human embryonic kidney 293 (HEK293) cells. Furthermore, we demonstrated that the anti-inflammatory effects were due to the suppression of pro-inflammatory cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and inducible nitric oxide synthase (iNOS) in HEK293 cells. The significance of the work is we are the first to report on the anti-cancer effects of saponins based on the anti-inflammatory, antioxidant, anti-angiogenesis, and apoptosis induction properties. In conclusion, green tea-derived saponins could be effective therapeutics for the treatment of cancer.     

Energy-saving manufacturing technology for high-strength metal products

The use of heat-strengthened blanks to manufacture cold-deformed rebar and high-performance bolts permits the elimination of some operations in the production process, with corresponding energy savings. The complete research cycle includes the development of the technology, formulation of the documentation, and industrial trials.     

Geometric and structural strengthening of metal components

The geometric and structural strengthening of metal components is compared. Combining geometric and structural strengthening has a synergetic effect. A mathematical model of such combined strengthening is presented. Practical applications of combined geometric and structural strengthening are considered, in producing stronger metal components and in improving the performance of intermediate products in thermal and mechanical treatment.     

Second generation bioethanol (SGB) production potential in Turkey

Energy demand is increasing by the years. Population's needs and technological investments bring the new approach about generating energy. It is considered that fossil fuels will not be able to respond to all energy requirements after approximately 150 years. Turkey imports nearly all of its petroleum and so this causes major economic problems. Turkey, as a major cereal producer, has a huge potential to grow energy crops and other cellulosic biomaterials and can obtain plant's residues, which are suitable to produce second generation bioethanol (SGB). With domestic production, bioethanol can reduce the dependence of petroleum for Turkey, and greenhouse gas emissions can be decreased. Taking into account Turkey's situation in fuel–oil consumption, costliness of gasoline and environmentally hazardous specification of fossil fuels, bioethanol gains more importance and increases in value. Especially, SGB production is rising. Foodstuffs are valuable, and producing ethanol from directly those materials can cause a crisis in Turkey because lignocellulosic bioethanol is becoming prominent. In this regard, bioethanol production in Turkey becomes a major alternative to petroleum and may be a key to new and clean energy source. Copyright © 2013 John Wiley & Sons, Ltd.     

Banana peel: an effective biosorbent for aflatoxins

This work reports the application of banana peel as a novel bioadsorbent for in vitro removal of five mycotoxins (aflatoxins (AFB1, AFB2, AFG1, AFG2) and ochratoxin A). The effect of operational parameters including initial pH, adsorbent dose, contact time and temperature were studied in batch adsorption experiments. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pH_pzc) analysis were used to characterise the adsorbent material. Aflatoxins’ adsorption equilibrium was achieved in 15 min, with highest adsorption at alkaline pH (6–8), while ochratoxin has not shown any significant adsorption due to surface charge repulsion. The experimental equilibrium data were tested by Langmuir, Freundlich and Hill isotherms. The Langmuir isotherm was found to be the best fitted model for aflatoxins, and the maximum monolayer coverage (Q₀) was determined to be 8.4, 9.5, 0.4 and 1.1 ng mg^?1 for AFB1, AFB2, AFG1 and AFG2 respectively. Thermodynamic parameters including changes in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were determined for the four aflatoxins. Free energy change and enthalpy change demonstrated that the adsorption process was exothermic and spontaneous. Adsorption and desorption study at different pH further demonstrated that the sorption of toxins was strong enough to sustain pH changes that would be experienced in the gastrointestinal tract. This study suggests that biosorption of aflatoxins by dried banana peel may be an effective low-cost decontamination method for incorporation in animal feed diets.